US20040225414A1 - System and method for controlling temperature of a liquid residing within a tank - Google Patents
System and method for controlling temperature of a liquid residing within a tank Download PDFInfo
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- US20040225414A1 US20040225414A1 US10/852,032 US85203204A US2004225414A1 US 20040225414 A1 US20040225414 A1 US 20040225414A1 US 85203204 A US85203204 A US 85203204A US 2004225414 A1 US2004225414 A1 US 2004225414A1
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Images
Classifications
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D23/00—Control of temperature
- G05D23/19—Control of temperature characterised by the use of electric means
- G05D23/1951—Control of temperature characterised by the use of electric means with control of the working time of a temperature controlling device
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H15/00—Control of fluid heaters
- F24H15/10—Control of fluid heaters characterised by the purpose of the control
- F24H15/14—Cleaning; Sterilising; Preventing contamination by bacteria or microorganisms, e.g. by replacing fluid in tanks or conduits
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H15/00—Control of fluid heaters
- F24H15/10—Control of fluid heaters characterised by the purpose of the control
- F24H15/172—Scheduling based on user demand, e.g. determining starting point of heating
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H15/00—Control of fluid heaters
- F24H15/10—Control of fluid heaters characterised by the purpose of the control
- F24H15/174—Supplying heated water with desired temperature or desired range of temperature
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H15/00—Control of fluid heaters
- F24H15/20—Control of fluid heaters characterised by control inputs
- F24H15/212—Temperature of the water
- F24H15/223—Temperature of the water in the water storage tank
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H15/00—Control of fluid heaters
- F24H15/20—Control of fluid heaters characterised by control inputs
- F24H15/269—Time, e.g. hour or date
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H15/00—Control of fluid heaters
- F24H15/20—Control of fluid heaters characterised by control inputs
- F24H15/281—Input from user
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H15/00—Control of fluid heaters
- F24H15/30—Control of fluid heaters characterised by control outputs; characterised by the components to be controlled
- F24H15/355—Control of heat-generating means in heaters
- F24H15/37—Control of heat-generating means in heaters of electric heaters
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H15/00—Control of fluid heaters
- F24H15/30—Control of fluid heaters characterised by control outputs; characterised by the components to be controlled
- F24H15/395—Information to users, e.g. alarms
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H15/00—Control of fluid heaters
- F24H15/40—Control of fluid heaters characterised by the type of controllers
- F24H15/414—Control of fluid heaters characterised by the type of controllers using electronic processing, e.g. computer-based
- F24H15/421—Control of fluid heaters characterised by the type of controllers using electronic processing, e.g. computer-based using pre-stored data
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H15/00—Control of fluid heaters
- F24H15/40—Control of fluid heaters characterised by the type of controllers
- F24H15/414—Control of fluid heaters characterised by the type of controllers using electronic processing, e.g. computer-based
- F24H15/45—Control of fluid heaters characterised by the type of controllers using electronic processing, e.g. computer-based remotely accessible
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H15/00—Control of fluid heaters
- F24H15/40—Control of fluid heaters characterised by the type of controllers
- F24H15/486—Control of fluid heaters characterised by the type of controllers using timers
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H9/00—Details
- F24H9/20—Arrangement or mounting of control or safety devices
- F24H9/2007—Arrangement or mounting of control or safety devices for water heaters
- F24H9/2014—Arrangement or mounting of control or safety devices for water heaters using electrical energy supply
- F24H9/2021—Storage heaters
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24H—FLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
- F24H9/00—Details
- F24H9/20—Arrangement or mounting of control or safety devices
- F24H9/25—Arrangement or mounting of control or safety devices of remote control devices or control-panels
- F24H9/28—Arrangement or mounting of control or safety devices of remote control devices or control-panels characterised by the graphical user interface [GUI]
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01K—MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR
- G01K7/00—Measuring temperature based on the use of electric or magnetic elements directly sensitive to heat ; Power supply therefor, e.g. using thermoelectric elements
- G01K7/42—Circuits effecting compensation of thermal inertia; Circuits for predicting the stationary value of a temperature
-
- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05D—SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES
- G05D23/00—Control of temperature
- G05D23/19—Control of temperature characterised by the use of electric means
- G05D23/1917—Control of temperature characterised by the use of electric means using digital means
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F24—HEATING; RANGES; VENTILATING
- F24D—DOMESTIC- OR SPACE-HEATING SYSTEMS, e.g. CENTRAL HEATING SYSTEMS; DOMESTIC HOT-WATER SUPPLY SYSTEMS; ELEMENTS OR COMPONENTS THEREFOR
- F24D17/00—Domestic hot-water supply systems
- F24D17/0026—Domestic hot-water supply systems with conventional heating means
- F24D17/0031—Domestic hot-water supply systems with conventional heating means with accumulation of the heated water
Landscapes
- Engineering & Computer Science (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- General Physics & Mathematics (AREA)
- Automation & Control Theory (AREA)
- Computer Hardware Design (AREA)
- Human Computer Interaction (AREA)
- Heat-Pump Type And Storage Water Heaters (AREA)
Abstract
A system for controlling a temperature of a liquid residing within a tank comprises at least one temperature sensor, at least one temperature control element, and logic. The at least one temperature sensor is configured to detect temperatures of the liquid, and the at least one temperature control element is configured to alter a temperature of the liquid. The logic is configured to automatically establish different temperature thresholds for different time periods. Each of the different temperature thresholds is associated with a different one of the time periods. The logic is further configured to perform, for each of the time periods, a comparison between a temperature detected by the at least one temperature sensor and the associated temperature threshold and to control the temperature control element based on the comparison.
Description
- This document is a continuation of and claims priority to U.S. patent application Ser. No. 10/295,061, entitled “System and Method for Controlling Temperature of a Liquid Residing within a Tank,” and filed on Nov. 15, 2002, which is incorporated herein by reference. U.S. patent application Ser. No. 10/295,061 claims priority to and the benefit of the filing date of the following commonly assigned provisional applications: (a) U.S. Provisional Application No. 60/332,602, entitled “Water Heating System and Method,” and filed on Nov. 15, 2001; (b) U.S. Provisional Application No. 60/353,546, entitled “System and Method for Controlling Water Temperature within a Water Tank,” and filed on Jan. 31, 2002; and (c) U.S. Provisional Application No. 60/417,926, entitled “System and Method for Controlling Water Temperature within a Water Tank,” and filed on Oct. 11, 2002. All of the foregoing patent applications are incorporated herein by reference.
- 1. Field of the Invention
- The present invention generally relates to liquid heating and cooling techniques and, in particular, to a system and method for controlling temperatures of liquids residing within tanks.
- 2. Related Art
- Water tanks are often employed to provide users with heated water, which is drawn from a water tank and usually dispensed from a faucet, showerhead, or like device. During operation, a water tank normally receives unheated water from a water source, such as a water pipe. The water tank includes a controller having a user interface that allows a user to set a desired temperature for the water being held by the tank. If the tank's water temperature falls below the desired temperature, then the controller activates a heating element for warming the tank's water. When activated, the heating element begins to heat the water within the tank, and the heating element continues to heat the water until the water's temperature reaches or exceeds the desired temperature.
- The water tank typically does not provide total thermal insulation, and heat from the water often dissipates through the tank and into the surrounding environment. Therefore, over time, the temperature of the water typically decreases. Furthermore, as water is drawn from the tank and used, unheated water from the water source is drawn into the tank to replenish the tank's water supply. This new water is typically at a lower temperature than the heated water within the tank causing the overall temperature of the tank's water to rapidly decrease during times of significant water usage. Due to the foregoing factors that tend to reduce the tank's water temperature, activation of the heating element is frequently required to maintain the temperature of the water at or close to the desired temperature. Moreover, activation of the heating element can be particularly frequent and/or long during times of high water usage and for water tanks providing poor thermal insulation.
- Activation of the heating element typically requires electrical power. In this regard, a heating element is normally comprised of one or more resistive elements that emit heat when electrical current is passed through the heating element. As a result, the operational costs associated with a water heater are directly related to the amount of heat generated by the heating element. More specifically, any increase in the amount of heat generated by the heating element normally increases the energy costs and, therefore, the overall operational costs associated with the water heater. Indeed, many consumers utilize a tank's energy efficiency as a primary factor when purchasing a water tank. Thus, there exists a need in the art for more efficient water tanks that operate with lower energy costs.
- Another problem with conventional water tanks pertains to failure of the heating element. For the reasons set forth above, a heating element within a water tank may be frequently activated and deactivated in an attempt to maintain the tank's water temperature at the desired level. Over time, the frequent transitions of the heating element increase the wear experienced by the heating element, and the heating element eventually fails. When the heating element fails, a user can either replace the water tank entirely or fix the water tank by replacing the failed heating element. However, during the time that it takes to fix or replace the water tank, the water tank often fails to maintain the water temperature at the desired level. In most situations, a user has no alternative source for heated water and, therefore, is not able to keep water at the desired temperature until the water tank is either fixed or replaced. This can be very inconvenient for the user, and the longer that it takes to fix or replace the water tank, the more the user is inconvenienced.
- Some water tanks referred to as “water coolers,” have cooling elements instead of heating elements in order to keep the water within the tanks at or below a desired temperature. Such tanks commonly hold drinking water that can be dispensed through a faucet, fountain, nozzle or other type of water dispensing device. In order to keep the water within a particular tank at or below the desired temperature, the cooling element is activated when it is detected that the water temperature has risen above the desired temperature. The cooling element cools the water within the tank until the water temperature falls below the desired temperature. Like the heating element, electrical power is typically required to activate the cooling element. Thus, the operational costs associated with a water cooler are directly related to the amount of cooling performed by the cooling element. More specifically, any increase in the amount of cooling performed by the cooling element normally increases the energy costs and, therefore, the overall operational costs associated with the water cooler.
- The present invention overcomes the inadequacies and deficiencies of the prior art as discussed hereinbefore. Generally, the present invention provides a system and method for controlling a temperature of a liquid residing within a tank.
- A system in accordance with one embodiment of the present invention comprises at least one temperature sensor, at least one temperature control element, and logic. The at least one temperature sensor is configured to detect temperatures of the liquid, and the at least one temperature control element is configured to alter a temperature of the liquid. The logic is configured to automatically establish different temperature thresholds for different time periods based on temperatures detected by the at least one temperature sensor. Each of the different temperature thresholds is associated with a different one of the time periods. The logic is further configured to perform, for each of the time periods, a comparison between a temperature detected by the at least one temperature sensor and the associated temperature threshold and to control the temperature control element based on the comparison.
- A system in accordance with another embodiment of the present invention comprises at least one temperature sensor, at least one temperature control element, and logic. The at least one temperature sensor is configured to detect temperatures of the liquid, and the at least one temperature control element is configured to alter a temperature of the liquid. The logic is configured to monitor the temperature control element and to automatically establish different temperature thresholds for different time periods based on the monitoring of the at least one temperature control element by the logic. Each of the different temperature thresholds is associated with a different one of the time periods. The logic is further configured to perform, for each of the time periods, a comparison between a temperature detected by the at least one temperature sensor and the associated temperature threshold and to control the at least one temperature control element based on the comparison.
- Various features and advantages of the present invention will become apparent to one skilled in the art upon examination of the following detailed description, when read in conjunction with the accompanying drawings. It is intended that all such features and advantages be included herein within the scope of the present invention and protected by the claims.
- The invention can be better understood with reference to the following drawings. The elements of the drawings are not necessarily to scale relative to each other, emphasis instead being placed upon clearly illustrating the principles of the invention. Furthermore, like reference numerals designate corresponding parts throughout the several views.
- FIG. 1 is a block diagram illustrating a water heating system in accordance with the prior art.
- FIG. 2 is a block diagram illustrating a controller depicted in FIG. 1.
- FIG. 3 is three-dimensional diagram illustrating a front view of the controller depicted in FIG. 2.
- FIG. 4 is a three-dimensional diagram illustrating a back view of the controller depicted in FIG. 2.
- FIG. 5 is a block diagram illustrating a liquid heating system in accordance with an exemplary embodiment of the present invention.
- FIG. 6A is block diagram illustrating circuitry depicted in FIG. 2, once the controller of FIG. 2 has been removed from the heating system depicted by FIG. 1.
- FIG. 6B is a block diagram illustrating a more detailed view of a controller depicted in FIG. 5.
- FIG. 7 is a block diagram illustrating an instruction execution system implementing control logic depicted in FIG. 6B.
- FIG. 8 is three-dimensional diagram illustrating an exemplary front view for the controller depicted in FIG. 6B.
- FIG. 9 is a three-dimensional diagram illustrating an exemplary back view for the controller depicted in FIG. 6B.
- FIG. 10 is a flow chart illustrating an exemplary architecture and functionality of the controller depicted in FIG. 6B.
- FIG. 11 is a block diagram illustrating a liquid cooling system in accordance with an exemplary embodiment of the present invention.
- FIG. 12 is a block diagram illustrating a more detailed view of a controller depicted in FIG. 11.
- FIG. 13 is a block diagram illustrating an instruction execution system implementing control logic depicted in FIG. 12.
- FIG. 14 is a flow chart illustrating an exemplary architecture and functionality of the controller depicted in FIG. 12.
- FIGS. 15 and 16 depict a flow chart illustrating an exemplary architecture and functionality of the controller depicted in FIG. 6B when the controller is operating in a learn mode in accordance with an exemplary embodiment of the present invention.
- FIG. 17 depicts an exemplary usage history schedule that may be created by the controller of FIG. 6B while operating in the learn mode.
- FIGS. 18 and 19 depict a flow chart illustrating an exemplary architecture and functionality of the controller depicted in FIG. 6B when the controller is operating in an operational mode in accordance with an exemplary embodiment of the present invention.
- FIGS. 20 and 21 depict a flow chart illustrating an exemplary architecture and functionality of the controller depicted in FIG. 12 when the controller is operating in a learn mode in accordance with an exemplary embodiment of the present invention.
- FIGS. 22 and 23 depict a flow chart illustrating an exemplary architecture and functionality of the controller depicted in FIG. 12 when the controller is operating in an operational mode in accordance with an exemplary embodiment of the present invention.
- FIG. 24 is a flow chart illustrating an exemplary architecture and functionality of the controller depicted in FIG. 6B when the controller is operating in a learn mode and is determining time slot classifications based on the rates of change of sensed water temperature.
- FIG. 25 is a flow chart illustrating an exemplary architecture and functionality of the controller depicted in FIG. 6B when the controller is operating in an operational mode and is determining time slot classifications based on the rates of change of sensed water temperature.
- FIG. 26 is a block diagram illustrating an exemplary embodiment of a heating element monitoring system that may be used to provide advanced warning of an imminent failure of a heating element.
- FIG. 27 is a block diagram illustrating an exemplary embodiment of a cooling element monitoring system that may be used to provide advanced warning of an imminent failure of a cooling element.
- FIG. 28 is a flow chart illustrating an exemplary architecture and functionality of control logic, such as depicted in FIGS. 26 and 27.
- FIG. 29 is a flow chart illustrating an exemplary architecture and functionality of control logic, such as depicted in FIG. 6B, in setting an upper threshold and a lower threshold for use during a current time slot.
- FIG. 30 is a flow chart illustrating an exemplary architecture and functionality of control logic, such as depicted in FIG. 12, in setting an upper threshold and a lower threshold for use during a current time slot.
- FIG. 31 is a block diagram illustrating a conventional water heating system employing multiple heating elements in accordance with the prior art.
- FIG. 32 is a block diagram illustrating a liquid heating system employing multiple heating elements in accordance with an exemplary embodiment of the present invention.
- FIG. 33 is a block diagram illustrating a more detailed view of a controller depicted in FIG. 32.
- FIG. 34 is a block diagram illustrating a liquid heating system employing multiple heating elements in accordance with an exemplary embodiment of the present invention.
- FIG. 35 is a block diagram illustrating a more detailed view of a controller and a control module depicted in FIG. 34.
- FIG. 36 is a block diagram illustrating a liquid cooling system employing multiple heating elements in accordance with an exemplary embodiment of the present invention.
- FIG. 37 is a block diagram illustrating a more detailed view of a controller depicted in FIG. 36.
- FIG. 38 is a flow chart illustrating an exemplary architecture and functionality of control logic, such as is depicted in FIGS. 36 and 37.
- FIG. 1 depicts a conventional
water heating system 15. Thesystem 15 includes awater tank 17 that receives and stores water from awater pipe 21. If desired, thetank 17 may reside on a base or stand 23 that supports thetank 17, as shown by FIG. 1. A temperature control element, referred to as a “heating element 25,” within thetank 17 heats, under the direction and control of acontroller 28, the water within thetank 17 to a desired temperature. The heated water within thetank 17 may be drawn through apipe 33 to one ormore dispensing devices 36, such as a faucet, nozzle, or shower head, for example, which dispenses the heated water for use by a user. The dispensingdevice 36 normally includes avalve 38 for controlling water flow and, more particularly, for controlling whether or not thedevice 36 dispenses water from thepipe 33. When thevalve 38 is opened, water flows out of the dispensingdevice 36 and water from thetank 17 flows out of thetank 17 and into thepipe 33. When thevalve 38 is closed, no water is dispensed from the dispensingdevice 36. If no water is being dispensed by any dispensingdevice 36 within thesystem 15, then water does not typically flow out of thetank 17. - Each dispensing
device 36 may receive unheated water from a water source, such aswater pipe 21, for example, and mix the unheated water with the heated water from thepipe 33 in order to dispense water at a desired temperature. Note that anothervalve 41 may be used to control the unheated water flow. Alternatively, there may be a single valve (not shown) for controlling the dispensing of both the unheated and heated water. It should be noted that thepipes tank 17 at locations other than those shown by FIG. 1. - A more detailed view of the
controller 28 is shown in FIG. 2. Thecontroller 28 Includes a pair ofinput connections 37 for receiving electrical power from anelectrical power source 39. Furthermore, auser interface 41 enables a user to provide an input for setting a desired temperature for the water within thetank 17. This desired temperature, which may be set by the user, will be referred to hereafter as a “temperature threshold.” - A temperature-based
switch 44 detects whether the tank's water temperature is above or below the temperature threshold, and activates theheating element 25 when theswitch 44 detects the water temperature to be below the temperature threshold. Typically, theswitch 44 activates theheating element 25 by enabling current to flow from theconnections 37 and through theheating element 25. By having current flow through the resistance of theheating element 25, heat is generated and transferred to the water within thetank 17 causing the temperature of the water to increase. - Once the water temperature reaches or exceeds the temperature threshold, the
switch 44 deactivates theheating element 25. Deactivation of theheating element 25 is typically achieved by preventing current from flowing from theconnections 37 to theheating element 25. - A common configuration of the
switch 44 includes two conductive contacts (not shown) having dissimilar thermal properties. Each of the contacts is coupled to one of theconnections 37 and to theheating element 25. Heat from the water within thetank 17 passes from the water through thetank 17 and to the contacts. As the water temperature changes, thermal stresses within the contacts tend to cause one of the contacts to move with respect to the other contact. The configuration of the contacts is such that the two contacts are separated when the water temperature is below the temperature threshold. The amount of separation is such that the thermal stresses cause the contacts to engage when the water temperature reaches the temperature threshold and to remain engaged if the water temperature exceeds the temperature threshold. Furthermore, when the temperature of the water falls back below the temperature threshold, the thermal stresses are insufficient for keeping the contacts engaged, causing the contacts to separate. - When the two contacts are engaged with one another, current is able to flow over the two contacts and through the
heating element 25. In other words, theswitch 44 is in a closed state, and theheating element 25 is activated. While theswitch 44 is in the closed state, theheating element 25 generates heat. However, when the contacts separate, current is prevented from flowing through theswitch 44 and, therefore, throughheating element 25. In other words, theswitch 44 is in an open state, and theheating element 25 is deactivated. While theswitch 44 is in an open state, theheating element 25 fails to generate heat. - FIGS. 3 and 4 show three-dimensional front and back views, respectively, of a
typical controller 28. As shown by FIG. 4, thecontroller 28 includes a thermallyconductive base 51, which can be mounted on the side of the tank 17 (FIG. 1). Furthermore, theconductive base 51 includesholes 53. To fixedly attach the base 51 to thetank 17, screws (not shown) can be passed through theholes 53 and into thetank 17. When thecontroller 28 is mounted on thetank 17, heat from the tank's water can pass through thetank 17 and through the thermallyconductive base 51, which is thermally connected to the temperature-based, switch 44 (FIG. 2). Thus, theswitch 44 should be able to efficiently receive heat from the water within thetank 17 and operate as described above. - The
user interface 41 shown by FIG. 3 comprises aturnable dial 57. Each position of thedial 57 corresponds to a different temperature, and the user establishes the temperature threshold by turning thedial 57 to the position that corresponds to the desired water temperature. In this regard, thedial 57 is mechanically coupled to at least one of the aforementioned contacts (not shown) within theswitch 44. As thedial 57 is turned to a new corresponding temperature, the position of one of the contacts, with respect to the other contacts, is changed such that the two contacts engage one another as the temperature of the tank's water reaches the new corresponding temperature. Moreover, turning thedial 57 to a new corresponding temperature establishes the new corresponding temperature as the temperature threshold until thedial 57 is later turned to another corresponding temperature. Thus, a user can change the temperature threshold utilized to control activation of theheating element 25 by turning thedial 57. - FIG. 5 depicts a
liquid heating system 100 that may be used to provide a heated liquid, such as water, for example, in accordance with the present invention. As can be seen by comparing FIG. 1 to FIG. 5, theliquid heating system 100 may be similar to or identical to conventionalwater heating system 15 except that theliquid heating system 100 of the present invention is controlled by adifferent controller 110. A more detailed view of an exemplary embodiment of thecontroller 110 is depicted in FIG. 6B. Note that theliquid heating system 100 will be described hereafter as a providing heated water to users of thesystem 100. However, in other embodiments, thesystem 100 may be used to provide other types of heated liquids. - As shown by FIG. 6B, the
controller 110 includescontrol logic 115 configured to control the operation and functionality of thecontroller 110. Thecontrol logic 115 can be implemented in software, hardware, or a combination thereof. In one exemplary embodiment, as illustrated by way of example in FIG. 7, thecontrol logic 115, along with its associated methodology, is implemented in software and stored inmemory 121 of aninstruction execution system 123, such a microprocessor, for example. - Note that the
control logic 115, when implemented in software, can be stored and transported on any computer-readable medium. In the context of this document, a “computer-readable medium” can be any means that can contain, store, communicate, propagate, or transport a program. The computer readable-medium can be, for example but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium. More specific examples (a nonexhaustive list) of the computer-readable medium would include the following: an electrical connection having one or more wires, a portable computer diskette, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, and a portable compact disc read-only memory (CDROM). Note that the computer-readable medium could even be paper or another suitable medium upon which the program is printed, as the program can be electronically captured, via for instance optical scanning of the paper or other medium, then compiled, interpreted or otherwise processed in a suitable manner if necessary, and then stored in a computer memory. As an example, thecontrol logic 115 may be magnetically stored and transported on a conventional portable computer diskette. - The
system 123 of FIG. 7 comprises one or moreconventional processing elements 127, such as a central processing unit (CPU) or digital signal processor (DSP), that communicate to and drive the other elements within thesystem 123 via alocal interface 131, which can include one or more buses. Furthermore, thesystem 123 may include aclock 134 that may be utilized to track time and/or control the synchronization of data transfers within thesystem 123. Thesystem 123 may also include one ormore data interfaces 138, such as analog and/or digital ports, for example, for enabling thesystem 123 to exchange data with the other elements of thecontroller 110. - The
control logic 115 preferably controls the operation of theheating element 25 based on the temperature of the water within thetank 17. In this regard, thecontroller 110 includes auser interface 145 that enables a user to provide, to thecontroller 110, various inputs, such as an input for setting the temperature threshold for thetank 17. During normal operation, thecontrol logic 115 is configured to control the operation of theheating element 25 in an attempt to maintain the water temperature within thetank 17 at or above the temperature threshold, which may change from time-to-time, as will be described in more detail hereafter. - To achieve the foregoing functionality, the
controller 110 utilizes atemperature sensor 152, such as a thermistor or thermocoupler, for example, for sensing the current water temperature of thetank 17. Thetemperature sensor 152 transmits a value of the sensed temperature to thecontrol logic 115, which activates or deactivates theheating element 25 based on the sensed temperature value. More specifically, thecontrol logic 115 preferably activates theheating element 25 if the sensed temperature is below the temperature threshold, and thecontrol logic 115 may keep theheating element 25 in the activation state until the sensed temperature reaches or exceeds the temperature threshold. While theheating element 25 is activated, theheating element 25 generates heat, which is transferred to the tank's water generally causing the water temperature to rise. - Once the sensed temperature reaches or exceeds the temperature threshold, the
control logic 115 deactivates theheating element 25 and keeps theheating element 25 in the deactivation state until the sensed temperature falls below the temperature threshold, at which point thecontrol logic 115 again activates theheating element 25. Thus, thecontroller 110 activates and deactivates theheating element 25, as appropriate, in an attempt to maintain the tank's water temperature within a desired range based on the temperature threshold. - Note that in other embodiments, if desired, the
control logic 115 may activate and deactivate theheating element 25 at slightly different temperature thresholds in order to provide hysteresis. For example, thecontrol logic 115 may activate theheating element 25 if the sensed temperature falls below a lower temperature threshold, and thecontrol logic 115 may deactivate theheating element 25 if the sensed temperature exceeds an upper temperature threshold (i.e., a threshold that is higher than the aforementioned lower threshold). - Various types of known heating devices may be utilized to implement the
heating element 25, and various types of techniques may be employed to activate and/or deactivate theheating element 25. In the preferred embodiment, theheating element 25 is a resistive device that generates heat when electrical current is passed through its resistive components. Thecontroller 110, therefore, includes a pair ofconnections 37 capable of receiving electrical power from apower source 39, such as a battery or a wall plug, for example. Theconnections 37 are coupled to aswitch 156, which operates under the direction and control of thecontrol logic 115. In this regard, when thecontrol logic 115 decides to activate theheating element 25, thecontrol logic 115 transmits, to theswitch 156, a control signal that causes theswitch 156 to close thereby causing electrical current to flow through theheating element 25. When thecontrol logic 115 decides to deactivate theheating element 25, thecontrol logic 115 transmits, to theswitch 156, a control signal that causes theswitch 156 to open thereby preventing electrical current from flowing through theheating element 25. - Note that the electrical power received by the
connections 37 may be utilized to power various controller components, such asuser interface 145,temperature sensor 152, and/or instruction execution system 123 (FIG. 7), for example. To this end, thecontroller 110 may include one ormore power converters 159 for converting the power fromconnections 37 to suitable forms or voltages for powering one or more other components of thecontroller 110. - In one exemplary embodiment, the
control logic 115 is configured to monitor the operational history of thetank 17 and to change or select the temperature threshold, when appropriate, such that the operation of thetank 17 is more efficient. The operational history preferably indicates a schedule of the water usage fromtank 17. In this regard, thecontrol logic 115 periodically stores information that is indicative of the tank's water usage over time. In other words, thecontrol logic 115 stores information, including time data from theclock 134, that tracks the tank's water usage. The data stored by thecontrol logic 115 for tracking the water's usage, including the time data stored fromclock 134, will be referred to hereafter as “usage history 161.” Thisusage history 161 may be stored in the memory 121 (FIG. 7) ofsystem 123 and can be analyzed by thecontrol logic 115 to determine time periods when water usage from thetank 17 is relatively high, relatively low, and/or average. - There may be various methodologies employed to analyze water usage. In one exemplary embodiment, water usage is analyzed by monitoring the state of the
heating element 25. In this regard, since thecontrol logic 115 controls the state of theheating element 25 by controlling the state of theswitch 156, thecontrol logic 115 should be aware of when theheating element 25 is activated and when theheating element 25 is deactivated. Thecontrol logic 115 preferably tracks the state of theheating element 25 to determine operational patterns associated with theheating element 25. - For example,
control logic 115 may determine recurring time periods when theheating element 25 is seldom in the activation state with respect to other time periods. Such recurring time periods should correspond to periods of low water usage from thetank 17 since an increase in the rate at whichheating element 25 heats the tank's water is normally caused by an increase in water usage. In this regard, high water usage causes more unheated water to be drawn into thetank 17 from thepipe 21 in order to replenish the heated water flowing out of thetank 17. The introduction of more unheated water generally decreases the overall temperature of the water causing theheating element 25 to remain in the activation state longer and/or more frequently in order to heat the water to the desired temperature range. Thus, low usage of theheating element 25 is generally indicative of low water usage, and conversely, high usage of theheating element 25 is generally indicative of high water usage. - The
control logic 115 may utilize a variety of methodologies to determine time periods when theheating element 25 is seldom in the activation state. For example, thecontrol logic 115 may determine, for each hour (or some other time period), how long theheating element 25 is activated and/or deactivated. Such information may be stored inmemory 121 as theusage history 161. Thecontrol logic 115 may then analyze theusage history 161 and determine that during certain repetitive time periods, such as the early morning hours of each day or during particular time periods of particular days, for example, theheating element 25 is rarely in the activation state. Such time periods should be time periods of low water usage and will be referred to hereafter as “energy savings time periods.” - After identifying the energy savings time periods, the
control logic 115 monitors theclock 134 to determine when the energy savings time periods occur. During such time periods, thecontrol logic 115 reduces the amount of heating that would otherwise be performed by theheating element 25 in normal operation. For example, thecontrol logic 115 may automatically turn off theheating element 25 by keeping theswitch 156 open during energy savings time periods. Alternatively, thecontrol logic 115 may lower the temperature threshold for activating theheating element 25 during energy savings time periods such that the amount of heat generated by theheating element 25 during such time periods is reduced. At the end of such periods, thecontrol logic 115 may resume normal operation. - The foregoing functionality has the effect of allowing, during the energy savings time periods, the overall temperature of the tank water to decrease below the normal temperature threshold without activating the
heating element 25. This helps to reduce the amount of heating required during the energy savings time periods and, therefore, helps to reduce the energy costs during such time periods. Furthermore, based on theusage history 161, it may be assumed that water usage is likely to be low during the energy savings time periods. Therefore, it is not likely that users will experience a significant decrease in performance as a result of the reduction in water temperature during the energy savings time periods. Thus, the aforementioned energy cost savings, which can be substantial over the life of thetank 17, are achieved without a significant reduction in performance of thesystem 100. - It should be noted that other methodologies may be employed to identify the energy savings time periods. For example, the user may input, via
input interface 145, data indicative of the energy savings time periods. In other words, the user may program when thecontrol logic 115 is configured to allow the water temperature to fall below the temperature threshold utilized in normal operation without activating theheating element 25. In another example, thecontrol logic 115 may receive readings from a sensor (not shown) that measures or tracks the amount of water that either flows out of or into thetank 17. Thecontrol logic 115 can then be configured to identify the time periods of low water flow as the energy savings time periods. Note that, as described above, the time periods of low water flow or, in other words, low water usage should correspond to the same time periods of low activation of theheating element 25. Thus, in either the embodiment, the same time periods should be identified as energy savings time periods. Note that various other methodologies may be employed to identify times of low water usage and, therefore, to identify energy savings time periods. - In one exemplary embodiment, the
control logic 115 is further configured to predict when theheating element 25 is about to fail. Thecontrol logic 115 is configured to then provide a warning to a user, viauser interface 145, for example. Thus, the user can take any desirable steps for proactively dealing with the predicted failure. For example, the user can replace theheating element 25 or thetank 17 at a time that is convenient to the user and prior to the failure, or the user may make preparations for replacing theheating element 25 or thetank 17, such as, for example, purchasing anew heating element 25 ortank 17 for when theheating element 25 does eventually fail. As a result, the user can minimize the consequences of a failingheating element 25 and, more particularly, can minimize the amount of time that thesystem 100 is incapable of delivering unheated water. - To predict when failure of the
heating element 25 is imminent, thecontrol logic 115 preferably monitors the electrical current (I) provided to theheating element 25 and/or the voltage (V) applied to theheating element 25. In this regard, the resistance (R) of theheating element 25 typically increases significantly just prior to a failure of theheating element 25. Thus, by monitoring the voltage and/or the current applied to theheating element 25, it is possible to determine whether or not the resistance of theheating element 25 is increasing by utilizing the equation V=IR. When thecontrol logic 115 determines that the resistance of theheating element 25 has increased to a level higher than a predefined threshold or has significantly increased over time, thecontrol logic 115 determines that a heating element failure is imminent and provides the user with a warning. - In one exemplary embodiment, the
monitoring element 162 is utilized to enable monitoring of theheating element 25 for failure. In this regard, themonitoring element 162 preferably includes circuitry (e.g., a voltmeter) for determining a voltage value corresponding to the voltage applied to theheating element 25, and themonitoring element 162 preferably includes circuitry (e.g., an ammeter) for determining a current value corresponding to the current applied to theheating element 25. Thecontrol logic 115 then divides the voltage value by the current value to determine the resistance of theheating element 25. - Note that if the voltage is regulated such that it is substantially constant, then the
logic 115 can be configured to predict when theheating element 25 is about to fail by determining when the current value (I) falls below a predefined threshold or significantly decreases over time. In such a case, a decrease in measured current corresponds to an increase in heating element resistance. Similarly, if the current is regulated such that it is substantially constant, then thelogic 115 can be configured to predict when theheating element 25 is about to fail by determining when the voltage value exceeds a predefined threshold or significantly increases over time. In such a case, an increase in measured voltage corresponds to an increase in resistance. - In order to communicate operational information, such as, for example, a warning about an imminent heating element failure, a current tank temperature, the current temperature threshold, etc., the
user interface 145 may include various communication devices. For example, theinterface 145 may include speakers for generating audio tones (e.g., beeps) or other types of messages and/or may include a display device, such as a liquid crystal display (LCD), for displaying visual messages. Note that the display device may produce textual or non-textual messages. For example, a LCD may be utilized to display a textual message while one or more light emitting diodes (LEDs) may be utilized to display a non-textual message. As an example, a single LED may be used to communicate whether or not a heating element failure is imminent. - The
user interface 145 may also include a wireless communication device for transmitting wireless signals, such as infrared or radio frequency (RF) signals, for example. The wireless signals may be transmitted to a remote device 174 (FIG. 6B) that interfaces the information from the wireless signals with a user. Thisremote device 174 may be mounted at any convenient location that is suitable for communicating with theuser interface 145. Alternatively, theremote device 174 may be a portable device, such as a Palm Pilot™, for example. - Furthermore, as previously set forth above, the
user interface 145 is preferably configured to allow a user to submit inputs, such as a command for changing the temperature threshold or for identifying the energy savings time periods, for example. Furthermore, when thecontrol logic 115 is implemented in software, theuser interface 145 may enable the downloading of code for changing or augmenting the code defining thecontrol logic 115. To enable the submission of such inputs, theinterface 145 may include any conventional input device, such as a keypad, a switch, and/or a dial, for example. Theuser interface 145 may also include a data port for receiving wireless (e.g., infrared, RF, etc.) or non-wireless data signals from theremote device 174. - Note that, in embodiments employing the
remote device 174, theremote device 174 may be utilized to monitor and/or control a plurality oftanks 17. For example, large residential and, particularly, commercial buildings often have a plurality oftanks 17 to provide users with sufficient warm water. A singleremote device 174 may be utilized to monitor and/or control multiple ones of thetanks 17. In this embodiment, eachtank 17 may be assigned a unique identifier, and the identifiers may be included in the communications betweenremote device 174 and theinterfaces 145 of themultiple tanks 17. - For example, to transmit a command or other input to the
controller 110 of one of thetanks 17, theremote device 174 may transmit the command or other input, along with the identifier of the onetank 17. Thecontrollers 110 of thetanks 17 may be configured to respond to commands or inputs only if such commands or inputs are accompanied by the identifier identifying itstank 17. Thus, only thecontroller 110 of the identifiedtank 17 should respond to the transmitted command or input. Similarly, thecontroller 110, when transmitting an output, such as a heating element warning, may accompany such output with the identifier of itstank 17. Thus, based on the accompanying identifier, theremote device 174 or a user of theremote device 174 can determine which of thetanks 17 transmitted the output (e.g., the heating element warning). - Note that various techniques, in addition to or in lieu of the techniques described above, may be employed to enable data to be exchanged with the
controller 110. As an example, U.S. patent application entitled “System and Method for Wireless Data Exchange Between an Applicant and a Handheld Device,” filed on Oct. 23, 2001, by Patterson et al., Ser. No. 10/035,370, which is incorporated herein by reference, describes techniques that may be employed for enabling infrared: communication between two devices. Such techniques may be employed to enable communication between theuser interface 145 and theremote communication device 174, if desired. - In addition, referring to FIGS. 8 and 9, it is possible to configure the
controller 110 to fit within the same orsimilar base 51 shown by FIGS. 3 and 4. Thus, thecontroller 110 can be retrofitted totanks 17 that are currently controlled by conventional controllers, such as thecontroller 28 shown in FIGS. 3 and 4. In this regard, to retrofit atank 17 with thecontroller 110 of the present invention, a user can simply remove the screws passing through theholes 53 of the base 51 mounted on thetank 17. Then, after disconnecting the conventional controller from itspower source 39 and from theheating element 25, the user can remove thecontroller 28 and itsbase 51 from thetank 17 leaving theheating element 25 andpower source 39 withopen connections heating element 25 andpower source 39, as shown by FIG. 6A. The user can then mount thecontroller 110 and itsbase 51 to thetank 17 and insert the screws or other attaching mechanisms through theholes 53 and into thetank 17 fixedly attaching thecontroller 110 to thetank 17 in place of theconventional controller 28. Then, to ensure that thecontroller 110 may begin controlling thetank 17, the user can ensure that theswitch 156 is conductively coupled to theconnections controller 110 should be able to control the operation of thetank 17 according to the techniques described herein. Note that, according to the retrofitting techniques described above, re-wiring of circuitry or wires outside of thecontrollers - It should be noted that the
controller 110 shown by FIG. 8 includes adial 57, similar toconventional controller 28, for enabling a user to set the temperature threshold. However, as previously set forth above, other types of input devices may be utilized in other embodiments to enable the user to submit such an input. - An exemplary use and operation of the
liquid heating system 100 and associated methodology are described hereafter with particular reference to FIG. 10. - In
block 201 of FIG. 10, a user initially sets the temperature threshold for thetank 17 by providing an input viauser interface 145. A temperature reading is then taken viatemperature sensor 152, as depicted byblock 204. The new temperature reading is analyzed by thecontrol logic 115 inblock 207 to determine whether or not it is less than the temperature threshold set inblock 201. If the new temperature reading is less than the temperature threshold, then thecontrol logic 115 ensures that theheating element 25 is activated and is, therefore, generating heat. However if the new temperature reading is not less than the temperature threshold, then thecontrol logic 115 ensures that theheating element 25 is deactivated and is, therefore, not generating heat. - To ensure that the
heating element 25 is activated, thecontrol logic 115, inblock 211, checks the state of theswitch 156. If theswitch 156 is open, then theheating element 25 is presently deactivated or is, in other words, turned “off,” and theheating element 25 is, therefore, not generating heat. Thus, thecontrol logic 115 activates theheating element 25 inblock 215 by transmitting, to theswitch 156, a control signal that causes theswitch 156 to transition from an open state to a closed state. As a result, current flows through theheating element 25 causing theheating element 25 to emit heat and to warm the water within thetank 17. - After activating the
heating element 25 inblock 215, thecontrol logic 115 preferably updates the usage history 161 (FIG. 7), inblock 217, in order to indicate the change in the state of theheating element 25. More specifically, thecontrol logic 115 preferably stores inmemory 121 data indicating the occurrence ofblock 215. This data preferably indicates the time, as determined fromclock 134, of such occurrence. At this point, theheating element 25 should be in the activated state or, in other words, should be turned on, as shown byblock 221. - If the
switch 156 is closed inblock 211, then theheating element 25 is presently activated or is, in other words, turned “on,” and theheating element 25 is, therefore, generating heat. In such a case, thecontrol logic 115 needs to take no further steps to ensure activation of theheating element 25. Moreover, the process proceeds directly to block 221 skippingblocks - After ensuring that the
heating element 25 is activated, thecontrol logic 115 then determines the resistance of theheating element 25 inblock 224. This is preferably achieved by measuring the voltage and current applied to theheating element 25 and by dividing the measured voltage by the measured current. Inblock 227, thecontrol logic 115 compares the resistance to a resistance threshold. The resistance threshold is preferably set such that, if the heating element's resistance exceeds the threshold, then failure of theheating element 25 is imminent. This may be achieved by setting the resistance threshold at a level significantly higher than the resistance normally measured for theheating element 25. As shown byblock 229, if the heating element's resistance exceeds the resistive threshold, then thecontrol logic 115, viauser interface 145, provides a warning message in order to notify a user of the impending heating element failure. If the heating element's resistance falls below the resistance threshold, then thecontrol logic 115 skips block 229. - As set forth above, if the
control logic 115 determines, inblock 207, that the new temperature reading from thesensor 152 is not less than the temperature threshold set inblock 201, then thecontrol logic 115 ensures that theheating element 25 is deactivated. To ensure that theheating element 25 is deactivated in the preferred embodiment, thecontrol logic 115, inblock 236, checks the state of theswitch 156. If theswitch 156 is closed, then theheating element 25 is presently activated or is, in other words, turned “on,” and theheating element 25 is, therefore, generating heat. Thus, thecontrol logic 115 deactivates theheating element 25 inblock 239 by transmitting, to theswitch 156, a control signal that causes theswitch 156 to transition from a closed state to an open state. As a result, current is prevented from flowing through theheating element 25 causing theheating element 25 to refrain from warming the water within thetank 17. - After deactivating the
heating element 25 inblock 239, thecontrol logic 115 preferably updates the usage history 161 (FIG. 7) inblock 242 in order to indicate the change in the state of theheating element 25. More specifically, thecontrol logic 115 preferably stores inmemory 121 data indicating the occurrence ofblock 239. This data preferably indicates the time, as determined fromclock 134, of such occurrence. At this point, theheating element 25 should be in the deactivated state or, in other words, should be turned off, as shown byblock 244. - If the
switch 156 is open inblock 236, then theheating element 25 is presently deactivated or is, in other words, turned “off,” and theheating element 25 is, therefore, not generating heat. In such a case, thecontrol logic 115 needs to take no further steps to ensure deactivation of theheating element 25. Moreover, the process proceeds to directly to block 244 skippingblocks - Note that the
control logic 115 may maintain data indicative of the state of theswitch 156 in order to enable implementation ofblocks control logic 115 may maintain a flag that is asserted when theswitch 156 is activated and that is deasserted when theswitch 156 is deactivated. In such an example, thecontrol logic 115 should assert the flag when performingblock 215 and should deassert the flag when performingblock 239. Moreover, thecontrol logic 115 can analyze such a flag to determine both the state of theheating element 25 inblock 211 and the state of theheating element 25 inblock 236. - After controlling the state of the
heating element 25, as described above, thecontrol logic 115 preferably determines, inblock 247, whether or not data should be provided to a user of thesystem 100. For example, it may be desirable to provide users with certain data (e.g., the temperature sensed by the sensor 152) during the operation of thesystem 100 either automatically or upon request. If so, thecontrol logic 115 transmits such data inblock 249 to theuser interface 145, which interfaces the data with a user. - For example, a user may desire to view an operational history of the
system 100. In such an example, the user may input, viauser interface 145, a request to retrieve the usage history 161 (FIG. 7). Such a request may be input via an interface device (e.g., a keypad) withininterface 145, or such a request may be input via aremote device 174 that wirelessly or non-wirelessly transmits the request to theinterface 145 of thecontroller 110. Thecontrol logic 115 preferably detects the user's request and, in response, retrieves theusage history 161 frommemory 121. Thecontrol logic 115 then transmits theusage history 161 to theuser interface 145, which interfaces theusage history 161 with the user inblock 249. This may be achieved, for example, by outputting the data via an interface device (e.g., an LCD) withininterface 145 or by wirelessly or non-wirelessly transmitting the data to aremote device 174, which then outputs the data to a user. - By controlling the state of the
heating element 25 according to the aforedescribed techniques, thecontroller 110 attempts to maintain the temperature of the water within thetank 17 at or above the temperature threshold. However, it may be desirable to change the temperature threshold. Thecontrol logic 115 determines inblock 252 whether or not the temperature threshold is to be changed. If the temperature threshold is to be changed, then thecontrol logic 115 proceeds back to block 201 and sets the temperature threshold to the appropriate level. If the temperature threshold is not to be changed, then thecontrol logic 115 proceeds directly to block 204 without performingblock 201. - As an example of a situation when the temperature threshold is to be changed, a user may submit an input to increase or decrease the temperature threshold. The
control logic 115 preferably detects such an input and, in response, proceeds to block 201 fromblock 252. Inblock 201, thecontrol logic 115 sets the temperature threshold to a new value based on the user's input. - In another example, the
control logic 115 may be configured to automatically change the temperature threshold based on the usage history 161 (FIG. 7) instead of a user's input. For example, thecontrol logic 115 may analyze theusage history 161 and determine that during a particular repetitive time period (e.g., during early morning hours of every day), the usage of water from thetank 17 is usually low as compared to other time periods. In such an example, thecontrol logic 115 identifies the particular repetitive time period as an energy savings period. Note that other energy savings periods may be identified based on theusage history 161 and/or based upon user inputs. Also note that thecontrol logic 115 can determine when an energy savings period is entered or exited by analyzing data from theclock 134. - Once an energy savings period is entered, the
control logic 115 determines, inblock 252, that the temperature threshold should be lowered. Thus, thecontrol logic 115 proceeds to block 201 and sets (e.g., lowers) the temperature threshold to the appropriate level. Once the energy savings period is exited, thecontrol logic 115 determines inblock 252 that the temperature threshold should be raised perhaps to the original threshold previously set by the user. Thus, thecontrol logic 115 proceeds to block 201 and sets (e.g., raises) the temperature threshold to the appropriate level. - To illustrate the foregoing, assume that a user, in
block 201, initially sets the temperature threshold to a first threshold. Also assume that repetitive energy savings time periods (e.g., the first four hours of every day) is identified and that thecontrol logic 115 is configured to lower the temperature threshold to a second threshold during the identified energy savings time periods. - Initially, the temperature threshold is set to the first threshold, and the
control logic 115 continually controls theheating element 25 based on comparisons of the temperature sensor readings to the first threshold inblock 207 until the energy time savings period is entered. However, the first time that block 252 is performed after entering into the energy savings time period, thecontrol logic 115 determines that the temperature threshold should be lowered to the second threshold. Thus, thecontrol logic 115 proceeds to block 201 and lowers the temperature threshold to the second temperature. Thecontrol logic 115 then continually controls theheating element 25 based on comparisons of the temperature sensor readings to the second threshold until the energy savings time period expires. Once the energy timesaving period expires, thecontrol logic 115, in performingblock 252 for the first time after expiration of the energy time savings period, determines that the temperature threshold should be raised back to the first threshold. Thus, thecontrol logic 115 proceeds to block 201 and raises the temperature threshold to the first threshold. Thecontrol logic 115 then continually controls theheating element 25 based on comparisons of the temperature sensor readings to the first threshold inblock 207 until the next energy time period is entered. The foregoing process is continually repeated provided that no other reasons for changing the temperature threshold is detected inblock 252. - Techniques similar to the ones described above for the
liquid heating system 100 may be utilized in an attempt to maintain the temperature of water within atank 17 below, instead of above, a desired temperature. Moreover, FIG. 11 depicts aliquid cooling system 300 in accordance with the present invention. Theliquid cooling system 300 may be similar to or identical to theliquid heating system 100 previously described except that the temperature control element within theliquid cooling system 300 is acooling element 305, instead of aheating element 25, and except that acontroller 310 is configured to keep the temperature of the water within thetank 17 at or below, instead of at or above, a temperature threshold. Referring to FIG. 12, thecontroller 310 may be similar to or identical to thecontroller 110 of FIG. 6B except that thecontroller 310 includeslogic 315 for controlling activation and deactivation of thecooling element 305 in accordance with techniques that will be described in more detail hereafter. Note that theliquid cooling system 300 will be described hereafter as a providing cooled water to users of thesystem 300. However, in other embodiments, thesystem 300 may be used to provide other types of cooled liquids. - The
control logic 315, like thecontrol logic 115 ofliquid heating system 100, can be implemented in software, hardware, or a combination thereof. As illustrated in FIG. 13, thecontrol logic 315, along with its associated methodology, may be implemented in software and stored inmemory 321 of aninstruction execution system 323. When implemented in software, thecontrol logic 315 can be stored and transported on any computer-readable medium. - The
system 323 of FIG. 13, like thesystem 123 of FIG. 7, may comprise one or moreconventional processing elements 327, such as a central processing unit (CPU), that communicate to and drive the other elements within thesystem 323 via alocal interface 331, which can include one or more buses. Furthermore, thesystem 323 may include aclock 334 that may be utilized to track time and/or control the synchronization of data transfers within thesystem 323. Thesystem 323 may also include one ormore data interfaces 338, such as analog and/or digital ports, for example, for enabling thesystem 323 to exchange data with the other elements of thecontroller 310. - The
controller 310 may utilize techniques similar to those employed by controller 110 (FIG. 6B) in order to control the operation of thecooling element 305. In this regard, like the controller 110 (FIG. 6B), thecontroller 310 preferably includes auser interface 145 that enables a user to provide, to thecontroller 310, various inputs, such as an input for setting the temperature threshold for thetank 17. During normal operation, thecontrol logic 315 is configured to control the operation of thecooling element 305 in an attempt to maintain the water temperature within thetank 17 at or below the temperature threshold, which may change from time-to-time, as will be described in more detail hereafter. - To achieve the foregoing functionality, the
temperature sensor 152 senses the current water temperature of thetank 17 and transmits a value of the sensed temperature to thecontrol logic 315, which activates or deactivates thecooling element 305 based on the sensed temperature value. More specifically, thecontrol logic 315 preferably activates thecooling element 305 if the sensed temperature is above the temperature threshold, and thecontrol logic 315 may keep thecooling element 305 in the activation state until the sensed temperature reaches or falls below the temperature threshold. While thecooling element 305 is activated, thecooling element 305 cools the water within thetank 17. - Once the sensed temperature reaches or falls below the temperature threshold, the
control logic 315 deactivates thecooling element 305 and keeps thecooling element 305 in the deactivation state until the sensed temperature rises above the temperature threshold, at which point thecontrol logic 315 again activates thecooling element 305. Thus, thecontroller 310 activates and deactivates thecooling element 305, as appropriate, in an attempt to maintain the tank's water temperature within a desired temperature range based on the threshold. Note that in other embodiments, if desired, thecontrol logic 315 may activate and deactivate thecooling element 305 at slightly different temperature thresholds in order to provide hysteresis. - Various types of known cooling elements may be utilized to implement the
cooling element 305, and various types of techniques may be employed to activate and/or deactivate thecooling element 305. To control activation and deactivation of thecooling element 305, thecontrol logic 315 preferably controls theswitch 156 similar to how thecontrol logic 115 controls theswitch 156 for activating and deactivating theheating element 25. In this regard, when thecooling element 305 is to be activated, thecontrol logic 315 causes theswitch 156 to close, thereby allowing electrical power to flow from thepower source 39 to thecooling element 305. When powered by thepower source 39, thecooling element 305 cools the water within thetank 17. When thecooling element 305 is to be deactivated, thecontrol logic 315 causes theswitch 156 to open, thereby preventing electrical power from flowing from thepower source 39 to thecooling element 305. When thecooling element 305 fails to receive power from thepower source 39, thecooling element 305 fails to cool the water within thetank 17. Thus, by controlling the state of theswitch 156, thecontrol logic 315 controls whether or not thecooling element 305 is activated or deactivated. - The
control logic 315 preferably tracks the water usage of the tank via similar techniques utilized by thecontrol logic 115 ofliquid heating system 100 and then adjusts the temperature threshold based on the tank's water usage over time. In this regard, thecontrol logic 315 preferably maintains a usage history 361 (FIG. 13), similar to theusage history 161 maintained bycontrol logic 115. Note the tank's water usage may be determined by monitoring the amount of water that enters or exits thetank 17 over time or by monitoring the state of thecooling element 305 over time. As with theheating element 25, low usage of thecooling element 305 is generally indicative of low water usage, and high usage of thecooling element 305 is generally indicative of high water usage. - Moreover, the
control logic 315 is configured to analyze theusage history 361 to identify energy savings time periods or, in other words, time periods when the usage or activation of thecooling element 315 is usually low. Techniques utilized by thecontrol logic 115 ofheating system 100 for identifying energy savings time periods may be utilized by thecontrol logic 315 ofcooling system 300 to also identify energy savings time periods. - After identifying the energy savings time periods, the
control logic 315 monitors theclock 334 to determine when the energy savings time periods occur. During such time periods, thecontrol logic 315 reduces the amount of cooling that would otherwise be performed by thecooling element 305 in normal operation. For example, thecontrol logic 315 may automatically turn off thecooling element 305 by keeping theswitch 156 open during energy savings time periods. Alternatively, thecontrol logic 315 may raise the temperature threshold for activating thecooling element 305 during energy savings time periods such that the amount of cooling performed by thecooling element 305 during such time periods is reduced. At the end of such periods, thecontrol logic 315 may resume normal operation. - The foregoing functionality has the effect of allowing, during the energy savings time periods, the overall temperature of the tank water to increase above the normal temperature threshold without activating the
cooling element 305. This helps to reduce the amount of cooling required during the energy savings time periods and, therefore, helps to reduce the energy costs during such time periods. Furthermore, based on theusage history 361, it may be assumed that water usage is likely to be low during the energy savings time periods. Therefore, it is not likely that users will experience a significant decrease in performance as a result of the increase in water temperature during the energy savings time periods. Thus, the aforementioned energy cost savings, which can be substantial over the life of thetank 17, are achieved without a significant reduction in performance of theliquid cooling system 300. Moreover, thecontrol logic 315 of thecooling system 300 essentially performs the same techniques utilized by thecontrol logic 115 of theheating system 100 in order to reduce operational costs except thatcontrol logic 315 restricts the amount of cooling performed by coolingelement 305 rather than restricting the amount of heating performed byheating element 25. - Note that the
control logic 315 may be configured to monitor the current and/or voltage provided from thepower source 39 to thecooling element 305 in order to predict when failure of thecooling element 305 is imminent. When thecontrol logic 315 detects such an imminent failure, thecontrol logic 315 may communicate a warning just as thecontrol logic 115 is configured to communicate a warning when it detects an imminent failure of theheating element 25. Note that the same techniques described above for communicating input and output with thecontroller 110 of theheating system 100 may be employed to communicate input and output with thecontroller 310 of thecooling system 300. Furthermore, thecontroller 310 may be retrofitted to atank 17 of a conventional cooling system in the same manner that thecontroller 110 is described above as being retrofitted to atank 17 of aheating system 100. - An exemplary operation of the
cooling system 300 and associated methodology are described hereafter with particular reference to FIG. 14. - In
block 401 of FIG. 14, a user initially sets the temperature threshold for the.tank 17 by providing an input viauser interface 145. A temperature reading is then taken viatemperature sensor 152, as depicted byblock 404. The new temperature reading is analyzed by thecontrol logic 315 inblock 407 to determine whether or not it is greater than the temperature threshold set inblock 401. If the new temperature reading is greater than the temperature threshold, then thecontrol logic 315 ensures that thecooling element 305 is activated and is, therefore, cooling the water within thetank 17. However if the new temperature reading is not greater than the temperature threshold, then thecontrol logic 315 ensures that thecooling element 305 is deactivated and is, therefore, not cooling the water within thetank 17. - To ensure that the
cooling element 305 is activated in the preferred embodiment, thecontrol logic 315, inblock 411, checks the state of theswitch 156. If theswitch 156 is open, then thecooling element 305 is presently deactivated or is, in other words, turned “off,” and thecooling element 305 is, therefore, not cooling the water with thetank 17. Thus, thecontrol logic 315 activates thecooling element 305 inblock 415 by transmitting, to theswitch 156, a control signal that causes theswitch 156 to transition from an open state to a closed state. As a result, power is provided to thecooling element 305 causing thecooling element 305 to cool the water within thetank 17. - After activating the
cooling element 305 inblock 415, thecontrol logic 315 preferably updates the usage history 361 (FIG. 13), inblock 417, in order to indicate the change in the state of thecooling element 305. More specifically, thecontrol logic 315 preferably stores inmemory 321 data indicating the occurrence ofblock 415. This data preferably indicates the time, as determined fromclock 334, of such occurrence. At this point, thecooling element 305 should be in the activated state or, in other words, should be turned on, as shown byblock 421. - If the
switch 156 is closed inblock 411, then thecooling element 305 is presently activated or is, in other words, turned “on,” and thecooling element 305 is, therefore, cooling the water within thetank 17. In such a case, thecontrol logic 315 needs to take no further steps to ensure activation of thecooling element 305. Moreover, the process proceeds directly to block 421 skippingblocks - After ensuring that the
cooling element 305 is activated, thecontrol logic 315 then tests thecooling element 305 inblock 424 to determine whether or not failure of thecooling element 305 is imminent. As shown byblocks cooling element 305 is imminent, thecontrol logic 315, viauser interface 145, provides a warning message in order to notify a user of the impending cooling element failure. If failure of thecooling element 305 is not imminent, then thecontrol logic 315 skips block 429. - As set forth above, if the
control logic 315 determines, inblock 407, that the new temperature reading from thesensor 152 is not greater than the temperature threshold set inblock 401, then thecontrol logic 315 ensures that thecooling element 305 is deactivated. To ensure that thecooling element 305 is deactivated in the preferred embodiment, thecontrol logic 315, inblock 436, checks the state of theswitch 156. If theswitch 156 is closed, then thecooling element 305 is presently activated or is, in other words, turned “on,” and thecooling element 305 is, therefore, cooling the water within thetank 17. Thus, thecontrol logic 315 deactivates thecooling element 305 inblock 439 by transmitting, to theswitch 156, a control signal that causes theswitch 156 to transition from a closed state to an open state. As a result, thecooling element 305 fails to receive power from thepower source 39 causing thecooling element 305 to refrain from cooling the water within thetank 17. - After deactivating the
cooling element 305 inblock 439, thecontrol logic 315 preferably updates the usage history 361 (FIG. 13) inblock 442 in order to indicate the change in the state of thecooling element 305. More specifically, thecontrol logic 315 preferably stores inmemory 321 data indicating the occurrence ofblock 439. This data preferably indicates the time, as determined fromclock 334, of such occurrence. At this point, thecooling element 305 should be in the deactivated state or, in other words, should be turned off, as shown byblock 444. - If the
switch 156 is open inblock 436, then thecooling element 305 is presently deactivated or is, in other words, turned “off,” and thecooling element 305 is, therefore, not cooling the water within thetank 17. In such a case, thecontrol logic 315 needs to take no further steps to ensure deactivation of thecooling element 305. Moreover, the process proceeds to directly to block 444 skippingblocks - Note that the
control logic 315 may maintain data indicative of the state of theswitch 156 in order to enable implementation ofblocks control logic 315 may maintain a flag that is asserted when theswitch 156 is activated and is deasserted when theswitch 156 is deactivated. In such an example, thecontrol logic 315 should assert the flag when performingblock 415 and should deassert the flag when performingblock 439. Moreover, thecontrol logic 315 can analyze such a flag to determine both the state of thecooling element 305 inblock 411 and the state of thecooling element 305 inblock 436. - After controlling the state of the
cooling element 305, as described above, thecontrol logic 315 preferably determines, inblock 447, whether or not data should be provided to a user of thesystem 300. For example, it may be desirable to provide users with certain data (e.g., the temperature sensed by the sensor 152) during the operation of thesystem 300 either automatically or upon request. If so, thecontrol logic 315 transmits such data inblock 449 to theuser interface 145, which interfaces the data with a user. - By controlling the state of the
cooling element 305 according to the aforedescribed techniques, thecontroller 310 attempts to maintain the temperature of the water within thetank 17 at or below the temperature threshold. However, it may be desirable to change the temperature threshold. Thecontrol logic 315 determines inblock 452 whether or not the temperature threshold is to be changed. If the temperature threshold is to be changed, then thecontrol logic 315 proceeds back to block 401 and sets the temperature threshold to the appropriate level. If the temperature threshold is not to be changed, then thecontrol logic 315 proceeds directly to block 404 without performingblock 401. - As an example of a situation when the temperature threshold is to be changed, a user may submit an input to increase or decrease the temperature threshold. The
control logic 315 preferably detects such an input and, in response, proceeds to block 401 fromblock 452. Inblock 401, thecontrol logic 315 sets the temperature threshold to a new value based on the user's input. - In another example, the
control logic 315 may be configured to automatically change the temperature threshold based on the usage history 361 (FIG. 13) instead of a user's input. For example, thecontrol logic 315 may analyze theusage history 361 and determine that during a particular repetitive time period (e.g., during early morning hours of every day), the usage of water from thetank 17 is usually low as compared to other time periods. In such an example, thecontrol logic 315 identifies the particular repetitive time period as an energy savings period. Note that other energy savings periods may be identified based on theusage history 361 and/or based upon user inputs. Also note that thecontrol logic 315 can determine when an energy savings period is entered or exited by analyzing data from theclock 334. - Once an energy savings period is entered, the
control logic 315 determines, inblock 452, that the temperature threshold should be raised. Thus, thecontrol logic 315 proceeds to block 401 and sets (e.g., raises) the temperature threshold to the appropriate level. Once the energy savings period is exited, thecontrol logic 315 determines inblock 452 that the temperature threshold should be lowered perhaps to the original threshold previously set by the user. Thus, thecontrol logic 315 proceeds to block 401 and sets (e.g., lowers) the temperature threshold to the appropriate level. - To illustrate the foregoing, assume that a user, in
block 401, initially sets the temperature threshold to a first threshold. Also assume that repetitive energy savings time periods (e.g., the first four hours of every day) is identified and that thecontrol logic 315 is configured to lower the temperature threshold to a second threshold during the identified energy savings time periods. - Initially, the temperature threshold is set to the first threshold, and the
control logic 315 continually controls thecooling element 305 based on comparisons of the temperature sensor readings to the first threshold inblock 407 until the energy time savings period is entered. However, the first time that block 452 is performed after entering into the energy savings time period, thecontrol logic 315 determines that the temperature threshold should be raised to the second threshold. Thus, thecontrol logic 315 proceeds to block 401 and raises the temperature threshold to the second temperature. Thecontrol logic 315 then continually controls thecooling element 305 based on comparisons of the temperature sensor readings to the second threshold until the energy savings time period expires. Once the energy timesaving period expires, thecontrol logic 315, in performingblock 452 for the first time after expiration of the energy time savings period, determines that the temperature threshold should be lowered back to the first threshold. Thus, thecontrol logic 315 proceeds to block 401 and lowers the temperature threshold to the first threshold. Thecontrol logic 315 then continually controls thecooling element 305 based on comparisons of the temperature sensor readings to the first threshold inblock 407 until the next energy time period is entered. The foregoing process is continually repeated provided that no other reasons for changing the temperature threshold is detected inblock 452. - It should be noted that the methodologies described above for controlling the
heating element 25 and thecooling element 305 may be combined in an effort to keep the temperature of the tank's water within a desired range having both an upper temperature threshold and a lower temperature threshold. In such an embodiment, both theheating element 25 and thecooling element 305 are positioned within thetank 17. If the temperature of the water rises above the desired range, thecooling element 305 can be activated in an effort to return the temperature of the water to the desired range. Furthermore, if the temperature of the water falls below the desired range, theheating element 25 can be activated in an effort to return the temperature of the water to the desired range. - In another exemplary embodiment of the present invention, the controller110 (FIG. 5) may be configured to monitor the water usage of the
tank 17 while operating in one mode of operation, referred to as the “learn mode,” and to automatically determine a usage pattern for thetank 17 based on this monitoring. Thecontroller 110 may be configured to then control the operation of theheating element 25 based on the usage pattern determined by thecontroller 110. Exemplary techniques for controlling the operation of theheating element 25 in such an embodiment will described in more detail hereinbelow. - In this regard, the
control logic 115 initially enters into a learn mode and, while operating in the learn mode, attempts to maintain the tank's water temperature within a desired temperature range by activating theheating element 25 when the water temperature within thetank 17 falls below a temperature threshold, which may be a default threshold or may be defined by user inputs received from theuser interface 145. In addition, while in the learn mode, thecontrol logic 115 preferably attempts to determine water usage patterns. In this regard, thecontrol logic 115 tracks the water usage of thetank 17 for a specified amount of time. For illustrative purposes, assume that the specified amount of time that thecontrol logic 115 remains in the learn mode tracking water usage is one week. However, it should be noted that other time periods are possible in other embodiments. - Moreover, for each day of the week, the
control logic 115 preferably monitors the state of theheating element 25 to determine when theheating element 25 is in an activation state, and thecontrol logic 115 defines theusage history 161 based on this monitoring. In an exemplary embodiment, each day of the week is partitioned into various time periods (e.g., hours), also referred to herein as “time slots,” and data indicative of the water usage for each time slot is stored in theusage history 161. Although other partition times are possible, assume that thecontrol logic 115 is configured to partition each day into hours and to monitor the water usage of thetank 17 accordingly, as will be described in more detail hereinbelow. - For reasons previously set forth hereinabove, the amount of heat generated by the
heating element 25 during a particular hour generally indicates the amount of water usage that occurs during the particular hour. In this regard, as described above, when water usage is low (i.e., when only a small amount of heated water is drawn from the tank 17), a significant amount of water already heated by theheating element 25 remains in thetank 17, and the temperature of the water within thetank 17 is not likely to rapidly decrease. Thus, the total activation time of theheating element 25 should be relatively low. - However, when water usage is high (i.e., when a large amount of heated water is drawn from the tank17), a significant amount of water heated by the
heating element 25 is drawn from thetank 17 and replenished with unheated water from thepipe 21. Therefore, the temperature of the water in thetank 17 tends to rapidly decrease causing the total activation time of theheating element 25 to significantly lengthen. - Moreover, the
control logic 115 for each hour of each day preferably stores, in theusage history 161, data indicative of a total activation time for theheating element 25. By analyzing this data, thecontrol logic 115 can determine which hours during the week correspond to low usage time periods and which hours correspond to high usage time periods. In particular, if the total activation time for a particular hour exceeds a predefined time threshold, then the particular hour is classified as a high usage time period or in other words, is associated with a high usage pattern. Otherwise, the particular hour is classified as a low usage time period or, in other words, is associated with a low usage pattern. As will be described in more detail hereafter, the usage history data may be utilized to control the temperature threshold or thresholds used to activate and deactivate theheating element 25 such that thesystem 100 operates in an efficient manner. - In this regard, after determining the
usage history 161, thecontrol logic 115 preferably places thecontroller 110 into an operational mode in which thecontrol logic 115 adjusts or otherwise selects the temperature threshold or thresholds for activating and/or deactivating theheating element 25 based on theusage history 161 gleaned from the learn mode. As an example, theusage history 161 may define a week's usage schedule of thesystem 100. More specifically, as described above, theusage history 161 in such an embodiment may associate each hour of a week with data indicative of whether thecontrol logic 115 detected a low usage pattern or a high usage pattern during the same hour of the week while in the learn mode. Each time the hour of the week repeats for subsequent weeks, thecontrol logic 115 utilizes, based on the hour's associated usage pattern, a particular water temperature threshold for controlling when theheating element 25 is activated. For example, if the associated usage pattern indicates low usage, thecontrol logic 115 preferably utilizes a low temperature threshold (e.g., 110 degrees Fahrenheit). However, if the associated usage pattern indicates high usage, thecontrol logic 115 preferably utilizes a higher temperature threshold (e.g., 140 degrees Fahrenheit). - Thus, the usage history schedule defined by the
data 161 corresponds to a schedule of temperature thresholds that may be used to control theheating element 25. If desired, thecontrol logic 110 may define such a threshold schedule and store data indicative of this schedule in theusage history 161. Thelogic 110 may then control theheating element 25 based on either the usage schedule or the temperature threshold schedule. - To better illustrate the foregoing, assume that between 7:00 a.m. and 8:00 a.m. on a Wednesday during the learn mode, the
control logic 115 detects a high usage pattern based on the total activation time of theheating element 25 during this hour (i.e., the total activation time falls below the time threshold). For each Wednesday thereafter between 7:00 a.m. and 8:00 a.m. while thecontroller 110 is in the operational mode, thecontrol logic 115 preferably utilizes a high temperature threshold to control activation of theheating element 25. In this regard, during the aforementioned hour of each Wednesday, thecontrol logic 115 preferably activates theheating element 25 when the water temperature measured by thetemperature sensor 152 is less than the high temperature threshold. Further, thecontrol logic 115 may deactivate theheating element 25 when the measured water temperature exceeds the high temperature threshold. Alternatively, in order to provide hysteresis, thecontrol logic 115 may deactivate theheating element 25 when the measured water temperatures exceeds a threshold that is slightly higher than the aforementioned high temperature threshold. - However, if the
control logic 115 instead detects a low usage pattern during the Wednesday of the learn mode between 7:00 a.m. and 8:00 a.m. (i.e., the total activation time of theheating element 25 exceeds the time threshold), then thecontrol logic 115 utilizes a low temperature threshold to control activation of theheating element 25 between 7:00 a.m. and 8:00 a.m. on each Wednesday during the operational mode. In this regard, during the aforementioned hour of each Wednesday, thecontrol logic 115 preferably activates theheating element 25 when the water temperature measured by thetemperature sensor 152 is less than the low temperature threshold. Further, thecontrol logic 115 may deactivate theheating element 25 when the measured water temperature exceeds the low temperature threshold. Alternatively, in order to provide hysteresis, thecontrol logic 115 may deactivate theheating element 25 when the measured water temperatures exceeds a threshold that is slightly higher than the aforementioned low temperature threshold. - By implementing the foregoing techniques, a lower temperature threshold for activating the
heating element 25 is utilized during time periods that correspond to low usage patterns, as indicated by theusage history 161, and a higher temperature threshold for activating theheating element 25 is utilized during time periods that correspond to high usage patterns, as indicated by theusage history 161. As a result, the overall operational costs and, in particular, the energy costs associated with thesystem 100 can be lowered without significantly impacting the system's performance thereby resulting in asystem 100 that is more efficient and less costly. - Note that the usage patterns indicated by the
usage history 161 based on measurements taken during the learn mode may, for some time periods, represent a poor estimate of the actual usage pattern experienced during the operational mode. For example, during the learn mode, a significant amount of water usage may occur for a particular hour of the week (e.g., Wednesday between 7:00 a.m. and 8:00 a.m.). Therefore, during the operational mode, this same hour of the week may be treated as a high usage time period, and the high temperature threshold may be utilized to control activation of theheating element 25. - However, the high water usage for this particular hour of the week during the learn mode may turn out to have been more of an anomaly than a regular occurrence. Thus, it is possible for low water usage to actually occur during the particular hour of the week for most weeks once the operational mode is begun. Further, it is possible for the actual usage pattern of the
tank 17 to change such that time periods indicated as high usage become regular periods of low usage and vice versa. - The
control logic 115 is preferably configured to continue monitoring the water usage of thesystem 100 even after transitioning into the operational mode. Moreover, if thecontrol logic 115 detects that the actual usage for a particular hour of the week does not regularly correspond to the type of usage indicated by theusage history 161, thecontrol logic 115 may modify theusage history 161 such that the usage pattern for the particular hour of the week is changed. Thus, in the foregoing example, thecontrol logic 115 may modify theusage history 161 to change the usage pattern for the aforementioned hour of the week (e.g., Wednesday between 7:00 a.m. and 8:00 a.m.) from a high usage to a low usage. Thus, for the particular hour of the week for subsequent weeks, a low temperature threshold is preferably utilized to control the activation of theheating element 25. - Note that, in an effort to prevent the
control logic 115 from changing theusage history 161 in response to an anomaly in the usage pattern, thecontrol logic 115 may be configured to modify theusage history 161, as described above, only if the number of detected usage misclassifications for a particular time period or time slot exceeds a predetermined threshold. A “usage misclassification” refers to an instance where the actual usage pattern for a time period fails to correspond to the type of usage indicated for the time period by theusage history 161. Further, if a relatively large number of usage misclassifications are defined by the usage history 161 (e.g., if the detected number of usage misclassifications exceeds a threshold), thecontrol logic 115 may revert back into the learn mode in order to make another attempt to define theusage history 161 such that theusage history 161 is a more accurate estimate of the weekly usage pattern that will be encountered. - Note that it is possible for the learn mode to continue once the operational mode begins (i.e., the learn mode and the operational mode may simultaneously occur), making reverting back into the learn mode unnecessary. Further, rather than characterizing a time period (e.g., an hour of the week) as a high usage period or a low usage period based on a single trial in the learn mode, multiple occurrences of the time period may be monitored and the results may be averaged. For example, it is possible for the
controller 110 to remain in the learn mode for a month. The total activation time measured between 8:00 a.m. and 9:00 a.m. for each Wednesday during this month may be averaged, and the aforementioned time period or time slot (i.e., Wednesday between 8:00 a.m. and 9:00 p.m.) may be characterized based on the averaged total activation time. - It should also be noted that it is not necessary for there to only be two monitored states of pattern usage. For example, rather than just monitoring the operation of the
system 100 for low or high water usage patterns, it is possible to monitor the operation of thesystem 100 for three (e.g., low, medium, or high) water usage patterns. Each such category may be respectively characterized by higher total activation times. For example, an hour of the week in which the total activation time of theheating element 25 is below a low time threshold may be associated with a low usage pattern by theusage history 161. Furthermore, an hour of the week in which the total activation time of theheating element 25 is above the low time threshold but below a high time threshold may be associated with a medium usage pattern, and an hour of the week in which the total activation time of theheating element 25 is above the high time threshold may be associated with a high usage pattern. - Further, the
control logic 115 may be configured to utilize a different temperature threshold for controlling activation of theheating element 25 for each of the aforementioned categories. For example, for an hour of the week associated with a low usage pattern, a low temperature threshold may be employed by thecontrol logic 115 to control activation of theheating element 25, thereby maintaining the water temperature in a low temperature range. For an hour of the week associated with a medium usage pattern, a medium temperature threshold, which is higher than the aforedescribed low temperature threshold, may be employed by thecontrol logic 115 to control activation of theheating element 25, thereby maintaining the water temperature in a higher temperature range. For an hour of the week associated with a high usage pattern, a high temperature threshold, which is higher than the aforedescribed medium temperature threshold, may be employed by thecontrol logic 115 to control activation of theheating element 25, thereby maintaining the water temperature in yet a higher temperature range. The monitored states may be further increased to a number higher than three states, if desired. - In addition, during consecutive time periods associated with low usage patterns by the
usage history 161, thecontrol logic 115, according to the techniques described above, preferably controls the activation of theheating element 25 based on a low temperature threshold. Thus, the water temperature of thetank 17 is maintained within a lower temperature range as compared to other time periods that are associated with high usage patterns. Due to prolonged periods of maintaining the water within thetank 17 within a lower temperature range, bacteria may begin to develop in the water. To ensure that bacteria levels within thetank 17 remain within acceptable levels, thecontrol logic 115 may be configured to ensure that the water within thetank 17 is raised to a sufficient temperature for a sufficient amount of time to substantially kill bacteria that may be growing within thetank 17. As an example, thecontrol logic 115, once a week, may be configured to utilize (regardless of the usage pattern defined by the usage history 161) a high temperature threshold (e.g., 150 degrees Fahrenheit) such that the water within thetank 17 is maintained within a high temperature range for a sufficient amount of time to ensure that enough bacteria is killed to keep the bacteria within thetank 17 within acceptable levels. - In another example, the
control logic 115 may detect how long the temperature of the water remains below a predetermined temperature threshold. If the amount of time exceeds a predetermined time threshold, then thecontrol logic 115 may activate theheating element 25 for a sufficient amount of time to sufficiently heat the water for killing bacteria. Various other techniques for ensuring that bacteria growth remains within acceptable margins are possible. - An exemplary operation of the
controller 110 according to the learn mode and operational mode described above will now be described in more detail with reference to FIGS. 15-19. For illustrative purposes, assume that thecontroller 110 partitions each day into hours, as described above, and assume that thecontroller 110 monitors and controls the state of theheating element 25 on an hourly basis, as will be described hereafter. Note that each partitioned hour will be generally be referred to as a time slot. However, it should be noted that time slots of other durations may be utilized in other embodiments. - In addition, to better illustrate hysteresis of temperature thresholds, assume that (for any given moment in time) two thresholds, a lower threshold and an upper threshold, are used to control the activation and deactivation, respectively, of the
heating element 25. The upper threshold is preferably slightly higher (e.g., by 5 degrees Fahrenheit) relative to the lower threshold. As will be described in more detail hereafter, the upper and lower thresholds used for a particular time slot during the operational mode are dependent on the usage pattern associated with the time slot by theusage history 161. - Initially, the
control logic 115 enters into the learn mode and begins monitoring the water usage of thetank 17. In this regard, after entering the learn mode, thecontrol logic 115 may wait until the beginning of the first time slot (e.g., wait for the top of the next hour), as shown byblock 502 of FIG. 15, before beginning the monitoring process. After beginning the monitoring process, thecontrol logic 115 sets or identifies an upper and lower threshold to be used for controlling theheating element 25 during the learn mode, as shown byblock 505. These thresholds may be default thresholds or may be controlled by a user of thesystem 100. As an example, inblock 505, the lower threshold may be set to 135 degrees Fahrenheit, and the upper threshold may be set to 140 degrees Fahrenheit. - In
block 508, thecontrol logic 115 takes a temperature reading of the water within thetank 17 via the temperature sensor 152 (FIG. 6B). As shown byblock 511, thecontrol logic 115 then determines whether the sensed temperature of the water is below the lower threshold. If not, thecontrol logic 115 refrains from activating theheating element 25. Instead, thecontrol logic 115 determines inblock 515 whether the current time slot has expired. In the present example, the current time period expires at the top of the next hour. - For example, if a “yes” determination is made in
block 502 at 8:00 a.m., then the current time slot begins at 8:00 a.m. and expires at 9:00 a.m. Thus, in performingblock 515 in such an example, thecontrol logic 115 may determine whether 9:00 a.m. has been reached. If 9:00 a.m. has not been reached and the current time period has, therefore, not expired, thecontrol logic 115 takes another temperature reading inblock 508 and continues monitoring for the current time slot. However, if the current time period has expired, thecontrol logic 115 determines inblock 518 the total amount of time, if any, that theheating element 25 was activated during the expired time slot. Techniques for determining this total amount of time, referred to as the “total activation time,” will be described in more detail. If the total activation time is less than a predetermined threshold, then thecontrol logic 115 classifies the expired time slot as a low water usage time slot, as shown byblocks control logic 115 classifies the expired time slot as a high water usage time slot, as shown byblocks - After classifying the expired time slot, the
control logic 115 determines inblock 535 whether all of the time slots for an entire week have been monitored and classified. If so, thecontrol logic 115 transitions to the operational mode, as shown byblock 538, and the learn mode ends. If not, thecontrol logic 115 begins monitoring the next time slot (e.g., the time slot beginning at 9:00 a.m. in the aforementioned example), as shown byblock 541. - If the
control logic 115 determines inblock 511 that the temperature just sensed inblock 508 is less than the lower threshold, thecontrol logic 115 activates theheating element 25 and begins tracking the activation time of theheating element 25, as shown byblocks block 552, thecontrol logic 115 takes a new temperature reading and then determines, inblock 555, whether the temperature sensed by this new reading is greater than the upper threshold. If so, thecontrol logic 115 stops tracking the activation time and determines a value indicative of the amount of time that elapsed betweenblocks 547 and 559 (i.e., indicative of the approximate amount of time that theheating element 25 was activated). As shown byblocks control logic 115 then stores the value in theusage history 161 and deactivates theheating element 25. Thecontrol logic 115 also takes a new temperature reading in block 508 (FIG. 15) and continues monitoring the current time slot. - If the
control logic 115 determines inblock 555 that the temperature sensed by the new temperature reading is less than the upper threshold, thecontrol logic 115 refrains from deactivating theheating element 25. Instead, thecontrol logic 115 determines whether the current time slot has expired, as shown byblock 564. If the current time period has not expired, thecontrol logic 115 returns to block 552. However, if the current time slot has expired, thecontrol logic 115 stops tracking the activation time and a value indicative of the amount of time that elapsed betweenblocks 547 and 571 (i.e., indicative of the approximate amount of time that theheating element 25 was activated.). As shown byblocks control logic 115 then stores this value and determines the total activation time for the current time slot, which has now expired. The total activation time corresponds to a sum of all of the values stored during the expired time slot viablocks block 573 is less than a time threshold, thecontrol logic 115 classifies the expired time slot as a low water usage time slot, as shown byblocks control logic 115 classifies the expired time slot as a high water usage time slot, as shown byblocks - After classifying the expired time slot, the
control logic 115 determines inblock 588 whether all of the time slots for an entire week have been monitored and classified. If so, thecontrol logic 115 transitions to the operational mode, as shown byblock 592, and the learn mode ends. If not, thecontrol logic 115 begins monitoring the next time slot according to the same techniques described above, as shown byblock 596. - Moreover, once the learn mode is complete, each time slot for an entire week has preferably been classified, and the classifications of the time slots are indicated by the data defining the
usage history 161. As an example, FIG. 17 depicts an exemplary table 599 that may be defined by theusage history 161 once thecontrol logic 115 has completed the learn mode. As shown by FIG. 17, each time slot may be classified as either a high water usage time slot or a low water usage time slot depending on the total amount of water usage that occurred for corresponding times during the learn mode. - After entering the operational mode, the
control logic 115, as shown byblock 602 of FIG. 18, may wait for the next time slot to begin before initiating the monitoring and control process depicted by FIGS. 18 and 19. Upon initiating this process, thecontrol logic 115 sets an upper and lower threshold depending on the classification of the current time slot, as indicated by theusage history 161. In this regard, if the current time slot is a low water usage time slot, as indicated by theusage history 161, thecontrol logic 115 preferably sets the upper and lower thresholds according to a low (as compared to thresholds associated with high water usage time slots) set of thresholds. As an example, thecontrol logic 115 may set the lower and upper thresholds to a first set of thresholds (e.g., 110 degrees Fahrenheit and 115 degrees Fahrenheit, respectively) if the current time slot is a low water usage time slot. However, if the current time slot is a high water usage time slot, as indicated by theusage history 161, then thecontrol logic 115 preferably sets the lower and upper thresholds to a second set of higher thresholds (e.g., 145 degrees Fahrenheit and 150 degree Fahrenheit, respectively). - For example, assume that the operational mode begins on a Tuesday at 10:00 a.m. As indicated by FIG. 17, such a time slot is classified as low water usage. Therefore, the
control logic 115, inblock 604, sets the upper and lower thresholds to the first set of lower thresholds (e.g., 110 degrees Fahrenheit and 115 degrees Fahrenheit, respectively) and uses the first set of lower thresholds to control theheating element 25, as will be described in more detail hereinbelow. In another example, assume that the operational mode begins on a Tuesday at 8:00 a.m. As indicated by FIG. 17, such a time slot is classified as high water usage. Therefore, thecontrol logic 115, inblock 604, sets the upper and lower thresholds to the second set of higher thresholds (e.g., 145 degrees Fahrenheit and 150 degree Fahrenheit, respectively) and uses the second set of higher thresholds to control theheating element 25, as will be described in more detail hereinbelow. Note that the upper and lower thresholds may be “set” by loading the thresholds into a particular register, by modifying a pointer to point to the thresholds, or by implementing any other suitable technique for indicating that these thresholds are to be used for controlling the activation of theheating element 25 during the current time slot. - In
block 608, thecontrol logic 115 takes a new temperature reading via thetemperature sensor 152. If the temperature sensed inblock 608 exceeds the lower threshold set inblock 604, then thecontrol logic 115 refrains from activating theheating element 25. Instead, thecontrol logic 115 determines whether the current time slot has expired, as shown byblocks control logic 115 returns to block 608. However, if the current time period has expired, thecontrol logic 115 determines the total activation time for the expired time slot, as shown byblock 619. Techniques for determining the total activation time will be described in more detail hereafter. The total activation time refers to the total amount of time that theheating element 25 was activated during the current time slot. Thecontrol logic 115 then compares, inblock 622, the total activation time to a time threshold, which is preferably the same time threshold used inblocks 521 and 577 (FIGS. 15 and 16) of the learn mode. - If the total activation time is less than the time threshold, then the expired time slot experienced low water usage. Thus, the
control logic 115, inblock 625, checks to determine whether theusage history 161 indeed indicates that the expired time slot is associated with low water usage. If so, then theusage history 161 has correctly predicted the expected water usage for the expired time slot. Thus, thecontrol logic 115 begins monitoring the next time slot, as shown byblock 631, and returns to block 604 to set the upper and lower thresholds for the next time slot based on theusage history 161. However, if theusage history 161 indicates that the expired time slot is associated with high water usage, then theusage history 161 has incorrectly predicted the expected water usage for the expired time slot. In other words, theusage history 161, based on the actual water usage experienced during the expired time slot, has misclassified the time slot. In such a situation, thecontrol logic 115 preferably logs or otherwise indicates the misclassification inblock 634. If a sufficiently high number of misclassifications are logged within a specified time period (i.e., if the frequency of misclassifications is high), then thecontrol logic 115 may determine inblock 637 to revert back to the learn mode in an attempt to redefine theusage history 161 such that it better predicts the time slot classifications. In response to such a determination, thecontrol logic 115 transitions from the operational mode to the learn mode and repeats the process depicted by FIGS. 15 and 16, as shown byblock 642. - If a determination is made in
block 622 that the total activation time exceeds the time threshold, then the expired time slot experienced high water usage. Thus, thecontrol logic 115, inblock 645, checks to determine whether theusage history 161 indeed indicates that the expired time slot is associated with high water usage. If so, then theusage history 161 has correctly predicted the expected water usage for the expired time slot. Thus, thecontrol logic 115 begins monitoring the next time slot, as shown byblock 631, and returns to block 604 to set the upper and lower thresholds for the next time slot based on theusage history 161. However, if theusage history 161 indicates that the expired time slot is associated with low water usage, then theusage history 161 has incorrectly predicted the expected water usage for the expired time slot. In such a situation, the control logic preferably logs or otherwise indicates the misclassification inblock 634 and then determines whether to revert back to the learn mode inblock 637 according to the techniques described above. - If the
control logic 115 determines inblock 612 that the temperature just sensed inblock 608 is less than the lower threshold, thecontrol logic 115 activates theheating element 25 and begins tracking the activation time of theheating element 25, as shown byblocks block 661, thecontrol logic 115 takes a new temperature reading and then determines, inblock 665, whether the temperature sensed by this new reading is greater than the upper threshold. If so, thecontrol logic 115 stops tracking the activation time and determines a value indicative of the amount of time that elapsed betweenblocks 665 and 668 (i.e., indicative of the approximate amount of time that theheating element 25 was activated). As shown byblocks control logic 115 then stores the value in theusage history 161 and deactivates theheating element 25. Thecontrol logic 115 also takes a new temperature reading in block 608 (FIG. 18) and continues monitoring the current time slot. - If the
control logic 115 determines inblock 665 that the temperature sensed by the new temperature reading is less than the upper threshold, thecontrol logic 115 refrains from deactivating theheating element 25. Instead, thecontrol logic 115 determines whether the current time slot has expired, as shown byblock 675. If the current time period has not expired, thecontrol logic 115 returns to block 661. However, if the current time slot has expired, thecontrol logic 115 stops tracking the activation time and determines a value indicative of the amount of time that elapsed betweenblocks 655 and 682 (i.e., indicative of the approximate amount of time that theheating element 25 was activated). As shown byblocks control logic 115 then stores this value and determines the total activation time for the current time slot, which has now expired. The total activation time corresponds to a sum of all of the values stored during the expired time slot viablocks control logic 115 then compares, inblock 686, the total activation time to a time threshold, which is preferably the same time threshold used inblocks 521 and 577 (FIGS. 15 and 16) of the learn mode. - If the total activation time is less than the time threshold, then the expired time slot experienced low water usage. Thus, the
control logic 115, inblock 688, checks to determine whether theusage history 161 indeed indicates that the expired time slot is associated with low water usage. If so, then theusage history 161 has correctly predicted the expected water usage for the expired time slot. Thus, thecontrol logic 115 begins monitoring the next time slot, as shown byblocks block 693 is preferably identical to block 604 (FIG. 18). - However, if the
usage history 161 indicates that the expired time slot is associated with high water usage, then theusage history 161 has incorrectly predicted the expected water usage for the expired time slot. In such a situation, thecontrol logic 115 preferably logs or otherwise indicates the misclassification inblock 695. If a sufficiently high number of misclassifications are logged within a specified time period (i.e., if the frequency of misclassifications is high), then thecontrol logic 115 may determine inblock 697 to revert back to the learn mode in an attempt to redefine theusage history 161 such that it better predicts the time slot classifications. In response to such a determination, thecontrol logic 115 transitions from the operational mode to the learn mode and repeats the process depicted by FIGS. 15 and 16, as shown byblock 699. - If a determination is made in
block 686 that the total activation time exceeds the time threshold, then the expired time slot experienced high water usage. Thus, thecontrol logic 115, inblock 701, checks to determine whether theusage history 161 indeed indicates that the expired time slot is associated with high water usage. If so, then theusage history 161 has correctly predicted the expected water usage for the expired time slot. Thus, thecontrol logic 115 begins monitoring the next time slot, as shown byblocks usage history 161 indicates that the expired time slot is associated with low water usage, then theusage history 161 has incorrectly predicted the expected water usage for the expired time slot. In such a situation, the control logic preferably logs or otherwise indicates the misclassification inblock 695 and then determines whether to revert back to the learn mode inblock 697. - It should be noted that the
controller 310 for controlling the temperature of water within aliquid cooling system 300, similar to thecontroller 110 described above, may be configured to operate in a learn mode and an operational mode. It should be apparent to one of ordinary skill in the art, upon examining this disclosure, that a methodology similar to the one depicted by FIGS. 15, 16, 18, and 19 may be utilized to implement such acooling system 300. Indeed, FIGS. 20-23 depict an exemplary methodology that may be used by thecontroller 310 for controlling the activation and deactivation of acooling element 305. As can be seen by comparing FIGS. 20-23 to FIGS. 15-19, the methodology depicted by FIGS. 20-23 is substantially similar to the one depicted by FIGS. 15-19. However, in FIGS. 20-23, blocks 711-718 are respectively performed in lieu ofblocks - It should be further noted that the categorizing of time slots may be based on temperature values in lieu of or in addition to temperature control element activation times. In this regard, the temperature of the water within the
tank 17 tends to rapidly decrease during times of high water usage for reasons previously set forth above. Thus, the temperature values sensed by thetemperature sensor 152 may be used to detect time periods of high water usage. More specifically, thecontrol logic temperature sensor 152 during the time slot is relatively high, and thecontrol logic temperature sensor 152 during the time slot is relatively low. - FIGS. 24 and 25 depict an exemplary methodology that may be employed by the
control logic 115 to classify time slots based on sensed temperature values. In this regard, as shown byblocks control logic 115 sets an upper temperature threshold and a lower temperature threshold after beginning the learn mode. Then, thecontrol logic 115 takes and stores a new temperature reading, as shown byblocks temperature sensor 152. If the new reading is below the lower temperature threshold set inblock 703, then thecontrol logic 115 activates theheating element 25, as shown byblocks block 703, thecontrol logic 115 deactivates theheating element 25, as shown byblocks 709 and 710. As shown byblock 711, thecontrol logic 115 continues implementing blocks 705-710 until the current time slot expires. - Once the time slot expires, the
control logic 115 preferably determines, based on the temperature readings stored inblock 706, varies rates of change of the temperatures sensed by thetemperature sensor 152 during the expired time period, as shown byblock 712. As an example, thecontrol logic 115 may determine the rate of temperature change (ΔT) for some fixed interval (e.g., every x minutes during the expired time slot, where x is any real number between 0 and 60 but preferably between 0 and a number significantly smaller than 60, such as 10, for example). Each such rate of temperature change may then be compared to a threshold to determine whether the expired time slot should be characterized as a high usage time slot or a low usage time slot. In particular, if any of the rates of change exceeds the threshold, then thecontrol logic 115 may classify the expired time slot as a high usage time slot, as shown byblocks control logic 115 may classify the expired time slot as a low usage time slot, as shown byblocks control logic 115 preferably stores, in theusage history 161, data indicative of the time slot's classification. - As shown by
blocks control logic 115 preferably exits the learn mode and enters the operational mode, as shown byblocks control logic 115, upon entering the operational mode, performs blocks 723-733 of FIG. 25 similar to blocks 703-713 of FIG. 24. However, inblock 704, thecontrol logic 115 sets the upper and lower thresholds for the current time slot based on the classification of the current time slot, as indicated by theusage history 161. As an example, if the current time slot is classified as a high usage slot by theusage history 161, thecontrol logic 115 preferably selects upper and lower thresholds that are respectively higher than the thresholds selected when the current time slot is classified as a low usage time slot. - Further, a “yes” determination in
block 733 indicates that the current time slot experienced high water usage. Thus, thecontrol logic 115 determines inblock 735 whether the expired time slot is classified as a high usage time slot by theusage history 161. If so, theusage history 161 correctly predicted the actual water usage for the expired time slot, and thecontrol logic 115 begins monitoring for the next time slot, as shown byblock 734. However, if the expired time slot is classified as a low usage time slot by theusage history 161, then theusage history 161 incorrectly predicted the actual water usage for the expired time slot. Therefore, thecontrol logic 115 logs the misclassification inblock 736, and thecontrol logic 115 may then determine whether to revert back to the learn mode, as shown byblocks - Conversely, a “no” determination in
block 733 indicates that the current time slot experienced low water usage. Thus, thecontrol logic 115 determines inblock 741 whether the expired time slot is classified as a low usage time slot by theusage history 161. If so, theusage history 161 correctly predicted the actual water usage for the expired time slot, and thecontrol logic 115 begins monitoring for the next time slot, as shown byblock 734. However, if the expired time slot is classified as a low usage time slot by theusage history 161, then theusage history 161 incorrectly predicted the actual water usage for the expired time slot. Therefore, thecontrol logic 115 logs the misclassification inblock 736, and thecontrol logic 115 may then determine whether to revert back to the learn mode, as shown byblocks cooling element 305, if desired. - In yet another example, the
control logic temperature sensor 152 rather than the rate of change of the sensed temperature. In this regard, during times of high water usage, the temperature of the water within thetank 17 is likely to reach a lower value than in times of low water usage. Thus, thecontrol logic - In particular, the
control logic 115 may be configured to classify a time slot as a high usage time slot if the lowest temperature value or a value close to the lowest temperature value sensed during the time slot falls below a specified threshold. If such a temperature value is higher than the threshold, then thecontrol logic 115 may be configured to classify the time slot as a low usage time slot. Further, thecontrol logic 315 ofcooling system 300 may be configured to classify a time slot as a high usage time slot if the highest temperature value or a value close to the highest temperature value sensed during the time slot exceeds a specified threshold. If such a temperature values is lower than the threshold, then thecontrol logic 315 may be configured to classify the time slot as a low usage time slot. - Additionally, the
control logic temperature control elements - Furthermore, the thresholds compared to the aforementioned parameters for determining water usage may be predefined, defined by a user, or dynamically determined by the
control logic control logic control logic temperature sensor 152 and determine that the rate of temperature change usually remains within a particular range over time. It may be assumed that rates of temperature change toward the lower end of the range occur during low usage time periods and that the rates of temperature change toward the upper end of the range occur during high usage time periods. Thus, thecontrol logic control logic blocks - In another example where the
logic control logic control logic control logic control logic 115 may classify a time slot as a high usage time slot if the total activation time of itsheating element 25 exceeds the threshold and may classify the time slot as a low usage time slot if the total activation time of itsheating element 25 falls below the threshold. - In another example where the
logic 115 uses absolute temperatures to classify time slots, thelogic 115 may be configured to determine a value indicative of the lowest temperature detected by thetemperature sensor 152 over a specified time interval. It may be assumed that such a value is detected during a high usage time period. Thus, thecontrol logic 115 may set a threshold to some value slightly higher than foregoing determined value and may use this threshold to classify time slots. In this regard, if the temperature of the water falls below this threshold during a particular time slot, thecontrol logic 115 may be configured to classify the time slot as a high usage time slot. Otherwise, the time slot may be classified as a low usage time slot. - Similarly, the
logic 315 may be configured to determine a value indicative of the highest temperature detected by thetemperature sensor 152 over a specified time interval. It may be assumed that such a value is detected during a high usage time period. Thus, thecontrol logic 315 may set a threshold to some value slightly lower than foregoing determined value and may use this threshold to classify time slots. In this regard, if the temperature of the water exceeds this threshold during a particular time slot, thecontrol logic 315 may be configured to classify the time slot as a high usage time slot. Otherwise, the time slot may be classified as a low usage time slot. - As set forth hereinabove, a value indicative of the resistance of the
heating element 25 may be measured and compared to a threshold to determine when failure of theheating element 25 is imminent. When imminent failure of theheating element 25 is detected, a warning may be provided in order to enable the problem to be proactively addressed. - Furthermore, similar techniques may be used to predict when failure of a
cooling element 305 is imminent and to provide a warning when it is determined that failure of thecooling element 305 is imminent. In this regard, an increase in the resistance of acooling element 305 may indicate that failure of thecooling element 305 is imminent. Therefore, a monitoring element 162 (FIG. 12) may be used to determine a value indicative of the resistance of thecooling element 305, and thecontrol logic 315 may compare this value to a threshold to determine whether failure of thecooling element 305 is imminent and, therefore, whether a warning should be provided. Note that other techniques for determining when failure of aheating element 25 orcooling element 305 are possible. - It should also be noted that it is not necessary for the
control logic heating element 25 or cooling element 305) and controlling the activation/deactivation state of the temperature control element as described herein. More specifically, it is possible for thecontrol logic monitoring element 162, to monitor the state (e.g., resistance) of atemperature control element temperature control element temperature control element control logic temperature control element temperature control element - Indeed, FIGS. 26 and 27 depict embodiments where control of the activation and deactivation of a temperature control element is retained by a
conventional controller 28 while amonitoring system temperature control element monitoring systems - In this regard, FIG. 28 depicts an embodiment where a
conventional controller 28 controls activation of aheating element 25 and where amonitoring element 162 andcontrol logic 767 determine when failure of theheating element 25 is imminent. More particularly, themonitoring element 162, inblock 771 of FIG. 28, preferably determines a value indicative of the heating element's resistance, and thecontrol logic 115 preferably compares this value to a threshold. The threshold is preferably set such that when the determined value exceeds the threshold, failure of theheating element 25 is imminent. Thus, when the determined value exceeds the threshold, thecontrol logic 767 controls the state of auser interface 145 such that a warning regarding the imminent failure of theheating element 25 is conveyed to a user, as shown byblocks 773 and 774 of FIG. 28. As an example, theuser interface 145 may comprise an LED (not shown) that is normally “off” (i.e., does not emit light) when failure of theheating element 25 is not imminent. When thecontrol logic 767 detects an imminent failure of theheating element 25, thecontrol logic 767 may activate the LED such that it emits light. In such an example, the emission of light from the LED is indicative of an imminent failure of theheating element 25. - Similarly, FIG. 27 depicts an embodiment where a
conventional controller 28 controls activation of acooling element 305 and where amonitoring element 162 andcontrol logic 767 determine when failure of thecooling element 305 is imminent. More particularly, themonitoring element 162, inblock 771 of FIG. 28, preferably determines a value indicative of the cooling element's resistance, and thecontrol logic 767 preferably compares this value to a threshold. The threshold is preferably set such that when the determined value exceeds the threshold, failure of thecooling element 305 is imminent. Thus, when the determined value exceeds the threshold, thecontrol logic 767 controls the state of auser interface 145 such that a warning regarding the imminent failure of thecooling element 305 is conveyed to a user, as shown byblocks 773 and 774 of FIG. 28. As an example, theuser interface 145 may comprise an LED (not shown) that is normally “off” (i.e., does not emit light) when failure of thecooling element 305 is not imminent. When thecontrol logic 767 detects an imminent failure of thecooling element 305, thecontrol logic 767 may activate the LED such that it emits light. In such an example, the emission of light from the LED is indicative of an imminent failure of thecooling element 305. - Of course, it is not necessary for a
conventional controller 28 to control the activation and deactivation of thetemperature control element control logic 767. According to the techniques previously described hereinabove, thecontrol logic 767 used to monitor atemperature control element temperature control element control logic 767 may be implemented via hardware, software, or any combination thereof. When implemented in software, thecontrol logic 767 may be stored on a computer-readable medium. - It should be further noted that it is not necessary for the value compared to a threshold in block773 of FIG. 28 to indicate the magnitude of the temperature control element's resistance. For example, as previously described hereinabove, it is possible for measured current values or voltage values to be indicative of the resistance of the temperature control element. In another example, the
monitoring element 162 may be configured to measure the change in the temperature control element's resistance over time. A threshold may be set such that failure of thetemperature control element control logic 767 may be configured to convey a warning when the measured value, which represents a difference in the temperature control element's resistance over time, exceeds the foregoing threshold. Various other techniques for predicting when failure of thetemperature control element - As previously described hereinabove, the
control logic tank 17 to be maintained at or close to a desired temperature (e.g., 130 degrees Fahrenheit), thecontrol logic control logic 115 and/or 315 may be configured to control hysteresis based on theusage history 161. - As an example, the
control logic usage history 161 and a lesser hysteresis effect for time slots associated with high water usage. For example, for time slots of low water usage, thecontrol logic 115 may activate and deactivate one or moretemperature control elements 25 when the temperature of the water respectively exceeds and falls below the temperature thresholds of 115 degrees Fahrenheit and 125 degrees Fahrenheit, thereby providing a 10 degree differential between the two thresholds. However, for time slots of high water usage, thecontrol logic 115 may activate and deactivate one or moretemperature control elements 25 when the temperature of the water exceeds and falls below 142 degrees Fahrenheit and 146 degrees Fahrenheit, thereby providing only a 4 degree differential between the two thresholds. - Note that there are various advantages that may be achieved by controlling the threshold hysteresis, as described above. For example, the threshold hysteresis may be controlled in order to increase the efficiency and/or performance of the
system tank 17 to be approximately 130 degrees Fahrenheit (e.g., a user sets the desired temperature to approximately 130 degrees Fahrenheit) for a particular time period. During such a time period, thecontrol logic 115 of theliquid heating system 100 may be configured to activate theheating element 25 based on a lower temperature threshold of 125 degrees Fahrenheit and to deactivate theheating element 25 based on an upper threshold temperature of 135 degrees Fahrenheit, thereby providing a ten degree hysteresis effect. However, if a high usage event (i.e., an event drawing a significant amount of water from the tank 17) occurs, it is possible for the temperature within thetank 17 to fall to undesirably low levels substantially below the lower temperature threshold. - Moreover, if temperature thresholds providing less hysteresis are used in lieu of the foregoing thresholds, then the lowest temperature to which the water falls due to the same high usage event may be higher than the lowest temperature for an embodiment using temperature thresholds that provide greater hysteresis. In this regard, assume that a lower temperature threshold of 128 degrees and an upper temperature threshold of 132 degrees are used to control the state of the
heating element 25, thereby providing only a four degree hysteresis effect. In such an embodiment, theheating element 25 is activated more frequently than in the previously described embodiment (i.e., the embodiment having a ten degree hysteresis effect). Indeed, thecontrol logic 115 is likely to respond (e.g., activate the heating element 25) more quickly in response to a high usage event. As a result, the lowest temperature reached by the water due to the high usage event may be higher for the embodiment having temperature thresholds that provide a smaller hysteresis effect (i.e., that have a lower temperature difference between the upper threshold and the lower threshold). - Thus, for time periods or time slots associated with high usage patterns by the
usage history 161, thecontrol logic 115 preferably decreases the hysteresis (i.e., decreases the temperature difference between the upper threshold and lower threshold) of the thresholds used to control theheating element 25 in addition to or in lieu of increasing the average temperature of the thresholds. Further, for time periods or time slots associated with high usage patterns by theusage history 161, thecontrol logic 315 preferably decreases the hysteresis effect of the thresholds used to control thecooling element 305 in addition to or in lieu of decreasing the average temperature of the thresholds. - As an example, in implementing
block control logic 115 may select an upper threshold and a lower threshold having a high temperature average and a low hysteresis, as shown byblocks usage history 161. Note that the temperature average (Tavg) may be calculated according to the equation: - T avg=(T upper +T lower)/2
- and the hysteresis (HYS) may be calculated according to the equation:
- HYS=T upper −T lower.
- Further, the
control logic 115 may select an upper threshold and a lower threshold having a low temperature average and a high hysteresis, as shown byblocks usage history 161. Of course, in other embodiments, thecontrol logic 115 may be configured to only adjust the temperature average or the hysteresis based on the classification of the current time slot, if desired. In this regard, it is not necessary to select the temperature thresholds such that both the temperature average and the hysteresis of the selected thresholds are different for different time slot classifications. - Conversely, in implementing
block control logic 315 may select an upper threshold and a lower threshold having a low temperature average and a low hysteresis, as shown byblocks usage history 161. Further, thecontrol logic 315 may select an upper threshold and a lower threshold having a high temperature average and a high hysteresis, as shown byblocks usage history 161. Of course, in other embodiments, thecontrol logic 315 may be configured to only adjust the temperature average or the hysteresis based on the classification of the current time slot, if desired. - Note that the
control logic 115 and/or 315 may also change the hysteresis for time slots of the same classification. For example, two time slots may both be classified as high water usage time slots. Nevertheless, during the learn mode, one of the time slots experience a higher amount of water usage than the other, and the parameters used to classify time slots (e.g., total activation times oftemperature control elements control logic 115 and/or 315 provides different hysteresis for the two time slots. - As an example, assume that it is desirable to maintain the temperature within the tank at approximately 140 degrees Fahrenheit for high water usage time slots and that the time slots are classified based on total activation times of one or more
temperature control elements control logic temperature control elements control logic temperature control element control logic temperature control elements tank 17 when the tank's water falls below and exceeds 138 degrees Fahrenheit and 141 degrees Fahrenheit. - In another example, absolute temperatures or temperature change rates sensed by the
temperature sensor 152 may provide a basis for controlling or setting the hysteresis. In this regard, during a time slot of exceptionally high water use, the temperature of the water within thetank 17 of thesystem 100 may fall to an undesirably low level even though the time slot may be classified as a high usage time slot and, therefore, be associated with relatively high temperature thresholds for activating and deactivating thetemperature control element - Moreover, if the
control logic 115 determines that, during a particular time slot, the temperature of the water fell below a specified threshold or that the temperature change rate exceeded a specified threshold, thecontrol logic 115 may be configured to set the temperature thresholds for future occurrences of the particular time slot such that a particularly small hysteresis is realized for the time slot. By using such thresholds to control aheating element 25, thecontrol logic 115 is likely to activate theheating element 25 more quickly in response to a high usage event occurring during the time slot, thereby helping to prevent the water temperature from falling as far when the expected high usage event occurs. - Note that various other methodologies for selecting a desired hysteresis bounds for activating and deactivating a
temperature control element - It should be noted that multiple
temperature control elements single tank 17, particularly if thetank 17 is relatively large requiring significant activation of the temperature control elements over time. Asingle controller temperature control elements multiple controllers temperature control elements temperature control elements - When a
controller temperature control element controller temperature control elements tank 17 or may activate a plurality of thetemperature control elements tank 17. Note that for determining water usage history for atank 17, thecontroller temperature control elements tank 17 within theheating system 100, thecontroller 110 preferably sums the activation times, for the time slot, of eachheating element 25 within thetank 17. Further, to determine the total activation time of a time slot for atank 17 within thecooling system 300, thecontroller 310 preferably sums the activation times, for the time slot, of eachcooling element 305 within thetank 17. - Note that it is possible for conventional heating and cooling systems employing multiple temperature control elements and controllers to be retrofitted with one or more controllers in accordance with the present invention. As an example, refer to FIG. 31, which depicts a
conventional heating system 797 havingmultiple heating elements conventional controller controllers controller 110 may be used to control bothheating elements heating elements controllers 110 that are added to thesystem 797. - In one exemplary embodiment, one of the
controllers other controller system 800 that is constructed by removing one of thecontrollers 28 a of FIG. 31 and replacing it with acontroller 810 configured to operate in accordance with the principles of the present invention. In this regard, thecontroller 810 may control one of theheating elements 25 a according to the techniques previously described hereinabove, and thecontroller 28 b may control theother heating element 25 b. - In addition, the
controller 810 of FIG. 32 may be configured to control the operation of theheating element 25 b that is also controlled byconventional controller 28 b. FIG. 33 depicts an exemplary configuration of thecontroller 810 for such an embodiment. As can be seen by comparing FIG. 33 to FIG. 6B, thecontroller 810 of FIG. 31 may be similar to thecontroller 110 of FIG. 6B. Indeed, thecontrol logic 815 of thecontroller 810 may control the operation of theheating element 25 a via theswitch 156 via techniques previously described hereinabove. Further, thecontroller 810 preferably also comprises anotherswitch 812 used by thecontrol logic 815 to control the operational state of theswitch 25 b. In this regard, rather than connecting thepower source 39 directly to thecontroller 28 b, thepower source 39 is connected to thecontroller 28 b through theswitch 812. Note that thecontrol logic 815, similar to thecontrol logic 115 of FIG. 6B, may be implemented in hardware, software, or any combination thereof. - Moreover, if the
heating element 25 b is to be activated, thecontrol logic 815 may transmit, to theswitch 812, a control signal that causes theswitch 812 to close thereby causing electrical current to flow from thepower source 39 to thecontroller 28 b. As previously described above, theconventional controller 28 b is configured to activate theheating element 25 b if the water temperature sensed by thecontroller 28 b is below the threshold set for thecontroller 28 b. In such a situation, thecontroller 28 b allows electrical current from thepower source 39 to pass through thecontroller 28 b to theheating element 25 b provided that the water temperature measured by thecontroller 28 b is less than the threshold temperature utilized by thecontroller 28 b. To deactivate theheating element 25 b, thecontrol logic 815 may transmit, to theswitch 812, a control signal that causes theswitch 812 to open thereby preventing electrical current from flowing to theheating element 25 b from thepower source 39. In such a situation, theheating element 25 b is in a deactivation state. - Note that there are various methodologies that may be employed by the
controller 810 to control the activation state of theheating elements control logic 815 determines that the temperature of the water within thetank 17 has fallen below a threshold such that, according to the techniques described herein, the water is to be heated, thecontrol logic 815 may attempt to activate bothheating elements switches heating element switches control logic 815 determines that the temperature of the water within thetank 17 has exceeded a threshold such that, according to the techniques described herein, heating of the water is no longer desirable, thecontrol logic 815 preferably ensures that bothheating elements switches - Also, in another embodiment, the
control logic 815 may attempt to selectively activate oneheating element temperature sensor 152, is within one temperature range, and thecontrol logic 815 may attempt to activate bothheating elements control logic 815 may be configured to ensure that bothheating elements control logic 815 may be configured to selectively activate only oneheating element control logic 815 may be configured to attempt to activate bothheating elements - Note that depending on the configuration of the
system 800, simultaneous activation of bothheating elements such systems 800, it may be desirable for thecontrol logic 815 to attempt to activate only oneheating element - As shown by FIG. 33, a
monitoring element 874 may be employed to enable thecontrol logic 815 to verify activation of theheating element 25 b. In this regard, in the configuration shown by FIG. 33, it is possible for theconventional controller 28 b to prevent activation of theheating element 25 b even when theswitch 812 is placed in a closed state by thecontrol logic 815. In such a situation, it is possible for thecontrol logic 815 to misidentify the correct water usage pattern unless steps are taken to verify or ensure activation of theheating element 25 b. - In this regard, if the activation of the
heating element 25 b is not verified or ensured, it is possible for thecontrol logic 815 to place theswitch 812 into a closed state and to monitor the operation of thesystem 800 assuming that theheating element 25 b is in an activation state. If thecontroller 28 b, in reality, prevents activation of theheating element 25 b due to the temperature of the water not exceeding the temperature threshold being utilized by thecontroller 28 b, then it is possible for thecontrol logic 815 to miscalculate the total amount of actual activation time for theheating elements control logic 815 may mischaracterize a particular time period or time slot as a high usage time slot instead of properly characterizing the time slot as a low usage state. To prevent such an error, thecontrol logic 812, after placing theswitch 812 into a closed state, may verify that themonitoring element 874 actually detects current or a voltage before assuming that theheating element 25 b is in an activation state. - Thus, when calculating the total activation time for a particular time period or time slot, the
control logic 815 may sum the total amount of time that theswitch 156 has been put in a closed state during the time period and the total amount of time that theswitch 812 has been put in a closed state during the time period. These two sums may be added to produce a total activation time. Thecontrol logic 815 may then sum the total amount of time that theswitch 812 was closed without current being detected by themonitoring element 874. This sum is indicative of the total time period that thecontrol logic 815 attempted to activate theheating element 25 b, but activation of theheating element 25 b was prevented by thecontroller 28 b. Moreover, thecontrol logic 815 may subtract the foregoing sum from the total activation time to yield an actual total activation time that accurately reflects the total amount of time that bothheating elements switch 812 is closed to the total activation time only if thecontrol logic 815 is able to verify, via themonitoring element 162, that theheating element 25 b is activated. Note that other techniques for ensuring an accurate total activation time calculation are possible. - It should be noted that the
controller 810 may be configured to utilize a plurality of parameters to classify and monitor time slots. In this regard, the plurality of parameters may be utilized to provide a better indication of usage patterns as compared to the utilization of any single parameter. For example, assume that theconventional controller 28 b is allowed to remain and to control theheating element 25 b, as described above for the foregoing embodiment depicted by FIG. 32. Before classifying time slots, thecontroller 810 may monitor the state of various parameters to determine patterns indicative of idle time periods (i.e., time periods when no or extremely low water usage occurs), low usage time periods, and high usage time periods. - For example, the
control logic 815 of thecontroller 810 may monitor the temperatures sensed by the controller'stemperature sensor 152 and the activation states of upper andlower heating elements sensor 152. Further, if similar thresholds are used to control both of theelements lower element 25 b and no or extremely short activation times of theupper element 25 a. Further, periods of low usage are likely to be characterized by more erratic temperature change rates and slightly longer activation times of thelower heating element 25 b, and periods of high usage are likely to be characterized by a combination of high temperature change rates and comparatively long activation times of bothheating elements - Moreover, the foregoing parameters may be monitored and patterns indicative of idle time periods may be automatically identified. In this regard, relatively constant temperature change rates may be a key factor to identify such time periods. This is particularly true in embodiments where the amount of thermal loss associated with the
tank 17 may vary, for example, when thetank 17 is located outdoors or in a room, such as a garage, that is not insulated. In this regard, the amount of thermal loss may vary drastically depending on the time of day as atmospheric temperatures typically decrease at night or depending on the season of the year as atmospheric temperatures typically decrease in winter and increase in summer. Moreover, even though activation times of theelements 25 a and/or 25 b for idle time periods may vary due to atmospheric temperature fluctuations, a relatively constant temperature change rate over a short duration (e.g., less than approximately one hour) may indicate an idle time period regardless of the aforementioned atmospheric temperature fluctuations. Thus, thecontrol logic 815 may detect idle time periods by detecting when the temperature change rate sensed by thesensor 152 remains substantially constant and when the activation times of theelements - After detecting idle time periods, the behavior of the
heating elements heating elements control logic 815 may then use these various normal activation times as reference times to classify time slots such that the water usage classification determined by thecontrol logic 815 accounts for thermal loss variations. - To better illustrate the foregoing, assume that the activation time of the
lower heating element 25 b, in general, increases substantially during the night as compared to the day due to more significant thermal losses at night. In such an example, thecontrol logic 815 may mischaracterize a low usage pattern at night as a high usage pattern since the activation times of theheating elements control logic 815 may account for the foregoing effect. - As an example, when classifying a time slot during the day, the
control logic 815 may compare the total activation time of theelement 25 b to the total activation time of theelement 25 b measured during a known idle time period occurring close to the time slot (i.e., occurring during the day). Depending on the difference, thecontrol logic 115 may classify the time slot. In particular, thecontrol logic 815 may classify the time slot as a high usage time slot only if the difference is relatively large (e.g., exceeds a threshold). - Further, when classifying a time slot at night, the
control logic 815 may compare the total activation time of theelement 25 b for the time slot to the total activation time of theelement 25 b measured during a known idle time period occurring close to the time slot (i.e., occurring at night). Depending on the difference, thecontrol logic 815 may classify the time slot. By using reference activation times from idle time slots occurring during or close to the same time of day as a particular time slot being classified, the difference between the total activation time of the particular time slot and the reference activation time is a better indication of actual water usage. - To better illustrate the foregoing, assume that the
tank 17 experiences more significant thermal losses at night generally causing higher total activation times for theheating elements control logic 815 may monitor the temperature change rates sensed by thetemperature sensor 152 in order to identify idle time slots. In this regard, thecontrol logic 815 detects that a particular time slot is an idle time slot if the temperature change rate sensed by thesensor 152 remains relatively constant during the particular time slot. Further, by comparing sensed temperature change rates for the idle time slots, thecontrol logic 815 may discover that daytime idle time slots have constant temperature rate changes that generally fall within a first temperature range and that nighttime idle time slots have constant temperature rate changes that generally fall within a second temperature range, which is significantly higher than the first temperature range. - Thus, upon entering the learn mode, the
control logic 815 may select the activation time thresholds used inblocks control logic 815 may utilize a first activation threshold inblocks control logic 815 may utilize a second activation threshold inblocks tank 17. In particular, the first activation threshold may correspond to (e.g., be slightly higher than) the total activation threshold detected for a daytime idle time slot, and the second activation threshold may correspond to (e.g., be slightly higher than) the total activation threshold detected for a nighttime idle time slot. - It should be noted that similar techniques may be employed to account for varying thermal losses due to seasonal changes. In this regard, the
control logic 815 may detect that idle time periods for the same time of day are associated with greater temperature change rates during the winter months and with lesser temperature change rates during the summer months. Thus, thecontrol logic 815 may select the activation thresholds used inblocks control logic 815 may select lower total activation time thresholds for time slots in the summer months and higher total activation time thresholds for time slots in the winter months. Further, it should be emphasized that the foregoing techniques for accounting for thermal loss variations have been presented for illustrative purposes, and various other techniques for accounting for thermal loss variations are possible without departing from the principles of the present invention. - Indeed, it should be noted that idle time periods may be detected by monitoring parameters other than temperature change rates. For example, idle time periods may be detected by monitoring water temperature patterns or activation patterns of a
temperature control element control logic - Turning now to another exemplary embodiment of the present invention, both of the
conventional controllers liquid heating system 825, such as is depicted by FIG. 34. In particular, one of theconventional controllers 28 a is replaced with acontroller 830 in accordance with the present invention, and the otherconventional controller 28 b is replaced with acontrol module 832, which will be described in more detail hereinbelow. Note that thecontrol module 832 may reside on a base 51 (FIGS. 8 and 9), which can be easily connected to thetank 17 according to techniques described hereinabove in the context of connectingcontroller 110 to thetank 17 via thebase 51. - As shown by FIG. 35, the
controller 830 may be similar to thecontroller 810 of FIG. 33. Indeed, thecontroller 830 may comprisecontrol logic 835 for controlling the operation of theheating elements control logic 835 may be implemented in hardware, software, or any combination thereof. - According to the techniques previously described hereinabove, the
control logic 835 may activate and deactivate theheating elements control logic 835 may be configured to control the state of theheating element 25 a viaswitch 156 and may be configured to control the state of theheating element 25 b viaswitch 812, which may reside within thecontroller 830 or may reside within thecontrol module 832, as shown by FIG. 35. Further, thecontrol logic 835 may determine whether to activate or deactivate theheating elements control logic 815 of FIG. 33. - As shown by FIG. 35, the
control module 832 may comprise atemperature sensor 837 configured to detect water temperature at or close to the proximity of theheating element 25 b. Thecontrol logic 835 may be configured to activate and deactivate theheating element 25 a based on the temperatures sensed by thetemperature sensor 152, and thecontrol logic 835 may be configured to activate and deactivate theheating element 25 b based on the temperatures sensed by thetemperature sensor 837. In an alternative embodiment, thecontrol logic 835 may be configured to activate and deactivate both of theheating elements temperature sensors - Furthermore, the
control module 832 may also comprise amonitoring element 841 configured to detect when failure of thecontrol element 25 b is imminent according to techniques previously described hereinabove. When an imminent failure of thecontrol element 25 b is detected, thecontrol logic 835 may be configured to convey a warning to a user viauser interface 145. - Note that accounting for thermal loss variations may be simplified when temperature sensors are located close to both the bottom and top of the
tank 17. In this regard, the temperature change rate of both upper andlower sensors upper sensor 152 and alower temperature sensor 837, thecontrol logic 835 can determine water usage. - In this regard, similar temperature change rates, as sensed by the
upper sensor 152 and thelower sensor 837, indicate an idle time period. Slightly different temperature change rates, as sensed by theupper sensor 152 and thelower sensor 837, indicate low water usage, and significantly different temperature change rates, as sensed by theupper sensor 152 and thelower sensor 837, indicate high water usage. Thus, thecontrol logic 835 may be configured to determine the difference between temperature change rates detected by theupper sensor 152 and thelower sensor 837 and to classify a current time slot based on this difference. In this regard, if the difference exceeds a particular threshold, thecontrol logic 835 may classify the time slot as a high water usage time slot. Note that multiple temperature sensors may be used to classify time slots in the foregoing manner regardless of whethermultiple heating elements - It should be noted that techniques similar to those described above for controlling
multiple heating elements multiple cooling elements single controller 850 may be used to controlmultiple cooling elements multiple controllers 850 may be used to control different ones ofmultiple cooling elements controller 850 in accordance with the present invention and aconventional controller 928, then an exemplary configuration of thecontroller 850 may be similar to the previously described configuration ofcontroller 810 forsystem 800, as can be seen by comparing FIGS. 33 and 37. - In particular, the
control logic 852, which may be implemented in hardware, software, or any combination thereof, may control activation and deactivation of thecooling element 305 b by controlling the state of aswitch 932 similar to how the control logic 815 (FIG. 33) controls the operation of theheating element 25 b viaswitch 812. Further, thecontroller 850 may employ amonitoring element 934, similar to themonitoring element 874 of FIG. 33, in order to enable thecontrol logic 852 to verify that thecooling element 305 b is actually activated when theswitch 932 is closed. Thecontrol logic 852 then adds the time that theswitch 932 is closed to the total activation time associated with a particular time period or slot only if thecontrol logic 852 is able to verify, via themonitoring element 934, that thecooling element 305 b is activated. Various techniques for achieving the foregoing are possible such as, for example, summing the amount of time that theswitches switch 932 is closed without thecooling element 305 b being activated. Further, the techniques described above for accounting for thermal loss variations may be employed within a liquid cooling system in order to account for thermal loss variations associated with thetank 17 of the cooling system. - In addition, for embodiments employing multiple
temperature control elements temperature control elements elements temperature control elements elements temperature control element element temperature control element particular tank 17 is activated for substantially the same amount of time, the amount of time before failure of any one of theelements - Therefore, if
multiple heating elements tank 17, the logic 815 (FIG. 33) preferably maintains a running sum of the total lifetime activation of eachheating element logic 815 also attempts to selectively activate theheating elements heating element other heating elements multiple cooling elements particular tank 17, the logic 852 (FIG. 37) preferably maintains a running sum of the total life-time activation of eachcooling element logic 852 also attempts to selectively activate thecooling elements cooling element other cooling elements - There are various techniques that may be employed by the
control logic particular tank 17 remain substantially equal. FIG. 38 depicts an exemplary methodology to ensure that the total lifetime activation of the temperature control elements within aparticular tank 17 remain substantially equal. FIG. 38 will now be described in more detail assuming that thecontrol logic 815 is implementing the methodology of FIG. 33 in an effort to ensure that the total life-time activation ofmultiple heating elements tank 17 remain substantially equal. However, it should be noted that the same methodology may be implemented by thecontrol logic 852 to ensure that the total lifetime activation ofmultiple cooling elements tank 17 remain substantially equal. - In order to ensure that the total life-time activation of
multiple heating elements tank 17 remain substantially equal, thecontrol logic 815, for eachheating element block 941 of FIG. 38, thecontrol logic 815 initially sets the value of the activation sum for eachheating element control logic 815 preferably monitors the temperature of the water within thetank 17 and determines whenheating elements control logic 815 may employ techniques similar to those described hereinabove for determining whether theheating elements control logic 815 may determine to selectively activate and deactivateheating elements usage history 161 of theheating elements - Indeed, the methodology, depicted by FIGS. 15-19 may be employed to determine when the
heating elements blocks heating elements blocks heating elements logic 815 to determine whenheating elements control logic 815 may select which of theheating elements - In any event, when the
control logic 815 determines that the water within thetank 17 is to be heated (e.g., when the temperature of the water falls below a temperature threshold indicating that heating or additional heating of the water is to be initiated), thelogic 815 preferably selects, for activation, theheating element blocks heating element control logic 815 may randomly select onesuch heating element heating elements - As shown by blocks948 and 952, the
control logic 815 activates the selectedheating element heating element heating element - When the
control logic 815 determines heating of the water within thetank 17 is to be stopped or reduced (e.g., when the temperature of the water exceeds a threshold indicating that heating of the water is to be stopped or reduced), thelogic 815 preferably selects, for deactivation, the activatedheating element blocks heating element control logic 815 may randomly select onesuch heating element heating elements block 959, thecontrol logic 815 deactivates the selectedheating element control logic 815 then retrieves, inblock 962, the time value that was stored when the deactivatedheating element heating element block 964, thecontrol logic 815 adds the difference (i.e., the result of block 962) to the activation sum of the deactivatedelement element - Note that, when one of the
heating elements other heating elements heating elements heating elements heating elements heating elements block 941. - In addition, it should be noted that FIG. 38 depicts an exemplary methodology for ensuring that each of the
temperature control elements same tank 17 is activated for substantially the same amount of time over the life of thetemperature control elements - Although the present invention has been described above as a employing a
tank 17 to hold and dispense water, it should be noted that other types of liquids may be held and dispensed by thetank 17. Further, the temperature of such liquids may be controlled according to the same techniques described hereinabove for controlling the temperature of water within thetank 17. - In addition, it should be noted that it is not necessary for a
temperature control element heating element 25 is “deactivated” when the state of theelement 25 is controlled such that the amount of heat provided by theelement 25 is significantly reduced. Further, acooling element 305 is “deactivated” when the state of theelement 305 is controlled such that the amount of cooling provided by theelement 305 is significantly reduced. Similarly, aheating element 25 is “activated” when the state of theelement 25 is controlled such that the amount of heat provided by theelement 25 is significantly increased, and acooling element 305 is “activated” when the state of theelement 305 is controlled such that the amount of cooling provided by theelement 305 is significantly increased. - Moreover, the tank's water usage may be monitored via techniques other than those described hereinabove. For example, the tank's water usage may be monitored by tracking the amount of heating or cooling provided by the
temperature control elements tank 17. In this regard, rather than calculating total activation time of theheating elements 25, a value indicative of the total amount of heat provided by theheating elements 25 may be calculated for a particular time period in order to determine the water usage associated with the time period. In general, the more heat provided by theheating elements 25, the higher the water usage. Note that the amount of current provided to aheating element 25 may be monitored in order to determine a value indicative of an amount of heat generated by theheating element 25. Similarly, rather than calculating a total activation time of thecooling elements 305, a value indicative of the total amount of cooling provided by the cooling elements may be calculated for a particular time period in order to determine the water usage associated with the time period. - In another example, the amount of water drawn into or out of the
tank 17 may be tracked in order to monitor the tank's water usage. In this regard, at least one sensor (not shown) for detecting the amount of water passing through each inlet of thetank 17 and/or at least one sensor (not shown) for detecting the amount of water passing through each outlet of thetank 17 may be employed to track water usage. Other techniques for monitoring water usage are possible in yet other embodiments. - It should be emphasized that the above-described embodiments of the present invention, particularly, any “preferred” embodiments, are merely possible examples of implementations, merely set forth for a clear understanding of the principles of the invention. Many variations and modifications may be made to the above-described embodiment(s) of the invention without departing substantially from the spirit and principles of the invention. All such modifications and variations are intended to be included herein within the scope of this disclosure and the present invention and protected by the following claims.
Claims (36)
1. A system for controlling a temperature of a liquid residing within a tank, comprising:
at least one temperature sensor configured to detect temperatures of the liquid;
at least one temperature control element configured to alter a temperature of the liquid; and
logic configured to automatically establish different temperature thresholds for different time periods based on temperatures detected by the at least one temperature sensor, each of the different temperature thresholds associated with a different one of the time periods, the logic further configured to perform, for each of the time periods, a comparison between a temperature detected by the at least one temperature sensor and the associated temperature threshold and to control the temperature control element based on the comparison.
2. The system of claim 1 , wherein the logic is configured to monitor the at least one temperature control element and to establish the temperature thresholds based on the monitoring of the at least one temperature control element by the logic.
3. The system of claim 1 , wherein the logic is configured to assign each of the time periods a classification based on a value indicative of an amount of liquid drawn from the tank during a correlated time period, the logic further configured to establish the temperature thresholds based on the classifications assigned to the time periods by the logic.
4. The system of claim 3 , wherein the value is based on temperatures detected by the at least one temperature sensor.
5. The system of claim 3 , wherein the logic is configured to monitor the at least one temperature control element, and wherein the value is based on the monitoring of the at least on temperature control element by the logic.
6. The system of claim 1 , wherein the logic is configured to define a usage history of the tank based on temperatures detected by the at least one temperature sensor, the logic further configured to establish the temperature thresholds based on the usage history.
7. The system of claim 6 , wherein the logic is further configured to determine a rate of temperature change for the liquid based on temperatures detected by the at least one temperature sensor, the logic further configured to define the usage history based on the determined rate of temperature change.
8. The system of claim 6 , wherein the logic is further configured to identify an idle time period within the usage history based on temperatures detected by the at least one temperature sensor.
9. The system of claim 6 , wherein the logic is further configured to monitor the at least one temperature control element and to identify an idle time period within the usage history based on the monitoring of the at least one temperature control element by the logic.
10. A system for controlling a temperature of a liquid residing within a tank, comprising:
at least one temperature sensor configured to detect temperatures of the liquid;
at least one temperature control element configured to alter a temperature of the liquid; and
logic configured to monitor the temperature control element and to automatically establish different temperature thresholds for different time periods based on the monitoring of the at least one temperature control element by the logic, each of the different temperature thresholds associated with a different one of the time periods, the logic further configured to perform, for each of the time periods, a comparison between a temperature detected by the at least one temperature sensor and the associated temperature threshold and to control the at least one temperature control element based on the comparison.
11. The system of claim 10 , wherein the logic is configured to assign each of the time periods a classification based on a value indicative of an amount of liquid drawn from the tank during a correlated time period, the logic further configured to establish the temperature thresholds based on the classifications assigned to the time periods by the logic.
12. The system of claim 11 , wherein the value is based on temperatures detected by the at least one temperature sensor.
13. The system of claim 11 , wherein the value is based on the monitoring of the at least one temperature control element by the logic.
14. The system of claim 10 , wherein the logic is configured to define a usage history of the tank based on the monitoring of the at least one temperature control element by the logic, the logic further configured to establish the temperature thresholds based on the usage history.
15. The system of claim 14 , wherein the logic is further configured to identify an idle time period within the usage history based on temperatures detected by the at least one temperature sensor.
16. The system of claim 14 , wherein the logic is further configured to identify an idle time period within the usage history based on the monitoring of the at least one temperature control element by the logic.
17. A system for controlling a temperature of a liquid residing within a tank, comprising:
means for determining a usage history of the tank;
means for establishing different temperature thresholds for different time periods based on the usage history;
means for comparing, for each of the time periods, the associated temperature threshold and a detected temperature of the liquid;
means for altering a temperature of the liquid; and
means for controlling the altering means based on the comparing means.
18. The system of claim 17 , wherein the establishing means comprises a temperature sensor for detecting a temperature of the liquid.
19. The system of claim 17 , wherein the establishing means comprises a means for monitoring the altering means.
20. A method for controlling a temperature of a liquid residing within a tank, comprising the steps of:
detecting temperatures of the liquid;
establishing different temperature thresholds for different time periods based on temperatures detected in the detecting step, each of the different temperature thresholds associated with a different one of the time periods;
comparing, for each of the time periods, the associated temperature threshold and a temperature detected in the detecting step; and
altering a temperature of the liquid based on the comparing step.
21. The method of claim 20 , wherein the altering step comprises the step of activating at least one temperature control element, wherein the method further comprises the step of monitoring the at least one temperature control element, and wherein the establishing step is based on the monitoring step.
22. The method of claim 20 , further comprising the step of assigning each of the time periods a classification based on a value indicative of an amount of liquid drawn from the tank during a correlated time period, wherein the establishing step is based on the assigned classifications.
23. The method of claim 22 , wherein the value is based the detecting step.
24. The method of claim 22 , wherein the altering step comprises the step of activating at least one temperature control element, wherein the method further comprises the step of monitoring the at least one temperature control element, and wherein the value is based on the monitoring step.
25. The method of claim 20 , further comprising the step of defining a usage history of the tank based on the detecting step, wherein the establishing step is based on the usage history.
26. The method of claim 25 , further comprising the step of determining a rate of temperature change of the liquid based on the detecting step, wherein the defining step is based on the determined rate of temperature change.
27. The method of claim 25 , further comprising the step of identifying an idle time period within the usage history based on the detecting step.
28. The method of claim 25 , wherein the altering step comprises the step of activating at least one temperature control element, and wherein the method further comprises the steps of:
monitoring the at least one temperature control element; and
identifying an idle time period within the usage history based on the monitoring step.
29. A method for controlling a temperature of a liquid residing within a tank, comprising the steps of:
detecting temperatures of the liquid;
altering, via a temperature control element, a temperature of the liquid;
monitoring the temperature control element;
establishing different temperature thresholds for different time periods based on the monitoring step, each of the different temperature thresholds associated with a different one of the time periods;
comparing, for each of the time periods, the associated temperature threshold and a temperature detected in the detecting step; and
controlling the temperature control element based on the comparing step.
30. The method of claim 29 , further comprising the step of assigning each of the time periods a classification based on a value indicative of an amount of liquid drawn from the tank during a correlated time period, wherein the establishing step is based on the assigned classifications.
31. The method of claim 30 , wherein the value is based the detecting step.
32. The method of claim 30 , wherein the value is based on the monitoring step.
33. The method of claim 29 , further comprising the step of defining a usage history of the tank based on the monitoring step, wherein the establishing step is based on the usage history.
34. The method of claim 33 , further comprising the step of identifying an idle time period within the usage history based on the detecting step.
35. The method of claim 33 , further comprising the step of identifying an idle time period within the usage history based on the monitoring step.
36. The method of claim 29 , wherein the controlling step is performed such that the temperature control element heats the liquid.
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US10/852,032 US20040225414A1 (en) | 2001-11-15 | 2004-05-24 | System and method for controlling temperature of a liquid residing within a tank |
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US10/852,032 US20040225414A1 (en) | 2001-11-15 | 2004-05-24 | System and method for controlling temperature of a liquid residing within a tank |
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US10/295,364 Abandoned US20030093185A1 (en) | 2001-11-15 | 2002-11-15 | System and method for monitoring temperature control elements that are used for altering temperatures of liquids |
US10/772,032 Expired - Lifetime US7065431B2 (en) | 2001-11-15 | 2004-02-04 | System and method for controlling temperature of a liquid residing within a tank |
US10/852,032 Abandoned US20040225414A1 (en) | 2001-11-15 | 2004-05-24 | System and method for controlling temperature of a liquid residing within a tank |
US11/409,229 Expired - Fee Related US7603204B2 (en) | 2001-11-15 | 2006-04-21 | System and method for controlling temperature of a liquid residing within a tank |
US11/691,723 Expired - Fee Related US7672751B2 (en) | 2001-11-15 | 2007-03-27 | System and method for controlling temperature of a liquid residing within a tank |
US12/577,457 Expired - Fee Related US7881831B2 (en) | 2001-11-15 | 2009-10-12 | System and method for controlling temperature of a liquid residing within a tank |
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US10/298,135 Abandoned US20030093186A1 (en) | 2001-11-15 | 2002-11-15 | System and method for controlling temperature of a liquid residing within a tank |
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US10/772,032 Expired - Lifetime US7065431B2 (en) | 2001-11-15 | 2004-02-04 | System and method for controlling temperature of a liquid residing within a tank |
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US12/577,457 Expired - Fee Related US7881831B2 (en) | 2001-11-15 | 2009-10-12 | System and method for controlling temperature of a liquid residing within a tank |
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- 2002-11-15 WO PCT/US2002/036582 patent/WO2003044610A1/en not_active Application Discontinuation
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2004
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2006
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Cited By (20)
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US20070191994A1 (en) * | 2001-11-15 | 2007-08-16 | Patterson Wade C | System and method for controlling temperature of a liquid residing within a tank |
US20100030396A1 (en) * | 2001-11-15 | 2010-02-04 | Patterson Wade C | System and method for controlling temperature of a liquid residing within a tank |
US7672751B2 (en) | 2001-11-15 | 2010-03-02 | A. O. Smith Corporation | System and method for controlling temperature of a liquid residing within a tank |
US7881831B2 (en) | 2001-11-15 | 2011-02-01 | A. O. Smith Corporation | System and method for controlling temperature of a liquid residing within a tank |
US20070034169A1 (en) * | 2004-06-30 | 2007-02-15 | Phillips Terry G | System and method for preventing overheating of water within a water heater tank |
US8061308B2 (en) | 2004-06-30 | 2011-11-22 | A. O. Smith Corporation | System and method for preventing overheating of water within a water heater tank |
US8660701B2 (en) | 2004-08-26 | 2014-02-25 | A. O. Smith Corporation | Modular control system and method for water heaters |
US10240817B2 (en) | 2004-08-26 | 2019-03-26 | A. O. Smith Corporation | Modular control system and method for water heaters |
US9057534B2 (en) | 2004-08-26 | 2015-06-16 | A. O. Smith Corporation | Modular control system and method for water heaters |
US8977791B2 (en) | 2004-08-26 | 2015-03-10 | A. O. Smith Corporation | Modular control system and method for a water heater |
US20100082134A1 (en) * | 2004-08-26 | 2010-04-01 | Phillips Terry G | Modular control system and method for a water heater |
US8064757B2 (en) | 2005-05-11 | 2011-11-22 | A. O. Smith Corporation | System and method for estimating and indicating temperature characteristics of temperature controlled liquids |
US8887671B2 (en) | 2006-03-27 | 2014-11-18 | A. O. Smith Corporation | Water heating systems and methods |
US8245669B2 (en) | 2006-03-27 | 2012-08-21 | A. O. Smith Corporation | Water heating systems and methods |
US20070246557A1 (en) * | 2006-03-27 | 2007-10-25 | Phillips Terry G | Water heating systems and methods |
US20070246556A1 (en) * | 2006-03-27 | 2007-10-25 | Patterson Wade C | Water heating system and method |
US20070248143A1 (en) * | 2006-03-27 | 2007-10-25 | Phillips Terry G | Water heating systems and methods |
US8490684B2 (en) * | 2006-09-25 | 2013-07-23 | Kelk Ltd. | Device and method for adjusting temperature of fluid |
US20090236072A1 (en) * | 2006-09-25 | 2009-09-24 | Kelk Ltd. | Device and method for adjusting temperature of fluid |
US11085667B2 (en) * | 2014-12-22 | 2021-08-10 | Battelle Memorial Institute | Estimation of temperature states for an electric water heater from inferred resistance measurement |
Also Published As
Publication number | Publication date |
---|---|
US20070191994A1 (en) | 2007-08-16 |
WO2003044610A1 (en) | 2003-05-30 |
US7603204B2 (en) | 2009-10-13 |
US7672751B2 (en) | 2010-03-02 |
US20030093186A1 (en) | 2003-05-15 |
US20040158361A1 (en) | 2004-08-12 |
US20030091091A1 (en) | 2003-05-15 |
AU2002352705A1 (en) | 2003-06-10 |
CA2492003C (en) | 2013-03-19 |
US20030093185A1 (en) | 2003-05-15 |
US20060190141A1 (en) | 2006-08-24 |
US20100030396A1 (en) | 2010-02-04 |
US7065431B2 (en) | 2006-06-20 |
CA2492003A1 (en) | 2003-05-30 |
US7881831B2 (en) | 2011-02-01 |
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Legal Events
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STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- FAILURE TO RESPOND TO AN OFFICE ACTION |
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Owner name: A. O. SMITH CORPORATION, WISCONSIN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SYNAPSE, INC.;REEL/FRAME:022719/0435 Effective date: 20090521 Owner name: A. O. SMITH CORPORATION,WISCONSIN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:SYNAPSE, INC.;REEL/FRAME:022719/0435 Effective date: 20090521 |