HYDROGEN GAS BUILDUP PREVENTION IN HOT WATER HEATERS

Abstract

A hot water heater includes a controller, a hot water tank and a sensor operatively coupled to the hot water tank and the controller. The sensor is configured to detect use of hot water from the hot water tank. The controller is operative to determine an interval of non-use of hot water from the hot water tank; and enable a drain cycle to withdraw a portion of water from the hot water tank.

Description

BACKGROUND

The present disclosure generally relates to appliances, and more particularly to preventing hydrogen gas buildup in a hot water heater.

In a hot water heater system, hydrogen gas can form as a byproduct of chemical reactions caused by the metals used in the construction of the tanks, particularly when the water in the hot water tank is stagnant. Since hydrogen gas is not soluble in water, any hydrogen gas formed will remain in the water heater plumbing system, tending to rise to the highest locations in the plumbing system. The hydrogen gas can also be trapped in the lower levels of the plumbing system.

During normal or regular operation of the hot water heater system, the amount of hydrogen gas buildup will be minimal and will tend to be vented from the plumbing system as hot water is discharged from the hot water tank, either through the dispensing of hot water from a tap, or the use of hot water by an appliance, such as a dishwasher or washing machine. However, if the hot water heater system is inactive for an extended period of time, there is a potential for a buildup of hydrogen gas generated in the tank.

In order to avoid problems associated with hydrogen gas build up, it is generally recommended that when a hot water heater system has been stagnant for a period of time, such as for example two weeks, the hot water faucets be opened for several minutes to vent any hydrogen gas that may have accumulated during the period of non-use.

It would be advantageous to be able to automatically vent a hot water heater system of any potential hydrogen gas buildup during periods where the hot water heating system is not used regularly.

Accordingly, it would be desirable to provide a hot water heater system that addresses at least some of the problems identified above.

BRIEF DESCRIPTION OF THE INVENTION

As described herein, the exemplary embodiments overcome one or more of the above or other disadvantages known in the art.

One aspect of the exemplary embodiments relates to a hot water heater. In one embodiment, the hot water heater includes a controller, a hot water tank and a sensor operatively coupled to the hot water tank and the controller. The sensor is configured to detect withdrawal of hot water from the hot water tank. The controller is operative in response to the sensor to detect the occurrence of a stagnant state and initiate the withdrawal of hot water from the tank in response to such detection. A stagnant state results when the time interval between withdrawals of water from the tank is greater than a predetermined interval selected to prevent or limit the generation of hydrogen gas in the hot water tank.

This and other aspects and advantages of the exemplary embodiments will become apparent from the following detailed description considered in conjunction with the accompanying drawings. It is to be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims. Moreover, the drawings are not necessarily drawn to scale and that, unless otherwise indicated, they are merely intended to conceptually illustrate the structures and procedures described herein. In addition, any suitable size, shape or type of elements or materials could be used.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1 is a schematic diagram of an exemplary hot water heater system incorporating aspects of the present disclosure.

FIG. 2 is a flow chart illustrating an exemplary process flow incorporating aspects of the present disclosure.

FIG. 3 is a schematic diagram of an exemplary hot water heater system incorporating aspect of the present disclosure.

FIG. 4 is a schematic diagram of another exemplary hot water heater system incorporating aspect of the present disclosure.

FIG. 5 is a flow chart illustrating an exemplary process flow incorporating aspects of the present disclosure.

FIG. 6 is a flow chart illustrating another exemplary process flow incorporating aspects of the present disclosure.

DETAILED DESCRIPTION OF THE EXEMPLARY EMBODIMENTS OF THE DISCLOSURE

Referring to FIG. 1, an exemplary hot water heater system incorporating aspects of the disclosed embodiments is generally designated by reference numeral 100. The aspects of the disclosed embodiments are directed to a hot water heater system that detects when the hot water heater has not been used for a period of time and automatically drains enough hot water from the hot water tank to prevent or satisfactorily limit the generation of hydrogen gas in the tank. Although the embodiments disclosed herein will be described with reference to the drawings, it should be understood that the embodiments disclosed can be embodied in many alternate forms. In addition, any suitable size, shape or type of elements or materials could be used.

As shown in FIG. 1, the hot water heater system 100 generally includes a hot water heater 10 and a controller 20. In the embodiment of FIG. 1, the hot water heater 10 includes a reservoir or water storage tank 12 for storing water and a heat source 14 for heating the water stored in the tank 12. The hot water heater 10 includes an inlet 16 for receiving water into the tank 12. The inlet 16 is typically connected to a water supply line for a home or building. The hot water heater 10 also includes an outlet 18 for supplying hot water from the tank 12 to the hot water portions of the plumbing system 30 to which the hot water heater 10 is connected. The plumbing system 30 can be part of a residential, commercial or other water plumbing system that incorporates a hot water heater and is generally used to provide a connection between the hot water heater 10 and one or more electrically operated appliances 40 that use hot water. Although the plumbing system 30 is referred to in FIG. 1, in one embodiment, there can be a direct connection from the hot water heater 10 to the appliance 40.

While the aspects of the disclosed embodiments can be applied to any system that incorporates a hot water heater 10, for the purposes of the description herein, such system will be described as a “plumbing system” or “home.” The hot water heater 10 can be any suitable hot water heater including an electric, gas or hybrid hot water heater. In one embodiment, the heat source 14 can comprise an electric heating element such as a resistive-type heating element, a gas burner such as a propane or natural gas burner, a heat pump type of heater, or any other type of heat source.

As briefly mentioned in the Background, in hot water systems including systems of the type illustrated in FIG. 1, when hot water has not been dispensed or discharged from the hot water tank 12 for an extended period of time, hydrogen gas can form as a byproduct of chemical reactions caused by the metals used in the construction of the tanks. If left unchecked, hydrogen gas can buildup in the hot water heater system 100 to an undesirable level. The aspects of the disclosed embodiments are configured to detect conditions conducive to hydrogen generation, before any significant hydrogen gas buildup has occurred. The time period for such conditions to develop or occur in a hot water heater 10 can vary, depending on one or more factors. Examples of such factors, can include, but are not limited to the area of the world and the elevation. Many water heaters come with a warning that hydrogen gas build up can occur after about two weeks of inactivity.

In the embodiment shown in FIG. 1, the controller 20 is provided for controlling aspects of the hot water heater system 100. In one embodiment, the controller 20 is configured to detect the occurrence of condition of the water in the tank hereinafter referred to as a stagnant state. A stagnant state is detected when the interval of time between successive withdrawals or dispensing of water from the tank exceeds a predetermined period which is preferably selected to be of a duration that is long enough to avoid short cycling or nuisance tripping, but short enough to prevent the generation of such gas or at least limit the build up of such gas in the plumbing system to an acceptable level. For purposes of the examples herein, the pre-determined period is selected to be not greater than fourteen days, although shorter or longer time periods can be contemplated, depending upon the particular hot water heater system application. When the controller 20 detects a stagnant state of the hot water heater 10, the controller 20 is configured to automatically enable a drain cycle of the hot water heater 10. A drain cycle of the hot water heater 10, as that term is used herein, generally refers to a cycle of the hot water heater system 100 that causes hot water to be discharged from the tank 12, and flow through the plumbing system so that hydrogen gas build up cannot occur. A drain cycle can typically be initiated by opening a hot water valve of the plumbing system 30 or running an electrical appliance that is coupled to the plumbing system 30 to withdraw water from the hot water heater. The aspects of the disclosed embodiments are generally directed to automatically flushing the hot water tank 12 and associated plumbing lines when the hot water in the hot water heater tank 12 has not or will not be used for an extended period of time in order to prevent hydrogen gas buildup.

In one embodiment, the controller 20 comprises or is coupled to or is in communication with a processor(s) that is operable to monitor and control the flow of hot water from the hot water tank 12, as well as execute the processes that are generally described herein. In one embodiment the controller 20 is comprised of machine-readable instructions that are executable by one or more processors or other suitable processing device(s). The processor(s) can include program code to perform particular tasks and/or data manipulations, as are generally described herein. In one embodiment, the processor(s) can include or be coupled to a memory and input/output devices. The memory typically comprises both non-volatile memory, such as semiconductor type random access memory, and non-volatile memory such as a magnetic computer disk.

As is shown in FIG. 1, in one embodiment, the controller 20 is coupled to a user interface 22. The user interface 22 can comprise any suitable control or display that will allow a user to program, set and adjust the functions and settings of the hot water heater system 100, as are generally described herein. In one embodiment, the user interface 22 comprises or includes a control panel 26 that allows a user to program the system 100 and set the hydrogen gas buildup prevention functions as are further described herein. These functions can include, but are not limited to, setting a hot water heater stagnation time period threshold, setting a vacation mode and programming the system 100 to activate an appliance 40 connected to the system 100 to enable a drain cycle. In one embodiment, the user interface 22 can include a display interface, such as a touch screen display. In alternate embodiments, the user interface 22 can include buttons or switches for manipulating and programming the settings of the system 100. In one embodiment, the user interface 22 comprises or is part of a control panel for the hot water heater 10. Alternatively, the user interface 22 can be part of a control panel for an appliance 40. The user interface 22 can also be located remotely from the hot water heater 10, and can be accessible through a computing device or a web based interface. For example, aspects of the disclosed embodiments allow the controller 20 and control panel 26 to be accessed and programmed using a mobile communication device 330, as will be further described herein.

As is illustrated in FIG. 1, in one embodiment, the system 100 includes one or more sensors 24 for monitoring the state of the hot water in the hot water tank 12. The sensor 24 is generally configured to provide one or more signals or commands to the controller 20 that will allow the controller 20 to detect a stagnant state, because water has not been withdrawn from the hot water tank 12 for an extended period of time. In one embodiment, the sensor(s) 24 can comprises water flow monitors for detecting the flow of water into, out of, or both into and out of the hot water tank 12. In this example, the sensor(s) 24 can be coupled to the tank 12 or one or both of the inlet 16 and outlet 18.

In another embodiment, the sensor(s) 24 can be configured to sense the activation of one or more loads of the hot water heater 10. The loads of the hot water heater 10 generally include any appliance 40 that utilizes hot water. In one embodiment, the sensor(s) 24 can also comprise a temperature measuring device that is configured to monitor and detect a temperature of the water in the hot water tank 12.

The sensor 24 can be coupled to the controller 20 via a wired or wireless communication connection or interface. For purposes of the description herein, wireless communication connections and interfaces can include, but are not limited to, wireless radio, WiFi, Bluetooth, Zigbee and ethernet wireless type devices and interfaces. In one embodiment, the sensor 24 can be integrated with the controller 20.

In one embodiment, the controller 20 can include, or be coupled to a clock/timer device 28. The clock/timer device 28 can comprise any suitable timing device that is capable of monitoring and providing real time data, providing an event clock or timing mechanism, or providing both real time and event timing capabilities. In one embodiment, the controller 20 is configured to use the clock/timer 28 to determine a stagnant state of the hot water heater 10, such as by determining an elapsed time since a last use of the hot water from the hot water tank 12. Although the clock/timer 28 will generally be referred to as a single clock or timing device, the clock/timer 28 can also include multiple clock/timer device. For example, the clock/timer 28 could include one clock/timer for monitoring an elapsed time since a last use of the hot water from the tank 12, and another clock/timer for monitoring a time since a change in state of the sensor 24.

By providing information corresponding to the state of the hot water in the hot water tank 12 to the controller 20, a stagnant state of the hot water tank 12 can be determined FIG. 2 illustrates one example of a process flow incorporating aspects of the disclosed embodiments. In one embodiment, the controller 20 monitors 202 the state of the sensor(s) 24. Based on an indication from the sensor 24, the controller 20 is configured to determine 204 the time or time interval since the last use or flow of hot water from the tank 12, the use being one that is sufficient to drain enough hot water from the hot water tank to prevent or satisfactorily limit the generation of hydrogen gas in the tank. Generally, a flow amounting to approximately 0.5 to 1 gallons, or lasting approximately one to five minutes is a sufficient use.

In one embodiment, determining the time, or a time interval, since the last use of the hot water from the tank 12 comprises comparing a current clock time to a clock time of last use. A difference between these two values can be used to determine if a pre-determined time threshold or interval has been exceeded. Alternatively, the clock/timer 28 can start a counter that is used to determine an elapsed period since the last use. The controller 20 is configured to determine 206 whether a predetermined time period or threshold time interval of non-use is met or exceeded. Since it is generally understood that the potential for hydrogen gas buildup in a typical domestic hot water heater system can occur after approximately two weeks of non-use, the predetermined time period or threshold time interval is selected to be not greater than two weeks. For example, a period of a few days or one week can be used as the threshold time interval. Alternatively, any suitable time period can be used that will prevent hydrogen gas buildup in the hot water heater 10 can be used as the predetermined time period or threshold time interval.

If it is determined 206 that the predetermined time period has not elapsed, in one embodiment, the controller 20 continues to monitor 202 the state of the sensor(s) 24. If the predetermined time period has elapsed, indicating that the hot water heater 10 is in a stagnant state, the controller 20 is configured to enable 208 a drain cycle of the hot water tank 12. The drain cycle is generally configured to allow a sufficient amount of hot water to be drawn from the hot water tank 12 in order to prevent any hydrogen gas buildup. In one embodiment, the amount of hot water drained from the hot water tank 12 in a drain cycle is in the range of approximately 0.5 to and including 1.0 gallons. In alternate embodiments, any suitable amount of hot water can be dispensed from the hot water tank 12 to ensure that any hydrogen gas that has built up in the tank 12 and plumbing system 30 has been vented or dispersed.

In one embodiment, the drain cycle can be an activation of one or more of the appliances 40 coupled to the hot water heater system 100 to withdraw water from the hot water heater. For example, in one embodiment, when the controller 20 determines 206 that there has not been any use of hot water from the tank 12 for a period of approximately one week, the controller 20, which is communicatively coupled to the hot water consuming appliances 40, can activate an appliance such as a dishwasher, to run through a hot water cycle for a few minutes and then drain the water. The cycle should be sufficient to drain an amount of water from the tank 12 that will also flush any built-up hydrogen gas from the tank 12. After the cycle is complete, the controller 20 continues to monitor 202 and measure 204 the time period of inactivity.

One embodiment of a system 300 incorporating aspects of the disclosed embodiments is illustrated in FIG. 3. In this example, the controller 20 is communicatively coupled, via wired or wireless connections, to the hot water heater 10, sensor 24, timer 28, the one or more appliances 40 and communication gateway 320. In this example, the appliances 40 include a dishwasher 42, a washer 44 and an electronically controlled hot water discharge valve 46. In one embodiment, the hot water discharge valve 46 is an electronically controlled valve coupled to a hot water faucet or other outlet. Activation of the valve 46 can allow hot water to be discharged from the hot water tank 12. Each of the appliances 40 is a consumer of hot water from the hot water heater 10, and when operated will allow hot water to be discharged from the hot water tank 12 shown in FIG. 1. The hot water is discharged from the hot water heater 10 to each of the appliances 40 through the plumbing system 30 that fluidly couples the hot water heater 10 to each of the appliances 40 in a manner that will be generally understood.

In the embodiment shown in FIG. 3, the controller 20 is communicatively coupled to a communication gateway or interface 320. The communication gateway 320 allows the homeowner or other user to communicate with, program and operate the controller 20 and hot water heater system 100 shown in FIG. 1 through one or both of a computing device 324 and mobile communication device 330. The communication connection between the device 324 and controller 20 can be via a wired or wireless connection, as is otherwise described herein. When using a mobile communication device 330, the communication gateway 320 allows the user to communicate with the controller 20 through a remote connection and network. In this example, the communication interface or gateway 320 includes a home router 322, a computing or communication device 324, a broadband communication interface or modem 326 and a communication network 328. The devices 324 and 330 can comprise any suitable computing or communication devices, such as for example, a home computer, a mobile phone, a smartphone, a pad or tablet type device. Generally, the devices 324 and 330 will comprise any device that is capable of communicating with the controller 20 over a wired or wireless connection, as are generally known, in a suitable communication format. The network 328 can comprise any suitable communication network, such as for example the Internet or a cellular communication network. In one embodiment, a user can utilize a mobile communication device 330, such as a smartphone, to communicate with the controller 20 to program the system 300 from a remote location to monitor the hot water system 100, detect a stagnation state of the hot water heater 10, and periodically cause hot water to be discharged from the hot water tank 12 to prevent hydrogen gas buildup.

In one embodiment, referring to FIG. 4, the hot water heater system 100 includes, is part of, or is coupled to a home energy gateway or manager (HEG) 50. The home energy manager 50 is communicatively coupled to one or more of the exemplary appliances 40 to initiate or activate a hot water consumption cycle of one or more of the appliances 40 to prevent hydrogen gas buildup. In one embodiment, the home energy manager 50 is part of a home energy management system. Home energy management (HEM) systems are generally used to reduce energy consumption in homes and buildings. A typical home energy management system is configured to communicate with and control electrical appliances in homes and buildings. These electrical appliances can include appliances 40 that make use of hot water from the hot water heater 10. Some functions of a home energy management system, and the home energy manager 50 are to create a network of appliances 40 in the home or building, monitor the usage of such appliances, record and store information, enable consumer interface with all appliances in the home, and set preferences and operation modes for the appliances. In the embodiment shown in FIG. 4, the home energy manager 50 is coupled to the controller 20 in a suitable manner, including wired or wireless connections. In alternate embodiments, the home energy manager 50 can be integrated with or comprise the controller 20, the user interface 22 or both the controller 20 and user interface 22, and include a connection to the sensor 24 as is generally described herein.

In one embodiment, appliances 40 that are communicatively coupled to the home energy manager 50 can be automatically controlled to run hot water, which will create water movement in the hot water tank 12. As an illustrative example, if a homeowner is expecting to be away from the home for an extended period of time, the homeowner can program the home energy manager 50 to activate one or more of the appliances 40 to run hot water at predetermined time intervals. At each time interval, an appliance 40, such as a dishwasher 42, can be controlled to withdraw a small amount of hot water from the hot water heater and then drain it. If the valves and drains of the appliances 40 cannot be separately controlled, the dishwasher 42 can be controlled to run through a suitable dish washing cycle(s) that uses hot water.

In one embodiment, the controller 20 and user interface 22 allow a user to program certain modes or states of the hot water system 100 that indicate periods of non-use and enable the automatic filling and draining of the hot water tank 12 to prevent hydrogen gas buildup. For example, in one embodiment, referring to FIG. 5, a vacation mode or state of the hot water heater system 100 can be detected or set 502. The term “vacation mode” generally refers to a programmable state of the hot water heater 10 that indicates that hot water from the hot water tank will not be regularly used. The aspects of the disclosed embodiments allow the hot water heater system 100 shown in FIG. 1, for example, to be programmed as part of the vacation mode, to activate a drain cycle of the hot water heater 10 at predetermined time intervals, without first needing to determine that the hot water heater 10 is in a stagnant state. In one embodiment, the vacation mode state can be set using the user interface 22 of FIG. 1 to program one or more of the hot water heater 10, an appliance 40 and controller 20. The vacation mode state will be recognized or detected by the controller 20. With reference to FIG. 3, in one embodiment, the vacation mode state can be set using one or both of the computing device 324 and mobile device 330.

In one embodiment, after the activation of the vacation mode state is detected 502, the clock/timer 28 is activated 504. This can include starting a counter that either counts up or counts down. In one embodiment, the controller 20 is configured to monitor 506 the elapsed time and determine 508 if the elapsed time exceeds a predetermined time interval. If yes, the controller 20 is configured to enable 510 a drain cycle, such as by enabling the activation of an appliance 40 to utilize hot water. In one embodiment, before enabling 510 the drain cycle, the controller 20 can confirm that the vacation mode is still set. Once the drain cycle is complete, the controller 20 can confirm that the vacation mode is still set 502 and reset or restart 504 the timer 28. If it is determined 508 that the elapsed time has not exceeded the predetermined time interval, the controller 20 continues to monitor 506 the elapsed time. In one embodiment, if the elapsed time has not exceeded the predetermined time interval, the controller 20 can confirm that the vacation mode is still set before continuing to monitor 506 the elapsed time.

Referring to FIG. 6, in an embodiment where the sensor 24 comprises a water temperature sensor, the controller 20 is configured to monitor 602 the temperature of the water in the hot water tank 12 in order to determine whether the hot water heater 10 is in a stagnant state. In this embodiment, the controller 20 can be configured to detect deviations or changes of the temperature of the hot water in the hot water tank 12. Temperature changes of the water in the hot water tank 12 that exceed a nominal or predetermined temperature deviation, generally referred to as dramatic changes, can be indicative of withdrawal of hot water from the hot water tank 12. A nominal deviation or change is generally indicative of the natural drop in temperature of the water in the hot water tank 12, which requires reheating of the water. For example, in one embodiment, the controller 20 can be configured to monitor the temperature of the water in the hot water tank every 10 minutes. If the detected temperature drop after 10 minutes is less than approximately 5 degrees, it can be determined that there is no water flow from the hot water tank 12, and the water is stagnant. In another embodiment, in an exemplary hot water heater 10 operating in an energy efficient mode, if a drop in temperature of the water on the order of approximately 0.2 degrees Fahrenheit occurs over an approximately 2 minute time period, the controller 20 is configured to determine that there is normal or regular water flow from the hot water tank 12, indicating that a stagnant state has not occurred. A larger flow might be determined by a temperature drop of approximately 8 degrees in approximately 10 minutes.

Alternatively, the controller 20 or home energy manager 50 can be configured to dynamically determine an average temperature or temperature change of the hot water in the tank 12 during normal or regular operation and use the dynamically determined average temperature to determine a stagnant state. In one embodiment, dynamically determining the average temperature or temperature change can comprise taking temperature measurements over a predetermined time interval and taking an average of the temperature readings. In one embodiment, the vacation mode can be used as an initial learning algorithm. For example, in one embodiment, when the controller 20 first detects that a vacation mode of the system has been set or such other suitable indication that the hot water heater 10 will not be used for an extended period, the controller 20 is configured to periodically read the water temperature of the water in the water heater 10 and determine how fast the water temp inside water heater decreases. In this example, the controller 20 is configured to read the water temperature approximately every minute. If the controller 20 determines that over a period of time such as approximately 10 minutes the water temperature drops only approximately 0.1 degrees Fahrenheit, then this temperature/time change factor of 0.1 degrees F./10 minutes, is set as the baseline for temperature change due to environmental loss and not water usage. This baseline can be used to determine a stagnant state. For example, if the controller 20 determines that over a period of time, such as one week, there has been a temperature drop corresponding to the baseline temperature/time change factor of 0.1 degrees F. in 10 minutes, the controller 20 can be configured to identify a stagnant state and automatically run some water through the dishwasher or washer. Although this dynamic process can be run when a vacation or such similar mode is first set, in one embodiment, the controller 10 can be configured to determine when the hot water heater 10 has been inactive for a predetermined period of time, and the initiate the dynamic learning process. For example, while the vacation mode can be used as the initial learning algorithm for dynamic learning process, in a situation where a vacation mode is not set, the aspects of the disclosed embodiments can detect that hot water is not being used and initiate a learning mode or state. In this embodiment, using dynamic process is used to determine the temperature/time factor and monitor the hot water heater 10 for a stagnant state. As another example of dynamically determining the temperature of the hot water heater 10, the controller 20, which in this example can include a real time clock, may read and store water temperature readings every minute or so. Based on the temperature readings, the controller 20 may determine that most water usage occurs between 5 pm and 10 pm on weekdays, because of large drops of water temperature over short periods of time. In this example, the controller 20 uses the temperature changes during the time period of midnight to 5 PM as the baseline of water temperature loss due to the environment. The temperature changes determined during this period of time can be set as the baseline or temperature/time change factor determining when hot water is not being used. For example, in one embodiment, the user manually enters the time period(s) during which most of the water is used. For instance, this could include one time period of 7 AM-8 AM and another time period of 5 PM-10 PM. The controller 20 can use any of the remaining time periods, such as 8 AM-5 PM and 10 PM-12 PM, to determine the baseline temperature/time change factor. The temperature drop or loss due to the environment can also be different for different seasons of the year, such as for example the seasons corresponding to the months of January-March, April-June, July-September and, October-December. The controller 20 can be configured to determine baseline temperature/time change factors for each of the seasons.

In one embodiment, the controller 20 is configured to determine and record the time of the day, or periods of time, when water draw from the hot water heater 10 is detected. As is otherwise described herein, a default indication of hot water draw from the hot water tank 10 is an approximate 0.2 degree temperature drop in approximately 2 minutes, or an approximately 8 degree temperature drop in approximately 10 minutes. The controller 20 can records the times of water draw for a per-determined period of time, such as one week. The controller 20 can determine the time periods of no water draw and determine the average temperature drop of water due to environment during these no water draw time periods. The value of this new average temperature drop can be designated as a maximum temperature loss per time period allowed to establish a stagnant state.

In one embodiment, determining whether the hot water heater 10 is in a stagnant state can include determining 604 whether a change in temperature of the hot water exceeds a predetermined threshold temperature change value or range, such as the baseline temperature/time change factor or maximum temperature loss per time period.

If it is determined 604 that a temperature change of the hot water exceeds the threshold value, this generally indicates that the hot water heater 10 is not in a stagnant state and the controller 20 can continue to monitor 602 the water temperature. In one embodiment, monitoring 602 can include setting a timer. At the expiration of a predetermined time period, the controller 20 can determine 604 whether there has been a temperature change within the predetermined time interval that exceeds the predetermined temperature threshold change. If yes, indicating that the hot water from the hot water tank 12 has been used, the controller 20 can reset the timer and continue to monitor 602 the water temperature.

If it is determined 604 that there has not been a change in temperature of the water in the hot water tank 12 exceeding the predetermined temperature threshold value, indicating a no-flow state, in one embodiment, the controller 20 determines 606 whether a predetermined time period since the last use of the hot water from the hot water tank 12 has elapsed. The determining step 606 can use the elapsed time of the timer in step 602 to determine in the predetermined time period has elapsed. In one embodiment, once the no-flow state is determined in 604, or the vacation mode is set, another timer can be started. The determining step 606 can use an elapsed time of this other timer in determining whether the predetermined time period has lapsed. In alternate embodiments, the step of determining 606 can include any suitable method for determining a time interval since the last use of hot water, including the process described with respect to steps 204 and 206 in FIG. 2.

If it is determined 606 that the predetermined time value is met or exceeded, in one embodiment, the controller 20 initiates 608 a hot water usage cycle of an appliance 40. Otherwise, the controller 20 continues to monitor 602 the hot water temperature to determine 604, 606 whether there is a change of temperature that exceeds a nominal threshold value within a predetermined time period, indicating use of the hot water.

In one embodiment, determining whether the hot water heater 10 is in a stagnant state can include monitoring the powering of the heat source 14, such as the heating elements. If there is limited or no power draw or consumption by the heat source 14 for a predetermined time period, such as one week, the controller 20 is configured to determine that the hot water heater 10 is in a stagnant state. While the heat source 14 will consume some energy in response to environmental heat loss of the hot water heater 10, the amount of energy required to reheat the water due to environmental heat loss will typically be distinguishable or less than the amount of energy require to heat the water after a water draw. For example, in one embodiment, the controller 20 is configured to detect the time that a heating source 14 is powered on. If the heat source 14 is on due to a water draw, the length of time the heat source 14 is on, such as approximately 5-8 minutes for example, will generally be greater than the period of time the heat source 14 is on due to environmental heat loss, which can be approximately in the range of 2 to 4 minutes. The controller 20 can detect the time the heat source 14 is on, compare the detected time value to a predetermined threshold, and determine if the hot water heater 10 is in a stagnant state.

The system 100 and controller 20 of FIG. 1 are generally configured to utilize program storage devices embodying machine-readable program source code that is adapted to cause the apparatus to perform and execute the method steps and processes disclosed herein. The program storage devices incorporating aspects of the disclosed embodiments may be devised, made and used as a component of a machine utilizing optics, magnetic properties and/or electronics to perform the procedures and methods disclosed herein. In alternate embodiments, the program storage devices may include magnetic media, such as a diskette, disk, memory stick or computer hard drive, which is readable and executable by a computer. In other alternate embodiments, the program storage devices could include optical disks, read-only-memory (“ROM”) floppy disks and semiconductor materials and chips. The computer program or software incorporating the processes and method steps incorporating aspects of the disclosed embodiments may be stored in one or more computer systems or on an otherwise conventional program storage device.

The exemplary embodiments described herein provide a system for automatically determining when the hot water in a hot water tank 12 has not been used or is stagnant. In order to prevent or eliminate any hydrogen gas buildup in the hot water heater system and associated plumbing, a fill and drain cycle of the hot water heater can be run. This can include automatically operating an electrically operated appliance fluidly coupled to the hot water heater. The aspects of the disclosed embodiments can automatically detect periods of non-use of the hot water heater based on times of use of the hot water heater, changes in temperature of the water in the hot water tank, or the setting of preprogrammed modes of the hot water heater or appliances. The periodic operation of the hot water heater system should prevent any buildup of hydrogen gas.

Thus, while there have been shown and described and pointed out fundamental novel features of the invention as applied to the exemplary embodiments thereof, it will be understood that various omissions and substitutions and changes in the form and details of devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.

Claims

1. A hot water heater comprising:

a controller;

a hot water tank; and

a sensor operatively coupled to the hot water tank and the controller, the controller being operative in response to the sensor to detect use of hot water from the hot water tank to determine an interval of non-use of hot water from the hot water tank; and enable a drain cycle to withdraw a portion of water from the hot water tank upon such determination.

2. The hot water heater of claim 1, wherein the sensor comprises a water flow sensor and wherein the interval of non-use is determined if a time interval of no water flow from the hot water tank exceeds a predetermined time threshold.

3. The hot water heater of claim 1, wherein the sensor comprises a water temperature sensor, wherein the interval of non-use is determined if any change in temperature of the water in the hot water tank during a pre-determined time interval does not exceed a pre-determined temperature change threshold value.

4. The hot water heater of claim 1, further comprising a user interface operatively coupled to the controller, the user interface enabling a vacation mode of the hot water heater to be set, and wherein the controller is configured to detect the vacation mode of the hot water heater and enable the drain cycle to withdraw a portion of water from the hot water tank at predetermined time intervals.

5. The hot water heater of claim 4, further comprising a wireless interface operatively coupling the user interface and the controller.

6. The hot water heater of claim 1, further comprising a wireless radio connection between the controller and the sensor.

7. The hot water heater of claim 1, further comprising an electrically operated hot water using appliance operatively coupled to the controller, wherein enabling the drain cycle comprises enabling operation of the electrically operated appliance to withdraw water from the water heater.

8. A hot water heater system comprising:

a hot water heater; and

a controller coupled to the hot water heater, the controller operative to: determine a stagnant state of the hot water heater; and enable a drain cycle of the hot water heater.

9. The hot water heater system of claim 8, wherein the drain cycle is enabled at predetermined time intervals during the stagnant state.

10. The hot water heater system of claim 8, further comprising a water flow sensor operatively coupled between the controller and the hot water heater and wherein the controller is operative to:

detect a flow of hot water from the hot water heater; and

determine an elapsed time from the detection of the detected flow; and

the stagnant state being indicated when the elapsed time is greater than the predetermined threshold time.

11. The hot water heater system of claim 8, further comprising a water temperature sensor operatively coupled between the controller and the hot water heater and wherein the controller is operative to determine the stagnant state by monitoring a temperature of hot water in the hot water heater; and

wherein the stagnant state being indicated when the temperature change does not exceed a predetermined temperature change threshold value during a time interval of predetermined duration.

12. The hot water heater system of claim 8, further comprising:

an appliance operatively coupled to the hot water heater and the controller;

wherein the controller is operative to enable the appliance to withdraw water from the hot water heater upon determination of a stagnant state.

13. The hot water heater system of claim 12, wherein the appliance comprises a dishwasher, a washer, or an electronically controlled hot water discharge valve.

14. The hot water heater system of claim 8, further comprising a user interface operatively coupled to the controller, the user interface enabling user selection of a vacation mode state of the hot water heater, wherein the controller is operative during the vacation mode to enable the drain cycle of the hot water heater at predetermined time intervals.

15. The hot water heater system of claim 14, further comprising an electrically operated appliance with a control panel operatively coupled to the controller, the user interface comprising the control panel.

16. The hot water heater system of claim 14, further comprising a wireless interface operatively coupling the user interface and controller.

17. The hot water heater system of claim 16, wherein the user interface comprises a mobile communication device.

18. The hot water heater system of claim 8, further comprising a home energy management system, the controller comprising a home energy manager of the home energy system.

19. A hot water heater system comprising:

a hot water heater;

an appliance coupled to the hot water heater and configured to withdraw hot water from the hot water heater; and

a home energy manager coupled to the hot water heater and the appliance, wherein the home energy manager is configured to enable the appliance to withdraw hot water from the hot water heater at predetermined time intervals.

20. The hot water heater system of claim 19, wherein the home energy manager is configured to detect a stagnant state of the hot water heater and enable the appliance to withdraw hot water from the hot water heater upon detection of the stagnant state.