Water heater with intermittent pilot and damper control

Abstract

A water heater includes a gas burner, a thermoelectric element, a pilot, a main valve, a damper, and a controller that actuates an intermittent spark generator to ignite a pilot flame of the pilot after a first predetermined condition is satisfied, moves the damper toward the open position when the energy generated by the thermoelectric element exceeds a threshold value, and opens the main valve to permit flow of gas to the gas burner after the damper is in the open position and after a second predetermined condition is satisfied. The first predetermined condition is different from the second predetermined condition and the first predetermined condition is selected to be satisfied before the second predetermined condition is satisfied.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 63 / 658,524, filed on Jun. 11, 2024, entitled “WATER HEATER WITH INTERMITTENT PILOT AND DAMPER CONTROL,” the disclosure of which is hereby incorporated herein by reference in its entirety.FIELD OF THE DISCLOSURE

[0002] The present invention relates generally to a water heater, and more particularly, to an energy-sustaining gas water heater.BACKGROUND OF THE DISCLOSURE

[0003] Although many improvements to water heating systems have been made over the years, there remains a need for further improvements in terms of, for example, improved performance, improved efficiency, cost effectiveness, and / or ease of use.SUMMARY OF THE DISCLOSURE

[0004] According to a first aspect of the present disclosure, a water heater is provided comprising a water storage tank defining an interior region configured to contain water to be heated; a heat source configured to generate heat for transfer to water when contained in the interior region of the water storage tank, the heat source including a gas burner configured to generate combustion gases; a flue extending through the interior region of the water storage tank and configured to exhaust the combustion gases generated by the gas burner; a temperature sensor positioned to directly or indirectly sense a temperature of the water when contained in the interior region of the water storage tank; a pilot associated with the gas burner and configured to fire the gas burner; a pilot valve configured to supply gas to the pilot; an intermittent spark generator associated with the pilot and configured to ignite a pilot flame; a thermoelectric element configured to generate energy from the pilot flame; a main valve associated with the gas burner and configured to supply gas to the gas burner; a damper extending within the flue and configured to move between a closed position to restrict the flow of the combustion gases through the flue and an open position to allow the flow of the combustion gases through the flue; and a controller coupled to the temperature sensor, the pilot valve, the intermittent spark generator, the thermoelectric element, and the damper. The controller is configured to: actuate the intermittent spark generator to ignite the pilot flame of the pilot after a first predetermined condition is satisfied, move the damper toward the open position when the energy generated by the thermoelectric element exceeds a threshold value, and open the main valve to permit flow of gas to the gas burner after the damper is in the open position and after a second predetermined condition is satisfied. The first predetermined condition is different from the second predetermined condition, and the first predetermined condition is selected to be satisfied before the second predetermined condition is satisfied.

[0005] Embodiments of the first aspect of the present disclosure can include any one or a combination of the following features:

[0006] the first predetermined condition being satisfied when the temperature of the water when contained in the interior region of the water storage tank drops at a rate exceeding a predetermined rate of temperature change;

[0007] the first predetermined condition being satisfied when the temperature of the water when contained in the interior region of the water storage tank drops below a predetermined difference between a setpoint temperature and a first differential temperature;

[0008] the second predetermined condition being satisfied when the temperature of the water when contained in the interior region of the water storage tank drops below a predetermined difference between a setpoint temperature and a second differential temperature, the first differential temperature being smaller than the second differential temperature;

[0009] the controller being further configured to move the damper from the closed position toward the open position when the energy generated by the thermoelectric element exceeds the threshold value and when the temperature of the water when contained in the interior region of the water storage tank is below the predetermined difference between the setpoint temperature and the second differential temperature;

[0010] the controller being further configured to open the main valve to allow ignition of the gas burner using energy generated by the thermoelectric element;

[0011] the threshold value of the energy generated by the thermoelectric element is at least 350 mV; and

[0012] a damper switch coupled to the controller, wherein the damper switch is configured to send to the controller a “fully open” signal related to the open position of the damper, and wherein the controller is configured to switch power from the damper to open the main valve in response to the “fully open” signal, using only energy generated by the thermoelectric element.

[0013] According to a second aspect of the present disclosure, a method of firing a water heater is provided. The water heater includes a gas burner coupled to receive gas via a main valve, a pilot coupled to receive gas via a pilot valve, an intermittent spark generator positioned to spark the pilot, a thermoelectric element, a flue, and a damper configured to move between a closed position and an open position relative to the flue. The method comprises the steps of: actuating the intermittent spark generator to ignite a pilot flame of the pilot after a first predetermined condition is satisfied, generating a threshold value of energy in the thermoelectric element via the pilot flame, moving the damper toward the open position when the threshold value of energy reaches the threshold value thus permitting combustion gases to flow through the flue, and opening the main valve to permit flow of gas to the gas burner after the damper is in the open position and after a second predetermined condition is satisfied. The first predetermined condition is different from the second predetermined condition, and the first predetermined condition is selected to be met before the second predetermined condition.

[0014] Embodiments of the second aspect of the present disclosure can include any one or a combination of the following features:

[0015] the first predetermined condition being satisfied when the temperature of water when contained in an interior region of a water storage tank of the water heater drops at a rate above a predetermined rate of temperature change;

[0016] the first predetermined condition being satisfied when the temperature of water when contained in an interior region of a water storage tank of the water heater drops below a predetermined difference between a setpoint temperature and a first differential temperature;

[0017] the second predetermined condition being satisfied when the temperature of the water when contained in the interior region of the water storage tank drops below a predetermined difference between a setpoint temperature and a second differential temperature, the first differential temperature being smaller than the second differential temperature;

[0018] moving the damper from the closed position toward the open position when the energy generated by the thermoelectric element exceeds the threshold value and when the temperature of the water when contained in the interior region of the water storage tank of the water heater is below a predetermined difference between a setpoint temperature and the second differential temperature;

[0019] opening the main valve to allow ignition of the gas burner using energy generated by the thermoelectric element; and

[0020] closing the main valve when the temperature of water when contained in an interior region of a water storage tank of the water heater is above the predetermined difference between the setpoint temperature and the first differential temperature and when the temperature of the water contained in the interior region of the water storage tank is above the predetermined difference between the setpoint temperature and the second differential temperature, routing power from the main valve to close the damper, and extinguishing the pilot.

[0021] According to a third aspect of the present disclosure, a controller for a water heater is provided. The water heater includes a water storage tank defining an interior region configured to contain water to be heated, a heat source including a gas burner including a pilot, a pilot valve, an intermittent spark generator, and a main valve, a thermoelectric element, and a damper configured to move between a closed position and an open position. The controller comprises a memory; a processor coupled to the memory; and programming stored in the memory. Execution of the programming by the processor configures the controller to: actuate the intermittent spark generator to ignite a pilot flame of the pilot when a first predetermined condition is satisfied, move the damper toward the open position when an energy generated by the thermoelectric element from the pilot flame exceeds a threshold value, and open the main valve to permit flow of gas to the gas burner after the damper is in the open position and after a second predetermined condition is satisfied. The first predetermined condition is different from the second predetermined condition, and the first predetermined condition is selected to be met before the second predetermined condition.

[0022] According to a fourth aspect of the present disclosure, a method for retrofitting a water heater is provided. The water heater includes a water storage tank defining an interior region configured to contain water to be heated, a flue, and a heat source including a gas burner, a pilot, a pilot valve, and a main valve. The method comprises the steps of: providing the water heater with an intermittent spark generator for igniting the pilot valve, a thermoelectric element, and a damper configured to move relative to the flue between a closed position and an open position; and providing a controller configured for: actuating the intermittent spark generator to ignite a pilot flame of the pilot when a first predetermined condition is satisfied, moving the damper toward the open position when an energy generated by the thermoelectric element from the pilot flame exceeds a threshold value, and opening the main valve to permit flow of gas to the gas burner after the damper is in the open position and after a second predetermined condition is satisfied. The first predetermined condition is different from the second predetermined condition, and the first predetermined condition is selected to be met before the second predetermined condition.

[0023] Embodiments of the fourth aspect of the present disclosure can include any one or a combination of the following features:

[0024] the first predetermined condition being satisfied when the temperature of the water contained in the interior region of the water storage tank drops at a rate above a predetermined rate of temperature change;

[0025] the first predetermined condition being satisfied when the temperature of the water contained in the interior region of the water storage tank drops below a predetermined difference between a setpoint temperature of the water contained in the interior region of the water storage tank and a first differential temperature of the water contained in the interior region of the water storage tank;

[0026] the second predetermined condition being satisfied when the temperature of the water contained in the interior region of the water storage tank drops below a predetermined difference between a setpoint temperature of the water contained in the interior region of the water storage tank and a second differential temperature of the water contained in the interior region of the water storage tank, the first differential temperature being smaller than the second differential temperature; and

[0027] opening the main valve to allow ignition of the gas burner using energy generated by the thermoelectric element.

[0028] These and other features, advantages, and objects of the present disclosure will be further understood and appreciated by those skilled in the art by reference to the following specification, claims, and appended drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In the drawings:

[0030] FIG. 1 is an elevation and partial cross-section illustrating a gas water heater according to an exemplary embodiment of the present invention;

[0031] FIG. 2 is a schematic diagram illustrating an electrical connection in a gas water heater according to an exemplary embodiment of the present invention;

[0032] FIG. 3 illustrates schematically an embodiment of a water heater according to an aspect of the invention;

[0033] FIG. 4 is a flowchart illustrating an exemplary method for heating water and controlling a flue damper in a water heater in a standby mode, according to an exemplary embodiment of the invention;

[0034] FIG. 5 is a flowchart illustrating an exemplary method for heating water and controlling a flue damper in a water heater in a recovery mode, according to an exemplary embodiment of the invention;

[0035] FIG. 6 is a flowchart illustrating an exemplary method for heating water and controlling a flue damper in a water heater based on a rate of water temperature change, according to an exemplary embodiment of the invention;

[0036] FIG. 7 is a flowchart illustrating an exemplary method for heating water and controlling a flue damper in a water heater based on differential water temperatures, according to an exemplary embodiment of the invention;

[0037] FIG. 8 is a flow diagram illustrating an exemplary method for heating water and controlling a flue damper in a water heater based on a rate of water temperature change, according to an exemplary embodiment of the invention; and

[0038] FIG. 9 is a flow diagram illustrating an exemplary method for heating water and controlling a flue damper in a water heater based on differential water temperatures, according to an exemplary embodiment of the invention.DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0039] Although the invention is illustrated and described herein with reference to specific embodiments, the invention is not intended to be limited to the details shown. Rather, various modifications may be made in the details within the scope and range of equivalents of the claims and without departing from the invention.

[0040] The invention is best understood from the following detailed description when read in connection with the accompanying drawing figures, which shows exemplary embodiments of the invention selected for illustrative purposes. The invention will be illustrated with reference to the figures. Such figures are intended to be illustrative rather than limiting and are included herewith to facilitate the explanation of the present invention.

[0041] According to some embodiments of the invention, an improved water heater is provided in which energy can be sustained within the water heater to allow for the reliable operation of the water heater even in the event of a power failure. For example, in some embodiments of the invention, the water heater can sustain energy during the standby mode and the recovery mode and / or power energy-saving devices while minimizing energy loss and controlling the stored water temperature.

[0042] In some embodiments of the invention, this may be accomplished without the use of external electric power, because the water heater can sustain the energy needed to power a damper while in the standby mode. For example, embodiments of the present invention can include damper control so that a pilot is not ignited all the time.

[0043] Referring now to the figures, selected embodiments of the invention are illustrated as non-limiting examples.

[0044] An exemplary embodiment of a water heater 10 is illustrated in FIGS. 1-3. Referring to FIGS. 1-3, the water heater 10 includes a tank 13 configured to store water to be heated. Although a gas-fired storage water heater is selected for purposes of illustration, the invention is not limited to gas-fired water heaters or to storage water heaters and can be applied to other forms of water heaters. Also, the invention can be utilized in residential, commercial, or other water heating systems.

[0045] The tank 13 of illustrated water heater 10 has a wall with an external surface and an internal surface defining an interior region 32 (FIG. 3) configured to contain water to be heated. The water heater 10 includes a heat source 36 (FIG. 3) including a gas burner 22 configured to generate combustion gases, a controller 34 (FIG. 3), and a temperature sensor 11 (e.g., a thermistor) or a thermostat (e.g., bimetallic or thermocouple-based thermostat) that is thermally coupled to (e.g., physically contacting) a wall portion of the water tank 13 and that monitors the temperature of the water in the water heater. Temperature sensor 11 is preferably located in an opening on tank 13 to directly or indirectly sense the temperature of the water when contained in the interior region 32 of the water storage tank 13.

[0046] Referring now to FIGS. 1 and 2, the water heater 10 includes a pilot burner 2 associated with the gas burner 22 and a pilot valve 12 configured to supply gas to the pilot burner 2. Additionally, the heater 10 can include a gas valve 7 configured to permit or prevent, or limit flow of gas to the gas burner 22. The controller 34 is configured to operate the gas valve 7 in response to a demand for heat signal. A pilot and thermopile assembly 1 includes the pilot burner 2 and two thermo-voltaic devices 3 and 4 located proximally thereto. Pilot burner 2 is lit when the water heater is brought into operation. For example, an intermittent spark generator, including, e.g., a spark coil, a transformer, an electrical circuit, and / or a spark plug, can be associated with the pilot burner 2 and configured to ignite a pilot flame.

[0047] The pilot flame from pilot burner 2, which may or may not be in contact with thermo-voltaic devices 3 and 4, provides heat energy to thermo-voltaic devices 3 and 4, which thereby generate electrical energy from the pilot flame. Thermo-voltaic devices 3 and 4 preferably comprise thermopiles, but are not necessarily limited thereto. The operation of thermopiles is well known to those of ordinary skill in the art and will not be further elaborated upon here except to note that the voltage produced by thermo-voltaic devices 3 and 4 is preferably in the milli-volt (mV) range.

[0048] While two thermopiles are shown in FIGS. 1 and 2, those of ordinary skill in the art will appreciate that more or fewer thermopiles may be used depending on the voltage and current required and the performance characteristics of thermopiles used. However, by using two or even more thermopiles in the manner illustrated, the output from a single pilot burner can be maximized while keeping the overall size of the pilot assembly to a minimum.

[0049] Thermo-voltaic devices 3 and 4 are preferably, but not necessarily, wired in series if plural devices are used. Lead wires 5 and 6 for thermo-voltaic device 3 are connected to the gas valve 7, and the lead wire 8 for the thermo-voltaic device 4 is connected to the gas valve 7, with wire 9 for the device 4 being connected to the thermostat 11 to provide power thereto, as shown. Thermo-voltaic device 3 supplies the power needed to hold open the pilot valve 12 located in the gas valve 7.

[0050] When thermostat 11 detects the need to heat the water, it closes the circuit between wire 9 supplying power to the thermostat 11 from thermo-voltaic devices 3 and 4 and wire 14 leading from thermostat 11 to damper 15, which is normally in a closed position. As a result of this completed circuit, power is delivered to damper motor 16, causing damper vane 17 to move into the full open vertical position.

[0051] When damper vane 17 reaches the full open vertical position, switches 18 and 19 are actuated. Switch 18 opens the circuit, providing power to the motor and acts in series with switch 19 to complete a circuit providing power to main gas valve 20. Main gas valve 20 then opens supplying gas through manifold 21 to the main burners 22, and main burners 22 are ignited by the pilot flame. The gas is burned in the combustion chamber 23. The products of combustion rise through the flue tubes 24, collector 25, and opened flue damper 15. The passage of exhaust gases from the at least one main burner 22 is controlled with flue 24 and flue damper 15. The combustion products then exit the water heater through draft diverter 26 into the installation's venting system (not shown).

[0052] When the temperature of the water in the tank reaches the set point of thermostat 11, thermostat 11 switches, opening the circuit between wire 9 supplying power to the thermostat and wire 14 leading to switch 18 in the flue damper 15, and closing the circuit between wire 9 supplying power to the thermostat 11 and wire 27 connected to a thermal switch 28. Thermal switch 28 is coupled to flue damper 15. Thermal switch 28 determines whether the at least one main burner 22 is firing after the temperature of the water in the tank reaches the set point of thermostat 11. It is contemplated that thermal switch 28 may determine whether the at least one main burner 22 is firing by sensing whether a temperature proximate to the main burner is equal to or greater than a predetermined threshold temperature.

[0053] If the at least one main burner 22 is determined to be firing, flue damper 15 is controlled to remain open, as shown at step 310. For example, if main gas valve 20 were to remain open after the temperature of the water in the tank reaches the set point of thermostat 11, thermal switch 28 would continue to sense heat from the main burners 22 and remain open. If thermal switch 28 remains open, the circuit is not completed, power is not supplied to damper motor 16, and damper vane 17 remains in the open position.

[0054] Alternatively, if the at least one main burner 22 is determined to not be firing, flue damper 15 is controlled to close, as shown at step 312. When thermal switch 28 no longer senses heat from the main burner or burners 22, thermal switch 28 closes, completing a circuit between thermostat 11 and wire 29 leading to damper 15. The completion of this circuit supplies power to damper motor 16 so that damper vane 17 moves to the closed position. When damper vane 17 moves to the closed position, switch 30 opens, interrupting power to damper motor 16.

[0055] If the damper vane 17 is caused to move to the closed position, the damper vane 17 preferably remains closed while the water heater is in standby, reducing energy loss from the water heater. Pilot burner 2 continues to burn so that the energy is available for another cycle when the water in the tank 13 becomes cold enough to again activate the thermostat 11, without the need for an external source of power to operate damper motor 16.

[0056] When power is interrupted in the circuit leading to switch 18 in the flue damper 15, the power to main gas valve 20 is interrupted. An exemplary thermal switch may be Model No. 36TXVG11 of Thermodisc, Inc., of 1320 South Main Street, Mansfield, OH 44907. Other switches are optionally used.

[0057] In general, the controller 34 illustrated in FIG. 3 can include devices such as a microprocessor, memory devices, analog input / output (I / O), digital I / O, power regulation, etc. (not shown), which serve to perform various operations. For example, such operations may include operations related to collecting and recording temperatures from temperature sensor 11 and acting upon those temperatures to control the intermittent spark generator to ignite the pilot flame of the pilot, movement of the damper 15 between the closed and the open positions, and opening or closing the main valve to permit or stop flow of gas to the gas burner. The controller 34 is operatively coupled to the temperature sensor 11, the heat source 36, the pilot valve 12, the spark ignition system, the thermoelectric elements 3 and 4, the main valve, and the damper 15.

[0058] The memory of the controller 34 generally stores the programming for the controller 34. Specifically, the memory stores instructions that, when executed by the controller 34, cause the controller 34 to provide functionality related to actuating the intermittent spark generator to ignite the pilot flame of the pilot, moving the damper toward the open position when the energy generated by the thermoelectric element exceeds a threshold value, and opening the main valve to permit flow of gas to the gas burner after the damper is in the open position and after a predetermined condition is satisfied, temperature detection programming, temperature indicator programming, etc. To facilitate these programs, the memory also stores temperature records comprising the time, temperature, and the rate of change in temperature of the water. For example, the memory stores various values, including but not limited to setpoint temperature of the water contained in the interior region 32 of the water storage tank 13, temperature thresholds, thermopile energy thresholds, rate of change of the temperature, predetermined time periods, etc.

[0059] FIG. 4 illustrates an overall method of heating water with a water heater according to an exemplary embodiment of the invention. As shown at step 402, the water heater is in a standby mode, in which the thermostat is satisfied, the pilot is off, the main burner is off, and the damper is closed. As shown at step 404, thermostat 11 detects a “call for heat,” for example, when a temperature and / or a flow and / or a pressure sensed by the temperature and / or flow and / or pressure sensor is below a setpoint (e.g., set by the user with a setpoint temperature knob for setting a desired setpoint temperature of the water) or prescribed temperature or flow or pressure. A call for heat may relate to the gas valve, which can have a temperature sensor (e.g., thermistor, RTD, thermocouple, etc.) that is in a shank / thermal well of the gas valve that is monitoring the water temperatures and the rate of change in temperature of the water. As the electro / mechanical controller(s) senses, calculates and / or gas valve sees either a rate of change of water temperature over time, or water temperatures below a certain temperature, it can charge a solenoid to open the flow path for gas to travel through a feed and / or pilot ultimately lighting the burner. When the electro / mechanical controller(s) starts the process of lighting a burner based on information or a signal from a temperature sensor (or electro / mechanical controller logic / device) it can be considered a “call for heat”.

[0060] As shown at step 406, in response to the “call for heat”, the pilot valve 12 opens, and an intermittent spark ignition generator associated with the pilot 2 ignites a pilot flame using energy from stored energy source (e.g., from a rechargeable battery). The pilot flame is ignited when a first predetermined condition is satisfied. The first predetermined condition is satisfied when the temperature of the water contained in the interior region of the water storage tank drops at a rate above (e.g., faster than) a predetermined rate of temperature change. For example, the first predetermined condition is satisfied when a ratio between a change (e.g., delta) dTwe in the temperature of the water contained in the interior region of the water storage tank over a time dT of this change in temperature is above (e.g., faster or greater than) a predetermined rate of temperature change measured in degrees Fahrenheit per second, such as 0.05° F. (degrees Fahrenheit) per second, for example:d⁢Tw⁢ed⁢T>0.05FS

[0061] As shown at step 408, thermopile assembly 1 including the thermo-voltaic devices 3 and 4 receives heat energy from the flame generated by pilot burner 2, and converts a portion of that heat energy into electrical energy. Numerous thermopile devices are commercially available and may be used herein. For example, thermopile assembly 1 is capable of generating about 350 mv. This electrical energy is supplied to gas valve 7 by wires 5, 6 and 8, 9. Thermopile assembly 1 provides a continuous source of electricity to the entire electrical system connected to gas valve 7. The pilot burner 2 heats the thermopile assembly 1 until a threshold voltage of about 350 mV is generated.

[0062] Because there is typically a delay in time of about two minutes as the thermopile assembly 1 heats up until it generates the threshold voltage of about 350 mV, embodiments of the present invention provide an energy efficient solution of monitoring the rate of water temperature change (e.g., drop) or water temperature differentials, not only the water temperature relative to a setpoint water temperature, to ignite the pilot burner 2 to start charging the thermopile assembly 1 early enough before the temperature of the water drops below the setpoint water temperature.

[0063] As shown at step 410, when the threshold voltage of about 350 mV is generated, a controller routes the electrical energy from the thermopile assembly 1 and starts moving the flue damper 15 from the closed position toward the open position. When a second predetermined condition is satisfied, the controller opens the main valve to permit flow of gas to the gas burner after the flue damper 15 is in the open position.

[0064] The second predetermined condition is satisfied when the temperature of the water contained in the interior region of the water storage tank drops below a predetermined difference between a setpoint temperature of the water contained in the interior region of the water storage tank and a second differential temperature of the water contained in the interior region of the water storage tank, where the first differential temperature is smaller than the second differential temperature.

[0065] The controller moves the flue damper 15 from the normally closed damper position to the open damper position preferably using only the electricity generated by the thermoelectric element (e.g., thermopile assembly 1).

[0066] As shown at step 412, a damper switch (e.g., switches 18 and 19) coupled to the controller is configured to send to the controller a “fully open” signal related to the open position of the flue damper 15.

[0067] As shown at step 414, the controller switches power from the flue damper 15 to open the main gas valve 20, in response to the “fully open” damper signal, preferably using only energy generated by the thermoelectric element (e.g., thermopile assembly 1).

[0068] As shown at step 416, the controller ignites the main gas burner 22, preferably using only energy generated by the thermoelectric element (e.g., thermopile assembly 1).

[0069] FIG. 5 illustrates an overall method of heating water with a water heater according to an exemplary embodiment of the invention. As shown at step 502, the water heater is in a recovery mode, in which the thermostat sees a “call for heat”, the pilot is on, the main burner is on, and the damper is open. As shown at step 504, thermostat 11 detects that the “call for heat” has been satisfied, for example, when a temperature and / or a flow and / or a pressure sensed by the temperature and / or flow and / or pressure sensor is at or above the setpoint or prescribed temperature or flow or pressure.

[0070] As shown at step 506, in response to the “call for heat” satisfied detection, the main gas valve 7 closes, extinguishing the burner 22.

[0071] As shown at step 508, the controller routes the electrical energy from the thermopile assembly 1 and starts moving the flue damper 15 from the open position toward the closed position.

[0072] As shown at step 510, the controller receives a signal from the damper indicating that the damper is closed and discontinues power to the damper 15.

[0073] At step 512, the controller shuts down the pilot valve 12, extinguishes the pilot flame, turns off the pilot, and discontinues the heat energy to thermopile assembly 1 from the flame generated by pilot burner 2.

[0074] At step 514, as the thermopile assembly 1 cools down, the stored energy (e.g., in the rechargeable battery) becomes the primary energy for the water heater 10.

[0075] At step 516, the water heater 10 is in a standby mode, in which the thermostat is satisfied, the pilot is off, the main burner is off, and the damper is closed.

[0076] FIG. 6 illustrates a method of heating water with a water heater based on the rate of temperature change of the water contained in the interior region 32 of the water storage tank 13, according to an exemplary embodiment of the invention.

[0077] As shown at step 602, while the water heater 10 is in a standby mode, in which the thermostat is satisfied, the pilot is off, the main burner is off, and the damper is closed, the controller 36 monitors, e.g., via temperature sensor 11, the temperature of the water contained in the interior region 32 of the water storage tank 13 and detects a rate of temperature change. The rate of temperature change can be determined, for example, as a ratio between a change (e.g., delta) dTwe in the temperature of the water contained in the interior region 32 of the water storage tank 13 over a period of time dT of this change in temperature.

[0078] At step 604, the controller 36 compares the detected rate of temperature change to a predetermined rate of temperature change, such as 0.05° F. (degrees Fahrenheit) per second, for example:d⁢Tw⁢ed⁢T>0.05FS

[0079] At step 606, if the detected rate of temperature change is not above the predetermined rate of temperature change, the controller 36 continues to monitor the temperature of the water contained in the interior region 32 of the water storage tank 13 for a rate of temperature change.

[0080] At step 608, if the detected rate of temperature change is above the predetermined rate of temperature change (e.g., water temperature drops fast due to excessive demand of hot water, such as filling a bathtub and taking a hot shower, for example), the controller 36 opens the pilot valve 12 and actuates the intermittent spark ignition generator associated with the pilot 2 to ignite a pilot flame to establish the thermopile. The pilot flame is ignited when or after a first predetermined condition is satisfied. The first predetermined condition is satisfied when the temperature of the water contained in the interior region of the water storage tank drops at a rate above the predetermined rate of temperature change.

[0081] When or after the first predetermined condition is satisfied, the controller 36 starts the pilot 2 to ignite a pilot flame and establish the thermopile.

[0082] The first predetermined condition can be, for example, a temperature differential from a setpoint temperature. For example, the temperature differential can be 2° F. (degrees Fahrenheit) from a set point of 125° F. (degrees Fahrenheit), instead of 10° F. (degrees Fahrenheit) from the setpoint for firing the main burner 22.

[0083] The thermopile assembly 1, including the thermo-voltaic devices 3 and 4, receives heat energy from the flame generated by pilot burner 2, and converts a portion of that heat energy into electrical energy. The pilot burner 2 heats the thermopile assembly 1 until a threshold voltage of about 350 mV is generated.

[0084] At step 610, the controller 36 compares the energy at the thermopile assembly 1 to the threshold voltage of about 350 mV. If the energy at the thermopile assembly 1 is not higher than the threshold voltage of about 350 mV, the controller 36 maintains the pilot valve 12 open and the pilot flame ignited to heat the thermopile assembly 1.

[0085] At step 612, when the threshold voltage of about 350 mV is generated, the controller 36 checks whether the temperature Twe of the water contained in the interior region 32 of the water storage tank 13 is equal to or drops below a predetermined difference SP-DIFF between a setpoint temperature SP of the water contained in the interior region 32 of the water storage tank 13 and a differential temperature DIFF of the water contained in the interior region 32 of the water storage tank 13. A second predetermined condition is satisfied when the temperature Twe of the water contained in the interior region 32 of the water storage tank 13 drops below the predetermined difference SP-DIFF between a setpoint temperature SP of the water contained in the interior region 32 of the water storage tank 13 and the differential temperature DIFF of the water contained in the interior region 32 of the water storage tank 13.

[0086] At step 614, when the second predetermined condition is satisfied (e.g., the temperature Twe of the water contained in the interior region 32 of the water storage tank 13 is equal to or drops below the predetermined difference SP-DIFF between the setpoint temperature SP of the water contained in the interior region 32 of the water storage tank 13 and the differential temperature DIFF of the water contained in the interior region 32 of the water storage tank 13), the controller 36 routes the electrical energy from the thermopile assembly 1 and starts moving the flue damper 15 from the closed position toward the open position, and opens the main valve to permit flow of gas to the gas burner after the flue damper 15 is in the open position.

[0087] At step 616, when the second predetermined condition is not satisfied (e.g., the temperature Twe of the water contained in the interior region 32 of the water storage tank 13 does not drop below the predetermined difference SP-DIFF between the setpoint temperature SP of the water contained in the interior region 32 of the water storage tank 13 and the differential temperature DIFF of the water contained in the interior region 32 of the water storage tank 13), the controller 36 starts a timer for a time period, for example about 90 seconds.

[0088] At step 618, when the time counted by the timer is not equal to or higher than 90 seconds (e.g., time is below 90 seconds), the controller 36 increments the timer and continues to maintain the pilot valve 12 open and the pilot flame ignited to heat the thermopile assembly 1 (step 608).

[0089] At step 620, when the time counted by the timer is equal to or higher than 90 seconds, the controller 36 closes the pilot valve 12 and resets the timer.

[0090] At step 622, the controller 36 starts a second timer for a time period, for example about 60 minutes or one hour, after which the controller 36 returns to step 602, in which the water heater 10 is in a standby mode, the thermostat is satisfied, the pilot is off, the main burner is off, and the damper is closed, and the controller 36 monitors, e.g., via temperature sensor 11, the temperature of the water contained in the interior region 32 of the water storage tank 13 and detects a temperature change.

[0091] FIG. 7 illustrates a method of heating water with a water heater based on differential temperatures of the water contained in the interior region 32 of the water storage tank 13, according to another exemplary embodiment of the invention.

[0092] As shown at step 702, while the water heater 10 is in a standby mode, in which the thermostat is satisfied, the pilot is off, the main burner is off, and the damper is closed, the controller 36 monitors, e.g., via temperature sensor 11, the temperature of the water contained in the interior region 32 of the water storage tank 13 and detects the temperature Twe of the water contained in the interior region 32 of the water storage tank 13.

[0093] At step 704, the controller 36 compares the detected temperature Twe of the water contained in the interior region 32 of the water storage tank 13 to a first predetermined difference SP-DIFFpilot between a setpoint temperature SP of the water contained in the interior region 32 of the water storage tank 13 and a first differential temperature DIFFpilot of the water contained in the interior region 32 of the water storage tank 13. The first differential temperature DIFFpilot of the water contained in the interior region 32 of the water storage tank 13 can be, for example, 4° F. (degrees Fahrenheit).

[0094] At step 706, if the detected temperature Twe of the water contained in the interior region 32 of the water storage tank 13 is not below the first predetermined difference SP-DIFFpilot between the setpoint temperature SP of the water contained in the interior region 32 of the water storage tank 13 and the first differential temperature DIFFpilot of the water contained in the interior region 32 of the water storage tank 13, the controller 36 continues to monitor the temperature Twe of the water contained in the interior region 32 of the water storage tank 13.

[0095] At step 708, if the detected temperature Twe of the water contained in the interior region 32 of the water storage tank 13 is below the first predetermined difference SP-DIFFpilot between the setpoint temperature SP of the water contained in the interior region 32 of the water storage tank 13 and the first differential temperature DIFFpilot of the water contained in the interior region 32 of the water storage tank 13, the controller 36 opens the pilot valve 12 and actuates the intermittent spark ignition generator associated with the pilot 2 to ignite a pilot flame to establish the thermopile. The pilot flame is ignited when a first predetermined condition is satisfied. The first predetermined condition is satisfied when the temperature Twe of the water contained in the interior region 32 of the water storage tank 13 is below the first predetermined difference SP-DIFFpilot between the setpoint temperature SP of the water contained in the interior region 32 of the water storage tank 13 and the first differential temperature DIFFpilot of the water contained in the interior region 32 of the water storage tank 13.

[0096] When the first predetermined condition is satisfied, the controller 36 starts the pilot 2 to ignite a pilot flame and energize the thermopile.

[0097] The thermopile assembly 1 including the thermo-voltaic devices 3 and 4 receives heat energy from the flame generated by pilot burner 2, and converts a portion of that heat energy into electrical energy. The pilot burner 2 heats the thermopile assembly 1 until a threshold voltage of about 350 mV is generated.

[0098] At step 710, the controller 36 compares the energy at the thermopile assembly 1 to the threshold voltage of about 350 mV. If the energy at the thermopile assembly 1 is not higher than the threshold voltage of about 350 mV, the controller 36 maintains the pilot valve 12 open and the pilot flame ignited to heat the thermopile assembly 1.

[0099] At step 712, when the threshold voltage of about 350 mV is generated, the controller 36 checks whether the temperature Twe of the water contained in the interior region 32 of the water storage tank 13 drops below a predetermined difference Twe≤SP-DIFFmv between a setpoint temperature SP of the water contained in the interior region 32 of the water storage tank 13 and a second differential temperature DIFFmv of the water contained in the interior region 32 of the water storage tank 13.

[0100] A second predetermined condition is satisfied when the temperature Twe of the water contained in the interior region 32 of the water storage tank 13 drops below the predetermined difference Twe≤SP-DIFFmy between the setpoint temperature SP of the water contained in the interior region 32 of the water storage tank 13 and the second differential temperature DIFFmv of the water contained in the interior region 32 of the water storage tank 13. The second differential temperature DIFFmv of the water contained in the interior region 32 of the water storage tank 13 can be, for example, 10° F. (degrees Fahrenheit).

[0101] At step 714, when the second predetermined condition is satisfied (e.g., the temperature Twe of the water contained in the interior region 32 of the water storage tank 13 drops below the predetermined difference Twe≤SP-DIFFmv between the setpoint temperature SP of the water contained in the interior region 32 of the water storage tank 13 and the second differential temperature DIFFmv of the water contained in the interior region 32 of the water storage tank 13), the controller 36 routes the electrical energy from the thermopile assembly 1 and starts moving the flue damper 15 from the closed position toward the open position, and opens the main valve to permit flow of gas to the gas burner after the flue damper 15 is in the open position.

[0102] When the second predetermined condition is satisfied, the controller 36 fires the main gas burner 22.

[0103] Regardless of the values of the first differential temperature DIFFpilot and the second differential temperature DIFFmv, for purposes of water heater efficiency and compliance with regulatory requirements, the first differential temperature DIFFpilot is smaller than the second differential temperature DIFFmv. In other words, the condition for firing the main gas burner 22 is more stringent than the condition for igniting the pilot 2.

[0104] At step 716, when the second predetermined condition is not satisfied (e.g., the temperature Twe of the water contained in the interior region 32 of the water storage tank 13 does not drop below the predetermined difference Twe≤SP-DIFFmv between the setpoint temperature SP of the water contained in the interior region 32 of the water storage tank 13 and the second differential temperature DIFFmy of the water contained in the interior region 32 of the water storage tank 13), the controller 36 starts a timer for a time period, for example about 90 seconds.

[0105] At step 718, when the time counted by the timer is not equal to or higher than 90 seconds (e.g., time is below 90 seconds), the controller 36 increments the timer and continues to maintain the pilot valve 12 open and the pilot flame ignited to heat the thermopile assembly 1 (step 708).

[0106] At step 720, when the time counted by the timer is equal to or higher than 90 seconds, the controller 36 closes the pilot valve 12 open and resets the timer.

[0107] At step 722, the controller 36 starts a second timer for about 60 minutes or one hour, after which the controller 36 returns to step 702, in which the water heater 10 is in a standby mode, the thermostat is satisfied, the pilot is off, the main burner is off, and the damper is closed, and the controller 36 monitors, e.g., via temperature sensor 11, the temperature of the water contained in the interior region 32 of the water storage tank 13 and detects the temperature Twe of the water contained in the interior region 32 of the water storage tank 13.

[0108] FIGS. 8 and 9 illustrate additional details of the methods of heating water with a water heater based on the rate of temperature change of the water contained in the interior region 32 of the water storage tank 13 (FIG. 6) and based on differential temperatures of the water contained in the interior region 32 of the water storage tank 13 (FIG. 6), respectively, according to the exemplary embodiments of the invention described above. The steps of the methods illustrated in FIGS. 8 and 9 are similar to the steps described with reference to FIGS. 6 and 7.

[0109] The illustrated embodiments of the present invention use the power generated from the pilot to preferably provide sufficient energy to operate the damper to substantially reduce the heat loss from the storage tank when the main burners 22 are not operating, while also providing sufficient power to operate a gas valve for providing gas to the main burner(s).

[0110] Because of the use of a low voltage thermopile, the safety circuits can be installed in series with the thermopile system to ensure the water heater operates when it is called upon to operate, and the damper opens before the main burner(s) operate to prevent heat spillage from the combustion chamber. The damper is opened and remains open during main burner(s) operation, and is closed to reduce the heat loss during no-burner operating times without any external power.

[0111] While in the standby mode, the pilot burns gas at a rate that is sufficient to sustain the energy required to operate the damper and gas valve. When the thermostat calls for heat, the damper opens up and allows the gas valve to open after the damper is proved to be opened. The gas flows to the main burner(s) and the combustion products flow through the flue tubes heating the water. The combustion gases exit through the flue collector and damper into the draft diverter, which is connected to the vent system. When the thermostat is satisfied the burners are shut off and the damper closes once it is proven that the gas valve has closed. The water heater continues to operate at the sustained energy level until the next call for operation by the thermostat. While operating at the sustained energy level the temperature of the water in the tank does not go beyond acceptable levels.

[0112] The illustrated embodiments of the present invention can improve the deliverability test or First Hour Rating (FHR) to over 75 gallons and current FHR values while reducing energy use and heat loss at a Uniform Energy Factor (“UEF”) greater than .68 for a 40-gallon tank.

[0113] The illustrated embodiments of the present invention can increase the UEF over .037 and the BTU saved is 3822, which is a value approaching power vent standby losses.

[0114] The illustrated embodiments of the present invention can allow for an atmospherically vented product, with no external electrical connection, to comply with the 2029 National Appliance Energy Conservation Act (“NAECA”) mandated standards for Residential Water Heaters (“RWH”).

[0115] While preferred embodiments of the invention have been shown and described herein, it will be understood that such embodiments are provided by way of example only. Numerous variations, changes and substitutions will occur to those skilled in the art without departing from the spirit of the invention. Accordingly, it is intended that the appended claims cover all such variations as fall within the spirit and scope of the invention.

Claims

1. A water heater comprising:a water storage tank defining an interior region configured to contain water to be heated;a heat source configured to generate heat for transfer to water when contained in the interior region of the water storage tank, the heat source including a gas burner configured to generate combustion gases;a flue extending through the interior region of the water storage tank and configured to exhaust the combustion gases generated by the gas burner;a temperature sensor positioned to directly or indirectly sense a temperature of the water when contained in the interior region of the water storage tank;a pilot associated with the gas burner and configured to fire the gas burner;a pilot valve configured to supply gas to the pilot;an intermittent spark generator associated with the pilot and configured to ignite a pilot flame;a thermoelectric element configured to generate energy from the pilot flame;a main valve associated with the gas burner and configured to supply gas to the gas burner;a damper extending within the flue and configured to move between a closed position to restrict the flow of the combustion gases through the flue and an open position to allow the flow of the combustion gases through the flue; anda controller coupled to the temperature sensor, the pilot valve, the intermittent spark generator, the thermoelectric element, and the damper, the controller being configured to:actuate the intermittent spark generator to ignite the pilot flame of the pilot after a first predetermined condition is satisfied,move the damper toward the open position when the energy generated by the thermoelectric element exceeds a threshold value, andopen the main valve to permit flow of gas to the gas burner after the damper is in the open position and after a second predetermined condition is satisfied,wherein the first predetermined condition is different from the second predetermined condition and the first predetermined condition is selected to be satisfied before the second predetermined condition is satisfied.

2. The water heater of claim 1, the first predetermined condition being satisfied when the temperature of the water when contained in the interior region of the water storage tank drops at a rate exceeding a predetermined rate of temperature change.

3. The water heater of claim 1, the first predetermined condition being satisfied when the temperature of the water when contained in the interior region of the water storage tank drops below a predetermined difference between a setpoint temperature and a first differential temperature.

4. The water heater of claim 3, the second predetermined condition being satisfied when the temperature of the water when contained in the interior region of the water storage tank drops below a predetermined difference between a setpoint temperature and a second differential temperature, the first differential temperature being smaller than the second differential temperature.

5. The water heater of claim 4, the controller being further configured to:move the damper from the closed position toward the open position when the energy generated by the thermoelectric element exceeds the threshold value and when the temperature of the water when contained in the interior region of the water storage tank is below the predetermined difference between the setpoint temperature and the second differential temperature.

6. The water heater of claim 1, the controller being further configured to open the main valve to allow ignition of the gas burner using energy generated by the thermoelectric element.

7. The water heater of claim 1, wherein the threshold value of the energy generated by the thermoelectric element is at least 350 mV.

8. The water heater of claim 1, further comprising a damper switch coupled to the controller, wherein the damper switch is configured to send to the controller a “fully open” signal related to the open position of the damper, and wherein the controller is configured to switch power from the damper to open the main valve in response to the “fully open” signal, using only energy generated by the thermoelectric element.

9. A method of firing a water heater having a gas burner coupled to receive gas via a main valve, a pilot coupled to receive gas via a pilot valve, an intermittent spark generator positioned to spark the pilot, a thermoelectric element, a flue, and a damper configured to move between a closed position and an open position relative to the flue, the method comprising the steps of:actuating the intermittent spark generator to ignite a pilot flame of the pilot after a first predetermined condition is satisfied,generating a threshold value of energy in the thermoelectric element via the pilot flame, moving the damper toward the open position when the threshold value of energy reaches the threshold value thus permitting combustion gases to flow through the flue, andopening the main valve to permit flow of gas to the gas burner after the damper is in the open position and after a second predetermined condition is satisfied,wherein the first predetermined condition is different from the second predetermined condition and the first predetermined condition is selected to be met before the second predetermined condition.

10. The method of claim 9, the first predetermined condition being satisfied when the temperature of water when contained in an interior region of a water storage tank of the water heater drops at a rate above a predetermined rate of temperature change.

11. The method of claim 9, the first predetermined condition being satisfied when the temperature of water when contained in an interior region of a water storage tank of the water heater drops below a predetermined difference between a setpoint temperature and a first differential temperature.

12. The method of claim 11, the second predetermined condition being satisfied when the temperature of the water when contained in the interior region of the water storage tank drops below a predetermined difference between a setpoint temperature and a second differential temperature, the first differential temperature being smaller than the second differential temperature.

13. The method of claim 12, further comprising the step of:moving the damper from the closed position toward the open position when the energy generated by the thermoelectric element exceeds the threshold value and when the temperature of the water when contained in the interior region of the water storage tank of the water heater is below a predetermined difference between a setpoint temperature and the second differential temperature.

14. The method of claim 9, further comprising the step of:opening the main valve to allow ignition of the gas burner using energy generated by the thermoelectric element.

15. The method of claim 9, further comprising the steps of:closing the main valve when the temperature of water when contained in an interior region of a water storage tank of the water heater is above the predetermined difference between the setpoint temperature and the first differential temperature and when the temperature of the water contained in the interior region of the water storage tank is above the predetermined difference between the setpoint temperature and the second differential temperature;routing power from the main valve to close the damper; andextinguishing the pilot.

16. A method for retrofitting a water heater having a water storage tank defining an interior region configured to contain water to be heated, a flue, and a heat source including a gas burner, a pilot, a pilot valve, and a main valve, the method comprising the steps of:providing the water heater with an intermittent spark generator for igniting the pilot valve, a thermoelectric element, and a damper configured to move relative to the flue between a closed position and an open position; andproviding a controller configured for:actuating the intermittent spark generator to ignite a pilot flame of the pilot when a first predetermined condition is satisfied,moving the damper toward the open position when an energy generated by the thermoelectric element from the pilot flame exceeds a threshold value, andopening the main valve to permit flow of gas to the gas burner after the damper is in the open position and after a second predetermined condition is satisfied,wherein the first predetermined condition is different from the second predetermined condition and the first predetermined condition is selected to be met before the second predetermined condition.

17. The method of claim 16, the first predetermined condition being satisfied when the temperature of the water contained in the interior region of the water storage tank drops at a rate above a predetermined rate of temperature change.

18. The method of claim 16, the first predetermined condition being satisfied when the temperature of the water contained in the interior region of the water storage tank drops below a predetermined difference between a setpoint temperature of the water contained in the interior region of the water storage tank and a first differential temperature of the water contained in the interior region of the water storage tank.

19. The method of claim 18, the second predetermined condition being satisfied when the temperature of the water contained in the interior region of the water storage tank drops below a predetermined difference between a setpoint temperature of the water contained in the interior region of the water storage tank and a second differential temperature of the water contained in the interior region of the water storage tank, the first differential temperature being smaller than the second differential temperature.

20. The method of claim 16, further comprising the step of:opening the main valve to allow ignition of the gas burner using energy generated by the thermoelectric element.

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