Apparatus and methods for controlling a water heater

• US 7,032,542 B2
• Filed: 06/08/2004
• Issued: 04/25/2006
• Est. Priority Date: 06/08/2004
• Status: Active Grant

• Current Assignee: Copeland Comfort Control LP (Emerson Electric Company)
• Original Assignee: Emerson Electric Company
• Inventors: Donnelly, Donald E., Buescher, Thomas P., Somorov, Michael
• Primary Examiner(s): WILSON, GREGORY A
• Application Number:
  US10/863,319
• Publication Number:
  US 20050279291A1
• Time in Patent Office: 686 Days
• Field of Search: 122/14.1, 122/14.2, 122/14.22, 122/447, 237/8.R, 219/483
• US Class Current: 122/14.2
• CPC Class Codes: F23M 2900/11021 Means for avoiding accidental fires in rooms where the combustion device is located
• CPC Class Codes: F23N 2225/18 feedwater temperature
• CPC Class Codes: F23N 5/245 using electrical or electromechanical means
• CPC Class Codes: F24H 15/174 Supplying heated water with desired temperature or desired range of temperature
• CPC Class Codes: F24H 15/184 Preventing harm to users from exposure to heated water, e.g. scalding
• CPC Class Codes: F24H 15/20 characterised by control inputs
• CPC Class Codes: F24H 15/225 at different heights of the tank
• CPC Class Codes: F24H 15/31 of valves having only one inlet port and one outlet port, e.g. flow rate regulating valves
• CPC Class Codes: F24H 15/414 using electronic processing, e.g. computer-based
• CPC Class Codes: F24H 9/2035 using fluid fuel

Abstract

A gas-powered water heater includes means for stepping down a line voltage from a receptacle remote from the tank, means for using the stepped down voltage to provide a low voltage, and means for using the low voltage to sense conditions pertaining to the heater and to control heater operation based on the sensed conditions. Using a plug-in transformer to provide power for microprocessor control makes it unnecessary to install a line voltage line to the heater.

Claims

1. A gas-fired water heater having a burner that heats water in a tank, the water heater comprising:

means for stepping down a line voltage from a line voltage receptacle remote from the tank to provide a stepped down voltage;

means for using the stepped down voltage to provide a low voltage lower than the stepped down voltage; and

means for using the low voltage to sense a plurality of conditions pertaining to the heater and to control heater operation based on the sensed conditions, said means using the low voltage comprising;

means for determining whether water is drawn from the tank; and

means for increasing a heating set-point based on the determining.

2. The water heater of claim 1 wherein the means for determining whether water is drawn from the tank comprises means for determining a temperature at a top of the tank and near a cold water inlet of the tank.

3. The water heater of claim 1 wherein the means for determining whether water is drawn from the tank comprises means for determining a temperature at a top of the tank and near a cold water pipe fitting of the tank.

6. The apparatus of claim 1 wherein the water-draw sensor comprises a surface-mounted temperature sensor near the bottom of the tank.

7. The apparatus of claim 1 wherein the water-draw sensor comprises a surface-mounted temperature sensor near a cold water inlet.

8. The apparatus of claim 1 wherein the water-draw sensor comprises a surface-mounted temperature sensor near a cold water pipe fitting.

9. The apparatus of claim 1 wherein the processor is configured to:

use the water-draw sensor to determine whether water is being drawn out of the tank;

increase a heating set-point based on the determining; and

call for heat until the temperature sensor indicates that the slightly increased set-point has been reached.

10. The apparatus of claim 9 wherein to increase a heating set-point comprises to increase the set-point by between 1 and 2 degrees F.

4. A gas-fired water heater having a burner that heats water in a tank, the water heater comprising:

means for stepping down a line voltage from a line voltage receptacle remote from the tank to Provide a stepped down voltage;

means for using the stepped down voltage to provide a low voltage lower than the stepped down voltage; and

means for using the low voltage to sense a plurality of conditions pertaining to the heater and to control heater operation based on the sensed conditions, said means using the low voltage comprising;

means for sensing flammable vapor; and

means for shutting off the heater based on an average resistance in the means for sensing flammable vapor.

5. An apparatus for controlling a gas-fired water heater having a tank, the apparatus comprising:

a controller; and

a plug-in transformer that steps down a line voltage to provide a stepped-down voltage to the controller;

wherein the transformer is plugged into a line voltage source remote from the controller;

the controller comprising a processor that draws a low voltage to control heater operation, and a circuit that draws the stepped-down voltage to provide the low voltage to the processor and operating power to at least one of an igniter and a gas valve of the heater;

the apparatus further comprising;

a temperature sensor that senses temperature near the top of the tank; and

a water-draw sensor configured to sense water being drawn from the tank;

the processor configured to control heater operation based on input from the sensors.

11. An apparatus for controlling a gas-fired water heater having a tank, the apparatus comprising:

a controller having a processor; and

a plug-in transformer that steps down a line voltage to provide a stepped-down voltage to the controller;

wherein the transformer is plugged into a line voltage source remote from the controller and remote from the tank;

the apparatus further comprising a flammable vapor (FV) sensor, the processor configured to;

determine an average resistance of the FV sensor over a predetermined period; and

control heater operation based on the average resistance.

12. The apparatus of claim 11 configured to shut down the heater if the average resistance reaches a predetermined value.

13. A processor-implemented method of operating a gas-fired water heater comprising:

determining whether water is being drawn out of a tank of the heater;

increasing a heating set-point based on the determining; and

calling for heat until the increased set-point has been reached.

14. The method of claim 13 wherein determining whether water is being drawn out comprises determining whether cold water is entering the tank.

15. The method of claim 14 wherein determining whether cold water is entering comprises sensing a temperature drop using a temperature sensor.

16. The method of claim 13 wherein increasing a heating set-point comprises increasing the set-point by between one and two degrees F.

17. A gas-fired water heater having a burner that heats water in a tank, the system comprising:

means for stepping down a line voltage from a line voltage receptacle remote from the tank to provide a stepped down voltage;

means for using the stepped down voltage to provide a low voltage lower than the stepped down voltage; and

means for using the low voltage to sense a plurality of conditions pertaining to the heater and to control heater operation based on the sensed conditions,

the means for using the low voltage comprising;

means for determining whether water is drawn from the tank; and

means for increasing a heating set-point based on the determining;

the means for determining whether water is drawn from the tank comprising means for determining a temperature at a top of the tank and near a cold water inlet of the tank.

18. A gas-fired water heater having a burner that heats water in a tank, the system comprising:

means for stepping down a line voltage from a line voltage receptacle remote from the tank to provide a stepped down voltage;

means for using the stepped down voltage to provide a low voltage lower than the stepped down voltage; and

means for using the low voltage to sense a plurality of conditions pertaining to the heater and to control heater operation based on the sensed conditions,

the means for using the low voltage comprising;

means for determining whether water is drawn from the tank; and

means for increasing a heating set-point based on the determining;

the means for determining whether water is drawn from the tank comprising means for determining a temperature at a top of the tank and near a cold water pipe fitting of the tank.

19. A gas-fired water heater having a burner that heats water in a tank, the system comprising:

means for stepping down a line voltage from a line voltage receptacle remote from the tank to provide a stepped down voltage;

means for using the stepped down voltage to provide a low voltage lower than the stepped down voltage; and

means for using the low voltage to sense a plurality of conditions pertaining to the heater and to control heater operation based on the sensed conditions;

the means for using the low voltage comprising;

means for sensing flammable vapor; and

means for shutting off the heater based on an average resistance in the means for sensing flammable vapor.

20. An apparatus for controlling a gas-fired water heater having a tank, the apparatus comprising:

a controller; and

a plug-in transformer that steps down a line voltage to provide a stepped-down voltage to the controller;

wherein the transformer is plugged into a line voltage source remote from the controller;

the controller comprising;

a processor that draws a low voltage to control heater operation; and

a circuit that draws the stepped-down voltage to provide the low voltage to the processor and operating power to at least one of an igniter and a gas valve of the heater;

the apparatus further comprising;

a temperature sensor that senses temperature near the top of the tank; and

a water-draw sensor configured to sense water being drawn from the tank;

the processor configured to control heater operation based on input from the sensors.

21. The apparatus of claim 20 wherein the water-draw sensor comprises a surface-mounted temperature sensor near the bottom of the tank.

22. The apparatus of claim 20 wherein the water-draw sensor comprises a surface-mounted temperature sensor near a cold water inlet.

23. The apparatus of claim 20 wherein the water-draw sensor comprises a surface-mounted temperature sensor near a cold water pipe fitting.

24. The apparatus of claim 20 wherein the processor is configured to:

use the water-draw sensor to determine whether water is being drawn out of the tank;

increase a heating set-point based on the determining; and

call for heat until the temperature sensor indicates that the increased set-point has been reached.

25. The apparatus of claim 24 wherein to increase a heating set-point comprises to increase the set-point by between 1 and 2 degrees F.

26. An apparatus for controlling a gas-fired water heater having a tank, the apparatus comprising:

a controller; and

a plug-in transformer that steps down a line voltage to provide a stepped-down voltage to the controller;

wherein the transformer is plugged into a line voltage source remote from the controller and remote from the tank;

the apparatus further comprising a flammable vapor (FV) sensor, the processor configured to;

determine an average resistance of the FV sensor over a predetermined period; and

control heater operation based on the average resistance.

27. The apparatus of claim 26 configured to shut down the heater if the average resistance reaches a predetermined value.