Proportional band temperature control for one or more heating elements

• US 20010009609A1
• Filed: 01/02/2001
• Published: 07/26/2001
• Est. Priority Date: 07/27/1999
• Status: Active Grant

• Current Assignee: AOS Holding Company (A O Smith Corporation)
• Original Assignee: Kenneth A. Bradenbaugh
• Inventors: Bradenbaugh, Kenneth A.
• Granted Patent: US 6,633,726 B2
• Time in Patent Office: Days
• US Class Current: 392/463
• CPC Class Codes: F24H 15/144 Measuring or calculating energy consumption
• CPC Class Codes: F24H 15/156 Reducing the quantity of energy consumed; Increasing efficiency
• CPC Class Codes: F24H 15/174 Supplying heated water with desired temperature or desired range of temperature
• CPC Class Codes: F24H 15/225 at different heights of the tank
• CPC Class Codes: F24H 15/242 Pressure
• CPC Class Codes: F24H 15/254 Room temperature
• CPC Class Codes: F24H 15/281 Input from user
• CPC Class Codes: F24H 15/37 of electric heaters
• CPC Class Codes: F24H 15/395 Information to users, e.g. alarms
• CPC Class Codes: F24H 15/407 using electrical switching, e.g. TRIAC
• CPC Class Codes: F24H 15/414 using electronic processing, e.g. computer-based
• CPC Class Codes: F24H 9/2021 Storage heaters
• CPC Class Codes: G05D 23/1909 whose output amplitude can only take two discrete values
• CPC Class Codes: H05B 1/0283 For heating of fluids, e.g. water heaters
• CPC Class Codes: H05B 3/82 Fixedly-mounted immersion heaters

Abstract

A water heater having a water tank and multiple electric resistance heating elements extending into the water tank for heating water in the tank. The water heater includes a proportional band temperature controller for conducting electric power to the electric resistance heating elements in bursts. Each burst of electric power is followed by a period during which the temperature controller does not conduct power to the electric resistance heating element. In one embodiment, each burst of electrical power lasts for about 95% or less of a cycle comprised of one burst of electric power followed by the period during which the temperature controller does not conduct electric power. Further, activation of the heating elements by the controller is carried out in a sequential or other timed or controlled fashion to permit uniform heating of the water in the tank.

Claims

1. A method of controlling a temperature of water in a water heater including a tank for storing water and a heating element capable of being powered by a power source, the method comprising the acts of:

determining an element characteristic of the heating element;

sensing a temperature of the water in the tank;

calculating an amount of power to be provided to the heating element based at least in part on the element characteristic and water temperature; and

transmitting the amount of power from the power source to the heating element.

2. A method as set forth in

claim 1

, wherein the element characteristic includes an element type.

3. A method as set forth in

claim 1

, wherein the element characteristic includes an element wattage.

4. A method as set forth in

claim 1

, wherein the element characteristic includes an element voltage.

5. A method as set forth in

claim 1

, wherein the element characteristic includes the location of the element within the tank.

6. A method as set forth in

claim 1

, wherein the water heater further includes a second heating element capable of being powered by the power source, the method further comprising the acts of:

determining a second element characteristic of the second heating element;

calculating an amount of power to be provided to the second heating element based at least in part on the second element characteristic and the water temperature; and

transmitting the amount of power from the power source to the second heating element.

7. A method as set forth in

claim 6

, wherein the act of calculating the first amount of power is based at least in part on the second element characteristic, and wherein the act of calculating the second amount of power is based in at least in part on the first element characteristic.

8. A method as set forth in

claim 1

, further comprising:

determining a tank characteristic of the tank; and

wherein the act of calculating the amount of power is based at least in part on the tank characteristic.

9. A method as set forth in

claim 8

, wherein the tank characteristic includes a tank capacity.

10. A method as set forth in

claim 8

, wherein the tank characteristic includes a tank diameter, tank radius, tank circumference or tank cross-sectional area.

11. A method as set forth in

claim 8

, wherein the tank characteristic includes a tank height.

12. A method as set forth in

claim 1

, further comprising:

sensing a second temperature of the water in the tank; and

wherein the act of calculating the amount of power is based at least in part on the second temperature.

13. A method as set forth in

claim 12

, wherein the first temperature is sensed by a first sensor, and wherein the second temperature is sensed by a second sensor.

14. A method as set forth in

claim 12

, wherein the second temperature is sensed after the first temperature.

15. A method as set forth in

claim 14

, further comprising:

calculating a slope of a line based at least in part on the first and second temperatures; and

wherein the act of calculating the amount of power is based at least in part on the calculated slope.

16. A method as set forth in

claim 1

, further comprising:

repeating the act of sensing a temperature of the water;

storing each sensed temperature, the storing act results in a usage pattern; and

wherein the act of calculating an amount of power is based in part on the usage pattern.

17. A method as set forth in

claim 1

, wherein the act of transmitting power comprises:

transmitting power from the power source to the heating element in a burst.

18. A method as set forth in

claim 6

, wherein the act of transmitting power from the power source to the first element comprises transmitting power from the power source to the first heating element in a first burst, andw herein the act of transmitting power from the power source to the second element comprises transmitting power from the power source to the second heating element in a second burst.

19. A method as set forth in

claim 18

, wherein the act of transmitting power from the power source to the second element in a second burst is after the act of transmitting power from the power source to the first element in a first burst.

20. A method as set forth in

claim 1

, further comprising the act of:

sensing an ambient temperature; and

wherein the act of calculating an amount of power is based at least in part on the environment temperature.

21. A method as set forth in

claim 3

, wherein the act of determining an element characteristic includes the acts of:

transmitting a voltage to the heating element; and

calculating an element wattage for the heating element.

22. A method as set forth in

claim 11

, wherein the act of calculating an amount of power includes the acts of:

providing a memory unit having a table comprising a plurality of water heater codes and respective heating data;

creating a first water heater code based at least in part on the element characteristic;

obtaining heating data from the table in response to the first water heater code; and

calculating the amount of power based at least in part on the first water heater code and the sensed temperature.

42. A software program as set forth in

claim 3

8, wherein the element characteristic includes an element voltage.

23. A method of controlling a temperature of water in a water heater including a tank for storing water and a heating element capable of being powered by a power source, the method comprising the acts of:

determining a tank characteristic of the tank;

sensing a temperature of the water in the tank;

calculating an amount of power to be provided to the heating element based at least in part on the tank characteristic and water temperature; and

transmitting the amount of power from the power source to the heating element.

24. A method as set forth in

claim 23

, wherein the tank characteristic includes a tank capacity.

25. A method as set forth in

claim 23

, wherein the tank characteristic includes a tank diameter, tank radius, tank circumference or tank cross-sectional area.

26. A method as set forth in

claim 23

, wherein the tank characteristic includes a tank height.

27. A method as set forth in

claim 23

, wherein the act of calculating an amount of power includes the acts of:

providing a memory unit having a table comprising a plurality of water heater codes and respective heating data;

creating a first water heater code based at least in part on the tank characteristic;

obtaining heating data from the table in response to the first water heater code; and

calculating the amount of power based at least in part on the first water heater code and the sensed temperature.

28. A method of controlling a temperature of water in a water heater including a tank for storing water and a heating element capable of being powered by a power source, the method comprising the acts of:

sensing an ambient temperature exterior to the water heater;

sensing a temperature of the water in the tank;

calculating an amount of power to be provided to the heating element based at least in part on the ambient temperature and the water temperature; and

transmitting the amount of power from the power source to the heating element.

29. A method as set forth in

claim 28

, the method further comprising the acts of:

determining an element characteristic of the heating element; and

wherein the act of calculating the amount of power is based at least in part on the element characteristic.

30. A method as set forth in

claim 28

, the method further comprising:

determining a tank characteristic of the tank; and

wherein the act of calculating the amount of power is based at least in part on the tank characteristic.

31. A method as set forth in

claim 28

, further comprising:

sensing a second temperature of the water in the tank; and

wherein the act of calculating the amount of power is based at least in part on the second temperature.

32. A method as set forth in

claim 31

, wherein the first temperature is sensed by a first sensor, and wherein the second temperature is sensed by a second sensor.

33. A method as set forth in

claim 31

, wherein the second temperature is sensed after the first temperature.

34. A method as set forth in

claim 33

, further comprising:

calculating a slope of a line based at least in part on the first and second temperatures; and

wherein the act of calculating the amount of power is based at least in part on the calculated slope.

35. A method as set forth in

claim 28

, further comprising:

repeating the act of sensing an ambient temperature;

storing each sensed temperature, the storing act results in a usage pattern; and

wherein the act of calculating an amount of power is based in part on the usage pattern.

36. A method as set forth in

claim 35

, further comprising:

repeating the act of sensing a temperature of the water;

storing each sensed ambient temperature.

37. A method as set forth in

claim 28

, wherein the act of transmitting power comprises transmitting power from the power source to the heating element in a burst.

38. A software program for generating a signal resulting in an amount of power to be transmitted to a heating element, the heating element being disposed within a tank containing a liquid and the liquid having a temperature being sensed by a temperature sensor, the software program generating the signal by:

obtaining a water heater code from a memory unit, the water heater code based at least in part on a one of a heating element characteristic and a tank characteristic.

receiving the temperature of the liquid from the temperature sensor;

calculating the amount of power to transmit to the heating element based at least in part on the water heater code and the sensed temperature; and

generating a signal resulting in the amount of power being provided to the heating element.

39. A software program as set forth in

claim 38

, wherein the water heater code is based at least in part on the element characteristic and the tank characteristic.

40. A software program as set forth in

claim 38

, wherein the element characteristic includes an element type.

41. A software program as set forth in

claim 38

, wherein the element characteristic includes an element wattage.

43. A software program as set forth in

claim 38

, wherein the element characteristic includes the location of the element within the tank.

44. A software program as set forth in

claim 38

, wherein the water heater further includes a second heating element capable of being powered by the power source, and wherein the water heater code is based at least in part on a second heating element characteristic.

45. A software program as set forth in

claim 44

, further comprising the acts of:

calculating a second amount of power to transmit to the second heating element based at least in part on the water heater code and the sensed temperature; and

generating a second signal resulting in the second amount of power being provided to the second heating element.

46. A software program as set forth in

claim 38

, wherein the tank characteristic includes a tank capacity.

47. A software program as set forth in

claim 38

, wherein the tank characteristic includes a tank diameter, tank radius, tank circumference or tank cross-sectional area.

48. A software program as set forth in

claim 38

, wherein the tank characteristic includes a tank height.

49. A software program as set forth in

claim 38

, further comprising:

sensing a second temperature of the liquid in the tank; and

wherein the act of calculating the amount of power is based at least in part on the second temperature.

50. A software program as set forth in

claim 49

, wherein the second temperature is sensed by a second sensor.

51. A software program as set forth in

claim 49

, wherein the second temperature is sensed after the first temperature.

52. A software program as set forth in

claim 51

, further comprising:

calculating a slope of a line based at least in part on the first and second temperatures; and

wherein the act of calculating the amount of power is based at least in part on the calculated slope.

53. A software program as set forth in

claim 38

, further comprising:

repeating the act of sensing a temperature of the water;

storing each sensed temperature, the storing act results in a usage pattern; and

wherein the act of calculating an amount of power is based at least in part on the water usage pattern.

54. A software program as set forth in

claim 38

, wherein the act of generating a signal comprises:

generating a signal resulting in the amount of power being delivered to the heating element in a burst with the burst being followed by a period in which no power is delivered to the heating element.

55. A software program as set forth in

claim 45

, wherein the act of generating a first signal comprises

generating a first signal resulting in the first amount of power being delivered to the first heating element in a first burst with the first burst being followed by a period in which no power is delivered to the first heating element, and wherein the act of generating a second signal comprises

generating a second signal resulting in the second amount of power being delivered to the second heating element in a second burst with the second burst being followed by a period in which no power is delivered to the second heating element.

56. A software program as set forth in

claim 55

, wherein the act of generating a second signal is after the act of generating a first signal.

57. A software program as set forth in

claim 38

, further comprising the act of:

sensing an environment temperature; and

wherein the act of calculating an amount of power is based at least in part on the environment temperature.

58. A water heater, comprising:

a water tank having a tank characteristic;

a water inlet line for introducing cold water into the tank;

a water outlet line capable of removing hot water from the tank;

a heating element having a heating surface disposed within the tank and having an element characteristic;

a temperature sensor capable of sensing a temperature of the water within the tank; and

a controller in communication with the heating element and the temperature sensor, the controller being operable to receive the sensed temperature from the temperature sensor, to calculate a heating strategy for the water heater based at least in part on a one of the element characteristic and the tank characteristic, and to generate a signal activating the heating element in response to the heating strategy.

59. A water heater as set forth in

claim 58

, wherein the heating strategy is based at least in part on the element characteristic and the tank characteristic.

60. A water heater as set forth in

claim 58

, wherein the element characteristic includes an element type.

61. A water heater as set forth in

claim 58

, wherein the element characteristic includes an element wattage.

62. A water heater as set forth in

claim 58

, wherein the element characteristic includes an element voltage.

63. A water heater as set forth in

claim 58

, wherein the element characteristic includes the location of the element within the tank.

64. A water heater as set forth in

claim 58

, wherein the tank characteristic includes a tank capacity.

65. A water heater as set forth in

claim 58

, wherein the tank characteristic includes a tank diameter, tank radius, tank circumference or tank cross-sectional area.

66. A water heater as set forth in

claim 58

, wherein the tank characteristic includes a tank height.

67. A water heater as set forth in

claim 58

, further comprising:

a second heating element having a second heating surface disposed within the tank and having a second element characteristic; and

wherein the controller is in communication with the heating element, and wherein the controller is operable to calculate a heating strategy for the water heater based in part on the second element characteristic, and to generate a signal activating the second heating element in response to the heating strategy.

68. A water heater as set forth in

claim 58

, wherein the controller is operable to control the supply of electric power to the first and second heating elements in bursts, each burst followed by a period during which electric power is not supplied to the heating element, the control circuit further operable to activate the first heating element or a first time period and to activate the second heating element for a second time period.

69. A water heater as set forth in

claim 59

, wherein the second heating element is activated after the first heating element is activated.

70. A water heater as set forth in

claim 59

, wherein the first and second time periods vary based on the heating strategy.

71. A storage-type water heater, comprising:

a permanently enclosed water tank to store water while the water is being heated to a set-point temperature;

a water inlet line for adding cold water to the water tank;

a water outlet line for withdrawing heated water from the water tank;

at least one electric resistance heating element extending into the water tank to heat water in the water tank;

at least one water temperature sensor operable to sense a water temperature; and

a control circuit operable to conduct electric power to the electric resistance heating element in bursts, each burst followed by a period during which electric power is not conducted to the electric resistance heating element, thereby improving the efficiency of heating the water in the water tank, and operable to change the proportion of on to off time in response to the sensed water temperature and at least one of an element characteristic, a tank characteristic, an external water tank temperature, a water consistency, and a history of water use.

72. A water heater as set forth in

claim 71

, wherein the element characteristic includes an element type.

73. A water heater as set forth in

claim 71

, wherein the element characteristic includes an element wattage.

74. A water heater as set forth in

claim 71

, wherein the element characteristic includes an element voltage.

75. A water heater as set forth in

claim 71

, wherein the element characteristic includes the location of the element within the tank.

76. A water heater as set forth in

claim 71

, wherein the tank characteristic includes a tank capacity.

77. A water heater as set forth in

claim 71

, wherein the tank characteristic includes a tank diameter, tank radius, tank circumference or tank cross-sectional area.

78. A water heater as set forth in

claim 71

, wherein the tank characteristic includes a tank height.

79. A water heater as set forth in

claim 71

, wherein the control circuit includes a microcontroller and a memory unit having a water heater code, the water heater code based at least in part on a one of the element characteristic and the tank characteristic, and wherein the microcontroller is operable to change the proportion of on to off time in response to at least the sensed water temperature and the water heater code.

80. A storage-type water heater, comprising:

a permanently enclosed water tank to store water while the water is being heated to a set-point temperature;

a water inlet line for adding cold water to the water tank;

a water outlet line for withdrawing heated water from the water tank;

at least one electric resistance heating element extending into the water tank to heat water in the water tank;

at least one water temperature sensor operable to sense a water temperature; and

a control circuit capable of conducting electric power to the electric resistance heating element in bursts, each burst followed by a period during which electric power is not conducted to the electric resistance heating element, thereby improving the efficiency of heating the water in the water tank, the control circuit including a microcontroller and software for operating the microcontroller to change the proportion of on to off time in response to the sensed water temperature and at least one of an element characteristic, a tank characteristic, an external water tank temperature, a water consistency, and a history of water use.

81. A water heater as set forth in

claim 80

, wherein the control circuit includes a memory unit having a water heater code based at least in part on one of the element characteristic and the tank characteristic, and wherein the software operates the microcontroller to change the proportion of on to off time in response to at least the sensed water temperature and the water heater code.

82. A water heater as set forth in

claim 81

, wherein the control circuit includes a memory unit having a heating strategy corresponding to the water heater code, and wherein the software operates the microcontroller to obtain the heating strategy in response to the water heater code and to change the proportion of on to off time in response to at least the sensed temperature and the heating strategy.

83. A water heater as set forth in

claim 80

, further comprising:

a second electric resistance heating element extending into the water tank to heat water in the water tank; and

wherein the control circuit is capable of conducting electric power to the second electric resistance heating element in bursts, each burst followed by a period during which electric power is not conducted to the second electric resistance heating element, thereby improving the efficiency of heating the water in the water tank, and wherein the software further operates the microcontroller to change the proportion of on to off time for the second resistance heating element in response to the sensed water temperature and at least one of an element characteristic, a tank characteristic, an external water tank temperature, a water consistency, and a history of water use.

84. A water heater as set forth in

claim 83

, wherein the burst provided to the second electric resistance heating element is after the burst provided to the first electric resistance heating element.