Electronic control system for electric water heater

Patent metadata

Field	Value
Publication number	US-10274226-B2
Application number	US-201314080422-A
Country	US
Kind code	B2
Filing date	Nov 14, 2013
Priority date	Feb 28, 2013
Publication date	Apr 30, 2019
Grant date	Apr 30, 2019

Abstract

In an electric water heater having adjustable set point and differential temperatures, upper and lower heating elements, and associated temperature sensors respectively operative to sense upper and lower tank water temperatures, a specially designed control system is provided for controlling the heating elements. The control system is operative to automatically set a selected setpoint temperature to a second setpoint temperature less than or equal to a predetermined magnitude, and to reduced the second setpoint temperature and/or the differential temperature, as a predetermined function of the magnitudes of detected time intervals between successive heat demands of the water heater, to reduce the energy cost associated with the water heater.

First claim

What is claimed is:

1. An electric liquid heating apparatus comprising:
a tank for storing liquid to be heated;
an upper electric heating element extending through an upper portion of an interior of said tank;
an upper temperature sensor operative to sense a temperature representative of a temperature of said liquid in said upper portion of said tank;
a lower electric heating element extending through a lower portion of the interior of said tank;
a lower temperature sensor operative to sense a temperature representative of a temperature of said liquid in said lower portion of said tank, said upper and lower temperature sensors externally mounted on said tank; and
a control system electrically coupled to said upper and lower electric heating elements and said upper and lower temperature sensors, the control system adapted to control the upper and lower electric heating elements in a non-simultaneous actuation manner, the control system using an algorithm executing a performance operation mode, such that:
(1) when an initial temperature detected by said upper temperature sensor is less than a predetermined magnitude:
said control system initiates a high demand routine where said control system determines that a heat demand exists in said upper portion of said tank, and
responsive to determining that said heat demand in said upper portion of said tank exists, said control system selects one of said upper and lower heating elements to meet said heat demand in said upper portion of said tank based on a sensed presence or absence of predetermined magnitudes of (a) said temperature of said liquid in said lower portion of said tank sensed by said lower temperature sensor, (b) a rate of change of said temperature of said liquid in said lower portion of said tank sensed by said lower temperature sensor, (c) said temperature of said liquid in said upper portion of said tank sensed by said upper temperature sensor, and (d) a rate of change of said temperature of said liquid in said upper portion of said tank sensed by said upper temperature sensor, and

(2) when said initial temperature detected by said upper temperature sensor is not less than said predetermined magnitude, said control system:
(a) activates said upper electric heating element to satisfy a heat demand in said upper portion of said tank, as detected by said upper temperature sensor, and,
(b) activates said lower electric heating element to satisfy a heat demand in said lower portion of said tank, as detected by said lower temperature sensor, only if no heating demand exists in said upper portion of said tank,
wherein said initial temperature is sensed by said upper temperature sensor responsive to initially activating said upper heating element.

2. The electric liquid heating apparatus of claim 1 wherein:
said upper and lower temperature sensors are thermistors externally mounted on said tank.

3. The electric liquid heating apparatus of claim 2 wherein:
said tank has annular side wall projections outwardly through which said upper and lower electric heating elements that are removable, and
said upper and lower thermistors are secured to said annular side wall projections in a manner permitting removal of said upper and lower electric heating elements therethrough without removing said upper and lower thermistors therefrom.

4. The electric liquid heating apparatus of claim 1 wherein:
said tank has a covered cavity associated therewith, and
said control system has an electronic controller portion and an associated user input display disposed in said covered cavity.

5. The electric liquid heating apparatus of claim 4 wherein said control system further comprises:
a data input port for receiving user input to said control system from a location remote from said tank.

6. The electric liquid heating apparatus of claim 1 wherein:
said electric liquid heating apparatus further comprises a water detector integrated with said control system and operative to detect the presence of water externally adjacent said tank, and
said control system is operative to generate an alarm and/or shut down operation of said electric liquid heating apparatus in response to detection of water by said water detector.

7. The electric liquid heating apparatus of claim 6 wherein:
said tank is covered by a jacket structure,
said control system includes an electronic controller portion supported on said tank,
said water detector has a probe portion disposed externally of said tank, and
said water detector is integrated with said control system via a sensing lead extending from said probe portion to said electronic controller portion between said tank and said jacket structure.

8. The electric liquid heating apparatus of claim 6 wherein:
wherein said control system is an electronic control system.

9. The electric liquid heating apparatus of claim 1 wherein:
said electric liquid heating apparatus is an electric water heater.

10. An electric liquid heating apparatus having an adjustable set point temperature and differential temperature, said electric liquid heating apparatus comprising:
a tank for storing liquid to be heated;
an upper electric heating element extending through an upper portion of an interior of said tank;
an upper temperature sensor operative to sense a temperature representative of a temperature of said liquid in said upper portion of said tank;
a lower electric heating element extending through a lower portion of the interior of said tank;
a lower temperature sensor operative to sense a temperature representative of a temperature of said liquid in said lower portion of said tank, said upper and lower temperature sensors externally mounted on said tank; and
a control system electrically coupled to said upper and lower electric heating elements and said upper and lower temperature sensors, the control system adapted to control the upper and lower electric heating elements in a non-simultaneous actuation manner, the control system using an algorithm executing an energy saver operation mode such that:
when a selected setpoint temperature is greater than a pre-determined setpoint temperature magnitude,
said control system automatically sets the selected setpoint temperature to a second setpoint temperature less than or equal to a predetermined magnitude, and
responsively, said control system reduces the second setpoint temperature and/or increases a differential temperature of said upper and lower heating elements as a predetermined function of the magnitudes of detected time intervals between successive heat demands of said electric liquid heating apparatus to reduce the energy cost associated with the operation of said electric liquid heating apparatus.

11. The electric liquid heating apparatus of claim 10 wherein:
said upper and lower temperature sensors are thermistors externally mounted on said tank.

12. The electric liquid heating apparatus of claim 11 wherein:
said tank has annular side wall projections outwardly through which said upper and lower electric heating elements that are removable, and
said upper and lower thermistors are secured to said annular side wall projections in a manner permitting removal of said upper and lower electric heating elements therethrough without removing said upper and lower thermistors therefrom.

13. The electric liquid heating apparatus of claim 10 wherein:
said tank has a covered cavity associated therewith, and
said control system has an electronic controller portion and an associated user input display disposed in said covered cavity.

14. The electric liquid heating apparatus of claim

Assignees

• Rheem Mfg Co

Inventors

• Chaudhry Raheel A
• Maciulewicz Stephen M
• Boros Jozef

Classifications

• G05D23/1934

  each space being provided with one sensor acting on one or more control means · CPC title

• F24H1/202

  with resistances · CPC title

• F24H9/2021 Primary

  Storage heaters · CPC title

• H05B3/42

  non-flexible · CPC title

• H05B1/0283

  For heating of fluids, e.g. water heaters · CPC title