Smart water heater system, method and computer readable media

• US 10,240,816 B2
• Filed: 05/29/2015
• Issued: 03/26/2019
• Est. Priority Date: 05/30/2014
• Status: Active Grant

• Current Assignee: University of Virginia Patent Foundation (University of Virginia)
• Original Assignee: University of Virginia Patent Foundation (University of Virginia)
• Inventors: Whitehouse, Cameron Dean, Prodhan, Md Anindya Tahsin
• Primary Examiner(s): Tran, Len
• Assistant Examiner(s): Hopkins, Jenna M
• Application Number:
  US14/725,453
• Publication Number:
  US 20150346740A1
• Time in Patent Office: 1,397 Days
• Field of Search: 236 121, 236 1211, 236 25, 392445, 392450, 392454
• CPC Class Codes: F24D 2200/04 Gas or oil fired boiler
• CPC Class Codes: F24D 2200/08 Electric heater
• CPC Class Codes: F24H 1/00 Water heaters, e.g. boilers, continuous-flow heaters or water-storage heaters steam boilers F22B
• CPC Class Codes: F24H 1/181 Construction of the tank
• CPC Class Codes: F24H 1/183 Inner linings
• CPC Class Codes: F24H 1/185 using electric energy supply F24H1/201 takes precedence
• CPC Class Codes: F24H 1/186 using fluid fuel
• CPC Class Codes: F24H 15/223 in the water storage tank
• CPC Class Codes: F24H 15/238 Flow rate
• CPC Class Codes: F24H 15/242 Pressure
• CPC Class Codes: F24H 15/281 Input from user
• CPC Class Codes: F24H 15/315 of mixing valves
• CPC Class Codes: F24H 15/414 using electronic processing, e.g. computer-based
• CPC Class Codes: F24H 15/45 remotely accessible
• CPC Class Codes: F24H 9/133 Storage heaters
• CPC Class Codes: F24H 9/2007 for water heaters
• CPC Class Codes: G05D 23/13 by varying the mixing ratio of two fluids having different temperatures
• CPC Class Codes: G05D 23/1306 for liquids G05D23/1393 takes precedence
• CPC Class Codes: G05D 23/1313 without temperature sensing element

Abstract

A smart water heater system (SWHS) for a domestic water system having a plurality of fixtures has a water tank having a cold water inlet and a heat source configured to heat the cold water. The SWHS may also have a mixing valve to blend cold water with the hot water to produce blended water, wherein the blended water is directed to the domestic water system. The SWHS may have a controller in communication with the mixing valve configured to identify which fixture is being used when the domestic water system is drawing water from the water tank, determine an average water temperature utilized by each fixture, and adjust the mixing valve based on which fixture is identified such that a temperature of the blended water is generally equal to the average water temperature for the identified fixture.

Claims

1. A smart water heater system for a domestic water system having a plurality of fixtures, comprising:

a water tank having;

a cold water inlet configured to receive cold water from a cold water supply;

a heat source configured to heat the cold water producing hot water;

a hot water outlet configured to discharge the hot water from the water tank;

a mixing valve configured to blend cold water from the cold water supply with the hot water from the hot water outlet to produce blended water, wherein the blended water is directed to the domestic water system;

a first flow meter configured to measure a flow rate of the blended water from the mixing valve;

a second flow meter configured to measure a flow rate of cold water supplied to the domestic water system;

a pressure sensor configured to measure a pressure of the cold water supplied to the water tank; and

a controller in communication with the mixing valve, the first flow meter, the second flow meter, and the pressure sensor, the controller being configured to;

determine, using measurements from the first flow meter, the second flow meter, and the pressure sensor, an average water temperature utilized by each fixture over time during an initialization period;

identify, using measurements from the first flow meter, the second flow meter, and the pressure sensor, one or more fixtures being used when the domestic water system is drawing water from the water tank; and

adjust the mixing valve such that the blended water is about equal to the average water temperature of an identified fixture when one fixture is being used and to the higher of the average water temperatures utilized by each identified fixture when multiple fixtures are used simultaneously.

2. The smart water heater system of claim 1, wherein the water tank has a first tank and a second tank separate from the first tank, wherein each tank is independently heated and temperature controlled by the heat source.

3. The smart water heater system of claim 2, wherein the controller is configured to heat the first tank to a hot water temperature set point and the second tank is heated to a warm water temperature set point.

4. The smart water heater system of claim 3, wherein the controller is configured to calculate the warm water temperature set point based on use profiles for each fixture.

5. The smart water heater system of claim 3, wherein the water from both the first tank and second tank are directed through the mixing valve before being supplied to the domestic water system.

6. The smart water heater system of claim 3, wherein the controller is configured to switch temperature set points for the first tank and the second tank periodically.

7. The smart water heater system of claim 3, wherein the hot water temperature set point is about 120°

F. and the warm water temperature set point is less than 120°

F. and greater than 85°

F.

8. The smart water heater system of claim 3, wherein the controller is configured to detect when a fixture is turned on and off repeatedly, and when detected, to adjust the mixing valve so a temperature of the blended water supplied to the corresponding fixture is temporarily increased.

9. The hot water heater system of claim 1, wherein the controller is configured to, using measurements from the first flow meter, the second flow meter, and the pressure sensor, determine a probability of a short event based on use profiles of the fixtures and when the probability is greater than a short event threshold set point the controller adjusts the mixing of the cold water and hot water such that no hot water is directed to the domestic water system.

10. The hot water heater system of claim 1, wherein the controller determines a pipe lag for each fixture using measurements from the first flow meter, the second flow meter, and the pressure sensor.

11. The hot water heater system of claim 1, wherein the controller is configured to reduce energy cost by limiting the temperature of the water in the water tank and in the domestic water system.

12. The hot water heater system of claim 2, wherein the controller is configured to reduce energy cost by limiting stand-by heat loss by storing water supplied to either the first tank or the second tank at a lower temperature than the hot water.

13. The hot water heater system of claim 1, wherein the system operates like a traditional hot water heater system initially after installation until after the initialization period.

14. A smart water heater system kit for a water heater system for a domestic water system having a plurality of fixtures, comprising:

a mixing valve configured to blend cold water from the cold water supply with the hot water from the hot water outlet of a water tank to produce blended water, where in the blended water is directed to the domestic water system;

a first flow meter configured to measure a flow rate of the blended water from the mixing valve;

a second flow meter configured to measure a flow rate of cold water supplied to the domestic water system;

a pressure sensor configured to measure a pressure of the cold water supplied to the water tank; and

a controller in communication with the mixing valve, the first flow meter, the second flow meter, and the pressure sensor, the controller being configured to;

determine, using measurements from the first flow meter, the second flow meter, and the pressure sensor, an average water temperature utilized be each fixture over time during an initialization period;

identify, using measurements from the first flow meter, the second flow meter, and the pressure sensor, one or more fixtures being used when the domestic water system is drawing water from the water tank; and

adjust the mixing valve such that the blended water is about equal to the average water temperature of an identified fixture when one fixture is being used and to the higher of the average water temperatures utilized by each identified fixture when multiple fixtures are used simultaneously.

15. A method of operating a smart water heater system for a domestic water system having a plurality of fixtures, the method comprising:

measuring the pressure of cold water supplied to a hot water tank of the system from a cold water supply during operation;

heating the cold water supplied to the hot water tank to produce hot water;

mixing cold water from the cold water supply with hot water from the hot water tank to produce blended water, where in the blended water is directed to the domestic water system;

measuring a flow rate of the blended water supplied to the domestic water system;

measuring a flow rate of the cold water supplied to the domestic water system from the cold water supply; and

operating a controller, wherein operating the controller includes;

identifying, using the measured pressure of cold water, flow rate of the blended water, and flow rate of the cold water, which fixture is being used when the domestic water system is drawing water from the hot water tank;

determining, using the measured pressure of cold water, flow rate of the blended water, and flow rate of the cold water, an average water temperature utilized by each fixture; and

adjusting a mixing valve such that the blended water is about equal to the average water temperature of an identified fixture when one fixture is being used and to the higher of the average water temperatures utilized by each identified fixture when multiple fixtures are used simultaneously.

16. The method of claim 15, wherein the controller determines a probability of a short event and when the probability is greater than a short event threshold set point the controller adjusts the mixing of the cold water and hot water such that no hot water is directed to the domestic water system.

17. The method of claim 15, wherein the controller determines a pipe lag for each fixture.

18. The method of claim 15, wherein the hot water heater system includes a hot water heater having a first tank and a second tank separate from the first tank, wherein each tank is independently heated and temperature controlled by the heat source and the controller is configured to heat the first tank to a hot temperature set point and the second tank is heat to a warm temperature set point.

19. The method of claim 18, wherein the controller calculates the warm temperature set point based on use profiles for each fixture.