Multi-tank water heater systems

• US 9,885,484 B2
• Filed: 01/23/2013
• Issued: 02/06/2018
• Est. Priority Date: 01/23/2013
• Status: Active Grant

• Current Assignee: Ademco Inc. (Resideo Technologies, Inc.)
• Original Assignee: Honeywell International Inc.
• Inventors: Young, Gregory, Holmberg, James, Hazzard, Fritz, Kasprzyk, Donald J., Hill, Bruce L.
• Primary Examiner(s): Wilson, Gregory A
• Application Number:
  US13/748,049
• Publication Number:
  US 20140203093A1
• Time in Patent Office: 1,840 Days
• Field of Search: None
• CPC Class Codes: F24D 12/02 having more than one heat source using heat pumps, in water central heating systems F24D3/18; in air central heating systems F24D5/12; in systems using heat storage masses F24D11/02
• CPC Class Codes: F24D 17/0031 with accumulation of the heated water
• CPC Class Codes: F24D 19/1051 for domestic hot water
• CPC Class Codes: F24D 19/1066 for the combination of central heating and domestic hot water
• 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 15/215 before heating
• CPC Class Codes: F24H 15/219 after heating
• CPC Class Codes: F24H 15/223 in the water storage tank
• CPC Class Codes: F24H 15/315 of mixing valves
• CPC Class Codes: F24H 15/36 of burners
• CPC Class Codes: F24H 15/414 using electronic processing, e.g. computer-based
• CPC Class Codes: Y02B 30/00 Energy efficient heating, ventilation or air conditioning [HVAC]

Abstract

A water heater system that includes a first water storage tank plumbed in series with a second water storage tank, and methods for controlling such a water heater system. In some instances, and in response to a water draw, a controller may activate both a first heat source associated with a first water storage tank and a second heat source associated for a second water storage tank. This rapid turn-on control may help reduce a drop in water temperature in the first water storage tank that might otherwise occur. The controller may also increase the setpoint temperature of the first water storage tank and/or the second water storage tank in response to a water draw.

Claims

1. A water heater system comprising:

a first water tank having a first water inlet, a first water outlet, a first heat source, and a first temperature sensor for sensing a measure related to a first temperature in the first water tank;

a second water tank having a second water inlet, a second water outlet, a second heat source, and a second temperature sensor for sensing a measure related to a second temperature in the second water tank, wherein the first water tank has a first water volume and the second water tank has a second water volume, wherein the first water volume is larger than the second water volume;

a water line fluidly connecting the first water outlet of the first water tank to the second water inlet of the second water tank for transporting water from the first water tank to the second water tank;

a controller for receiving the measure related to the first temperature measured by the first temperature sensor and the measure related to the second temperature measured by the second temperature sensor, and for issuing control commands to the first heat source and the second heat source to control the temperature in the first water tank and the second water tank; and

the controller configured to detect a water draw from the second water tank, and to activate both the first heat source of the first water tank and the second heat source of the second water tank in direct response to the detected water draw, even when the controller does not detect the water draw via the first temperature sensor.

2. The water heater system of claim 1, wherein the controller is configured to issue control commands such that the first water tank is controlled to a first temperature setpoint and the second water tank is controlled to a second temperature setpoint, wherein the first temperature setpoint is lower than the second temperature setpoint.

3. The water heater system of claim 1, wherein the first heat source has a first heat output and the second heat source has a second heat output, wherein the ratio of the second heat output to the second water volume is greater than the ratio of the first heat output to the first water volume.

4. A water heater system comprising:

a first water tank having a first water inlet, a first water outlet, a first heat source, and a first temperature sensor for sensing a measure related to a first temperature in the first water tank;

a second water tank having a second water inlet, a second water outlet, a second heat source, and a second temperature sensor for sensing a measure related to a second temperature in the second water tank;

a water line fluidly connecting the first water outlet of the first water tank to the second water inlet of the second water tank for transporting water from the first water tank to the second water tank;

a controller for receiving the measure related to the first temperature measured by the first temperature sensor and the measure related to the second temperature measured by the second temperature sensor, and for issuing control commands to control the temperature in the first water tank and the second water tank; and

wherein the controller is configured to issue control commands such that the first water tank is controlled to a first temperature setpoint and the second water tank is controlled to a second temperature setpoint, wherein the first temperature setpoint is lower than the second temperature setpoint, and wherein the controller is configured to increase the first temperature setpoint of the first water tank when the controller senses a water draw from the second water tank.

5. The water heater system of claim 4, wherein during periods of low water usage, the controller is configured to issue control commands such that water in the first water tank warms to room temperature without activating the first heat source.

6. The water heater system of claim 4, wherein the second temperature setpoint of the second water tank is approximately equal to or above a desired outlet water temperature of the water heater system.

7. The water heater system of claim 4, wherein the first water tank has a first water volume and the second water tank has a second water volume, and wherein the first heat source has a first heat output and the second heat source has a second heat output, wherein the ratio of the second heat output to the second water volume is greater than the ratio of the first heat output to the first water volume.

8. The water heater system of claim 4, wherein the first water tank has a first water volume and the second water tank has a second water volume, wherein the first water volume is larger than the second water volume.

9. The water heater system of claim 4, wherein when the controller senses a water draw from the second water tank, both the first and the second heat source are activated.

10. The water heater system of claim 4, wherein the controller includes a first controller associated with the first water tank and a second controller associated with the second water tank, wherein one of the first controller and the second controller operates as a master and the other of the first controller and the second controller operates as a slave to the master.

11. A method for controlling a water heater system including a first water tank and a second water tank, wherein the first water tank includes a first water inlet, a first water outlet, a first temperature sensor, and a first heat source, and the second water tank includes a second water inlet, a second water outlet, a second temperature sensor, and a second heat source, wherein the second water inlet of the second water tank is configured to receive water from the first water outlet of the first water tank, the method comprising:

sensing a water draw from the second water tank;

activating both the first heat source and the second heat source in direct response to sensing the water draw, even when the water draw is not sensed in the first water tank.

12. The method of claim 11, further comprising:

controlling the first heat source to maintain a first setpoint temperature in the first water tank;

controlling the second heat source to maintain a second setpoint temperature in the second water tank; and

wherein the first setpoint temperature is lower than the second setpoint temperature.

13. The method of claim 12, wherein the second setpoint temperature of the second water tank is approximately equal to or above a desired outlet water temperature of the water heater system.

14. The method of claim 11, wherein the first water tank has a first water volume and the second water tank has a second water volume, wherein the first water volume is larger than the second water volume.

15. The method of claim 11, wherein the first water tank has a first water volume and the second water tank has a second water volume, and wherein the first heat source has a first heat output and the second heat source has a second heat output, wherein the ratio of the second heat output to the second water volume is greater than the ratio of the first heat output to the first water volume.

16. A method for controlling a water heater system including at least two water tanks, the method comprising:

storing a first setpoint temperature for a first water tank, the first water tank having a first water inlet, a first water outlet, a first temperature sensor, and a first heat source;

storing a second setpoint temperature for a second water tank, the second water tank having a second water inlet, a second water outlet, a second temperature sensor, and a second heat source, wherein the second water inlet is configured to receive water from the first water outlet of the first water tank;

sensing a water draw from the second water tank;

increasing the first setpoint temperature of the first water tank to a third setpoint temperature in direct response to sensing a water draw from the second water tank.

17. The method of claim 16, wherein the first setpoint temperature is lower than the second setpoint temperature.

18. The method of claim 16, wherein the third setpoint temperature is lower than the second setpoint temperature but higher than the first setpoint temperature.