Storage water heater

Patent metadata

Field	Value
Publication number	US-12092343-B2
Application number	US-202118265688-A
Country	US
Kind code	B2
Filing date	Jan 22, 2021
Priority date	Jan 22, 2021
Publication date	Sep 17, 2024
Grant date	Sep 17, 2024

Abstract

A storage water heater is provided that allows for improved maintenance of hygiene in a lower part of a hot-water storage tank and in a passage connected to the lower part of the hot-water storage tank. A storage water heater includes a heating device, a hot-water storage tank, a first passage, and a controller. The hot-water storage tank stores hot water. The first passage is connected to a lower part of the hot-water storage tank. The controller is configured to selectively switch between a heat-up operation and a recirculation operation. In the heat-up operation, hot water heated by the heating device is delivered to an upper part of the hot-water storage tank. In the recirculation operation, hot water flowing out from the upper part of the hot-water storage tank is delivered to the lower part of the hot-water storage tank via the first passage.

First claim

The invention claimed is:

1. A storage water heater comprising:
a heater;
a hot-water storage tank that stores hot water;
a first passage connected to a lower part of the hot-water storage tank; and
a controller configured to selectively switch between a heat-up operation and a recirculation operation, the heat-up operation being an operation in which hot water flowing out from the lower part of the hot-water storage tank is delivered to the heater via the first passage and then hot water heated by the heater is delivered to an upper part of the hot-water storage tank, the recirculation operation being an operation in which hot water flowing out from the upper part of the hot-water storage tank is delivered to the lower part of the hot-water storage tank via the first passage,
the hot-water storage tank including a water supply port through which tap water is supplied to the hot-water storage tank,
the controller being configured to, on the basis of an amount of the tap water supplied to the hot-water storage tank from the water supply port, vary a duration of the recirculation operation,
during the recirculation operation, the hot-water flowing out from the upper part of the hot-water storage tank being delivered to the lower part of the hot-water storage tank through the heater,
the storage water heater further comprising:
a switch;
a second passage that connects the switch and an inlet portion of the heater to each other;
a third passage that connects an outlet portion of the heater and the switch to each other;
a fourth passage that connects the switch and the upper part of the hot-water storage tank to each other; and
a circulator disposed in the second passage or in the third passage, the circulator being configured to form a flow of hot water that travels from the inlet portion of the heater toward the outlet portion of the heater,
wherein the first passage connects the lower part of the hot-water storage tank and the switch to each other,
wherein the switch is configured to selectively switch between a heat-up operation state and a recirculation operation state, the heat-up operation state being an operation state in which the first passage and the second passage communicate with each other and in which the third passage and the fourth passage communicate with each other, the recirculation operation state being an operation state in which the fourth passage and the second passage communicate with each other and in which the third passage and the first passage communicate with each other, and
wherein the controller is configured to, in the heat-up operation, control the switch to the recirculation operation state, and is configured to, in the recirculation operation, control the switch to the recirculation operation state.

2. The storage water heater of claim 1 , wherein, in the recirculation operation, the hot water flowing out from the upper part of the hot-water storage tank is heated by the heater before the hot water is delivered to the lower part of the hot-water storage tank via the first passage.

3. The storage water heater of claim 1 , wherein the controller is configured to, in both the heat-up operation and the recirculation operation, activate the circulator to form the flow of hot water that travels from the inlet portion of the heater toward the outlet portion of the heater.

4. The storage water heater of claim 1 ,
wherein the switch is a four-way valve, the four-way valve including a first water inlet-outlet port, a second water inlet-outlet port, a third water inlet-outlet port, and a fourth water inlet-outlet port,
wherein the first water inlet-outlet port of the four-way valve and the first passage are connected to each other,
wherein the second water inlet-outlet port of the four-way valve and the second passage are connected to each other,
wherein the third water inlet-outlet port of the four-way valve and the third passage are connected to each other, and
wherein the fourth water inlet-outlet port of the four-way valve and the fourth passage are connected to each other.

5. The storage water heater of claim 1 ,
wherein the switch includes two three-way valves, the two three-way valves each including a first water inlet-outlet port, a second water inlet-outlet port, and a third water inlet-outlet port,
wherein the first water inlet-outlet port of each of the two three-way valves and the first passage are connected to each other,
wherein the second water inlet-outlet port of one of the two three-way valves and the second passage are connected to each other,
wherein the second water inlet-outlet port of an other one of the two three-way valves and the third passage are connected to each other, and
wherein the third water inlet-outlet port of each of the two three-way valves and the fourth passage are connected to each other.

6. The storage water heater of claim 1 , wherein the controller is configured to increase the duration of the recirculation operation as the amount of the tap water supplied to the hot-water storage tank increases and is configured to decrease the duration of the recirculation operation as the amount of the tap water supplied to the hot-water storage tank decreases.

7. The storage water heater of claim 1 , wherein the amount of the tap water is estimated from an amount of hot water that has been drawn from the hot-water storage tank.

8. The storage water heater of claim 7 , wherein the amount of the hot water that has been drawn from the hot-water storage tank is computed on the basis of a heat quantity of warm water that is supplied to an external location.

9. The storage water heater of claim 8 , further comprising:
a water flow detector configured to measure an amount of the warm water; and
a warm-water-temperature detector configured to measure a temperature of the warm water,
wherein the heat quantity of the warm water is calculated from the amount of the warm water and the temperature of the warm water.

10. The storage water heater of claim 1 ,
wherein the controller includes a hot-water-temperature detector configured to detect a temperature of hot water stored in the hot-water storage tank, and
wherein the controller is configured to, depending on the temperature of the hot water stored in the hot-water storage tank detected by the hot-water-temperature detector, cause the recirculation operation to be continued to keep the temperature of the hot water stored in the hot-water storage tank outside a predetermined temperature range.

11. The storage water heater of claim 10 , wherein the hot-water-temperature detector comprises a plurality of thermistors arranged in an up-and-down direction of the hot-water storage tank and configured to detect the temperature of the hot water stored in the hot-water storage tank.

12. The storage water heater of claim 1 ,
wherein the controller includes a tap-water-temperature detector configured to detect a temperature of tap water that is supplied to the hot-water storage tank, and
wherein the controller is configured to, depending on the temperature of the tap water, decrease a duration of the recirculation operation as the temperature of the tap water increases, and increase a duration of the recirculation operation as the temperature of the tap water decreases.

13. The storage water heater of claim 12 , wherein the tap-water-temperature detector comprises a thermistor disposed between a water supply end and the hot-water storage tank and configured to detect the temperature of the tap water, the water supply end being an end through which the tap water is supplied.

14. The storage water heater of claim 1 , wh

Assignees

• Mitsubishi Electric Corp

Inventors

• Morikawa Akira
• Toyoshima Masaki
• Katsumata Noriaki

Classifications

• F24D17/0031

  with accumulation of the heated water · CPC title

• F24H9/2007

  for water heaters · CPC title

• F24H4/04

  Storage heaters · CPC title

• F24H15/14

  Cleaning; Sterilising; Preventing contamination by bacteria or microorganisms, e.g. by replacing fluid in tanks or conduits · CPC title

• F24H15/429

  for selecting operation modes · CPC title