A gas water heater with a local hot water circulation pipe and a control method

Abstract

The present invention discloses a gas water heater with a local hot water circulation pipe and a control method, which includes a water heater body. A gas boiler is placed inside the water heater body. The output end of the gas boiler is divided into two paths. One path is a hot water circulation pipe, and the other path is the second water outlet pipe of the gas boiler. The output end of the second water outlet pipe of the gas boiler is connected to a common hot water pipe. The hot water circulation pipe is in parallel with the common hot water pipe. The output ends of the hot water circulation pipe and the common hot water pipe are gathered and then connected to the input end of a circulating return pipe. The output end of the circulating return pipe is gathered with the output end of the cold water inlet pipe and then connected to the water inlet of the gas boiler. By adding a hot water circulation pipe to replace the zero-cold water circulation system in the gas water heater, the present invention uses the hot water circulation pipe to store hot water, and when the water outlet valve is opened next time, the hot water in the hot water circulation pipe is used to replace the incompletely heated cold water flowing out of the water heater, so as to achieve the purpose of stably flowing out hot water even when the water outlet valve is frequently opened and closed.

Description

Technical Field

[0001] The present invention relates to the technical field of gas water heaters, and particularly to a gas water heater with a local hot water circulation pipe and a control method therefor. Background Art

[0002] When an ordinary gas water heater is in use, due to the ignition delay of the gas boiler, every time the user opens and closes the hot water outlet switch, cold water flows into the gas boiler, resulting in local cold water during the bathing process. This drawback not only wastes water resources but also brings an unpleasant user experience.

[0003] To address this problem, gas water heaters with a zero-cold-water system have emerged on the market to improve traditional gas water heaters. The zero-cold-water gas water heater is connected to the outside through a hot water pipe, a cold water pipe, and a return pipe, with the cold water pipe and the return pipe responsible for the water inlet and return functions respectively. Although the existing zero-cold-water gas water heaters solve the problem of cold water flowing out of the hot water outlet before and during bathing by circulating hot water, they require users to pre-bury a return pipe in the building during installation. For buildings without pre-buried pipes, they cannot be installed and used, making them inapplicable to existing buildings.

[0004] The cold water before bathing does not affect the user experience during bathing, and users can generally accept it. However, the hot water during bathing has a greater impact on the user experience. Due to the inherent drawbacks of gas water heaters, every time it is opened and closed, a certain amount of cold water will flow into the gas boiler and flow out of the water valve without being fully heated. If cold water flows out every time the user opens and closes the switch during bathing, the bathing experience will be greatly reduced. For the problem of cold water flowing out of the gas water heater before bathing, only the use of a zero-cold-water gas water heater can solve it. For the problem of cold water flowing out of the gas water heater during bathing, there are relatively more solutions. And compared with the cold water problem before bathing, the cold water problem of the gas water heater during bathing has a greater impact on users. Therefore, it is necessary to focus on solving the cold water problem of the gas water heater during bathing. Summary of the Invention

[0005] In order to overcome the above defects existing in the prior art, the purpose of the present invention is to provide a gas water heater with a local hot water circulation pipe and a control method therefor. By adding a hot water circulation pipe to the gas water heater instead of a zero-cold-water circulation system, the hot water circulation pipe is used to store hot water, and when the water outlet valve is opened next time, the hot water in the hot water circulation pipe is used to replace the incompletely heated cold water flowing out of the water heater, so as to achieve the purpose of stably flowing out hot water even when the water outlet valve is frequently opened and closed.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is:

[0007] A gas water heater with a local hot water circulation pipe, comprising a water heater body 14. A gas boiler 5 is placed inside the water heater body 14. The output end of the gas boiler 5 is divided into two paths. One path is a hot water circulation pipe 10, and the other path is a second gas boiler water outlet pipe 11-1. The output end of the second gas boiler water outlet pipe 11-1 is connected to a common hot water pipe 11-2. The hot water circulation pipe 10 is in parallel with the common hot water pipe 11-2. The output ends of the hot water circulation pipe 10 and the common hot water pipe 11-2 are gathered and then connected to the input end of a circulating return pipe 8 after being communicated with the output end of a hot water outlet pipe 15. The output end of the circulating return pipe 8 is gathered with the output end of a cold water inlet pipe 1 and then connected to the water inlet of the gas boiler 5.

[0008] The water inlet of the gas boiler 5 is connected to the output ends of the cold water inlet pipe 1 and the circulating return pipe 8 by a straight-through three-way valve. A check valve 6 is installed on the side of the circulating return pipe 8 at the connection. The check valve 6 only allows the water in the circulating return pipe 8 to flow in a one-way direction towards the gas boiler 5. The gas boiler 5 heats the cold water by igniting gas.

[0009] The hot water circulation pipe 10 includes a hot water circulation pipe main body 10-1, a first gas boiler water outlet pipe 10-2, and a hot water circulation pipe connecting pipe 10-3. Among them, the input end of the first gas boiler water outlet pipe 10-2 is communicated with the gas boiler 5. The output end of the first gas boiler water outlet pipe 10-2 is divided into two paths. One path is connected to the input end of the hot water circulation pipe main body 10-1, and the other path is connected to the input end of the hot water circulation pipe connecting pipe 10-3. The output end of the hot water circulation pipe connecting pipe 10-3 is gathered with the output end of the second gas boiler water outlet pipe 11-1 and then communicated with the common hot water pipe 11-2. After the output end of the common hot water pipe 11-2 is connected to the output end of the hot water outlet pipe 15 and then gathered with the output end of the hot water circulation pipe main body 10-1, it is communicated with the circulating return pipe 8.

[0010] The output end of the hot water circulation pipe connecting pipe 10-3 is connected to the output end of the second gas boiler water outlet pipe 11-1 and the input end of the common hot water pipe 11-2 by a straight-through three-way valve. The input end of the hot water circulation pipe main body 10-1 is connected to the output end of the first gas boiler water outlet pipe 10-2 and the input end of the hot water circulation pipe connecting pipe 10-3 by a straight-through three-way valve. A No. 2 electric valve 4 is provided on the first gas boiler water outlet pipe 10-2. A No. 1 electric valve 3 is provided on the hot water circulation pipe connecting pipe 10-3.

[0011] The output end of the common hot water pipe 11-2 is connected to the output end of the hot water outlet pipe 15 by a straight-through three-way valve. A No. 5 electric valve 13 is provided on the common hot water pipe 11-2. The output end of the hot water circulation pipe main body 10-1 is connected to the input end of the circulating return pipe 8 and the output end of the hot water outlet pipe 15 by a straight-through three-way valve. A No. 3 electric valve 9 is provided on the circulating return pipe 8.

[0012] The input end of the circulating return pipe 8 is connected to the output end of the main body of the hot water circulation pipe 10-1 and the output end of the hot water outlet pipe 15 by a straight-through three-way valve.

[0013] A No. 4 electric valve 12 is provided at the connection between the connection port of the main body of the hot water circulation pipe 10-1 and the hot water outlet pipe 15 and the connection port of the ordinary hot water pipe 11-2 and the hot water outlet pipe 15.

[0014] A circulating return pump 7 is installed on the circulating return pipe 8. The circulating return pump 7 is located between the check valve 6 and the No. 3 electric valve 9. When starting, it circulates and conveys the water in the main body of the hot water circulation pipe 10-1 in one direction.

[0015] An equipment control module 2 is provided inside the water heater body 14. The equipment control module 2 is integrated into the control system of the water heater body 14 and is used to control the No. 1 electric valve 3, the No. 2 electric valve 4, the No. 3 electric valve 9, the No. 4 electric valve 12, the No. 5 electric valve 13 and the circulating return pump 7 on the water heater pipeline, and realizes the normal operation of the system by an automatic control method.

[0016] An operation method of a gas water heater with a local hot water circulation pipe includes the following steps;

[0017] The equipment control module 2 controls the start and stop of the No. 1 electric valve 3, the No. 2 electric valve 4, the No. 3 electric valve 9, the No. 4 electric valve 12, the No. 5 electric valve 13 and the circulating return pump 7, and controls the flow of hot water among the hot water circulation pipe 10, the circulating return pipe 8 and the hot water outlet pipe 15.

[0018] In the initial state of the gas water heater, the No. 2 electric valve 4, the No. 3 electric valve 9 and the No. 5 electric valve 13 are closed, the No. 1 electric valve 3 and the No. 4 electric valve 12 are opened, and the circulating return pump 7 is closed. The opening and closing of the water outlet valve 16 is used as the input signal of the control system.

[0019] When the water outlet valve 16 is opened, the controller is started and the opening times are calculated. If the valve opening times are 1, it means that the hot water valve is opened for the first time. The control system maintains the initial state, allowing the hot water flowing out of the gas boiler 5 to flow into the hot water circulation pipe and then flow out from the water outlet valve 16. If the opening times of the water outlet valve are greater than 1, the control system starts the timer. Since the heating time of gas water heaters on the market usually does not exceed 10 seconds, the timing time of the timer is set to 10 seconds to wait for the gas boiler to heat. Within 10 seconds after the water outlet valve 16 is opened, the cold water not fully heated by the gas boiler flows into the hot water circulation pipe, and the hot water stored in the pipe flows out from the water outlet valve 16. When the timing time of the timer reaches 10 seconds, the cold water flowing into the gas boiler 5 has been fully heated. At this time, the control system controls the No. 5 electric valve 13, the No. 2 electric valve 4 and the No. 3 electric valve 9 to open, and the No. 1 electric valve 3 and the No. 4 electric valve 12 to close.

[0020] At this time, the hot water flowing out of the gas boiler 5 directly flows through the ordinary hot water pipe 11-2 and flows out from the water outlet valve 16; at the same time, the circulating return pump 7 is turned on, and the cold water in the hot water circulation pipe 10 and the circulating return pipe 8 is circulated into the gas boiler 5 for reheating, and the reheating time is also set to 10 seconds; when the timer 1 reaches 20 seconds, the control system closes the circulating pump and resets the timer 1 to stop timing; when the water outlet valve 16 is closed, the control system returns to the initial state and waits for the next opening signal of the water outlet valve 16. Each time the water outlet valve 16 is closed, the system will start the timer 2 to record the closing time length of the water outlet valve 16. If the hot water valve is not opened again within 1 hour after the water outlet valve 16 is closed, the control system will enter the standby state.

[0021] Advantages of the present invention:

[0022] 1. The present invention uses the hot water circulation pipe to reheat the cold water flowing back to the gas boiler during the gas ignition delay in the opening and closing process of the gas water heater, solving the cold water problem caused by the inherent problems of the traditional gas water heater during the bathing process due to opening and closing, and significantly improving the bathing experience and comfort.

[0023] 2. The principle of the hot water circulation pipe of the present invention is simple and the structure is easy to implement. Compared with the existing zero-cold water gas water heaters, it has low energy consumption, is easy to install, is not restricted by installation conditions, is suitable for new decoration or the transformation conditions of existing gas water heaters, and has a wider application range. Description of the Drawings

[0024] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0025] Figure 2 It is a schematic diagram of the control signal of the present invention.

[0026] In the figure: 1, cold water inlet pipe; 2, equipment control module; 3, No. 1 electric valve; 4, No. 2 electric valve; 5, gas boiler; 6, check valve; 7, circulating return pump; 8, circulating return pipe; 9, No. 3 electric valve; 10-1, main body of hot water circulation pipe; 10-2, first gas boiler water outlet pipe; 10-3, hot water circulation pipe connecting pipe; 11-1, second gas boiler water outlet pipe; 11-2, ordinary hot water pipe; 12, No. 4 electric valve; 13, No. 5 electric valve; 14, water heater body; 15, hot water outlet pipe; 16, water outlet valve. Specific Embodiments

[0027] The present invention will be further described in detail below in conjunction with the embodiments.

[0028] As Figure 1As shown in the figure, the present invention provides a gas water heater with a local hot water circulation pipe and a control method. The gas water heater with a local hot water circulation pipe includes a water heater body 14, a gas boiler 5, a hot water circulation pipe 10, a circulation return pipe 8, a common hot water pipe 11-2, a circulation return pump 7, a No. 1 electric valve 3, a No. 2 electric valve 4, a No. 3 electric valve 9, a No. 4 electric valve 12, a No. 5 electric valve 13, a check valve 6, and an equipment control module 2.

[0029] The technical idea of the present invention is to replace the zero cold water circulation system by adding a hot water circulation pipe in the gas water heater. The hot water circulation pipe is used to return the cold water caused by the gas ignition delay during the opening and closing process of the gas water heater to the gas boiler for reheating. When the water outlet valve is opened next time, the hot water in the hot water circulation pipe is used to replace the incompletely heated cold water flowing out of the water heater, so as to achieve the purpose of stably flowing out hot water even when the water outlet valve is frequently opened and closed.

[0030] The gas boiler 5 is connected to the cold water inlet pipe 1 and the circulation return pipe 8 by a straight-through three-way valve. The gas boiler 5 can heat cold water by igniting gas.

[0031] The hot water circulation pipe 10 is composed of a pipeline hot water circulation pipe main body 10-1, a gas boiler water outlet pipe 1 10-2, and a hot water circulation pipe connecting pipe 10-3. The pipeline hot water circulation pipe main body 10-1 is the main part of the hot water circulation pipe, and the length of the pipeline hot water circulation pipe main body 10-1 is determined according to the amount of water flowing out of the gas water heater during the period from the gas boiler igniting to heating the cold water into hot water.

[0032] The left side of the main body 10-1 of the hot water circulation pipe is connected to the pipe 10-2 and the connecting pipe 10-3 of the hot water circulation pipe by a straight-through three-way valve. The pipe 10-2 is connected to the gas boiler 5, and an electric valve No. 2 4 is provided on the first water outlet pipe 10-2 of the gas boiler. The connecting pipe 10-3 of the hot water circulation pipe is connected to the second water outlet pipe 11-1 of the gas boiler and the ordinary hot water pipe 11-2 by a straight-through three-way valve, and an electric valve No. 1 3 is provided on the connecting pipe 10-3 of the hot water circulation pipe. The right side of the ordinary hot water pipe 11-2 is connected to the hot water outlet pipe 15 by a straight-through three-way valve, and an electric valve No. 5 13 is provided on the ordinary hot water pipe 11-2. The right side of the main body 10-1 of the hot water circulation pipe is connected to the circulating return pipe 8 and the hot water outlet pipe 15 by a straight-through three-way valve, and an electric valve No. 3 9 is provided on the circulating return pipe 8. An electric valve No. 4 12 is provided between the connection port of the main body 10-1 of the hot water circulation pipe and the hot water outlet pipe 15 and the connection port of the ordinary hot water pipe 11-2 and the hot water outlet pipe 15. The left side of the circulating return pipe 8 is connected to the gas boiler 5 and the cold water inlet pipe 1 by a straight-through three-way valve, and a check valve 6 is installed on the side of the circulating return pipe 8 at the connection, allowing only the water in the circulating return pipe 8 to flow in a single direction towards the gas boiler 5. The right side of the circulating return pipe 8 is connected to the main body 10-1 of the hot water circulation pipe and the hot water outlet pipe 15 by a straight-through three-way valve.

[0033] The circulating return pump 7 is installed on the circulating return pipe 8, between the check valve 6 and the electric valve No. 3 9, and when starting, it circulates and conveys the water in the hot water circulation pipe 10 in a single direction.

[0034] The device control module 2 is integrated into the control system of the water heater body 14, and is used to control the electric valves on the water heater pipes, namely the electric valve No. 1 3, the electric valve No. 2 4, the electric valve No. 3 9, the electric valve No. 4 12, the electric valve No. 5 13 and the circulating return pump 7, and adopts an automatic control method to realize the normal operation of the system.

[0035] A control method for a gas water heater with a local hot water circulation pipe includes the following steps:

[0036] As Figure 2 shown: When in use, the gas water heater is externally powered. When the user first opens the water outlet valve 16, the device control module 2 starts, controls the electric valve No. 2 4, the electric valve No. 3 9, and the electric valve No. 5 13 to close, and the electric valve No. 1 3 and the electric valve No. 4 12 to open; at this time, the cold water inlet pipe 1 connected to the water supply pipe introduces cold water into the pipe inside the gas boiler 5, the gas boiler 5 starts, the heated cold water first flows through the first water outlet pipe 10-2 of the gas boiler in the hot water circulation pipe and the main body 10-1 of the hot water circulation pipe, and then flows out from the water outlet valve 16. The hot water temperature flowing out of the gas boiler 5 gradually rises. After reaching the set temperature, the user can use it normally.

[0037] When the water outlet valve 16 is closed for the first time, the device control module 2 controls the 2nd electric valve 4, the 3rd electric valve 9, and the 5th electric valve 13 to close, and the 1st electric valve 3 and the 4th electric valve 12 to open. At this time, the cold water inlet pipe 1 stops supplying water, and the hot water heated by the gas boiler 5 stays in the hot water circulation pipe 10-1. The gas boiler 5 is in the closed state and will not waste extra gas.

[0038] When the water outlet valve 16 is opened again, the device control module 2 starts the timing function, controls the 2nd electric valve 4, the 3rd electric valve 9, and the 5th electric valve 13 to close, and the 1st electric valve 3 and the 4th electric valve 12 to open, and the gas boiler 5 starts. At this time, the cold water inlet pipe 1 connected to the water supply pipe guides cold water into the pipeline inside the gas boiler 5. The cold water flows through the gas boiler 5 and into the gas boiler outlet pipeline 10-2 and the main body of the hot water circulation pipe 10-1. At this time, the cold water flowing in squeezes out the hot water in the circulation pipe, and the hot water in the circulation pipe flows out from the water outlet valve 16, realizing the function of flowing out hot water when the water outlet valve 16 is opened during the use of the gas water heater. The length of the main body 10-1 of the hot water circulation pipe is determined according to the amount of water flowing out of the gas water heater during the time period from when the gas boiler ignites to when it heats the cold water into hot water. Since the time interval between each opening and closing of the water outlet valve 16 is very short during the bathing process, the main body 10-1 of the hot water circulation pipe only needs to meet the most basic heat preservation effect for the hot water.

[0039] Gas water heaters on the market usually adopt high-power heating technology and an efficient heating system, which can quickly heat cold water into hot water, and the heating time usually does not exceed 10 seconds. Therefore, when 10 seconds have passed since the gas boiler 5 starts ignition and the cold water sent from the cold water inlet pipe 1 to the pipeline of the gas boiler 5 has been heated to the set temperature, when the timing time of the device control module 2 reaches 10 seconds, the device control module 2 controls the 2nd electric valve 4, the 3rd electric valve 9, and the 5th electric valve 13 to open, and the 1st electric valve 3 and the 4th electric valve 12 to close. At this time, the hot water flowing out of the gas boiler 5 directly flows through the ordinary hot water pipe 11-2 and flows out from the water outlet valve 16. At the same time, the circulation return pump 7 is turned on to circulate the cold water in the gas boiler outlet pipeline 10-2, the main body 10-1 of the hot water circulation pipe, and the circulation return pipe 8 into the gas boiler 5 for reheating, and the heating time is also set to 10 seconds.

[0040] When the timing time of the device control module 2 reaches 20 seconds, under the pumping of the circulating return pump 7, the cold water in the gas boiler outlet pipe 10-2, the main body of the hot water circulation pipe 10-1 and the circulating return pipe 8 has been heated into hot water by the gas boiler 5. At this time, the device control module 2 controls the opening of the No. 2 electric valve 4, the No. 3 electric valve 9 and the No. 5 electric valve 13, closes the No. 1 electric valve 3 and the No. 4 electric valve 12, stops the circulating return pump 7 from working, and the gas boiler 5 continues to maintain the working state. At this time, the hot water flowing out of the gas boiler 5 continues to flow through the ordinary hot water pipe 11-2 and flows out from the outlet valve 16.

[0041] When the outlet valve 16 is closed again, the device control module 2 controls the closing of the No. 2 electric valve 4, the No. 3 electric valve 9 and the No. 5 electric valve 13, and opens the No. 1 electric valve 3 and the No. 4 electric valve 12. At this time, the cold water inlet pipe 1 stops supplying water, and the hot water heated by the gas boiler 5 stays in the gas boiler outlet pipe 10-2, and the gas boiler 5 is in the closed state. After that, every time the outlet valve 16 is opened or closed, the system will repeat the above steps to run.

[0042] A determination program is set in the device control module 2. When the outlet valve 16 is opened, the device control module 2 starts and makes the water heater run according to the steps. When the outlet valve 16 is closed, the device control module 2 runs the determination program. If the outlet valve 16 is not opened again within 1 hour after the closing of the outlet valve this time, the device control module 2 enters the standby state.

Claims

1. A gas water heater with a local hot water circulation pipe, characterized in that, It includes a water heater body (14), inside which a gas boiler (5) is placed. The output end of the gas boiler (5) is divided into two paths. One path is a hot water circulation pipe (10), and the other path is the second gas boiler water outlet pipe (11-1). The output end of the second gas boiler water outlet pipe (11-1) is connected to a common hot water pipe (11-2). The hot water circulation pipe (10) is in parallel with the common hot water pipe (11-2). The output ends of the hot water circulation pipe (10) and the common hot water pipe (11-2) converge with the output end of the hot water outlet pipe (15) and then communicate with the input end of the circulation return pipe (8). The output end of the circulation return pipe (8) converges with the output end of the cold water inlet pipe (1) and then is connected to the water inlet of the gas boiler (5). The hot water circulation pipe (10) includes a hot water circulation pipe main body (10-1), the first gas boiler water outlet pipe (10-2), and a hot water circulation pipe connecting pipe (10-3). Among them, the input end of the first gas boiler water outlet pipe (10-2) communicates with the gas boiler (5). The output end of the first gas boiler water outlet pipe (10-2) is divided into two paths. One path is connected to the input end of the hot water circulation pipe main body (10-1), and the other path is connected to the input end of the hot water circulation pipe connecting pipe (10-3). The output end of the hot water circulation pipe connecting pipe (10-3) converges with the output end of the second gas boiler water outlet pipe (11-1) and then communicates with the common hot water pipe (11-2). After the output end of the common hot water pipe (11-2) is connected to the output end of the hot water outlet pipe (15), it converges with the output end of the hot water circulation pipe main body (10-1) and then communicates with the circulation return pipe (8).

2. The gas water heater with a local hot water circulation pipe according to claim 1, characterized in that, The water inlet of the gas boiler (5) is connected to the output ends of the cold water inlet pipe (1) and the circulation return pipe (8) by a straight-through three-way valve. A check valve (6) is installed on the side of the circulation return pipe (8) at the connection. The check valve (6) only allows the water in the circulation return pipe (8) to flow in a single direction towards the gas boiler (5). The gas boiler (5) heats the cold water by igniting gas.

3. A gas water heater with a local hot water circulation pipe according to claim 1, characterized in that, The output end of the hot water circulation pipe connecting pipe (10-3) is connected to the output end of the second gas boiler water outlet pipe (11-1) and the input end of the common hot water pipe (11-2) by a straight-through three-way valve. The input end of the hot water circulation pipe main body (10-1) is connected to the output end of the first gas boiler water outlet pipe (10-2) and the input end of the hot water circulation pipe connecting pipe (10-3) by a straight-through three-way valve. A No. 2 electric valve (4) is provided on the first gas boiler water outlet pipe (10-2). A No. 1 electric valve (3) is provided on the hot water circulation pipe connecting pipe (10-3). The output end of the common hot water pipe (11-2) is connected to the output end of the hot water outlet pipe (15) by a straight-through three-way valve. A No. 5 electric valve (13) is provided on the common hot water pipe (11-2). The output end of the hot water circulation pipe main body (10-1) is connected to the input end of the circulation return pipe (8) and the output end of the hot water outlet pipe (15) by a straight-through three-way valve. A No. 3 electric valve (9) is provided on the circulation return pipe (8).

4. The gas water heater with a local hot water circulation pipe according to claim 1, characterized in that, The input end of the circulating return pipe (8) is connected to the output end of the main body of the hot water circulating pipe (10-1) and the output end of the hot water outlet pipe (15) by a straight-through three-way valve.

5. A gas water heater with a local hot water circulation pipe according to claim 1, characterized in that, A No. 4 electric valve (12) is provided between the connection port of the main body of the hot water circulating pipe (10-1) and the hot water outlet pipe (15) and the connection port of the ordinary hot water pipe (11-2) and the hot water outlet pipe (15).

6. The gas water heater with a local hot water circulation pipe according to claim 1, characterized in that, A circulating return pump (7) is installed on the circulating return pipe (8). The circulating return pump (7) is located between the check valve (6) and the No. 3 electric valve (9). When starting, it circulates and transports the water in the main body of the hot water circulating pipe (10-1) in one direction.

7. A gas water heater with a local hot water circulation pipe according to claim 1, characterized in that, An equipment control module (2) is provided inside the water heater body (14). The equipment control module (2) is integrated into the control system of the water heater body (14) and is used to control the No. 1 electric valve (3), No. 2 electric valve (4), No. 3 electric valve (9), No. 4 electric valve (12), No. 5 electric valve (13) and the circulating return pump (7) on the water heater pipeline, and realizes the normal operation of the system by an automatic control method.

8. The operating method of a gas water heater with a local hot water circulation pipe according to any one of claims 1-7, characterized in that It includes the following steps; Control the start and stop of the No. 1 electric valve (3), No. 2 electric valve (4), No. 3 electric valve (9), No. 4 electric valve (12), No. 5 electric valve (13) and the circulating return pump (7) through the equipment control module (2), and control the flow of hot water between the hot water circulating pipe (10), the circulating return pipe (8) and the hot water outlet pipe (15). In the initial state of the gas water heater, the No. 2 electric valve (4), No. 3 electric valve (9) and No. 5 electric valve (13) are closed, the No. 1 electric valve (3) and No. 4 electric valve (12) are opened, and the circulating return pump (7) is closed. The opening and closing of the water outlet valve (16) is used as the input signal of the control system. When the water outlet valve (16) is opened, start the controller and calculate the number of opening times. If the number of valve opening times is 1, it means that the hot water valve is opened for the first time. The control system maintains the initial state, allowing the hot water flowing out of the gas boiler (5) to flow into the hot water circulating pipe and then flow out from the water outlet valve (16). If the number of times the water outlet valve is opened is greater than 1, the control system starts the timer. Since the heating time of gas water heaters on the market usually does not exceed 10 seconds, the timing time of the timer is set to 10 seconds to wait for the gas boiler to heat up. Within 10 seconds after the water outlet valve (16) is opened, the cold water that has not been fully heated by the gas boiler flows into the hot water circulating pipe, and the hot water stored in the pipe flows out from the water outlet valve (16). When the timing time of the timer reaches 10 seconds, the cold water flowing into the gas boiler (5) has been fully heated. At this time, the control system controls the No. 5 electric valve (13), No. 2 electric valve (4) and No. 3 electric valve (9) to open, and the No. 1 electric valve (3) and No. 4 electric valve (12) to close. At this time, the hot water flowing out of the gas boiler (5) directly flows through the ordinary hot water pipe (11-2) and flows out from the water outlet valve (16); at the same time, the circulating return pump (7) is turned on, and the cold water in the hot water circulation pipe (10) and the circulating return pipe (8) is circulated into the gas boiler (5) for reheating, and the heating time is also set to 10 seconds; when the timer 1 reaches 20 seconds, the control system shuts down the circulating pump and resets the timer 1 to stop timing; when the water outlet valve (16) is closed, the control system returns to the initial state, waiting for the next opening signal of the water outlet valve (16). Each time the water outlet valve (16) is closed, the system starts the timer 2 to record the closing time length of the water outlet valve (16). If the hot water valve is not opened again within 1 hour after the water outlet valve (16) is closed, the control system enters the standby state.

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