Gas water heater and gas water heater system

Abstract

The utility model belongs to the technical field of gas water heater systems, and discloses a gas water heater and a gas water heater system, a first water pump and a main heat exchanger are connected end to end to form an internal circulation loop, when water in the internal circulation loop needs to be preheated, a second water pump is controlled to stop working, and meanwhile, the first water pump and a combustor are controlled to work; an inner circulation loop formed by connecting the first water pump and the main heat exchanger end to end is communicated, the first water pump pumps part of hot water in the hot water outlet pipe into the inner circulation pipeline and sends the hot water into the cold water inlet pipe through the inner circulation one-way valve, cold water in the cold water inlet pipe enters the main heat exchanger, and waste heat in the main heat exchanger is used for heating the fed cold water. The temperature in the whole internal circulation loop is uniform, when a user uses hot water and all the hot water in the internal circulation loop flows out, the main heat exchanger is basically in a stable heating state, no cold water flows out any more, and the problem that flowing-out water is alternately changed in a cold and hot mode is avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of gas water heater systems, in particular to a gas water heater and a gas water heater system. Background Art

[0002] In the prior art, gas water heaters have the problems of temperature rise when water is stopped and temperature drop of secondary water. Specifically, after the user stops using water for a period of time, the gas water heater automatically stops heating, and the water in the water outlet pipe is still high-temperature hot water. Moreover, due to the residual temperature of the heat exchanger, the water in the heat exchange tube in the heat exchanger will continue to be heated. When the user uses water again, the high-temperature hot water in the water outlet pipe will be provided to the user first. This is the problem of temperature rise when water is stopped, which can easily scald the user. After the hot water in the water outlet pipe is discharged, the cold water in the water inlet pipe enters the heat exchanger and is delivered to the user after heat exchange and temperature rise in the heat exchanger. However, since the cold water in the water inlet pipe has not yet had time to exchange heat and temperature rise with the heat exchanger, low-temperature cold water is delivered to the water outlet pipe for the user. This is the problem of temperature drop of secondary water, which seriously affects the user experience. Utility Model Content

[0003] One of the technical problems solved by the utility model is to provide a gas water heater which can ensure that the water delivered to the user is water of suitable temperature, avoid the problem of water being hot or cold, and improve the user's water use experience.

[0004] The second technical problem solved by the utility model is to provide a gas water heater system, which can prevent cold water from flowing out once hot water starts to flow out when a user uses the gas water heater system.

[0005] The first technical problem mentioned above is solved by the following technical solution:

[0006] A gas water heater, comprising an internal circulation pipeline and a cold water inlet pipe, a main heat exchanger and a hot water outlet pipe connected in sequence, wherein the internal circulation pipeline has an internal circulation water inlet end and an internal circulation water outlet end arranged opposite to each other, the cold water inlet pipe is connected to the internal circulation water outlet end at an internal circulation connection position, and the internal circulation water inlet end is connected to the hot water outlet pipe;

[0007] The inner circulation pipeline is provided with a first water pump and an inner circulation one-way valve, and the inner circulation one-way valve is used to make the water in the inner circulation pipeline flow in one direction from the inner circulation water inlet end to the inner circulation water outlet end;

[0008] The cold water inlet pipe is provided with a second water pump, and the internal circulation communication position is located between the cold water inlet of the main heat exchanger and the second water pump.

[0009] Compared with the background technology, the gas water heater provided by the utility model has the following beneficial effects:

[0010] In the gas water heater, the first water pump and the main heat exchanger are connected end to end to form an internal circulation loop. When it is necessary to preheat the water in the internal circulation loop, the second water pump is controlled to stop working, and the first water pump and the burner are controlled to work at the same time. The internal circulation loop formed by the first water pump and the main heat exchanger connected end to end is connected. The first water pump pumps a part of the hot water in the hot water outlet pipe into the internal circulation pipeline, and sends it into the cold water inlet pipe through the internal circulation one-way valve. The cold water in the cold water inlet pipe enters the main heat exchanger, and the waste heat in the main heat exchanger is used to heat the cold water sent in, so that the temperature in the entire internal circulation loop is relatively uniform. When the user uses hot water, when all the hot water in the internal circulation loop flows out, the main heat exchanger is basically in a stable heating state, and no cold water will flow out, avoiding the problem of alternating hot and cold water flowing out.

[0011] In some embodiments, the internal circulation one-way valve is arranged between the first water pump and the internal circulation water outlet.

[0012] In some embodiments, an insulated water tank is provided on the cold water inlet pipe, and the insulated water tank is located between the internal circulation connection position and the cold water inlet.

[0013] In some embodiments, the gas water heater further comprises a first temperature detection unit for detecting the outlet water temperature of the thermal insulation water tank.

[0014] The above second technical problem is solved by the following technical solution:

[0015] A gas water heater system, comprising a water return device and a gas water heater as described in any of the above schemes, wherein the water return device comprises an external circulation pipeline, and an external circulation switch valve and an external circulation check valve both arranged on the external circulation pipeline;

[0016] The external circulation pipeline has an external circulation water inlet end and an external circulation water outlet end, the external circulation water inlet end is connected to the hot water outlet pipe, the cold water inlet pipe is connected to the external circulation water outlet end at the external circulation connection position, the external circulation pipeline and the internal circulation pipeline are arranged in parallel and the internal circulation pipeline is closer to the main heat exchanger than the external circulation pipeline; the external circulation one-way valve is used to make the water in the internal circulation pipeline flow in one direction from the external circulation water inlet end to the external circulation water outlet end;

[0017] The gas water heater also includes a cold water main pipe, which is connected to the cold water inlet pipe at a cold water supply position. The internal circulation connection position, the second water pump, the cold water supply position and the external circulation connection position are arranged in sequence along the extension direction of the cold water inlet pipe.

[0018] Compared with the background technology, the gas water heater system provided by the utility model has the following beneficial effects:

[0019] The gas water heater system, including the above-mentioned gas water heater, can not only avoid the problem of alternating hot and cold water flowing out, but also has an additional water return device, which includes an external circulation pipeline arranged in parallel with the internal circulation pipeline, the internal circulation pipeline is closer to the main heat exchanger than the internal circulation pipeline, and an external circulation switch valve and an external circulation check valve are arranged on the external circulation pipeline; when the main controller receives the external circulation preheating instruction, it controls the second water pump and the burner to work, and the external circulation loop formed by the external circulation switch valve and the main heat exchanger is turned on, and the second water pump circulates the water in the external circulation loop to heat the water in the external circulation loop, so that the water temperature in the entire external circulation loop is relatively uniform, and once the user uses hot water, the hot water will flow out directly.

[0020] In some embodiments, the gas water heater system further includes a second temperature detection unit for detecting the water temperature at the hot water outlet of the main heat exchanger.

[0021] In some embodiments, the gas water heater further includes a main controller, and the water return device further includes:

[0022] A water return controller, the water return controller communicates with the main controller via a wireless communication module, and the water return controller is electrically connected to the external circulation switch valve;

[0023] The energy storage battery is used to supply power to the external circulation switch valve and the return water controller.

[0024] In some embodiments, the water return device further comprises:

[0025] The third temperature detection unit is used to detect the water temperature of the water inlet end of the external circulation, and the third temperature detection unit is electrically connected to the return water controller.

[0026] In some embodiments, the water return device further comprises:

[0027] The water return housing, the external circulation pipeline, the water return controller, the energy storage battery, the external circulation switch valve, the external circulation one-way valve and the third temperature detection unit are all arranged in the water return housing.

[0028] In some embodiments, the water return housing is provided with a disassembly port for allowing the energy storage battery to enter and exit the inner cavity of the water return housing; the water return housing is sealed with a movable sealing cover for opening and closing the disassembly port. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a schematic diagram of the principle of the gas water heater system provided by the embodiment of the utility model.

[0030] In the figure:

[0031] 100, gas water heater; 101, cold water inlet pipe; 102, cold water main pipe; 103, heat preservation water tank; 104, first temperature detection unit; 105, second temperature detection unit; 106, first water pump; 107, internal circulation pipeline; 1071, internal circulation water inlet end; 1072, internal circulation water outlet end; 108, internal circulation one-way valve; 109, main controller; 110, second wireless communication unit; 111, main heat exchanger; 112, second water pump; 113, hot water outlet pipe; 114, flow detection unit;

[0032] 200, water return device; 201, external circulation pipeline; 2011, external circulation water inlet end; 2012, external circulation water outlet end; 202, external circulation switch valve; 203, external circulation check valve; 204, third temperature detection unit; 205, first wireless communication unit; 206, water return controller; 207, energy storage battery;

[0033] 300. Water-using parts. DETAILED DESCRIPTION

[0034] The present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only the parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0035] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0036] In the present utility model, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0037] In the description of this embodiment, the terms "upper", "lower", "right", etc., are based on the directions or positions shown in the drawings, and are only for the convenience of description and simplified operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation of the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0038] like Figure 1 As shown, an embodiment of the utility model provides a gas water heater system, including a gas water heater 100, the gas water heater 100 includes a burner and a main heat exchanger 111, the main heat exchanger 111 has a cold water inlet and a hot water outlet, the cold water inlet is connected to a cold water inlet pipe 101, and the hot water outlet is connected to a hot water outlet pipe 113. In other words, the cold water inlet pipe 101, the main heat exchanger 111 and the hot water outlet pipe 113 are connected in sequence, and a second water pump 112 is provided on the cold water inlet pipe 101.

[0039] The cold water inlet pipe 101 and the hot water outlet pipe 113 are connected at the water-using end through a mixing valve, and the outlet of the mixing valve is connected to a water-using component 300, such as a faucet or a shower, etc. The gas water heater 100 also includes a cold water main pipe 102, which is connected to the cold water inlet pipe 101 at the cold water supply position. Specifically, the inlet of the second water pump 112 is connected to the cold water main pipe 102.

[0040] When the gas water heater 100 is working, the second water pump 112 works, and a part of the cold water sent into the cold water inlet pipe 101 by the cold water main pipe 102 is sent into the main heat exchanger 111 through the cold water inlet. The burner works to heat the cold water flowing through the main heat exchanger 111 to form high-temperature hot water, and the high-temperature hot water enters the hot water outlet pipe 113 through the hot water outlet. Another part of the cold water sent into the cold water inlet pipe 101 by the cold water main pipe 102 and the high-temperature hot water are mixed by the mixing valve and sent to the water-using component 300 for user use.

[0041] The gas water heater 100 also includes an internal circulation pipeline 107, which has an internal circulation water inlet end 1071 and an internal circulation water outlet end 1072 that are relatively arranged. The internal circulation water outlet end 1072 is connected to the cold water inlet pipe 101 at the internal circulation connecting position, and the internal circulation water inlet end 1071 is connected to the hot water outlet pipe 113. A first water pump 106 and an internal circulation one-way valve 108 are arranged on the internal circulation pipeline 107. The internal circulation one-way valve 108 is used to make the water in the internal circulation pipeline 107 flow in one direction from the internal circulation water inlet end 1071 to the internal circulation water outlet end 1072; the internal circulation connecting position is located between the cold water inlet and the second water pump 112.

[0042] Exemplarily, the first water pump 106 , the second water pump 112 , the internal circulation pipeline 107 , and the internal circulation check valve 108 are all arranged inside the shell of the gas water heater 100 .

[0043] The gas water heater 100 further includes a main controller 109 , which is electrically connected to the first water pump 106 and the second water pump 112 . The main controller 109 is used to control the start and stop of the first water pump 106 and the start and stop of the second water pump 112 .

[0044] The first water pump 106 and the main heat exchanger 111 are connected end to end to form an internal circulation loop. When it is necessary to preheat the water in the internal circulation loop, the second water pump 112 is controlled to stop working, and the first water pump 106 and the burner are controlled to work at the same time. The internal circulation loop formed by the first water pump 106 and the main heat exchanger 111 connected end to end is connected. The first water pump 106 pumps a part of the hot water in the hot water outlet pipe 113 into the internal circulation pipeline 107, and sends it into the cold water inlet pipe 101 through the internal circulation one-way valve 108. The cold water in the cold water inlet pipe 101 enters the main heat exchanger 111, and the waste heat in the main heat exchanger 111 is used to heat the sent cold water, so that the temperature in the entire internal circulation loop is relatively uniform. When the user uses hot water, when all the hot water in the internal circulation loop flows out, the main heat exchanger 111 is basically in a stable heating state, and no cold water will flow out, thereby avoiding the problem of alternating hot and cold water flowing out.

[0045] In some embodiments, the internal circulation check valve 108 is disposed between the internal circulation water outlet 1072 and the first water pump 106. The internal circulation check valve 108 can prevent the cold water provided by the second water pump 112 from flowing to the first water pump 106, and prevent the water from flowing to the first water pump 106 through the internal circulation check valve 108 when the second water pump 112 is working.

[0046] In some embodiments, a heat preservation water tank 103 is provided on the cold water inlet pipe 101, and the heat preservation water tank 103 is located between the internal circulation connection position and the cold water inlet of the main heat exchanger 111. The gas water heater 100 also includes a first temperature detection unit 104, which is used to detect the outlet water temperature of the heat preservation water tank 103. Exemplarily, the first temperature detection unit 104 is a temperature sensor electrically connected to the main controller 109.

[0047] When the use of hot water is stopped, the first water pump 106 is controlled to work to open the internal circulation loop. The first water pump 106 sends the hot water in the hot water outlet pipe 113 into the cold water inlet pipe 101 through the internal circulation pipeline 107, and continuously enters the insulated water tank 103; the cold water in the insulated water tank 103 will enter the main heat exchanger 111 for heat exchange and temperature rise. When the outlet water temperature of the insulated water tank 103 is not less than the first preset temperature, it means that all the water in the insulated water tank 103 has become hot water, indicating that the internal circulation preheating is completed, and the first water pump 106 is controlled to stop working.

[0048] When the user uses hot water, the second water pump 112 delivers cold water into the insulated water tank 103, and the hot water in the insulated water tank 103 enters the main heat exchanger 111, and then is delivered to the water-using component 300 through the hot water outlet pipe 113 for use by the user. When all the hot water in the insulated water tank 103 flows out, the gas water heater 100 has been running for a period of time, and the burner has been able to stably heat the inflowing cold water in the main heat exchanger 111, so that no cold water flows out of the hot water outlet pipe 113, so that the user can get stable hot water.

[0049] In some embodiments, the gas water heater system also includes a return water device 200, which includes an external circulation pipeline 201, and an external circulation switch valve 202 and an external circulation check valve 203 both arranged on the external circulation pipeline 201, wherein the external circulation pipeline 201 has an external circulation water inlet end 2011 and an external circulation water outlet end 2012, the external circulation water inlet end 2011 is connected to the hot water outlet pipe 113, the cold water inlet pipe 101 is connected to the external circulation water outlet end 2012 at the external circulation connection position, the external circulation pipeline 201 and the internal circulation pipeline 107 are arranged in parallel, and the internal circulation pipeline 107 is closer to the main heat exchanger 111 than the external circulation pipeline 201.

[0050] The gas water heater 100 also includes a cold water main pipe 102, which is connected to the cold water inlet pipe 101 at the cold water supply position. The internal circulation connection position, the second water pump 112, the cold water supply position and the external circulation connection position are arranged in sequence along the extension direction of the cold water inlet pipe 101.

[0051] When the main controller 109 receives the external circulation preheating instruction, it controls the second water pump 112 and the burner to work, and the external circulation loop formed by the external circulation switch valve 202 and the main heat exchanger 111 is turned on. The second water pump 112 makes the water in the external circulation loop circulate, so as to heat the water in the external circulation loop and make the water temperature in the entire external circulation loop more uniform. Once the user uses hot water, the hot water will flow out directly.

[0052] In some embodiments, the gas water heater 100 further includes a second temperature detection unit 105 for detecting the water temperature of the hot water outlet. Exemplarily, the second temperature detection unit 105 is a temperature sensor electrically connected to the main controller 109 .

[0053] When the user does not use hot water, the water temperature of the hot water outlet is monitored in real time by the second temperature detection unit 105. When the water temperature of the hot water outlet is lower than the second preset temperature, the external circulation preheating is automatically started so that hot water flows out when the user uses water.

[0054] In some embodiments, the gas water heater 100 also includes a main controller 109, and the return water heater 200 also includes a return water controller 206 and a storage battery 207, wherein the return water controller 206 communicates with the main controller 109 via a wireless communication module, and the return water controller 206 is electrically connected to the external circulation switch valve 202; the energy storage battery 207 is used to power the external circulation switch valve 202 and the return water controller 206.

[0055] The energy storage battery 207 is used to power the return water controller 206, the external circulation switch valve 202 and the external circulation check valve 203. The return water device 200 is provided with a return water controller 206 separately, and the return water controller 206 and the main controller 109 communicate through a wireless communication module. There is no need to arrange exposed wires, which reduces exposed wiring and avoids wiring confusion, thereby improving the aesthetic effect of the gas water heater system and thus improving the user experience.

[0056] Specifically, the wireless communication module includes a first wireless communication unit 205 and a second wireless communication unit 110, wherein the first wireless communication unit 205 is electrically connected to the return water controller 206, the second wireless communication unit 110 is electrically connected to the main controller 109, and the first wireless communication unit 205 and the second wireless communication unit 110 are wirelessly connected.

[0057] In some embodiments, the water return device 200 further includes a third temperature detection unit 204 for detecting the water temperature of the external circulation water inlet end 2011, and the third temperature detection unit 204 is electrically connected to the water return controller 206. Exemplarily, the third temperature detection unit 204 is a temperature sensor.

[0058] When the external circulation loop is turned on and the water in the external circulation loop is circulated through the second water pump 112, the burner heats the water in the main heat exchanger 111 and monitors the water temperature at the external circulation water inlet 2011 in real time through the third temperature detection unit 204. When the water temperature at the external circulation water inlet 2011 reaches the third preset temperature, the preheating of the water in the external circulation loop is completed, and the return water controller 206 controls the external circulation switch valve 202 to close.

[0059] When the user just starts to use hot water, since the water in the external circulation loop has been preheated, the hot water outlet pipe 113 is full of hot water, so the water flowing out of the water-using component 300 is hot water, and there is no need to wait, achieving a zero cold water effect.

[0060] In some embodiments, since the water return device 200 is close to the mixing valve, the water return device 200 is more likely to contact water. Therefore, the water return device 200 further includes a water return housing, and the external circulation pipeline 201, the water return controller 206, the energy storage battery 207, the external circulation switch valve 202, the external circulation check valve 203 and the third temperature detection unit 204 are all arranged in the water return housing. The electrical components of the water return device 200 are waterproofed by the water return housing to ensure that the electrical components in the water return device 200 can work normally.

[0061] In some embodiments, a disassembly port is provided on the water return housing for allowing the energy storage battery 207 to enter and exit the inner cavity of the water return housing; a movable sealing cover is sealedly connected to the water return housing for opening and closing the disassembly port.

[0062] When the energy storage battery 207 runs out of power, the disassembly port can be opened through the sealing cover to replace the energy storage battery 207 to meet the power demand of the electrical components in the water return device 200. Exemplarily, when the sealing cover closes the disassembly port, a seal, such as a sealing strip, is provided between the contact surface of the sealing cover and the water return housing to prevent water vapor from entering the water return housing through the gap between the sealing cover and the water return housing. It should be noted that the connection between the sealing cover and the water return housing can be a screw connection, a clamping connection, etc., which is not specifically limited here.

[0063] In some embodiments, a flow detection unit 114 is provided at the inlet of the insulated water tank 103 for detecting the water flow at the inlet of the insulated water tank 103 .

[0064] In some embodiments, the gas water heater further includes an internal circulation control operation unit and an external circulation control operation unit, wherein the internal circulation control operation unit is used to start and close the internal circulation preheating function, and the external circulation control operation unit is used to start and close the external circulation preheating function. Exemplarily, the external circulation control operation unit and the internal circulation control operation unit are both arranged in the shell of the gas water heater and are electrically connected to the main controller 109. It should be noted that the external circulation control operation unit and the internal circulation control operation unit can be a button switch, a touch screen, etc., which is not specifically limited here.

[0065] In other embodiments, the external circulation control operation unit and the internal circulation control operation unit can also be both arranged in the return water shell and electrically connected to the return water controller 206; the external circulation control operation unit can also be arranged in the shell of the gas water heater and electrically connected to the main controller 109, and the internal circulation control operation unit can be arranged in the return water shell and electrically connected to the return water controller 206.

[0066] If the internal circulation preheating function is turned on, when the user stops using the gas water heater, the burner is controlled to be extinguished, the first water pump 106 is controlled to work, and the water in the internal circulation loop circulates until the outlet water temperature of the insulated water tank 103 is not less than the first preset temperature. The water in the internal circulation loop is preheated and the first water pump 106 is turned off.

[0067] If the external circulation preheating function is turned on, when the user stops using the gas water heater, the water temperature at the hot water outlet is monitored in real time, and when the water temperature at the hot water outlet is lower than the second preset temperature, the burner and the second water pump 112 are controlled to work, and the external circulation switch valve 202 is opened, and the water in the external circulation loop circulates until the water temperature at the external circulation water inlet end 2011 reaches the third preset temperature, that is, the preheating of the water in the external circulation loop is completed, the second water pump 112 and the burner are turned off, and the external circulation switch valve 202 is closed.

[0068] The gas water heater system can realize water preheating in the outer circulation loop and water preheating in the inner circulation loop independently without affecting each other, thereby avoiding that the water preheating time in the circulation loop is affected when only one of the inner circulation preheating function and the outer circulation preheating function is started.

[0069] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the implementation methods of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the scope of protection of the present invention. It is not necessary and impossible to list all implementation methods here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention shall be included in the scope of protection of the claims of the present invention.

Claims

1. A gas water heater, characterized in that: The invention comprises an internal circulation pipeline (107) and a cold water inlet pipe (101), a main heat exchanger (111) and a hot water outlet pipe (113) which are connected in sequence, wherein the internal circulation pipeline (107) has an internal circulation water inlet end (1071) and an internal circulation water outlet end (1072) which are arranged opposite to each other, the cold water inlet pipe (101) is connected to the internal circulation water outlet end (1072) at an internal circulation connection position, and the internal circulation water inlet end (1071) is connected to the hot water outlet pipe (113); The internal circulation pipeline (107) is provided with a first water pump (106) and an internal circulation one-way valve (108), and the internal circulation one-way valve (108) is used to allow water in the internal circulation pipeline (107) to flow in one direction from the internal circulation water inlet end (1071) to the internal circulation water outlet end (1072); The cold water inlet pipe (101) is provided with a second water pump (112), and the internal circulation communication position is located between the cold water inlet of the main heat exchanger (111) and the second water pump (112).

2. The gas water heater according to claim 1, characterized in that: The internal circulation one-way valve (108) is arranged between the first water pump (106) and the internal circulation water outlet (1072).

3. The gas water heater according to claim 2, characterized in that: The cold water inlet pipe (101) is provided with a heat-insulating water tank (103), and the heat-insulating water tank (103) is located between the internal circulation connection position and the cold water inlet.

4. The gas water heater according to claim 3, characterized in that: It also includes a first temperature detection unit (104) for detecting the outlet water temperature of the thermal insulation water tank (103).

5. Gas water heater system, characterized in that: It comprises a water return device (200) and the gas water heater (100) according to any one of claims 1 to 4, wherein the water return device (200) comprises an external circulation pipeline (201), and an external circulation switch valve (202) and an external circulation check valve (203) both arranged on the external circulation pipeline (201); The external circulation pipeline (201) has an external circulation water inlet end (2011) and an external circulation water outlet end (2012); the external circulation water inlet end (2011) is connected to the hot water outlet pipe (113); the cold water inlet pipe (101) is connected to the external circulation water outlet end (2012) at the external circulation connection position; the external circulation pipeline (201) and the internal circulation pipeline (107) are arranged in parallel, and the internal circulation pipeline (107) is closer to the main heat exchanger (111) than the external circulation pipeline (201); the external circulation one-way valve (203) is used to allow water in the internal circulation pipeline (107) to flow in one direction from the external circulation water inlet end (2011) to the external circulation water outlet end (2012); The gas water heater (100) further comprises a cold water main pipe (102), wherein the cold water main pipe (102) is connected to the cold water inlet pipe (101) at a cold water supply position, and the internal circulation connection position, the second water pump (112), the cold water supply position and the external circulation connection position are arranged in sequence along the extension direction of the cold water inlet pipe (101).

6. The gas water heater system according to claim 5, characterized in that: It also includes a second temperature detection unit (105) for detecting the water temperature at the hot water outlet of the main heat exchanger (111).

7. The gas water heater system according to claim 5, characterized in that: The gas water heater (100) further comprises a main controller, and the water return device (200) further comprises: A water return controller (206), the water return controller (206) communicates with the main controller via a wireless communication module, and the water return controller (206) is electrically connected to the external circulation switch valve (202); The energy storage battery (207) is used to supply power to the external circulation switch valve (202) and the return water controller (206).

8. The gas water heater system according to claim 7, characterized in that: The water return device (200) further comprises: The third temperature detection unit (204) is used to detect the water temperature of the external circulation water inlet end (2011), and the third temperature detection unit (204) is electrically connected to the return water controller (206).

9. The gas water heater system according to claim 8, characterized in that: The water return device (200) further comprises: The water return shell, the external circulation pipeline (201), the water return controller (206), the energy storage battery (207), the external circulation switch valve (202), the external circulation check valve (203) and the third temperature detection unit (204) are all arranged in the water return shell.

10. The gas water heater system according to claim 9, characterized in that: The water return housing is provided with a disassembly and assembly port for allowing the energy storage battery (207) to enter and exit the inner cavity of the water return housing; the water return housing is sealed with a movable sealing cover for opening and closing the disassembly and assembly port.

Images