Method and system for controlling a hot water circulation system and hot water circulation system

Abstract

The application discloses a hot water circulation system control method and system and a hot water circulation system. The control method comprises the following steps: when the first port and the second port of the switching valve are in bidirectional communication and the first port is in unidirectional communication with the third port, starting a water pump in the water heater according to the difference between the set temperature and the outlet water temperature of the water heater; controlling the first port and the third port of the switching valve to be in bidirectional communication and the first port to be in unidirectional communication with the second port according to the difference between the set temperature and the inlet water temperature of the switching valve. Through switching of the connection passage in the switching valve of the hot water circulation system, switching between different water supply pipelines is realized, so that only one water supply pipeline participates in water circulation in the hot water circulation system, thereby reducing the circulation load, ensuring that the first water supply pipeline and the second water supply pipeline can both achieve the zero cold water effect, and providing a more comfortable use experience for users.

Description

Technical Field

[0001] This invention relates to the field of water heater technology, and in particular to a control method, system, and hot water circulation system for a hot water circulation system. Background Technology

[0002] Gas water heaters with circulation function are very common in the market nowadays. However, when a user's home has multiple water supply pipes (such as multiple bathrooms) connected in parallel, the area that needs to be circulated increases and the distance becomes longer. At this time, due to the influence of inconsistent water head, the zero cold water effect of some water supply pipes will be relatively poor. When using hot water, users need to let some cold water run off first, which will waste water resources. At the same time, the inability to provide hot water immediately will also worsen the user experience. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to address the defect of poor zero-cold-water effect when water is circulated in parallel pipelines, and to provide a control method, system and hot water circulation system for a hot water circulation system.

[0004] The present invention solves the above-mentioned technical problems through the following technical solution:

[0005] A first aspect of the present invention provides a control method for a hot water circulation system, the hot water circulation system including a water heater, a switching valve, a first water supply pipeline, and a second water supply pipeline;

[0006] The switching valve includes three ports: the first port is connected to the inlet of the water heater, the second port is connected to the outlet of the first water supply pipe, and the third port is connected to the outlet of the second water supply pipe; the outlet of the water heater is connected to both the inlet of the first water supply pipe and the inlet of the second water supply pipe.

[0007] The control method for the hot water circulation system includes the following steps:

[0008] When the first port and the second port of the switching valve are bidirectionally connected and the first port is unidirectionally connected to the third port, the water pump in the water heater is controlled to start according to the difference between the set temperature and the outlet water temperature of the water heater.

[0009] The first and third ports of the switching valve are bidirectionally connected, and the first port is unidirectionally connected to the second port, based on the difference between the set temperature and the inlet water temperature of the switching valve.

[0010] Optionally, the step of controlling the water pump in the water heater to start based on the difference between the set temperature and the outlet water temperature of the water heater specifically includes:

[0011] If the difference between the set temperature and the outlet water temperature is greater than or equal to the first set value, the water pump in the water heater is controlled to start.

[0012] Optionally, the step of controlling the bidirectional connection between the first port and the third port of the switching valve and the unidirectional connection from the first port to the second port based on the difference between the set temperature and the inlet water temperature of the switching valve specifically includes:

[0013] If the difference between the set temperature and the inlet water temperature of the switching valve is less than or equal to the second set value, then the first port and the third port of the switching valve are connected bidirectionally and the first port is connected unidirectionally to the second port.

[0014] Optionally, the step of controlling the bidirectional connection between the first port and the third port of the switching valve and the unidirectional connection from the first port to the second port based on the difference between the set temperature and the inlet water temperature of the switching valve specifically includes:

[0015] If the difference between the set temperature and the inlet water temperature of the switching valve is greater than the second set value, then in response to the water pump's operating time being greater than the first duration, the first port and the third port of the switching valve are controlled to be bidirectionally connected and the first port is controlled to be unidirectionally connected to the second port.

[0016] Optionally, the control method for the hot water circulation system further includes:

[0017] The water pump is controlled to stop operating based on the difference between the set temperature and the inlet temperature of the water heater, or the difference between the outlet temperature of the water heater and the set temperature.

[0018] Optionally, the step of controlling the water pump to stop operating based on the difference between the set temperature and the inlet water temperature of the water heater, or the difference between the outlet water temperature of the water heater and the set temperature, specifically includes:

[0019] If the difference between the outlet water temperature of the water heater and the set temperature is greater than or equal to a third set value, or if the difference between the set temperature and the inlet water temperature of the water heater is less than or equal to a fourth set value, then the water pump is controlled to stop running.

[0020] Optionally, the step of controlling the water pump to stop operating based on the difference between the set temperature and the inlet water temperature of the water heater, or the difference between the outlet water temperature of the water heater and the set temperature, specifically includes:

[0021] If the difference between the outlet water temperature of the water heater and the set temperature is less than the third set value, and the difference between the set temperature and the inlet water temperature of the water heater is greater than the fourth set value, then in response to the water pump's operating time being greater than the second time, the water pump is controlled to stop operating.

[0022] A second aspect of the present invention provides a control system for a hot water circulation system, the hot water circulation system including a water heater, a switching valve, a first water supply pipeline, and a second water supply pipeline;

[0023] The switching valve includes three ports: the first port is connected to the inlet of the water heater, the second port is connected to the outlet of the first water supply pipe, and the third port is connected to the outlet of the second water supply pipe; the outlet of the water heater is connected to both the inlet of the first water supply pipe and the inlet of the second water supply pipe.

[0024] The control system is used to control the water pump in the water heater to start based on the difference between the set temperature and the outlet water temperature of the water heater when the first port and the second port of the switching valve are bidirectionally connected and the first port is unidirectionally connected to the third port; and to control the first port and the third port of the switching valve to be bidirectionally connected and the first port to the second port to be unidirectionally connected based on the difference between the set temperature and the inlet water temperature of the switching valve.

[0025] A third aspect of the present invention provides a hot water circulation system, including a water heater, a switching valve, a first water supply pipeline, a second water supply pipeline, and the control system described in the second aspect;

[0026] The switching valve includes three ports: the first port is connected to the inlet of the water heater, the second port is connected to the outlet of the first water supply pipeline, and the third port is connected to the outlet of the second water supply pipeline; the outlet of the water heater is connected to the inlet of the first water supply pipeline and the inlet of the second water supply pipeline, respectively.

[0027] Optionally, the water heater includes a first temperature sensor and a second temperature sensor, wherein the first temperature sensor is used to measure the inlet water temperature of the water heater, and the second temperature sensor is used to measure the outlet water temperature of the water heater.

[0028] The switching valve includes a third temperature sensor for measuring the inlet water temperature of the switching valve.

[0029] Based on common knowledge in the field, the above optional conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.

[0030] The positive and progressive effects of this invention are as follows: When controlling the hot water circulation system, with the first and second ports of the switching valve bidirectionally connected and the first port unidirectionally connected to the third port, the water pump in the water heater is started based on the difference between the set temperature and the outlet water temperature of the water heater; then, based on the difference between the set temperature and the inlet water temperature of the switching valve, the first and third ports of the switching valve are bidirectionally connected and the first port unidirectionally connected to the second port; by switching the connection path within the switching valve in the hot water circulation system, the switching between different water supply pipes is realized, so that only one water supply pipe participates when water is circulating in the hot water circulation system, thereby reducing the circulation load and ensuring that both the first and second water supply pipes can achieve the effect of zero cold water, thus providing users with a more comfortable user experience. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of a hot water circulation system provided in Embodiment 1 of the present invention.

[0032] Figure 2 The flowchart shows the control method of the hot water circulation system provided in Embodiment 1 of the present invention.

[0033] Figure 3 This is a flowchart of a control method for a hot water circulation system in a specific embodiment of Embodiment 1 of the present invention. Detailed Implementation

[0034] The present invention will be further illustrated by way of embodiments below, but the present invention is not limited to the scope of the embodiments described herein.

[0035] Example 1

[0036] This embodiment provides a control method for a hot water circulation system. For example... Figure 1 As shown, the hot water circulation system includes a water heater 11, a switching valve 12, a first water supply pipe 13, and a second water supply pipe 14. The switching valve 12 has three ports: a first port connected to the inlet of the water heater 11, a second port connected to the outlet of the first water supply pipe 13, and a third port connected to the outlet of the second water supply pipe 14. The outlet of the water heater 11 is connected to the inlets of both the first and second water supply pipes. The water heater 11 includes a water pump 111, a first temperature sensor 112, and a second temperature sensor 113. The first temperature sensor 112 measures the inlet water temperature of the water heater, and the second temperature sensor 113 measures the outlet water temperature of the water heater.

[0037] like Figure 2 As shown, the control method of the hot water circulation system includes the following steps:

[0038] S1. When the first and second ports of the switching valve are bidirectionally connected and the first port is unidirectionally connected to the third port, the water pump in the water heater is started according to the difference between the set temperature and the outlet water temperature of the water heater.

[0039] S2. Based on the difference between the set temperature and the inlet water temperature of the switching valve, control the first port and the third port of the switching valve to be bidirectionally connected, and the first port to be unidirectionally connected to the second port.

[0040] In this embodiment, the first port of the switching valve is bidirectionally connected to the second port and unidirectionally connected to the third port. That is, the first water supply pipe in the hot water circulation system participates in water circulation. At this time, the difference between the set temperature and the outlet water temperature of the water heater can be used to determine that the water temperature in the hot water circulation system is low. At this time, the water pump in the water heater is started, and the water heater starts heating, so that the water temperature in the first water supply pipe gradually increases.

[0041] During the water heater's heating process, the difference between the set temperature and the inlet water temperature of the switching valve indicates that the water temperature in the first water supply pipe meets the zero-cold-water requirement. At this point, the switching valve is switched from its original connection mode to a bidirectional connection between the first and third ports and a unidirectional connection from the first port to the second port. This means the second water supply pipe participates in the water circulation system, the water pump continues to work, and the water heater continues to heat the water, gradually increasing the water temperature in the second water supply pipe. The first and second water supply pipes are connected in parallel. By switching the participation of the first and second water supply pipes in the water circulation through the switching valve, the working pressure on the water heater and water pump can be reduced, ensuring that the water flows and heats according to the predetermined path. This prevents inconsistent water head from affecting the zero-cold-water effect of the water supply pipes, ensuring that users get hot water as soon as they turn on the tap, thus improving the user experience.

[0042] In one optional implementation, step S1 specifically includes: if the difference between the set temperature and the outlet water temperature is greater than or equal to the first set value, then control the water pump in the water heater to start.

[0043] In this embodiment, the first water supply pipe and the second water supply pipe in the hot water circulation system are circulated and heated. If the difference between the set temperature and the outlet water temperature is greater than or equal to the first set value, it means that the outlet water temperature of the water heater is too low and the water temperature in the hot water circulation system needs to be heated. At this time, circulation is started for heating.

[0044] Specifically, the first set value can be between 3℃ and 7℃. The size of the first set value will affect the control effect of the hot water circulation system. If the first set value is too small, the circulation will be frequently turned on, resulting in waste of resources. If the first set value is too large, the water temperature of the water heater will be low, and the water temperature will not meet the user's needs, affecting the user experience.

[0045] In one optional implementation, step S2 specifically includes: if the difference between the set temperature and the inlet water temperature of the switching valve is less than or equal to the second set value, then control the first port and the third port of the switching valve to be bidirectionally connected and the first port to be unidirectionally connected to the second port.

[0046] In this embodiment, the hot water circulation system is already activated. The inlet temperature of the switching valve is approximately the same as the temperature of the water flowing within the hot water circulation system. If the difference between the set temperature and the inlet temperature of the switching valve is less than or equal to the second set value, meaning the inlet temperature of the switching valve has risen to near the set temperature, it indicates that the water temperature in the first water supply pipe meets the requirement of zero cold water. At this time, the first and third ports of the switching valve are connected bidirectionally, and the first port is connected unidirectionally to the second port, allowing the second water supply pipe in the hot water circulation system to participate in water circulation. The water pump continues to operate, and the water heater continues to heat, gradually increasing the water temperature in the second water supply pipe. After the first water supply pipe has finished heating, the piping system is reconfigured through the switching valve before heating the second water supply pipe. This reduces the water pump pressure, decreases energy consumption, and ensures the normal operation of the hot water circulation system.

[0047] In one optional implementation, step S2 specifically includes: if the difference between the set temperature and the inlet water temperature of the switching valve is greater than the second set value, then in response to the pump's operating time being greater than the first duration, controlling the first port and the third port of the switching valve to be bidirectionally connected and the first port to be unidirectionally connected to the second port.

[0048] In this embodiment, under special circumstances such as cooling of the external environment, the inlet water temperature of the switching valve may fail to reach the target temperature for a long time, that is, the difference between the set temperature and the inlet water temperature of the switching valve is greater than the second set value. At this time, the system makes a judgment based on the running time of the water pump. If the running time of the water pump is greater than the first time, the system controls the switching valve to close, switching to bidirectional connection between the first port and the third port and unidirectional connection from the first port to the second port. This can prevent the hot water circulation system from being unable to switch the water supply pipeline, and prevent the water heater from continuously heating a certain water supply pipeline, thus preventing the water heater from being damaged due to continuous operation and ensuring the safety of the system.

[0049] Specifically, the initial duration can be 5 to 10 minutes, which can ensure that the water heater works normally and prevent problems such as the inability to switch the switching valve.

[0050] In one optional implementation, the control method for the hot water circulation system further includes:

[0051] S3. Control the water pump to stop running based on the difference between the set temperature and the inlet water temperature of the water heater, or the difference between the outlet water temperature of the water heater and the set temperature.

[0052] In this embodiment, both the first and second water supply pipes in the hot water circulation system have been heated, the water pump stops running, the water heater stops heating, and the circulation ends.

[0053] In one optional implementation, step S3 specifically includes: if the difference between the outlet water temperature of the water heater and the set temperature is greater than or equal to a third set value, or if the difference between the set temperature and the inlet water temperature of the water heater is less than or equal to a fourth set value, then control the water pump to stop running.

[0054] In this embodiment, if the difference between the water outlet temperature and the set temperature is greater than or equal to the third set value, it indicates that the water outlet temperature has exceeded the user's set temperature. At this point, heating is considered complete, and the water pump and heater are stopped. Conversely, if the difference between the set temperature and the water inlet temperature is less than or equal to the fourth set value, it indicates that the water inlet temperature is close to the user's set temperature. Heating is also considered complete at this point, and the water pump and heater are stopped. Timely shutdown of the water pump and heater prevents excessively high water temperatures, avoiding scalding to the user, and also saves energy.

[0055] Specifically, the third setting value can be 4℃ to 6℃ to prevent the temperature from getting too high. The second setting value needs to be slightly higher than the third setting value, preferably 2℃ higher, to ensure that the temperature in the hot water circulation system first meets the conditions for controlling the switching valve to switch. The system will switch the switching valve before controlling the water pump to stop running, thereby ensuring that both the first and second water supply pipes in the hot water circulation system are heated normally.

[0056] The fourth setting value can be between 8℃ and 12℃. If the fourth setting value is too small, it may increase the possibility of thermal imbalance. If the fourth setting value is too large, in summer or other times when the ambient temperature is high, the inlet water temperature under unheated conditions may cause the water pump to stop running, affecting the normal operation of the hot water circulation system.

[0057] In one optional implementation, if the difference between the outlet water temperature of the water heater and the set temperature is less than a third set value, and the difference between the set temperature and the inlet water temperature of the water heater is greater than a fourth set value, then in response to the water pump's operating time being greater than a second time, the water pump is controlled to stop operating.

[0058] In this embodiment, under certain special circumstances, the water temperature in the hot water circulation system may fail to reach the target temperature for an extended period. Specifically, the difference between the water heater's outlet temperature and the set temperature may be less than a third set value, while the difference between the set temperature and the water heater's inlet temperature may be greater than a fourth set value. In this case, the system makes a judgment based on the pump's operating time. If the pump's operating time exceeds a second set time, the system controls the pump to stop. This prevents the pump from continuously operating without stopping, avoids pump wear and tear due to continuous operation, and ensures system safety.

[0059] Specifically, the second duration can be 5 to 10 minutes, which can ensure that the water pump works normally and prevent the water pump from failing to stop.

[0060] In a specific embodiment, such as Figure 3 As shown, T0 represents the user's set temperature, Tout represents the water outlet temperature of the water heater, Tmid represents the inlet temperature of the switching valve, Tin represents the inlet temperature of the water heater, T1 represents the first set value, T2 represents the second set value, T3 represents the third set value, T4 represents the fourth set value, S represents the running time of the water pump, S1 represents the first duration, and S2 represents the second duration. The control method of the hot water circulation system includes:

[0061] First, when the first and second ports of the switching valve are bidirectionally connected and the first port is unidirectionally connected to the third port, the water pump in the water heater is started according to the difference between the set temperature and the outlet water temperature of the water heater. That is, when Tout≤T0-T1 is satisfied, the water pump in the water heater is started.

[0062] Then, based on the difference between the set temperature and the inlet water temperature of the switching valve, the first and third ports of the switching valve are controlled to be bidirectionally connected, and the first port is controlled to be unidirectionally connected to the second port. That is, when Tmid ≥ T0 - T2, the first and third ports of the switching valve are controlled to be bidirectionally connected, and the first port is controlled to be unidirectionally connected to the second port. In particular, if the condition Tmid ≥ T0 - T2 cannot be met, that is, Tmid < T0 - T2, when the pump's running time S is greater than the first time S1, the first and third ports of the switching valve are also controlled to be bidirectionally connected, and the first port is controlled to be unidirectionally connected to the second port.

[0063] Finally, the water pump is controlled to stop operating based on the difference between the set temperature and the inlet water temperature of the water heater, or the difference between the outlet water temperature of the water heater and the set temperature. Specifically, the water pump stops operating when Tout ≥ T0 + T3 or Tin ≥ T0 - T4. In particular, if the conditions Tout ≥ T0 + T3 or Tin ≥ T0 - T4 cannot be met (i.e., Tout < T0 + T3 and Tin < T0 - T4), the water pump is also controlled to stop operating when the pump's operating time S is greater than the second duration S2.

[0064] Example 2

[0065] This embodiment provides a control system for a hot water circulation system, the hot water circulation system including a water heater, a switching valve, a first water supply pipeline, and a second water supply pipeline;

[0066] The switching valve includes three ports: the first port is connected to the inlet of the water heater, the second port is connected to the outlet of the first water supply pipe, and the third port is connected to the outlet of the second water supply pipe; the outlet of the water heater is connected to both the inlet of the first water supply pipe and the inlet of the second water supply pipe.

[0067] The control system is used to implement the control method in Embodiment 1.

[0068] It should be noted that the working principle of the control system of the hot water circulation system in this embodiment is the same as that of the control method of the hot water circulation system in Embodiment 1, so it will not be described again here.

[0069] Example 3

[0070] This embodiment provides a hot water circulation system, including a water heater, a switching valve, a first water supply pipeline, a second water supply pipeline, and the control system described in Embodiment 2;

[0071] The switching valve includes three ports: the first port is connected to the inlet of the water heater, the second port is connected to the outlet of the first water supply pipeline, and the third port is connected to the outlet of the second water supply pipeline; the outlet of the water heater is connected to the inlet of the first water supply pipeline and the inlet of the second water supply pipeline, respectively.

[0072] In one optional embodiment, the water heater includes a first temperature sensor and a second temperature sensor, wherein the first temperature sensor is used to measure the inlet water temperature of the water heater, and the second temperature sensor is used to measure the outlet water temperature of the water heater.

[0073] The switching valve includes a third temperature sensor for measuring the inlet water temperature of the switching valve.

[0074] In this embodiment, the water temperature varies at different locations within the hot water circulation system. A first temperature sensor measures the inlet water temperature of the water heater, indicating locations with lower water temperatures. A second temperature sensor measures the outlet water temperature of the water heater, indicating locations with higher water temperatures. A third temperature sensor, located within the hot water circulation system, measures the inlet water temperature of the switching valve, indicating locations with moderate water temperatures. By placing temperature sensors at different points, the water temperature at different points in the hot water circulation system can be controlled, providing a basis for strictly controlling the hot water temperature and ensuring that the water temperature in the hot water circulation system better meets the user's needs.

[0075] While specific embodiments of the present invention have been described above, those skilled in the art should understand that these are merely illustrative examples, and the scope of protection of the present invention is defined by the appended claims. Those skilled in the art can make various changes or modifications to these embodiments without departing from the principles and essence of the present invention, but all such changes and modifications fall within the scope of protection of the present invention.

Claims

1. A control method for a hot water circulation system, characterized in that, The hot water circulation system includes a water heater, a switching valve, a first water supply pipeline, and a second water supply pipeline; The switching valve includes three ports: the first port is connected to the inlet of the water heater, the second port is connected to the outlet of the first water supply pipe, and the third port is connected to the outlet of the second water supply pipe; the outlet of the water heater is connected to both the inlet of the first water supply pipe and the inlet of the second water supply pipe. The control method for the hot water circulation system includes the following steps: When the first port and the second port of the switching valve are bidirectionally connected and the first port is unidirectionally connected to the third port, the water pump in the water heater is controlled to start according to the difference between the set temperature and the outlet water temperature of the water heater. The first and third ports of the switching valve are bidirectionally connected, and the first port is unidirectionally connected to the second port, based on the difference between the set temperature and the inlet water temperature of the switching valve.

2. The control method for the hot water circulation system as described in claim 1, characterized in that, The step of controlling the water pump in the water heater to start based on the difference between the set temperature and the outlet water temperature of the water heater specifically includes: If the difference between the set temperature and the outlet water temperature is greater than or equal to the first set value, the water pump in the water heater is controlled to start.

3. The control method for the hot water circulation system as described in claim 1, characterized in that, The step of controlling the bidirectional connection between the first and third ports of the switching valve and the unidirectional connection from the first port to the second port based on the difference between the set temperature and the inlet water temperature of the switching valve specifically includes: If the difference between the set temperature and the inlet water temperature of the switching valve is less than or equal to the second set value, then the first port and the third port of the switching valve are connected bidirectionally and the first port is connected unidirectionally to the second port.

4. The control method for the hot water circulation system as described in claim 3, characterized in that, The step of controlling the bidirectional connection between the first and third ports of the switching valve and the unidirectional connection from the first port to the second port based on the difference between the set temperature and the inlet water temperature of the switching valve specifically includes: If the difference between the set temperature and the inlet water temperature of the switching valve is greater than the second set value, then in response to the water pump's operating time being greater than the first duration, the first port and the third port of the switching valve are controlled to be bidirectionally connected and the first port is controlled to be unidirectionally connected to the second port.

5. The control method for the hot water circulation system as described in claim 1, characterized in that, The control method for the hot water circulation system also includes: The water pump is controlled to stop operating based on the difference between the set temperature and the inlet temperature of the water heater, or the difference between the outlet temperature of the water heater and the set temperature.

6. The control method for the hot water circulation system as described in claim 5, characterized in that, The step of controlling the water pump to stop operating based on the difference between the set temperature and the inlet water temperature of the water heater, or the difference between the outlet water temperature of the water heater and the set temperature, specifically includes: If the difference between the outlet water temperature of the water heater and the set temperature is greater than or equal to a third set value, or if the difference between the set temperature and the inlet water temperature of the water heater is less than or equal to a fourth set value, then the water pump is controlled to stop running.

7. The control method for the hot water circulation system as described in claim 6, characterized in that, The step of controlling the water pump to stop operating based on the difference between the set temperature and the inlet water temperature of the water heater, or the difference between the outlet water temperature of the water heater and the set temperature, specifically includes: If the difference between the outlet water temperature of the water heater and the set temperature is less than the third set value, and the difference between the set temperature and the inlet water temperature of the water heater is greater than the fourth set value, then in response to the water pump's operating time being greater than the second time, the water pump is controlled to stop operating.

8. A control system for a hot water circulation system, characterized in that, The hot water circulation system includes a water heater, a switching valve, a first water supply pipeline, and a second water supply pipeline; The switching valve includes three ports: the first port is connected to the inlet of the water heater, the second port is connected to the outlet of the first water supply pipe, and the third port is connected to the outlet of the second water supply pipe; the outlet of the water heater is connected to both the inlet of the first water supply pipe and the inlet of the second water supply pipe. The control system is used to control the water pump in the water heater to start based on the difference between the set temperature and the outlet water temperature of the water heater when the first port and the second port of the switching valve are bidirectionally connected and the first port is unidirectionally connected to the third port; and to control the first port and the third port of the switching valve to be bidirectionally connected and the first port to the second port to be unidirectionally connected based on the difference between the set temperature and the inlet water temperature of the switching valve.

9. A hot water circulation system, characterized in that, It includes a water heater, a switching valve, a first water supply pipeline, a second water supply pipeline, and a control system as described in claim 8; The switching valve includes three ports: the first port is connected to the inlet of the water heater, the second port is connected to the outlet of the first water supply pipeline, and the third port is connected to the outlet of the second water supply pipeline; the outlet of the water heater is connected to the inlet of the first water supply pipeline and the inlet of the second water supply pipeline, respectively.

10. The hot water circulation system as described in claim 9, characterized in that, The water heater includes a first temperature sensor and a second temperature sensor. The first temperature sensor is used to measure the inlet water temperature of the water heater, and the second temperature sensor is used to measure the outlet water temperature of the water heater. The switching valve includes a third temperature sensor for measuring the inlet water temperature of the switching valve.

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