Three-way valve and gas water heater

Abstract

The utility model relates to gas water heater technical field discloses a tee bend valve and gas water heater. Among them tee bend valve includes valve body, valve seat and valve rod, valve seat sets up in valve cavity and will valve cavity divide into hot water chamber and cold water chamber, backwater import communicates with hot water chamber, cold water export communicates with cold water chamber, valve seat has conversion cavity, backwater export communicates with conversion cavity, valve seat is equipped with the first through -hole of conversion cavity and hot water chamber and the second through -hole of conversion cavity and cold water chamber, valve rod is equipped in valve cavity and is worn in first through -hole and second through -hole, and there is overflow gap between valve rod and first through -hole and second through -hole, valve rod is equipped with valve core, and valve core has the first working position of plugging first through -hole and the second working position of plugging second through -hole. The gas water heater with the tee bend valve can effectively solve the problem that hot water is also discharged from the cold water pipe during the preheating process.

Description

Technical Field

[0001] This utility model relates to the field of gas water heater technology, and in particular to a three-way valve and a gas water heater. Background Technology

[0002] In existing technologies, such as Figure 1 The zero-cold-water gas water heater system shown typically has an H-valve 10 with a one-way flow function installed under the sink faucet in the furthest bathroom room. The H-valve 10 connects the hot and cold water pipes and links them to the water heater's return pipe 210 and outlet pipe 220, creating a closed-loop circulation system between the external water circuit and the water heater. When the zero-cold-water function is activated, the water pump 230 in the water heater operates, the H-valve 10 opens, and the pump 230 drives the cold water in the circulation system into the water heater for preheating. After preheating, the time to get hot water from the faucet is significantly reduced.

[0003] However, since the H valve 10 connects the hot and cold water pipes, when the cold water end of the faucet is opened during the preheating process, the hot water in the outlet pipe 220 will also flow out, that is, hot water comes out from the cold water pipe. On the one hand, this does not meet the user's needs; on the other hand, hot water will also come out when the cold water faucet is opened during the preheating process, which will affect the normal preheating of the system and may also cause the water heater to start erroneously.

[0004] Therefore, there is still room for improvement. Utility Model Content

[0005] One of the technical problems solved by this utility model is to provide a three-way valve with a first working position and a second working position. When the three-way valve is connected to the gas water heater body, it can assist in the preheating of the gas water heater, and there will be no hot water at the cold water outlet during the preheating process.

[0006] The second technical problem solved by this utility model is to provide a gas water heater that can effectively solve the problem of hot water coming out even when the cold water tap is turned on during the preheating process, and prevent hot water from entering the cold water pipe while achieving zero cold water.

[0007] The first technical problem mentioned above is solved by the following technical solution:

[0008] A three-way valve, comprising:

[0009] The valve body has a valve cavity, a return water outlet for connecting to the return water pipe of the gas water heater, a return water inlet for connecting to the outlet pipe of the gas water heater and the terminal water device, and a cold water outlet for connecting to the terminal water device.

[0010] A valve seat is disposed in the valve cavity and divides the valve cavity into a hot water cavity and a cold water cavity. The return water inlet is connected to the hot water cavity, and the cold water outlet is connected to the cold water cavity.

[0011] The valve seat has a switching chamber, and the return water outlet is connected to the switching chamber; the valve seat is provided with a first connecting hole connecting the switching chamber to the hot water chamber and a second connecting hole connecting the switching chamber to the cold water chamber;

[0012] A valve stem is disposed within the valve cavity and passes through the first connecting hole and the second connecting hole, with a flow clearance between the valve stem and both the first and second connecting holes; a valve core is disposed on the valve stem, the valve core having a first working position for blocking the first connecting hole and a second working position for blocking the second connecting hole.

[0013] The three-way valve described in this utility model has the following advantages compared with the prior art:

[0014] The valve core of this utility model's three-way valve can switch between a second working position and a first working position. When the valve core is in the second working position, it blocks the second connecting hole of the valve seat. Due to the flow gap between the valve stem and the first connecting hole, the hot water chamber is connected to the switching chamber through the first connecting hole. If the return water outlet of the three-way valve is connected to the return water pipe of the gas water heater, and the return water inlet is connected to the outlet water pipe of the gas water heater, then the liquid circulates between the outlet water pipe, the return water inlet, the return water outlet, the return water pipe, and the heat exchange unit inside the gas water heater body for preheating, enabling the gas water heater to have a zero-cold-water function. At the same time, because the second connecting hole is blocked by the valve core, even if the cold water tap is turned on at the end of the water supply device, no hot water will flow out, thus not affecting the preheating process and preventing the gas water heater from starting erroneously. When the valve core is in the first working position, it blocks the first connecting hole of the valve seat. Due to the flow gap between the valve stem and the second connecting hole, the switching chamber is connected to the cold water chamber through the second connecting hole. It is worth noting that when the return water pipe is connected to the cold water supply pipe, and the cold water supply pipe is simultaneously connected to the inlet of the heat exchange unit inside the gas water heater, and the hot water pipe of the terminal water device is connected to both the return water inlet and the outlet water pipe, and the cold water pipe of the terminal water device is connected to the cold water outlet, this is the normal water supply mode. The cold water supply pipe, return water pipe, return water outlet, cold water outlet, and the cold water pipe of the terminal water device are connected to supply cold water. At the same time, the cold water from the cold water supply pipe can also enter the heat exchange unit inside the gas water heater and be heated, and then flow sequentially along the outlet water pipe into the hot water pipe of the terminal water device to supply hot water.

[0015] In one embodiment, the three-way valve is further provided with a reset element, which is used to give the valve core a tendency to switch from the second working position to the first working position.

[0016] In one embodiment, the three-way valve is further provided with a shut-off valve assembly, which is located at the return water inlet and can selectively disconnect the return water inlet and the valve chamber.

[0017] In one embodiment, the valve stem is further provided with a connecting cap, the valve seat includes a first valve plate and a second valve plate spaced apart, the first connecting hole is provided on the first valve plate, the second connecting hole is provided on the second valve plate, the valve core is provided between the first valve plate and the second valve plate, and can selectively block the first connecting hole or the second connecting hole.

[0018] In one embodiment, the valve core includes a first surface and a second surface disposed opposite to each other, the area of ​​the first surface being larger than the area of ​​the second connecting hole, so as to seal against the second valve plate when the valve core is placed in the second working position; the area of ​​the second surface being larger than the area of ​​the first connecting hole, so as to seal against the first valve plate when the valve core is placed in the first working position.

[0019] In one embodiment, the first valve plate is provided with a first sealing protrusion protruding toward the second surface, and the second surface can seal against the first sealing protrusion.

[0020] And / or, the second valve plate is provided with a second sealing protrusion protruding toward the first surface, and the first surface can seal against the second sealing protrusion.

[0021] In one embodiment, the valve stem is further provided with a connecting cap, one end of the reset member is connected to the connecting cap, and the other end is connected to the inner wall of the valve body.

[0022] In one embodiment, multiple reset members are provided, and the multiple reset members are arranged in parallel and spaced apart; and / or, a guide structure is also provided in the valve body, and the valve stem is slidably connected to the guide structure.

[0023] In one embodiment, the three-way valve is further provided with an electromagnetic drive, which is used to drive the valve stem to switch between the first working position and the second working position.

[0024] The second technical problem mentioned above is solved by the following technical solution:

[0025] A gas water heater, characterized in that it includes a gas water heater body and a three-way valve as described in any of the above embodiments, the gas water heater includes a heat exchange unit and a return water pipe, the inlet of the heat exchange unit is connected to a cold water supply pipe and the outlet is connected to an outlet water pipe; the return water pipe is connected to both the return water outlet and the cold water supply pipe, the return water inlet is connected to the outlet water pipe, and the cold water outlet is used to connect to a terminal water device.

[0026] Compared with the prior art, the gas water heater of the present invention has the following beneficial effects:

[0027] The gas water heater of this invention is equipped with the aforementioned three-way valve. During the preheating stage of the gas water heater, the valve core is in the second working position. At this time, the liquid circulates between the outlet pipe, return water inlet, return water outlet, return water pipe, and the heat exchange unit of the gas water heater for preheating, enabling the gas water heater to have a zero-cold-water function. During the preheating process, the return water outlet and cold water outlet are disconnected, so no cold water flows out of the cold water pipe, thus not affecting the preheating. After preheating is completed, the valve core is in the first working position. At this time, the cold water supply pipe, return water pipe, cold water inlet, and cold water outlet are connected to supply cold water. The liquid in the cold water supply pipe is heated by heat exchange and then directly enters the hot water pipe through the outlet pipe, without mixing with cold water, resulting in a better user experience. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of this utility model, the drawings used in the description of the embodiments of this utility model will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on the content of the embodiments of this utility model and these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of a zero-cold-water gas water heater system provided in the background art;

[0030] Figure 2 This is a schematic diagram of the valve core of the three-way valve provided in a specific embodiment of the present invention being placed in the first working position;

[0031] Figure 3 This is a schematic diagram of the valve core of the three-way valve provided in a specific embodiment of the present invention being placed in the second working position;

[0032] Figure 4 This is a schematic diagram of a gas water heater provided in a specific embodiment of this utility model, with the valve core of the three-way valve placed in the second working position;

[0033] Figure 5This is a schematic diagram of a gas water heater provided in a specific embodiment of this utility model, with the valve core of the three-way valve placed in the first working position.

[0034] Label Explanation:

[0035] 100. Heat exchange unit;

[0036] 210. Return water pipe; 220. Outlet water pipe; 230. Water pump;

[0037] 300. Three-way valve; 310. Valve body; 311. Valve seat; 301. Valve chamber; 302. Hot water chamber; 303. Cold water chamber; 304. Switching chamber; 305. First connecting hole; 306. Second connecting hole; 320. Valve stem; 321. Valve core; 322. First surface; 323. Second surface; 324. Connecting cap; 330. Return water inlet; 340. Return water outlet; 350. Cold water outlet; 360. Reset component; 370. Shut-off valve assembly; 380. First valve plate; 381. First sealing protrusion; 390. Second valve plate; 391. Second sealing protrusion;

[0038] 1. Cold water supply pipe; 2. Hot water pipe; 3. Cold water pipe; 4. Terminal water supply device;

[0039] 10. H valve. Detailed Implementation

[0040] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0041] In the description of this application, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0042] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0043] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0044] like Figure 2 and Figure 3 As shown, this embodiment provides a three-way valve 300, including a valve body 310, a valve seat 311, and a valve stem 320. The valve body 310 has a valve cavity 301, a return water outlet 340 for connecting to the return water pipe 210 of a gas water heater, a return water inlet 330 for connecting to the outlet water pipe 220 of a gas water heater, and a cold water outlet 350 for connecting to a terminal water device 4. The valve seat 311 is disposed in the valve cavity 301 and divides the valve cavity 301 into a hot water cavity 302 and a cold water cavity 303. The return water inlet 330 communicates with the hot water cavity 302, and the cold water outlet 350 communicates with the cold water cavity 303. The valve seat 311 has a switching cavity 304, and the return water outlet 340 communicates with the switching cavity 304. The valve seat 311 is provided with a connection to the switching cavity 304. 4. A first connecting hole 305 is connected to the hot water chamber 302, and a second connecting hole 306 is connected to the conversion chamber 304 and the cold water chamber 303; a valve stem 320 is disposed in the valve chamber 301 and passes through the first connecting hole 305 and the second connecting hole 306. There is a flow gap between the valve stem 320 and the first connecting hole 305 and the second connecting hole 306. Specifically, the diameter of the valve stem 320 is smaller than the aperture of the first connecting hole 305 and the second connecting hole 306, so that there is a circumferential gap between the valve stem 320 and the first connecting hole 305 and the second connecting hole 306, forming a flow gap; a valve core 321 is provided on the valve stem 320, and the valve core 321 has a first working position for blocking the first connecting hole 305 and a second working position for blocking the second connecting hole 306.

[0045] The valve core 321 of the three-way valve 300 can switch between the second working position and the first working position. When the valve core 321 is in the second working position, the valve core 321 blocks the second connecting hole 306 of the valve seat 311. Since there is a flow gap between the valve stem 320 and the first connecting hole 305, the hot water chamber 302 is connected to the switching chamber 304 through the first connecting hole 305. If the return water outlet 340 of the three-way valve 300 is connected to the return water pipe 210 of the gas water heater, and the return water inlet 330 is connected to the outlet water pipe 220 of the gas water heater, then the liquid circulates between the outlet water pipe 220, the return water inlet 330, the return water outlet 340, the return water pipe 210 and the heat exchange unit 100 in the gas water heater body for preheating, so that the gas water heater has a zero cold water function. At the same time, since the second connecting hole 306 is blocked by the valve core 321, even if the cold water tap of the terminal water device 4 is turned on, no hot water will flow out, thus not affecting the preheating process and not causing the gas water heater to start erroneously. When the valve core 321 is in the first working position, the valve core 321 blocks the first connecting hole 305 of the valve seat 311. Since there is also a flow gap between the valve stem 320 and the second connecting hole 306, the switching chamber 304 is connected to the cold water chamber 303 through the second connecting hole 306. It is worth noting that when the return water pipe 210 is connected to the cold water supply pipe 1, and the cold water supply pipe 1 is simultaneously connected to the inlet of the heat exchange unit 100 inside the gas water heater body, the hot water pipe 2 of the terminal water device 4 is connected to both the return water inlet 330 and the outlet pipe 220, and the cold water pipe 3 of the terminal water device 4 is connected to the cold water outlet 350, this is the normal water supply mode. The cold water supply pipe 1, the return water pipe 210, the return water outlet 340, the cold water outlet 350, and the cold water pipe 3 of the terminal water device 4 are connected to supply cold water. At the same time, the cold water from the cold water supply pipe 1 can also enter the heat exchange unit 100 inside the gas water heater body to be heated, and then flow sequentially along the outlet pipe 220 into the hot water pipe 2 of the terminal water device 4 to supply hot water.

[0046] like Figure 4 and Figure 5 As shown, this embodiment also discloses a gas water heater, including a gas water heater body and a three-way valve 300 as described in any of the above schemes. The gas water heater includes a heat exchange unit 100, a return water pipe 210, and a water pump 230. The inlet of the heat exchange unit 100 is connected to a cold water supply pipe 1, and the outlet is connected to an outlet pipe 220. The return water pipe 210 is connected to both the return water outlet 340 and the cold water supply pipe 1, the return water inlet 330 is connected to the outlet pipe 220, and the cold water outlet 350 is used to connect to a terminal water device 4. Specifically, the terminal water device 4 is provided with a hot water pipe 2 and a cold water pipe 3. The hot water pipe 2 is connected to both the return water inlet 330 and the outlet pipe 220, and the cold water pipe 3 is connected to the cold water outlet 350.

[0047] The gas water heater is equipped with the aforementioned three-way valve 300 between the gas water heater body and the terminal water device 4. Compared to existing gas water heaters where the return pipe 210 is connected to the outlet pipe 220, hot water in the outlet pipe 220 will flow out when the cold water tap is turned on, causing the heating unit to malfunction and hot water to flow out of the return pipe 210; and during the preheating process, hot water will also flow out when the cold water tap is turned on, affecting the normal preheating of the system, the gas water heater disclosed in this embodiment is equipped with the aforementioned three-way valve 300. During the preheating stage, such as... Figure 4 As shown, valve core 321 is in the second working position. At this time, liquid circulates between the outlet pipe 220, return water inlet 330, return water outlet 340, return water pipe 210, and the heat exchange unit 100 of the gas water heater for preheating, enabling the gas water heater to have a zero-cold-water function. During preheating, the connection between return water outlet 340 and cold water outlet 350 is broken, so no cold water flows out of the cold water pipe 3, thus not affecting preheating. After preheating is complete, as... Figure 5 As shown, valve core 321 is in the second working position. At this time, cold water supply pipe 1, return pipe 210, cold water inlet and cold water outlet 350 are connected to supply cold water. After being heated by heat exchange, the liquid in cold water supply pipe 1 directly enters the hot water pipe 2 through outlet pipe 220, without mixing with cold water, resulting in a better user experience.

[0048] Specifically, continue to refer to Figure 1 and Figure 3 The three-way valve 300 is also equipped with a reset element 360, which is used to give the valve core 321 a tendency to switch from the second working position to the first working position. The reset element 360 ensures that the valve core 321 can be stably placed in the first working position, and can also drive the valve core 321 to switch from the second working position to the first working position. It is worth noting that the valve core 321 switches from the first working position to the second working position under the push of the fluid, overcoming the elastic force of the reset element 360.

[0049] In other embodiments, to enable the valve core 321 to switch between the first and second working positions, the three-way valve 300 is also equipped with an electromagnetic drive component. The electromagnetic drive component's electromagnetic driving force is used to drive the valve stem 320 to switch between the first and second working positions. The electromagnetic drive component can be controlled by the gas water heater's control system.

[0050] Furthermore, the three-way valve 300 is also provided with a shut-off valve assembly 370, which is located at the return water inlet 330 and can selectively disconnect the return water inlet 330 and the hot water chamber 302 of the valve chamber 301. For example, the shut-off valve assembly 370 will only open when the liquid temperature in the return water inlet 330 is lower than its opening temperature. The opening temperature can be set to match the preset temperature of the gas water heater, and the shut-off valve assembly 370 is controlled by the gas water heater's control system to stop preheating by disconnecting the return water inlet 330 and the hot water chamber 302 after preheating to the preset temperature.

[0051] In one embodiment, the valve seat 311 includes a first valve plate 380 and a second valve plate 390 spaced apart. A first connecting hole 305 is disposed on the first valve plate 380, and a second connecting hole 306 is disposed on the second valve plate 390. The first valve plate 380 and the second valve plate 390 extend to the inner side of the valve body 310. The first valve plate 380 separates the hot water chamber 302 and the switching chamber 304, and the second valve plate 390 separates the switching chamber 304 and the cold water chamber 303. The valve core 321 is disposed between the first valve plate 380 and the second valve plate 390.

[0052] It is understood that the diameters of the first connecting hole 305 and the second connecting hole 306 are both larger than the valve stem 320, so that when the valve stem 320 passes through the first valve plate 380 and the second valve plate 390, it is convenient to move and change its position, and the aforementioned flow gap can be formed between the first valve plate 380 and the second valve plate 390 away from the end connected to the valve seat 311.

[0053] Specifically, the valve core 321 includes a first surface 322 and a second surface 323 disposed opposite to each other. The diameters of the first connecting hole 305 and the second connecting hole 306 are both smaller than that of the valve core 321. That is, the area of ​​the first surface 322 is larger than the area of ​​the second connecting hole 306, so that when the valve core 321 is placed in the second working position, it can seal against the second valve plate 390 to block the second connecting hole 306; the area of ​​the second surface 323 is larger than the area of ​​the first connecting hole 305, so that when the valve core 321 is placed in the first working position, it can seal against the first valve plate 380 to block the first connecting hole 305.

[0054] Preferably, the first valve plate 380 is provided with a first sealing protrusion 381 protruding towards the second surface 323, and the second surface 323 can seal against the first sealing protrusion 381. The first sealing protrusion 381 improves the sealing performance between each valve core 321 and the first valve plate 380, ensuring that no other liquid can enter when a liquid passage is formed, thus guaranteeing the reliability of liquid flow. Similarly, the second valve plate 390 is provided with a second sealing protrusion 391 protruding towards the first surface 322, and the first surface 322 can seal against the second sealing protrusion 391.

[0055] Specifically, the valve stem 320 is also provided with a connecting cap 324, which is used to install the reset member 360. Exemplarily, the reset member 360 is configured as a spring, with one end connected to the connecting cap 324 and the other end connected to the inner wall of the valve body 310. When the valve stem 320 is in the second working position, the spring is compressed.

[0056] Optionally, multiple reset elements 360 are provided, and the multiple reset elements 360 are arranged in parallel and spaced apart. By providing multiple reset elements 360, the reset of the valve stem 320 is made more reliable in one direction, and the force on the valve stem 320 in the circumferential direction is more uniform in another direction.

[0057] Preferably, the valve body 310 is further provided with a guide structure, which can be used to guide the sliding connection of the valve stem 320, making the sliding of the valve stem 320 smoother and more accurate in direction. For example, the guide structure can be set as a groove or a through hole, and those skilled in the art can set it as needed, without specific limitations here.

[0058] As an optional solution for a gas water heater, the shut-off valve assembly 370 includes a shut-off valve body 310 and a temperature sensing element that are communicatively connected to the main controller of the gas water heater. The temperature sensing element is used to detect the temperature of the liquid in the return water inlet 330. Exemplarily, the temperature sensor can be located inside the return water inlet 330; the shut-off valve body 310 is located in the return water inlet 330. When the temperature sensor detects that the water temperature in the return water inlet 330 has reached a preset temperature, the main controller controls the shut-off valve body 310 to block the return water inlet 330, completing the preheating process.

[0059] In other embodiments, the shut-off valve assembly 370 includes a temperature-sensitive valve body 310 disposed at the return water inlet 330. The temperature-sensitive valve body 310 is configured to deform according to different temperatures. For example, it maintains the flow of liquid in the return water inlet 330 when the liquid temperature is lower than the closing temperature, and closes the return water inlet 330 when the liquid temperature is not lower than the closing temperature. Exemplarily, the temperature-sensitive valve body 310 may be a paraffin-type temperature-sensitive valve body 310 or a bimetallic strip temperature-sensitive valve body 310, etc.

[0060] In the specific implementation of the above embodiments, the technical features can be combined in any non-contradictory way. For the sake of brevity, not all possible combinations of the above technical features are described. However, as long as the combination of these technical features is not contradictory, it should be considered to be within the scope of this specification.

[0061] The specific embodiments described above are merely illustrative of several implementations of this utility model, and while the descriptions are detailed, they should not be construed as limiting the scope of this utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these all fall within the protection scope of this utility model. Therefore, the protection scope of this utility model patent should be determined by the appended claims.

Claims

1. A three-way valve, characterized in that, include: The valve body (310) has a valve chamber (301), a return water outlet (340) for connecting the return water pipe (210) of the gas water heater, a water outlet pipe (220) for connecting the gas water heater and the return water inlet (330) of the terminal water device (4), and a cold water outlet (350) for connecting the terminal water device (4). A valve seat (311) is disposed in the valve cavity (301) and divides the valve cavity (301) into a hot water cavity (302) and a cold water cavity (303). The return water inlet (330) is connected to the hot water cavity (302), and the cold water outlet (350) is connected to the cold water cavity (303). The valve seat (311) has a switching chamber (304), and the return water outlet (340) is connected to the switching chamber (304); the valve seat (311) is provided with a first connecting hole (305) connecting the switching chamber (304) and the hot water chamber (302) and a second connecting hole (306) connecting the switching chamber (304) and the cold water chamber (303); A valve stem (320) is disposed in the valve cavity (301) and passes through the first connecting hole (305) and the second connecting hole (306). There is a flow gap between the valve stem (320) and the first connecting hole (305) and the second connecting hole (306). A valve core (321) is disposed on the valve stem (320). The valve core (321) has a first working position for blocking the first connecting hole (305) and a second working position for blocking the second connecting hole (306).

2. The three-way valve according to claim 1, characterized in that, The three-way valve is also provided with a reset member (360), which is used to make the valve core (321) tend to switch from the second working position to the first working position.

3. The three-way valve according to claim 1, characterized in that, The three-way valve is also provided with a shut-off valve assembly (370), which is located at the return water inlet (330) and can selectively disconnect the return water inlet (330) and the valve chamber (301).

4. The three-way valve according to claim 1, characterized in that, The valve seat (311) includes a first valve plate (380) and a second valve plate (390) spaced apart. The first connecting hole (305) is disposed on the first valve plate (380), and the second connecting hole (306) is disposed on the second valve plate (390). The valve core (321) is disposed between the first valve plate (380) and the second valve plate (390) and can selectively block the first connecting hole (305) or the second connecting hole (306).

5. The three-way valve according to claim 4, characterized in that, The valve core (321) includes a first surface (322) and a second surface (323) disposed opposite to each other. The area of ​​the first surface (322) is larger than the area of ​​the second connecting hole (306) so that when the valve core (321) is placed in the second working position, it seals against the second valve plate (390). The area of ​​the second surface (323) is larger than the area of ​​the first connecting hole (305) so that when the valve core (321) is placed in the first working position, it seals against the first valve plate (380).

6. The three-way valve according to claim 5, characterized in that, The first valve plate (380) is provided with a first sealing protrusion (381) protruding toward the second surface (323), and the second surface (323) can seal against the first sealing protrusion (381); And / or, the second valve plate (390) is provided with a second sealing protrusion (391) protruding toward the first surface (322), and the first surface (322) can seal against the second sealing protrusion (391).

7. The three-way valve according to claim 2, characterized in that, The valve stem (320) is also provided with a connecting cap (324), one end of the reset member (360) is connected to the connecting cap (324), and the other end is connected to the inner wall of the valve body (310).

8. The three-way valve according to claim 2, characterized in that, Multiple reset components (360) are provided, and the multiple reset components (360) are arranged in parallel and spaced apart; and / or, a guide structure is also provided inside the valve body (310), and the valve stem (320) is slidably connected to the guide structure.

9. The three-way valve according to claim 1, characterized in that, The three-way valve is also provided with an electromagnetic drive, which is used to drive the valve stem (320) to switch between the first working position and the second working position.

10. A gas-fired water heater, characterized in that, The gas water heater includes a gas water heater body and a three-way valve as described in any one of claims 1-9. The gas water heater includes a heat exchange unit (100) and a return water pipe (210). The inlet of the heat exchange unit (100) is connected to a cold water supply pipe (1), and the outlet is connected to an outlet pipe (220). The return water pipe (210) is connected to both the return water outlet (340) and the cold water supply pipe (1). The return water inlet (330) is connected to the outlet pipe (220). The cold water outlet (350) is used to connect to a terminal water device (4).

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