Control method for reducing water temperature rise of water heater during water stop, water heater and device

Abstract

The application discloses a control method for reducing temperature rise and drop of a water heater when water supply is stopped, a water heater and a device. The water heater comprises a heat exchanger, a preheating heat exchanger and a burner. The heat exchanger is connected with a water inlet pipe and a water outlet pipe. The water inlet pipe is provided with a first water inlet branch with a first water inlet control valve and a second water inlet branch with a second water inlet control valve. The control method comprises the following steps: when the water stop time is less than a first preset time, the first water inlet control valve is opened at a first valve opening degree; when the first preset time is less than the water stop time and the water stop time is less than a second preset time, the first water inlet control valve is opened at a second valve opening degree; and when the water stop time is greater than or equal to the second preset time, the first water inlet control valve is opened at a third valve opening degree. According to the control method, the preheating heat exchanger is arranged, so that the temperature rise and drop of the water heater when the water supply is stopped can be solved. The water inlet control valve is adjusted to adjust the amount of cold water for heat exchange with hot water, so that the constant temperature performance of the hot water outlet can be better maintained.

Description

Technical Field

[0001] This invention relates to the field of water heater technology, and more specifically, to a control method for reducing the temperature rise and fall of a water heater during water outages, a computer-readable storage medium, and a water heater. Background Technology

[0002] When a water heater is turned off midway through use, the residual heat continues to heat the water in the heat exchanger tubes. This causes a temperature rise and fall when the water is turned back on, which can easily scald users and negatively impact the user experience. Reducing these temperature rises and falls during water outages is a common concern in the industry.

[0003] To address the issue of temperature rise during water outages, the current common practice is to add bypass pipes to the heat exchanger or at the inlet and outlet to reduce the temperature rise. However, this method has limited effectiveness in improving the temperature rise during water outages. When the temperature rise during water outages is relatively high, it still fails to significantly reduce the temperature rise, and it does not solve the problem of temperature drop during water outages. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the aforementioned technical problems in the prior art. To this end, the present invention proposes a control method for reducing the temperature rise and drop during water outages in water heaters, which can effectively reduce both temperature rise and temperature drop during water outages.

[0005] The present invention also proposes a computer-readable storage medium.

[0006] This invention also proposes a water heater.

[0007] The water heater includes a heat exchanger, a preheating heat exchanger, and a burner. The heat exchanger is adapted to connect an inlet pipe and an outlet pipe, and a heat exchange flow path is formed inside the heat exchanger. The burner is adapted to heat the heat exchanger. The inlet pipe has a first inlet branch and a second inlet branch. The first inlet branch exchanges heat with the outlet pipe at the preheating heat exchanger before connecting to the heat exchanger. The second inlet branch is directly connected to the heat exchanger. A first inlet control valve for adjusting the flow rate is provided on the first inlet branch, and a second inlet control valve for adjusting the flow rate is provided on the second inlet branch. The control method for reducing the temperature rise and fall of a water heater during water outages according to an embodiment of the present invention includes: when the water outage time of the heat exchanger is less than a first preset time, the first water inlet control valve is opened with a first valve opening degree; when the water outage time of the heat exchanger is greater than or equal to the first preset time and less than a second preset time, the first water inlet control valve is opened with a second valve opening degree; when the water outage time of the heat exchanger is greater than or equal to the second preset time, the first water inlet control valve is opened with a third valve opening degree; wherein, the first valve opening degree is less than the second valve opening degree, and the third valve opening degree is less than the second valve opening degree.

[0008] According to the present invention, the control method for reducing the temperature rise and fall of a water heater during water outages can solve the problems of temperature rise and fall during water outages by setting up a preheating heat exchanger. Furthermore, by adjusting the valve opening of the first inlet control valve to adjust the amount of cold water exchanging heat with the hot water, the constant temperature performance of the hot water can be better maintained.

[0009] According to some embodiments of the present invention, as the water outage time of the heat exchanger increases, the valve opening of the first inlet control valve first increases and then decreases.

[0010] According to some embodiments of the present invention, the water heater has a pre-cleaning phase before reuse, during which the first inlet control valve is kept open.

[0011] Furthermore, the first inlet control valve is closed after the pre-cleaning phase is completed.

[0012] According to a second aspect of the present invention, a computer-readable storage medium stores a control program thereon for reducing the temperature rise and fall of a water heater during water outages. When the control program is executed by a processor, it implements the control method described above.

[0013] According to a third aspect of the present invention, a water heater is used to implement the above-described control method for reducing the temperature rise and drop during water outages in a water heater.

[0014] Furthermore, the water inlet pipe also includes: a water inlet interface section and a preheating pipe section, wherein the water inlets of the first water inlet branch and the second water inlet branch are connected to the water inlet interface section, the water outlets of the first water inlet branch and the second water inlet branch are connected to the preheating pipe section, and the preheating pipe section is connected to the water inlet of the heat exchanger;

[0015] The first water inlet branch includes a first water inlet section and a first water outlet section. The water inlet section and the cold side inlet of the preheating heat exchanger are connected and conductive through the first water inlet section. The preheating pipe section and the cold side outlet of the preheating heat exchanger are connected and conductive through the first water outlet section. The first water inlet control valve is installed on the first water inlet section.

[0016] Specifically, the water outlet pipe includes: a water outlet interface section and a hot water pipe section. The hot side inlet of the preheating heat exchanger is connected to the water outlet of the heat exchanger through the hot water pipe section, and the hot side outlet of the preheating heat exchanger is connected to the water outlet interface section.

[0017] According to some embodiments of the present invention, the preheating heat exchanger has a cold side cavity and a hot side cavity, the cold side cavity is disposed on the inlet pipe and communicates with the inlet pipe, the hot side cavity is disposed on the outlet pipe and communicates with the outlet pipe, and the cold side cavity and the hot side cavity exchange heat through contact.

[0018] According to some embodiments of the present invention, the preheating heat exchanger is a plate heat exchanger.

[0019] Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of a water heater;

[0021] Figure 2 This is a flowchart illustrating the control method for reducing the temperature rise and fall during water outages in water heaters;

[0022] Figure 3 This is a graph showing the relationship between the valve opening degree of the first inlet control valve and the water outage time.

[0023] Figure 4 This is a schematic diagram of the control logic of the first inlet control valve during the pre-cleaning stage.

[0024] Figure label:

[0025] Water heater 10, heat exchanger 1, preheating heat exchanger 2, cold side inlet 21, cold side outlet 22, hot side inlet 23, hot side outlet 24, water inlet pipe 3, first water inlet branch 31, first water inlet section 311, first water outlet section 312, second water inlet branch 32, water inlet interface section 33, preheating pipe section 34, water outlet pipe 4, water outlet interface section 41, hot water pipe section 42, first water inlet control valve 5, second water inlet control valve 6, water inlet temperature probe 71, mixing water temperature probe 72, water outlet temperature probe 73, water flow sensor 74. Detailed Implementation

[0026] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0027] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0028] The following is combined with Figures 1-4 A detailed description of the control method for reducing the temperature rise and fall of the water heater 10 during water outages, according to an embodiment of the present invention.

[0029] Reference Figure 1 As shown, the water heater 10 may include: a heat exchanger 1, a preheating heat exchanger 2, and a burner. The heat exchanger 1 is adapted to connect an inlet pipe 3 and an outlet pipe 4. A heat exchange flow path is formed inside the heat exchanger 1. The burner is adapted to heat the heat exchanger 1 to raise the water temperature inside the heat exchanger 1. Cold water enters the water heater 10 through the inlet pipe 3, is heated into hot water in the heat exchanger 1, and then flows out through the outlet pipe 4 for user use. A faucet or other water outlet element may be installed at the end of the outlet pipe 4.

[0030] The inlet pipe 3 has a first inlet branch 31 and a second inlet branch 32. The first inlet branch 31 exchanges heat with the outlet pipe 4 at the preheating heat exchanger 2 before connecting to the heat exchanger 1. The second inlet branch 32 is directly connected to the heat exchanger 1. Since the outlet pipe 4 and the first inlet branch 31 exchange heat at the preheating heat exchanger 2, and the water temperature in the outlet pipe 4 is higher (e.g., hot water) while the water temperature in the first inlet branch 31 is lower (e.g., cold water), the temperature rise in the outlet pipe 4 during water outages can be transferred to the first inlet branch 31 to preheat the cold water in the first inlet branch 31. This reduces the temperature rise during water outages and, by preheating the cold water, helps to quickly reach the user-set temperature, preventing the problem of temperature drop during water outages when the tap is first turned on because the heat generated is insufficient to heat the cold water before it flows through the heat exchanger 1.

[0031] A first water inlet control valve 5 is installed on the first water inlet branch 31 to adjust the water flow rate in the first water inlet branch 31; a second water inlet control valve 6 is installed on the second water inlet branch 32 to adjust the water flow rate in the second water inlet branch 32.

[0032] In some embodiments, when the water flow rate entering the water heater 10 is too large and the water temperature is low, the maximum load combustion of the water heater 10 still cannot meet the hot water temperature required by the user. At this time, it is necessary to reduce the total water inflow to achieve the hot water temperature required by the user. The water volume of the first water inlet branch 31 and the second water inlet branch 32 can be adjusted by adjusting the valve opening of the first water inlet control valve 5 and the second water inlet control valve 6, thereby achieving the purpose of adjusting the total water volume.

[0033] Reference Figures 2-3 As shown, the control method for reducing the temperature rise and fall of the water heater 10 during water outages according to an embodiment of the present invention may include:

[0034] Step S1: When the water outage time of heat exchanger 1 is less than the first preset time (i.e., water outage time < first preset time), the first water inlet control valve 5 is opened at the first valve opening degree.

[0035] Step S2: When the water outage time of heat exchanger 1 is greater than or equal to the first preset time and less than the second preset time (i.e., the first preset time ≤ water outage time < the second preset time), the first water inlet control valve 5 is opened with the second valve opening.

[0036] Step S3: When the water outage time of heat exchanger 1 is greater than or equal to the second preset time (i.e., the water outage time ≥ the second preset time), the first water inlet control valve 5 is opened at the third valve opening degree.

[0037] Among them, the opening degree of the first valve is less than that of the second valve, and the opening degree of the third valve is less than that of the second valve.

[0038] It should be noted that in this invention, the term "water outage time" refers to the water outage time when the water heater 10 briefly turns off the water and then restarts, that is, the time of the brief water outage.

[0039] Reference Figure 3 As shown, as the water outage time T of heat exchanger 1 increases, the valve opening K of the first inlet control valve 5 first increases and then decreases. The second valve opening can be the maximum valve opening.

[0040] Specifically, when the first inlet control valve 5 of the first inlet branch 31 is in the open state, the first inlet control valve 5 can adjust the valve opening according to the water outage time T, such as... Figure 3 As shown, in the case of a very brief water outage followed by immediate re-interruption, because the water flow in heat exchanger 1 has a short residence time and absorbs less heat, the temperature rise during the outage is low. Therefore, not much cold water is needed for heat exchange and cooling, and the opening of the first inlet control valve 5 is small (first valve opening). Regarding the temperature rise during the outage, after a period of inactivity, a temperature rise peak will appear, and then the temperature will gradually cool down as the outage time extends. Therefore, if water is turned on at the peak of the temperature rise, more cold water is needed to lower the temperature, so the opening of the first inlet control valve 5 is at its maximum (second valve opening). If water is turned on again during the cooling period of the outage temperature rise, the water temperature has gradually cooled, so the opening of the first inlet control valve 5 also decreases accordingly until it reaches its minimum (third valve opening).

[0041] Cold water from inlet pipe 3 and hot water from outlet pipe 4 exchange heat in preheating heat exchanger 2, causing the hot water temperature to decrease and thus reducing the temperature rise during water outages. Furthermore, the amount of cold water exchanging heat with the hot water can be adjusted by regulating the opening of the first inlet control valve 5 according to the water outage temperature, ensuring a constant temperature for the hot water. After absorbing heat from outlet pipe 4 in preheating heat exchanger 2, the cold water from inlet pipe 3 can compensate for the insufficient heat generated during startup, which may have prevented the water flow in heat exchanger 1 from reaching the user-set temperature (temperature drop during water outage). In other words, this invention allows for complementary temperature rise and fall when the water supply is shut off and restarted, better maintaining the constant temperature performance of the hot water.

[0042] In the description of this invention, it should be understood that 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 indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0043] According to the control method for reducing the temperature rise and drop of water heater 10 during water outages according to the embodiments of the present invention, by setting up a preheating heat exchanger 2, the problems of temperature rise during water outages (e.g. when the water is turned off and then on again) and temperature drop during water outages (e.g. when the faucet is just turned on) of water heater 10 can be solved. Furthermore, by adjusting the valve opening of the first inlet control valve 5 to adjust the amount of cold water exchanging heat with the hot water, the constant temperature performance of the hot water can be better maintained, thereby improving the user experience.

[0044] The water heater 10 has a pre-cleaning phase before reuse, during which the first inlet control valve 5 remains open. During the brief period when the water is turned off, the water in the heat exchanger 1 stops flowing. When the water is turned off and then turned back on, the machine performs a pre-cleaning process. During this phase, the burner is in a non-ignited state, and ignition resumes after a period of pre-cleaning. During the pre-cleaning phase, the water is flowing. If the first inlet control valve 5 were closed, the water in the heat exchanger 1 would continue to absorb residual heat, causing the outlet water temperature to often be higher than the set temperature, resulting in a temperature rise problem during water outages. Therefore, keeping the first inlet control valve 5 open during the pre-cleaning phase allows the cold water in the inlet pipe 3 and the hot water in the outlet pipe 4 to exchange heat at the preheating heat exchanger 2, reducing the temperature rise during water outages in the water heater 10.

[0045] Furthermore, the first water inlet control valve 5 is closed after the pre-cleaning stage. Specifically, after the pre-cleaning stage, the burner is in the ignition state and can heat the water in the heat exchanger 1 normally. Therefore, it is not necessary to open the first water inlet control valve 5 to prevent the outlet water temperature from falling below the user-set temperature when the first water inlet control valve 5 is opened, resulting in water outage and temperature drop.

[0046] Specifically, refer to Figure 4 As shown, the pre-cleaning stage time is t1, and the opening time of the first water inlet control valve 5 is t2. When t2 < t1, the first water inlet control valve 5 is kept in the open state; when t2 ≥ t1, the first water inlet control valve 5 is closed.

[0047] Optionally, the pre-cleaning phase can last from 3 to 20 seconds.

[0048] According to a second aspect of the present invention, a computer-readable storage medium stores a control program thereon for reducing the temperature rise and fall of the water heater 10 during water outages. When the control program is executed by a processor, it implements the control method of the above-described embodiments.

[0049] According to a third aspect of the present invention, a water heater 10 is used to implement the control method for reducing the temperature rise and drop when the water heater 10 is shut off, as described in the above embodiment.

[0050] Reference Figure 1As shown, the water inlet pipe 3 may further include: a water inlet interface section 33 and a preheating pipe section 34. The water inlets of the first water inlet branch 31 and the second water inlet branch 32 are connected to the water inlet interface section 33, and the water outlets of the first water inlet branch 31 and the second water inlet branch 32 are connected to the preheating pipe section 34. The preheating pipe section 34 is connected to the water inlet of the heat exchanger 1.

[0051] The first water inlet branch 31 may include: a first water inlet section 311 and a first water outlet section 312. The water inlet interface section 33 and the cold side inlet end 21 of the preheating heat exchanger 2 are connected and conductive through the first water inlet section 311. The preheating pipe section 34 and the cold side outlet end 22 of the preheating heat exchanger 2 are connected and conductive through the first water outlet section 312. The first water inlet control valve 5 is installed on the first water inlet section 311.

[0052] Specifically, the outlet pipe 4 may include an outlet interface section 41 and a hot water pipe section 42. The hot-side inlet 23 of the preheating heat exchanger 2 is connected to the outlet of the heat exchanger 1 via the hot water pipe section 42, and the hot-side outlet 24 of the preheating heat exchanger 2 is connected to the outlet interface section 41. In this way, water in the heat exchanger 1 enters the preheating heat exchanger 2 from the outlet of the heat exchanger 1 through the hot water pipe section 42, enters the preheating heat exchanger 2 from the hot-side inlet 23, enters the outlet interface section 41 from the hot-side outlet 24, and finally flows out for user use.

[0053] The preheating heat exchanger 2 has a cold side cavity and a hot side cavity. The cold side cavity is located on and connected to the inlet pipe 3, and the hot side cavity is located on and connected to the outlet pipe 4. The cold side cavity and the hot side cavity exchange heat through contact. The hot side inlet end 23 and the hot side outlet end 24 are adapted to be connected to the hot side cavity, and the cold side inlet end 21 and the cold side outlet end 22 are adapted to be connected to the cold side cavity.

[0054] Optionally, the cold side cavity and the hot side cavity are stacked or arranged adjacent to each other, thereby maximizing the wall contact between the cold side cavity and the hot side cavity 222, which can increase the heat exchange area and enable the heat of the hot water in the hot side cavity to be quickly transferred to the cold water in the cold side cavity, thereby improving the heat exchange efficiency.

[0055] Optionally, the cold side cavity, cold side inlet 21, and cold side outlet 22 are located at one end of the preheating heat exchanger 2 near the inlet pipe 3, and the hot side cavity, hot side inlet 23, and hot side outlet 24 are located at one end of the preheating heat exchanger 2 near the outlet pipe 4, which helps to simplify the water circuit structure.

[0056] When the water heater 10 is working, cold water flows into the inlet pipe 3 from the inlet interface section 33 and then splits into two branches. The first inlet branch 31 is connected to the cold side cavity. A portion of the cold water flows from the inlet interface section 33 into the cold side cavity through the first inlet section 311. After heat exchange in the preheating heat exchanger 2, the first inlet branch 31 enters the preheating pipe section 34 through the first outlet section 312. The second inlet branch 32 serves as a bypass branch and is directly connected to the preheating pipe section 34. The water from the first inlet branch 31, which is preheated by the preheating heat exchanger 2, merges with the cold water from the second inlet branch 32 into the preheating pipe section 34 and enters the heat exchanger 1. After absorbing heat and being heated to hot water in the heat exchanger 1, the water flows through the hot water pipe section 42 into the hot side cavity of the preheating heat exchanger 2. When a certain amount of hot water is stored in the hot side cavity, it flows from the hot side outlet 24 through the outlet interface section 41, and the water heater 10 outputs hot water.

[0057] Reference Figure 1 As shown, the preheating heat exchanger 2 is located on the side of the burner away from the heat exchanger 1, that is, the heat exchanger 1 is located above the burner and the preheating heat exchanger 2 is located below the burner. In this way, more of the heat from the burner is transferred to the heat exchanger 1, and less or no heat is transferred to the preheating heat exchanger 2, preventing the overall water temperature of the preheating heat exchanger 2 from rising and causing the outlet water temperature of the water heater 10 to be higher than the user-set temperature.

[0058] Reference Figure 1 As shown, an inlet water temperature probe 71 and a mixing water temperature probe 72 are installed on the inlet pipe 3, and an outlet water temperature probe 73 is installed on the outlet pipe 4. The inlet water temperature probe 71 is installed on the inlet interface section 33 to measure the temperature of the inlet interface section 33. The mixing water temperature probe 72 is installed on the preheating pipe section 34 to measure the temperature of the preheating pipe section 34. The outlet water temperature probe 73 is installed on the hot water pipe section 42 to measure the temperature of the hot water pipe section 42, i.e., to measure the outlet water temperature of the water heater 10.

[0059] A water flow sensor 74 can also be installed on the water inlet pipe 3 to detect the water inlet volume of the water heater 10.

[0060] Optionally, the preheating heat exchanger 2 is a plate heat exchanger. The burner is a flame burner or a flameless catalytic burner.

[0061] In some alternative embodiments, the burner includes a flame burner and a flameless catalytic burner. When the flame burner is burning, it can heat the flameless catalytic burner to cause catalytic combustion in the flameless catalytic burner. The heat generated by the flameless catalytic burner is transferred to the heat exchanger 1 through thermal radiation to raise the water temperature in the heat exchanger 1.

[0062] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. In addition, those skilled in the art can combine and integrate the different embodiments or examples described in this specification.

[0063] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A method for controlling the temperature rise and fall of a water heater during water outages, characterized in that, The water heater includes: a heat exchanger, a preheating heat exchanger, and a burner. The heat exchanger is adapted to connect an inlet pipe and an outlet pipe. A heat exchange flow path is formed inside the heat exchanger. The burner is adapted to heat the heat exchanger. The inlet pipe has a first inlet branch and a second inlet branch. The first inlet branch exchanges heat with the outlet pipe at the preheating heat exchanger and then connects to the heat exchanger. The second inlet branch is directly connected to the heat exchanger. A first inlet control valve for adjusting the flow rate is provided on the first inlet branch, and a second inlet control valve for adjusting the flow rate is provided on the second inlet branch. The control method includes: When the water outage time of the heat exchanger is less than the first preset time, the first water inlet control valve opens at the first valve opening degree. When the water outage time of the heat exchanger is greater than or equal to the first preset time and less than the second preset time, the first water inlet control valve opens at the second valve opening degree. When the water outage time of the heat exchanger is greater than or equal to the second preset time, the first water inlet control valve opens at the third valve opening degree. Wherein, the opening degree of the first valve is less than that of the second valve, and the opening degree of the third valve is less than that of the second valve.

2. The control method according to claim 1, characterized in that, As the water outage time of the heat exchanger increases, the valve opening of the first inlet control valve first increases and then decreases.

3. The control method according to claim 1, characterized in that, The water heater has a pre-cleaning phase before being used again, during which the first inlet control valve is kept open.

4. The control method according to claim 3, characterized in that, After the pre-cleaning phase is completed, the first inlet control valve is closed.

5. A computer-readable storage medium, characterized in that, It stores a control program to reduce the temperature rise and fall of the water heater when the water supply is interrupted. When the processor executes the control program, it implements the control method as described in any one of claims 1-4.

6. A water heater, characterized in that, This method is used to implement the control method for reducing the temperature rise and fall of a water heater during water outages as described in any one of claims 1-4.

7. The water heater according to claim 6, characterized in that, The water inlet pipe further includes: a water inlet interface section and a preheating pipe section, wherein the water inlets of the first water inlet branch and the second water inlet branch are connected to the water inlet interface section, the water outlets of the first water inlet branch and the second water inlet branch are connected to the preheating pipe section, and the preheating pipe section is connected to the water inlet of the heat exchanger. The first water inlet branch includes a first water inlet section and a first water outlet section. The water inlet section and the cold side inlet of the preheating heat exchanger are connected and conductive through the first water inlet section. The preheating pipe section and the cold side outlet of the preheating heat exchanger are connected and conductive through the first water outlet section. The first water inlet control valve is installed on the first water inlet section.

8. The water heater according to claim 7, characterized in that, The water outlet pipe includes a water outlet interface section and a hot water pipe section. The hot side inlet of the preheating heat exchanger is connected to the water outlet of the heat exchanger through the hot water pipe section, and the hot side outlet of the preheating heat exchanger is connected to the water outlet interface section.

9. The water heater according to claim 6, characterized in that, The preheating heat exchanger has a cold side cavity and a hot side cavity. The cold side cavity is located on the water inlet pipe and is connected to the water inlet pipe. The hot side cavity is located on the water outlet pipe and is connected to the water outlet pipe. The cold side cavity and the hot side cavity exchange heat through contact.

10. The water heater according to claim 6, characterized in that, The preheating heat exchanger is a plate heat exchanger.

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