Gas water heater and control method thereof

Abstract

The invention belongs to the technical field of water heaters, and discloses a gas water heater and a control method of the gas water heater. The gas water heater comprises a heat exchange assembly, a water way assembly and a water pump. The heat exchange assembly comprises a first-stage heat exchanger and a second-stage heat exchanger which are connected in series. The water path assembly comprises a water inlet pipe, a water outlet pipe and a bypass pipe, the water inlet pipe communicates with the second-stage heat exchanger, the water outlet pipe communicates with the first-stage heat exchanger, and the bypass pipe can communicate with the water outlet pipe and the water inlet pipe to form an inner circulation flow channel; the water pump is arranged on the water inlet pipe, located on the downstream of the communicating position of the water inlet pipe and the bypass pipe and used for driving inflow water or fluid in the inner circulation flow channel to flow. The gas water heater can achieve first-stage energy efficiency, internal circulation is achieved by arranging the bypass pipe, a water tank in the prior art is replaced with the second-stage heat exchanger, and the gas water heater is beneficial to simplifying the result, reducing the cost and solving the problem of cold hot water; the water pump position is optimized, the number of water pumps is reduced, and cost is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of water heaters, and in particular to a gas water heater and a control method thereof. Background Art

[0002] With the improvement of living standards, users have put forward high requirements for water use comfort. Gas water heaters have the characteristics of fast heating and no need for preheating, which has promoted the rapid development of gas water heaters. However, during the use of gas water heaters, there is a situation of turning off the water. When the water is turned off, the remaining temperature of the burner and the flue gas will continue to heat the hot water in the pipeline, resulting in a temperature rise to form high-temperature water; when the water heater is restarted, the high-temperature water caused by the temperature rise during water stoppage and the cold water entering during the startup process of the water heater bring an uncomfortable experience to users, that is, there is the so-called "cold and hot water" problem.

[0003] To solve the "cold and hot water" problem, a circulating pipeline is added to the existing gas water heater, and a separate water tank needs to be added to the water inlet pipe to store cold water. When the gas water heater turns off the water, the cold water in the water tank is mixed with part of the high-temperature water with temperature rise during water stoppage through internal circulation to solve the cold and hot water problem. However, this structure requires adding a separate water tank, which increases the cost and the overall size of the gas water heater; moreover, there are too many water circuits in the gas water heater, and each water circuit requires power drive, resulting in a complex structure and high cost. Summary of the Invention

[0004] The purpose of the present invention is to provide a gas water heater and a control method thereof, which can solve the problems of "cold and hot water" and the complex structure that each water circuit requires power drive.

[0005] To achieve this purpose, the present invention adopts the following technical solutions:

[0006] A gas water heater, comprising:

[0007] A heat exchange assembly, including a first-stage heat exchanger and a second-stage heat exchanger connected in series;

[0008] A water circuit assembly, including a water inlet pipe, a water outlet pipe and a bypass pipe. The water inlet pipe is connected to the second-stage heat exchanger, the water outlet pipe is connected to the first-stage heat exchanger, and the bypass pipe can connect the water outlet pipe and the water inlet pipe to form an internal circulation flow path;

[0009] A water pump is arranged on the water inlet pipe and is located downstream of the connection position of the water inlet pipe and the bypass pipe. The water pump is used to drive the inlet water or the fluid in the internal circulation flow path to flow.

[0010] As an alternative solution for the above gas water heater, a switching valve is provided on the bypass pipe, and the volume of the bypass pipe between the switching valve and the water inlet pipe is smaller than the volume of the bypass pipe between the switching valve and the water outlet pipe.

[0011] As an alternative solution for the above gas water heater, the length of the bypass pipe between the switching valve and the water inlet pipe is smaller than the length of the bypass pipe between the switching valve and the water outlet pipe;

[0012] And / or, the flow area of the bypass pipe between the switching valve and the water inlet pipe is smaller than the flow area of the bypass pipe between the switching valve and the water outlet pipe.

[0013] As an alternative solution for the above gas water heater, a check valve is provided on the bypass pipe, the check valve can prevent the fluid in the bypass pipe from flowing from the water inlet pipe to the water outlet pipe, and the check valve is arranged between the switching valve and the water inlet pipe.

[0014] As an alternative solution for the above gas water heater, the gas water heater further includes a return pipe communicated with the internal circulation flow path, the return pipe is used to communicate with an external water pipeline, and the water pump is located downstream of the return pipe to drive the flowing back water.

[0015] As an alternative solution for the above gas water heater, the return pipe is connected to the bypass pipe, and the connection position of the return pipe and the bypass pipe is between the check valve and the water inlet pipe.

[0016] As an alternative solution for the above gas water heater, the water pump is arranged at one end of the water inlet pipe connected to the bypass pipe.

[0017] As an alternative solution for the above gas water heater, the gas water heater further includes a burner, the primary heat exchanger is used to absorb the heat generated by the combustion of the gas in the burner, and the secondary heat exchanger is used to absorb the heat of the flue gas;

[0018] An intermediate temperature detector is arranged between the outlet of the secondary heat exchanger and the inlet of the primary heat exchanger, and the intermediate temperature detector is communicatively connected with the burner.

[0019] As an alternative solution for the above gas water heater, at least part of the secondary heat exchanger is arranged above the primary heat exchanger;

[0020] And / or, the secondary heat exchanger includes heat exchange pipes, and the heat exchange pipes are wound around at least part of the outer wall of the primary heat exchanger;

[0021] And / or, the secondary heat exchanger is of a hollow structure, and the secondary heat exchanger is sleeved outside the primary heat exchanger.

[0022] As an alternative embodiment of the above gas water heater, a throttling element is connected to the inlet and / or outlet of the secondary heat exchanger.

[0023] As an alternative embodiment of the above gas water heater, a secondary heat exchange flow channel communicating the water inlet pipe and the primary heat exchanger is provided in the secondary heat exchanger;

[0024] The secondary heat exchange flow channel extends in a bent manner;

[0025] And / or, the flow area of the secondary heat exchange flow channel is larger than the flow area of the pipeline communicating the inlet and outlet of the secondary heat exchange flow channel;

[0026] And / or, flow disturbing members are provided in the secondary heat exchange flow channel.

[0027] A control method for a gas water heater, which is applied to the above gas water heater, and the control method for the gas water heater includes:

[0028] When the gas water heater starts and discharges water, the water pump starts to drive the water flow in the water inlet pipe towards the heat exchange assembly;

[0029] When the gas water heater shuts off the fire and stops discharging water, the water pump starts to make the fluid in the internal circulation flow channel flow, so as to balance the fluid temperature in the internal circulation flow channel.

[0030] As an alternative embodiment of the control method for the above gas water heater, the water outlet temperature of the secondary heat exchanger is detected. When the water outlet temperature is lower than a preset temperature, the gas water heater ignites and maintains for a preset duration.

[0031] Advantages of the present invention:

[0032] In the gas water heater provided by the present invention, by providing a bypass pipe to form an internal circulation flow channel, on the one hand, it can drive the water in the internal circulation flow channel to circulate when the gas water heater closes the water, so that the residual heat of the burner can evenly heat the water in the internal circulation flow channel, avoiding the abnormal increase of the local water temperature to form scalding water, and solving the problem of too high water outlet temperature when the gas water heater is restarted; on the other hand, the water circulation in the internal circulation flow channel can heat the cold water in the internal circulation flow channel, such as part of the cold water in the water inlet pipe, avoiding the problem of cold water discharge when the gas water heater is restarted, providing sufficient heating time for the newly entered cold water in the water inlet pipe, ensuring that the gas water heater can be used immediately and realizing zero cold water.

[0033] The water pump is arranged on the water inlet pipe. It can not only provide power for the flow of water in the internal circulation flow channel to quickly and evenly mix the cold perm water, but also provide power for the cold water entering the water inlet pipe when the gas water heater is in the startup state, avoiding the influence of insufficient water source pressure on the water inlet of the gas water heater. By arranging the water pump on the water inlet pipe, the water pump can provide power both when water is inlet and when the gas water heater shuts off water, and can also provide power for the mixing of water in the internal circulation flow channel. There is no need to additionally increase a pump, which is beneficial to reducing the number of parts and lowering the cost.

[0034] In addition, by arranging the secondary heat exchanger, not only can the heat of the flue gas be utilized to improve the heat utilization rate, but the secondary heat exchanger can also play the role of the water tank in the prior art, that is, a certain amount of water can be stored in the secondary heat exchanger, increasing the total amount of the mixed hot water. So when the gas water heater is turned on again, a certain amount of uniformly heated mixed water can be provided for the user first, thereby providing sufficient heating time for the cold water newly entering the water inlet pipe and realizing the continuous and uninterrupted supply of hot water. Description of the Drawings

[0035] Figure 1 It is a schematic structural diagram of the gas water heater provided by the present invention.

[0036] In the figure:

[0037] 10, housing; 20, heat exchange assembly; 21, primary heat exchanger; 22, secondary heat exchanger; 31, water inlet pipe; 32, water outlet pipe; 33, bypass pipe; 34, return pipe; 40, water pump; 50, on-off valve; 60, check valve; 71, intermediate temperature detector; 72, inlet water temperature detector; 73, outlet water temperature detector; 80, flow detector. Detailed Embodiments

[0038] The present invention will be further described in detail below with reference to the drawings and embodiments. It can be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention. Additionally, it should be noted that for the sake of description, only the parts related to the present invention rather than all the structures are shown in the drawings.

[0039] In the description of the present invention, unless otherwise clearly defined and limited, the terms "connected", "connected to", and "fixed" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0040] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may include direct contact between the first and second features, or may include indirect contact between the first and second features through additional features therebetween. Moreover, the first feature being "above", "over" and "on top of" the second feature includes the first feature being directly above and obliquely above the second feature, or merely indicating that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature includes the first feature being directly below and obliquely below the second feature, or merely indicating that the first feature has a lower horizontal height than the second feature.

[0041] In the description of this embodiment, the orientation or positional relationships such as "upper", "lower", "right", etc. are based on the orientation or positional relationships shown in the drawings, and are only for the convenience of description and simplifying the operation, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention. In addition, the terms "first" and "second" are only used for distinction in description and have no special meaning.

[0042] As Figure 1 shown, this embodiment provides a gas water heater, which includes a housing 10, a burner (not shown in the figure) disposed in the housing 10, a heat exchange assembly 20, and a water circuit assembly. The water circuit assembly includes a water inlet pipe 31 and a water outlet pipe 32. Both the water inlet pipe 31 and the water outlet pipe 32 are connected to the heat exchange assembly 20, so that the water introduced from the water inlet pipe 31 can absorb the heat generated by the combustion of the burner in the heat exchange assembly 20 and then the water with increased temperature flows out through the water outlet pipe 32.

[0043] To optimize the energy efficiency of the gas water heater, the heat exchange assembly 20 includes a primary heat exchanger 21 and a secondary heat exchanger 22 arranged in series. The secondary heat exchanger 22 is communicated with the water inlet pipe 31, and the primary heat exchanger 21 is communicated with the water outlet pipe 32. After the water in the water inlet pipe 31 is sequentially heat-exchanged through the primary heat exchanger 21 and the secondary heat exchanger 22, it flows out through the water outlet pipe 32. Through two-stage heat exchange, the heat generated by the burner can be fully utilized, the heat utilization rate and the water heating efficiency can be improved, so as to improve the performance of the gas water heater.

[0044] In this embodiment, the primary heat exchanger 21 is used to absorb the heat generated by the combustion of the gas in the burner, and the secondary heat exchanger 22 is used to absorb the heat of the flue gas generated by the combustion of the gas, so as to fully utilize the flue gas heat and avoid heat waste.

[0045] To improve the heat utilization rate, the water in the water inlet pipe 31 first enters the secondary heat exchanger 22 to absorb the heat of the flue gas for preheating, and then enters the primary heat exchanger 21 to absorb the heat generated by the combustion for further heating, which is beneficial to improving the heat exchange rate and the heating efficiency.

[0046] During the use of a gas water heater, there is a situation where the water supply is temporarily shut off. When the water supply is shut off, the burner does not work, but the remaining heat of the burner will continuously heat the water in the primary heat exchanger 21, resulting in an increase in water temperature to form high-temperature water. When the water heater is restarted, the high-temperature water caused by the water temperature rise during the shutdown and the cold water entering during the startup process of the water heater bring an uncomfortable experience to the user, that is, there is the problem of "cold and hot water" commonly referred to.

[0047] To solve the above problems, the gas water heater further includes a bypass pipe 33 and a water pump 40. The bypass pipe 33 can connect the water outlet pipe 32 and the water inlet pipe 31, so that the water inlet pipe 31, the secondary heat exchanger 22, the primary heat exchanger 21 and the water outlet pipe 32 can be connected in sequence to form an internal circulation flow path; the water pump 40 is arranged on the water inlet pipe 31 and is located downstream of the connection position of the water inlet pipe 31 and the bypass pipe 33.

[0048] By setting up the bypass pipe 33 to form an internal circulation flow path, on the one hand, it can drive the water in the internal circulation flow path to circulate when the gas water heater shuts off the water supply, so that the remaining heat of the burner can evenly heat the water in the internal circulation flow path, avoiding the local water temperature from rising abnormally to form overheated water and solving the problem of too high water outlet temperature when the gas water heater is restarted; on the other hand, the water circulation in the internal circulation flow path can heat the cold water in the internal circulation flow path, such as part of the cold water in the water inlet pipe 31, avoiding the problem of cold water coming out when the gas water heater is restarted, providing sufficient heating time for the newly entered cold water in the water inlet pipe 31, ensuring that the gas water heater can be used immediately and achieving zero cold water.

[0049] The water pump 40 is arranged on the water inlet pipe 31, which can not only provide power for the flow of water in the internal circulation flow path to quickly and evenly mix cold and hot water, but also provide power for the cold water entering the water inlet pipe 31 when the gas water heater is in the startup state, avoiding the influence of insufficient water source pressure on the water inlet of the gas water heater. By arranging the water pump 40 on the water inlet pipe 31, the water pump 40 can provide power when the water is inlet and can also provide power for the mixing of water in the internal circulation flow path when the gas water heater shuts off the water supply, without the need to add an extra pump, which is beneficial to reducing the number of parts and lowering the cost.

[0050] In addition, by setting up the secondary heat exchanger 22, not only can the heat of the flue gas be utilized to improve the heat utilization rate, but the secondary heat exchanger 22 can also play the role of a water tank in the prior art, that is, a certain amount of water can be stored in the secondary heat exchanger 22 to increase the total amount of mixed hot water, so that when the gas water heater is restarted and used, a certain amount of uniformly heated mixed water can be provided for the user first, thus providing sufficient heating time for the newly entered cold water in the water inlet pipe 31 and realizing the continuous and uninterrupted supply of hot water.

[0051] To increase the driving force of the water pump 40 on the water in the internal circulation flow path, the water pump 40 is arranged at one end of the bypass pipe 33 connected to the water inlet pipe 31. That is to say, the length of the water inlet pipe 31 between the water pump 40 and the bypass pipe 33 is less than the length of the water inlet pipe 31 between the secondary heat exchanger 22 and the water pump 40. The driving force of the water pump 40 on the water in the bypass pipe 33 is greater, which is beneficial to the smooth start of the water flow in the internal circulation flow path.

[0052] To realize the on-off control of the bypass pipe 33, a switching valve 50 is arranged on the bypass pipe 33. The switching valve 50 can be started when the gas water heater shuts off the water, so as to connect the water inlet pipe 31 and the water outlet pipe 32 through the bypass pipe 33.

[0053] It can be understood that when the gas water heater is started, the water inlet pipe 31 is in the water passing state. When the gas water heater shuts off the water, the secondary heat exchanger 22, the primary heat exchanger 21, and the water in the water outlet pipe 32 are all heated water, while the water in the water inlet pipe 31 is unheated cold water. In the water shut-off state, the burner does not start, and the waste heat generated by it is limited. In order to avoid the relatively low mixed water temperature after the water circulation in the internal circulation flow path is mixed, the volume of the bypass pipe 33 between the switching valve 50 and the water inlet pipe 31 is less than the volume of the bypass pipe 33 between the switching valve 50 and the water outlet pipe 32, so as to increase the length of the bypass pipe 33 storing the heated hot water, increase the storage amount of the hot water in the internal circulation flow path when the gas water heater shuts off the water, so as to increase the mixed water temperature, and make the outlet water temperature closer to the water temperature required by the user when the gas water heater starts to supply water again.

[0054] Optionally, the bypass pipe 33 includes a first bypass pipe section and a second bypass pipe section. The water pump 40 is located at the connection position of the first bypass pipe section and the second bypass pipe section. The first bypass pipe section is connected to the water outlet pipe 32, and the second bypass pipe section is connected to the water inlet pipe 31. The length and / or the flow area of the first bypass pipe section is greater than the length and / or the flow area of the second bypass pipe section.

[0055] In some embodiments, the flow areas of the first bypass pipe section and the second bypass pipe section are equal, and the length of the first bypass pipe section is greater than the length of the second bypass pipe section; or, the lengths of the first bypass pipe section and the second bypass pipe section are equal, and the flow area of the first bypass pipe section is greater than the flow area of the second bypass pipe section.

[0056] In some other embodiments, the length of the first bypass pipe section is greater than the length of the second bypass pipe section, and the flow area of the first bypass pipe section is greater than the flow area of the second bypass pipe section, so as to further increase the amount of hot water stored in the bypass pipe 33 when the gas water heater is in the water shut-off state.

[0057] In order to increase the temperature of the mixed water in the inner circulation channel, the bypass pipe 33 includes a first bypass pipe section and a second bypass pipe section, and the water pump 40 is located at the connecting position between the first bypass pipe section and the second bypass pipe section. The first bypass pipe section is connected to the water outlet pipe 32, and the second bypass pipe section is connected to the water inlet pipe 31. The flow area of the first bypass pipe section is greater than the flow area of the second bypass pipe section.

[0058] To prevent the water in the bypass pipe 33 from flowing back toward the water outlet pipe 32 when the switch valve 50 is opened, a one-way valve 60 is provided on the bypass pipe 33 to prevent the fluid in the bypass pipe 33 from flowing from the water inlet pipe 31 to the water outlet pipe 32 .

[0059] In order to ensure the water inlet efficiency of the water inlet pipe 31, the one-way valve 60 is arranged between the switch valve 50 and the water inlet pipe 31. This arrangement makes the length of the bypass pipe 33 between the one-way valve 60 and the water inlet pipe 31 shorter. When the gas water heater starts to inlet water, a small amount of water entering the water inlet pipe 31 will stay in the bypass pipe 33, and most of the water can directly enter the heat exchange component 20, so as to improve the response speed of water inlet and avoid the waste of cold water.

[0060] The gas water heater further includes a return pipe 34 connected to the internal circulation flow channel, and the return pipe 34 is used to connect to the external water pipeline. The water flowing into the external water pipeline through the water outlet pipe 32 can flow into the internal circulation flow channel through the return pipe 34, and then be reheated by the heat exchange component 20 to reheat the cold water in the external water pipeline, thereby achieving zero cold water and improving the user experience.

[0061] To simplify the structure, the water pump 40 is located downstream of the return pipe 34 so that the water pump 40 can drive the water passing through the return pipe 34 to drive the return water to pass through the water inlet pipe 31, the heat exchange component 20 and the water outlet pipe 32 in sequence.

[0062] In some embodiments, the return pipe 34 is connected to the bypass pipe 33, and the connection position of the return pipe 34 and the bypass pipe 33 is located between the one-way valve 60 and the water inlet pipe 31, and the return water enters the water inlet pipe 31 for circulation.

[0063] In some other embodiments, the return pipe 34 is connected to the water inlet pipe 31 , so that the return water can also pass through the water inlet pipe 31 and be heated by the heat exchange component 20 to be heated.

[0064] In order to facilitate the control of the outlet water temperature of the gas water heater, a water inlet temperature detection component 72 is provided on the water inlet pipe 31. The water inlet temperature detection component 72 is used to detect the water temperature in the water inlet pipe 31 to obtain the inlet water temperature, thereby facilitating the control of the working parameters of the burner, such as the power and start-up time of the burner, according to the outlet water temperature required by the user, so as to make the outlet water temperature more accurate.

[0065] Optionally, a water outlet temperature detector 73 is provided on the water outlet pipe 32. The water outlet temperature detector 73 is used to detect the water temperature in the water outlet pipe 32 to detect whether the actual water outlet temperature meets the user's requirements, so as to conveniently adjust the operating parameters of the burner according to the actual water outlet temperature.

[0066] To facilitate the adjustment of the water outlet temperature, the gas water heater further includes a control component. The control component is electrically connected to the water inlet temperature detector 72, the water outlet temperature detector 73, and the burner respectively. The temperatures detected by the water inlet temperature detector 72 and the water outlet temperature detector 73 are transmitted to the control component, and the control component adjusts the operating parameters of the burner according to the received temperature information to achieve feedback regulation and improve the accuracy of the water outlet temperature.

[0067] To better control the water temperature in the internal circulation flow path when the water is turned off, an intermediate temperature detector 71 is provided between the outlet of the secondary heat exchanger 22 and the inlet of the primary heat exchanger 21. The intermediate temperature detector 71 is communicatively connected to the burner. The intermediate temperature detector 71 can detect the water temperature after being heated by the secondary heat exchanger 22. When the gas water heater is in the water-off state, the mixed water temperature in the internal circulation flow path can be obtained according to the water temperature detected by the intermediate temperature detector 71. When the water temperature is lower than the preset temperature value, the burner is started to heat the water temperature in the internal circulation flow path, ensuring that when the gas water heater starts to supply water again, the water outlet temperature is close to the set temperature required by the user, so as to better meet the user's needs.

[0068] Optionally, the intermediate temperature detector 71, the water inlet temperature detector 72, and the water outlet temperature detector 73 are temperature sensors, such as thermistors, as long as they can detect the water temperature.

[0069] In this embodiment, at least part of the secondary heat exchanger 22 is disposed above the primary heat exchanger 21. Utilizing the characteristics that the flue gas and heat flow upward is beneficial to the contact heat exchange between the flue gas and the secondary heat exchanger 22, so as to make full use of the heat of the flue gas and improve the heat utilization rate.

[0070] In some embodiments, the secondary heat exchanger 22 includes heat exchange tubes. The heat exchange tubes are smaller in size than the water tank, and their placement positions and arrangement methods are more flexible, which is beneficial to optimizing the overall machine space and reducing the overall machine size to improve the product competitiveness.

[0071] In some embodiments, the heat exchange tubes are bent and coiled on the top surface of the primary heat exchanger 21. On the one hand, it increases the effective area for the heat exchange tubes to intercept the flue gas from above, thereby increasing the contact area between the heat exchange tubes and the flue gas and improving the heat exchange effect; on the other hand, the heat exchange tubes coiled on the top surface of the primary heat exchanger 21 can reduce the space occupied by the heat exchange tubes, making the layout of the primary heat exchanger 21 and the secondary heat exchanger 22 more compact, so as to optimize the layout and reduce the overall machine size.

[0072] In some other embodiments, the heat exchange tubes can be wound around the first-stage heat exchanger 21 along the circumferential direction of the first-stage heat exchanger 21 to increase the length of the second-stage heat exchanger 22 and the area of contact with the flue gas. This can not only increase the amount of water in the second-stage heat exchanger 22, but also make reasonable use of the internal space of the gas water heater and reduce the overall size of the machine.

[0073] In some other embodiments, the second-stage heat exchanger 22 has a hollow structure, so that the second-stage heat exchanger 22 can be sleeved outside the first-stage heat exchanger 21. Similarly, while absorbing the heat of the flue gas, it can also absorb the heat diffused outward by the first-stage heat exchanger 21, further improving the heat utilization rate.

[0074] To improve the heat utilization effect of the second-stage heat exchanger 22, throttling elements are provided at the inlet and / or outlet of the second-stage heat exchanger 22. The throttling elements can slow down the water flow rate entering the second-stage heat exchanger 22, so that the water in the second-stage heat exchanger 22 can fully exchange heat with the flue gas and improve the utilization rate of the heat of the flue gas.

[0075] Optionally, the throttling element can be a capillary tube, a throttle valve, an orifice plate or a regulating valve, as long as it can control the water flow rate entering the second-stage heat exchanger 22.

[0076] In some embodiments, the second-stage heat exchanger 22 includes a second-stage heat exchange flow channel that connects the water inlet pipe 31 and the first-stage heat exchanger 21. The second-stage heat exchange flow channel bends and extends to extend the length of the second-stage heat exchange flow channel on the basis of the overall size of the second-stage heat exchanger 22 remaining unchanged. On the one hand, it is beneficial to full heat exchange, and on the other hand, it can increase the amount of water stored in the second-stage heat exchanger 22 to meet the water outlet demand before the newly entered cold water is heated when the gas water heater is restarted.

[0077] In some embodiments, the flow area of the second-stage heat exchange flow channel can be larger than the flow areas of the pipelines connected to its inlet and outlet. That is to say, the flow area of the water inlet pipe 31 is smaller than the flow area of the second-stage heat exchange flow channel, and the flow area of the pipeline between the second-stage heat exchanger 22 and the first-stage heat exchanger 21 is smaller than the flow area of the second-stage heat exchange flow channel. By increasing the flow area of the second-stage heat exchange flow channel, on the one hand, the amount of water stored in the second-stage heat exchanger 22 can be increased, and on the other hand, the flow speed of the water entering the second-stage heat exchange flow channel can be slowed down so that the water can be fully heated.

[0078] In some embodiments, flow disturbing elements are provided in the second-stage heat exchange flow channel. The flow disturbing elements can change the flow state of the water in the second-stage heat exchange flow channel, cause the fluid to generate turbulence or secondary flow, destroy the laminar layer close to the wall surface, and strengthen the convective heat transfer, thereby optimizing the heat transfer performance.

[0079] Optionally, the flow disturbing elements can be protrusions protruding from the inner wall of the second-stage heat exchange flow channel, baffle plates or spiral structures, etc.

[0080] In some embodiments, a flow detection component 80 is provided on the water inlet pipe 31. The flow detection component 80 is used to detect the flow rate in the water inlet pipe 31 to determine whether the gas water heater is receiving water or whether there are faults such as blockages.

[0081] This embodiment also provides a control method for a gas water heater, which can be applied to the above gas water heater. The control method specifically includes:

[0082] When the gas water heater starts and discharges water, the water pump 40 starts to drive the water flow in the water inlet pipe 31 towards the heat exchange component 20, thereby preparing hot water.

[0083] When the gas water heater shuts off and stops discharging water, the water pump 40 starts to make the water in the internal circulation flow path flow, so as to balance the water temperature in the internal circulation flow path and avoid the appearance of cold or scalding water.

[0084] By starting the water pump 40 when the gas water heater shuts off and stops discharging water, it is possible to drive the fluid flow in the internal circulation flow path, thereby neutralizing the water temperature and avoiding the problem of cold or scalding water. In addition, the water pump 40 can provide power for the gas water heater to intake cold water and also provide power for the water circulation in the internal circulation flow path. There is no need to set up multiple pumps, which is beneficial to simplifying the structure and reducing costs.

[0085] After the water circulates in the internal circulation flow path, the outlet water temperature of the secondary heat exchanger 22 is detected. When the outlet water temperature is lower than the preset temperature, the gas water heater ignites and maintains for a preset duration to heat the water temperature in the internal circulation flow path through the heat generated by the burner combustion, so that the water temperature meets the usage requirements.

[0086] In some embodiments, the preset temperature and the preset duration can be fixed values set before leaving the factory. In some other embodiments, the preset temperature can be set according to the target outlet water temperature set by the user. For example, it is 0.5 - 1 times the target outlet water temperature set by the user. The preset duration can be set according to the difference between the detected outlet water temperature and the target outlet water temperature. For example, the greater the difference, the longer the preset duration.

[0087] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, various obvious changes, re-adjustments, and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent substitutions, and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A gas water heater, characterized in that, Comprising: A heat exchange assembly (20), including a first-stage heat exchanger (21) and a second-stage heat exchanger (22) connected in series; A water circuit assembly, including a water inlet pipe (31), a water outlet pipe (32) and a bypass pipe (33), the water inlet pipe (31) communicates with the second-stage heat exchanger (22), the water outlet pipe (32) communicates with the first-stage heat exchanger (21), and the bypass pipe (33) can communicate the water outlet pipe (32) and the water inlet pipe (31) to form an internal circulation flow path; A water pump (40), arranged on the water inlet pipe (31) and downstream of the connection position between the water inlet pipe (31) and the bypass pipe (33), and the water pump (40) is used to drive the water inlet or the fluid flow in the internal circulation flow path.

2. The gas water heater according to claim 1, wherein A switching valve (50) is arranged on the bypass pipe (33), and the volume of the bypass pipe (33) between the switching valve (50) and the water inlet pipe (31) is smaller than the volume of the bypass pipe (33) between the switching valve (50) and the water outlet pipe (32).

3. The gas water heater according to claim 2, characterized in that, The length of the bypass pipe (33) between the switching valve (50) and the water inlet pipe (31) is smaller than the length of the bypass pipe (33) between the switching valve (50) and the water outlet pipe (32); And / or, the flow area of the bypass pipe (33) between the switching valve (50) and the water inlet pipe (31) is smaller than the flow area of the bypass pipe (33) between the switching valve (50) and the water outlet pipe (32).

4. The gas water heater according to claim 2, wherein A check valve is arranged on the bypass pipe (33), and the check valve can prevent the fluid in the bypass pipe (33) from flowing from the water inlet pipe (31) to the water outlet pipe (32), and the check valve is arranged between the switching valve (50) and the water inlet pipe (31).

5. The gas water heater according to claim 4, characterized in that, The gas water heater further includes a return pipe (34) communicating with the internal circulation flow path, the return pipe (34) is used to communicate with an external water use pipeline, and the water pump (40) is located downstream of the return pipe (34) to drive the return water to flow.

6. The gas water heater according to claim 5, wherein The return pipe (34) is connected to the bypass pipe (33), and the connection position between the return pipe (34) and the bypass pipe (33) is between the check valve and the water inlet pipe (31).

7. The gas water heater according to any one of claims 1-6, characterized in that, The water pump (40) is arranged at one end of the water inlet pipe (31) connected to the bypass pipe (33).

8. The gas water heater according to any one of claims 1-6, characterized in that, The gas water heater further includes a burner, the first-stage heat exchanger (21) is used to absorb the heat generated by the combustion of the gas in the burner, and the second-stage heat exchanger (22) is used to absorb the heat of the flue gas; An intermediate temperature detector (71) is arranged between the outlet of the second-stage heat exchanger (22) and the inlet of the first-stage heat exchanger (21), and the intermediate temperature detector (71) is communicatively connected with the burner.

9. The gas water heater according to any one of claims 1-6, characterized in that, At least part of the second-stage heat exchanger (22) is arranged above the first-stage heat exchanger (21); And / or, the second-stage heat exchanger (22) includes heat exchange tubes, and the heat exchange tubes are wound around at least part of the outer wall of the first-stage heat exchanger (21); And / or, the secondary heat exchanger (22) is of a hollow structure, and the secondary heat exchanger (22) is sleeved outside the primary heat exchanger (21).

10. The gas water heater according to any one of claims 1-6, characterized in that, A throttling element is connected to the inlet and / or outlet of the secondary heat exchanger (22).

11. The gas water heater according to any one of claims 1-6, characterized in that, A secondary heat exchange flow channel communicating the water inlet pipe (31) and the primary heat exchanger (21) is arranged in the secondary heat exchanger (22). The secondary heat exchange flow channel extends in a curved manner. And / or, the flow area of the secondary heat exchange flow channel is larger than the flow area of the pipeline communicating the inlet and outlet of the secondary heat exchange flow channel. And / or, a flow disturbing element is arranged in the secondary heat exchange flow channel.

12. A control method for a gas water heater, characterized in that, Applied to the gas water heater according to any one of claims 1-11, the control method of the gas water heater includes: When the gas water heater starts and discharges water, the water pump (40) starts to drive the water flow in the water inlet pipe (31) to flow towards the heat exchange assembly (20). When the gas water heater shuts off the fire and stops discharging water, the water pump (40) starts to make the fluid in the internal circulation flow channel flow so as to balance the fluid temperature in the internal circulation flow channel.

13. The control method of the gas water heater according to claim 12, wherein, Detect the water outlet temperature of the secondary heat exchanger (22), and when the water outlet temperature is lower than a preset temperature, the gas water heater ignites and maintains for a preset duration.

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