Gas water heating device and control method thereof

Abstract

The invention discloses a gas water heating device and a control method thereof. The gas water heating device comprises a burner, a heat exchanger and a fan. Water flowing into the heat exchanger exchanges heat with smoke generated by the burner and then flows out of the heat exchanger. The heat exchanger comprises a first-stage heat exchanger and a second-stage heat exchanger which are sequentially arranged in the flowing direction of flue gas; the second-stage heat exchanger comprises a shell with a preset volume and a heat exchange pipe penetrating through an inner cavity of the shell, the interior of the heat exchange pipe is used for circulating smoke, and the smoke entering the heat exchange pipe exchanges heat with water contained in the inner cavity of the shell through the heat exchange pipe; the gas water heating device further comprises a bypass water way, and the bypass water way and the heat exchanger are arranged in parallel. An internal circulation water path can be formed in the gas water heating device, is provided with a water pump and comprises a shell inner cavity, a first-stage heat exchanger and a bypass water path. According to the invention, the comprehensive use experience of a user can be improved while energy conservation and environmental protection are realized.

Description

Technical Field

[0001] The present invention relates to the technical field of water heaters, and particularly to a gas water heating device and its control method. Background Art

[0002] Existing water heaters mainly include: gas water heaters, solar water heaters, air source heat pump water heaters, electric water heaters, etc. Among them, as a typical instant water heater, a gas water heater mainly includes components such as a blower, a burner, and a heat exchanger.

[0003] For gas water heaters, how to improve the comprehensive user experience while achieving energy conservation and environmental protection is an urgent technical problem to be solved at present and also a direction that can be continuously optimized and improved in the long term in the future. Summary of the Invention

[0004] Aiming at the defects existing in the prior art, an embodiment of the present invention provides a gas water heating device and its control method, which can improve the comprehensive user experience while achieving energy conservation and environmental protection.

[0005] The specific technical solution of the embodiment of the present invention is as follows:

[0006] A gas water heating device, the gas water heating device includes: a burner, a heat exchanger, and a blower. The water flowing into the heat exchanger exchanges heat with the flue gas generated by the burner and then flows out of the heat exchanger; the heat exchanger includes a primary heat exchanger and a secondary heat exchanger, and the primary heat exchanger and the secondary heat exchanger are arranged in sequence along the flow direction of the flue gas; the secondary heat exchanger includes a shell with a predetermined volume capable of containing water and a heat exchange tube passing through the inner cavity of the shell. The inside of the heat exchange tube is used for the flue gas to flow through, and the flue gas entering the heat exchange tube exchanges heat with the water contained in the inner cavity of the shell through the heat exchange tube; the gas water heating device further includes a bypass water path, and the bypass water path is arranged in parallel with the heat exchanger; an internal circulation water path can be formed inside the gas water heating device, and a water pump is arranged in the internal circulation water path. The internal circulation water path includes the inner cavity of the shell, the primary heat exchanger, and the bypass water path. Under the action of the water pump, the water in the internal circulation water path can circulate.

[0007] In a preferred embodiment, the secondary heat exchanger further has a heat preservation structure, and the heat preservation structure is used for heat preservation of the inner cavity of the shell.

[0008] In a preferred embodiment, the heat preservation structure is a heat preservation layer surrounding the outside of the shell.

[0009] In a preferred embodiment, the heat preservation structure is a cavity arranged outside the shell, and the cavity is formed by the gap between a jacket arranged outside the shell and the shell.

[0010] In a preferred embodiment, the cavity outside the housing communicates with the heat exchange tubes, and the flue gas flowing out of the heat exchange tubes flows into the cavity outside the housing.

[0011] In a preferred embodiment, in the water flow direction, the inner cavity of the housing and the primary heat exchanger are arranged in series or in parallel.

[0012] In a preferred embodiment, the gas water heating device further includes a water inlet pipe and a water outlet pipe communicating with the heat exchanger. The water flowing through the water inlet pipe flows into the heat exchanger, exchanges heat with the flue gas generated by the burner, then flows out of the heat exchanger and into the water outlet pipe; the bypass water path includes a bypass pipe, one end of the bypass pipe is connected to the water outlet pipe and the other end of the bypass pipe is connected to the water inlet pipe.

[0013] In a preferred embodiment, in the water flow direction, the inner cavity of the housing and the primary heat exchanger are connected in series. Under the action of the water pump, the water in the internal circulation water path can sequentially circulate through the inner cavity of the housing, the primary heat exchanger, and the bypass water path.

[0014] In a preferred embodiment, in the water flow direction, the inner cavity of the housing and the primary heat exchanger are connected in series. Under the action of the water pump, the water in the internal circulation water path can sequentially circulate through the primary heat exchanger, the inner cavity of the housing, and the bypass water path.

[0015] In a preferred embodiment, the water pump is arranged on the water outlet pipe and is located upstream of the connection between the bypass pipe and the water outlet pipe along the water flow direction, or the water pump is arranged on the water inlet pipe and is located downstream of the connection between the bypass pipe and the water inlet pipe along the water flow direction.

[0016] In a preferred embodiment, a switching valve is further arranged on the bypass pipe. When the water in the internal circulation water path circulates, the switching valve is in a closed state to enable the water in the bypass pipe to flow through; alternatively, a three-way valve is arranged at the connection between the water outlet pipe and the bypass pipe. When the water in the internal circulation water path circulates, the three-way valve connects the water outlet pipe and the bypass pipe; alternatively, a three-way valve is arranged at the connection between the water inlet pipe and the bypass pipe. When the water in the internal circulation water path circulates, the three-way valve connects the bypass pipe and the water inlet pipe.

[0017] In a preferred embodiment, the three-way valve is a flow-adjustable three-way valve.

[0018] In a preferred embodiment, a switching valve is provided on the bypass pipe. When water flows out of the gas water heater from the outlet pipe, the switching valve is in an off state so that the water in the bypass pipe does not flow.

[0019] In a preferred embodiment, an electric water valve is provided on the bypass pipe for regulating the water flow rate in the bypass pipe.

[0020] In a preferred embodiment, when the water in the internal circulation water path circulates, the electric water valve has a first opening degree so that the water in the bypass pipe circulates.

[0021] In a preferred embodiment, when water flows out of the gas water heater from the outlet pipe, the electric water valve has a second opening degree smaller than the first opening degree so that the water in the bypass pipe does not flow, or so that part of the water entering the gas water heater from the inlet pipe flows into the bypass pipe and part flows into the inner cavity of the secondary heat exchanger housing.

[0022] In a preferred embodiment, when water flows out of the gas water heater from the outlet pipe, the electric water valve has a second opening degree so that the water in the bypass pipe does not flow, or so that part of the water entering the gas water heater from the inlet pipe flows into the bypass pipe and part flows into the inner cavity of the secondary heat exchanger housing.

[0023] In a preferred embodiment, a three-way valve is provided at the connection between the outlet pipe and the bypass pipe. The three-way valve includes a first interface and a second interface connected to the outlet pipe, and a third interface connected to the bypass pipe; the first interface is located upstream of the second interface; when water flows out of the gas water heater from the outlet pipe, the first interface and the second interface are connected; when the water in the internal circulation water path circulates, the first interface and the third interface are connected.

[0024] In a preferred embodiment, a three-way valve is provided at the connection between the inlet pipe and the bypass pipe. The three-way valve includes a first interface and a second interface connected to the inlet pipe, and a third interface connected to the bypass pipe; the first interface is located upstream of the second interface; when water flows into the gas water heater from the inlet pipe, the first interface and the second interface are connected; when the water in the internal circulation water path circulates, the second interface and the third interface are connected.

[0025] In a preferred embodiment, a check valve is provided on the bypass pipe. The check valve is used to make water flow unidirectionally only from the end of the bypass pipe connected to the outlet pipe to the end of the bypass pipe connected to the inlet pipe.

[0026] In a preferred embodiment, the primary heat exchanger, the fan, and the secondary heat exchanger are arranged in sequence along the flow direction of the flue gas, and at least part of the flue gas discharged by the fan can exchange heat with the water in the inner cavity of the housing after entering the heat exchange tubes.

[0027] In a preferred embodiment, the fan is arranged above the primary heat exchanger, and the secondary heat exchanger is arranged obliquely above the primary heat exchanger.

[0028] In a preferred embodiment, the ratio of the volume of the heat exchange tubes passing through the inner cavity of the housing to the volume of the inner cavity of the housing ranges from 1 / 3 to 1 / 2.

[0029] In a preferred embodiment, the gas water heating device further includes a controller, a first temperature sensor for detecting the water temperature entering the inner cavity of the housing, a second temperature sensor for detecting the water temperature flowing out of the primary heat exchanger, and a third temperature sensor for detecting the water temperature between the inner cavity of the housing and the primary heat exchanger. The controller is electrically connected to the first temperature sensor, the second temperature sensor, and the third temperature sensor.

[0030] In a preferred embodiment, the gas water heating device further includes a controller and a flow sensor in the internal circulation water path. The controller is electrically connected to the flow sensor.

[0031] In a preferred embodiment, the primary heat exchanger and the inner cavity of the housing are arranged in parallel.

[0032] The water flowing into the water inlet pipe enters the primary heat exchanger and the inner cavity of the housing respectively and then flows into the water outlet pipe.

[0033] A control method for a gas water heating device, which is applied to any of the above-mentioned gas water heating devices. The gas water heating device has an internal circulation state. The control method includes:

[0034] When the gas water heating device operates in the internal circulation state, control the water pump to work so that the water in the internal circulation water path can circulate through the inner cavity of the housing, the primary heat exchanger, and the bypass water path.

[0035] In a preferred embodiment, when the gas water heating device operates in the internal circulation state, control the burner to be in a working state.

[0036] In a preferred embodiment, when the gas water heating device operates in the internal circulation state, when the preset combustion conditions are met, control the burner of the gas water heating device to be in a working state.

[0037] In a preferred embodiment, the preset combustion condition is that the water pump operates for a preset time; alternatively, the preset combustion condition is that the temperature of the water in the internal circulation water path is less than a first preset temperature before the burner is turned on.

[0038] In a preferred embodiment, the gas water heater further includes a smoke exhaust pipe for exhausting the flue gas heat-exchanged with the heat exchanger from the gas water heater, and the smoke exhaust pipe is provided with a wind guard; the control method further includes: before the burner is started, the wind guard is in a closed state; after the burner is started, the wind guard is in an open state.

[0039] In a preferred embodiment, when controlling the water pump to operate, the burner is simultaneously controlled to be in an operating state.

[0040] In a preferred embodiment, the combustion load of the burner in the internal circulation state is a preset load, and the preset load is between 2KW and 20KW.

[0041] In a preferred embodiment, after the preset stop condition is satisfied, the burner is controlled to stop operating, or both the burner and the water pump are controlled to stop operating.

[0042] In a preferred embodiment, the preset stop condition includes that the burner operates for a preset duration, or the water temperature between the primary heat exchanger and the secondary heat exchanger reaches a second preset temperature.

[0043] In a preferred embodiment, the preset duration of the burner operation is determined according to the working load of the burner, the water temperature of the internal circulation water path when the burner is started, and the user-set temperature.

[0044] In a preferred embodiment, when the gas water heater operates in the internal circulation state, the burner is controlled to be in a non-operating state.

[0045] In a preferred embodiment, the gas water heater has a kitchen water use mode and a normal water use mode.

[0046] In a preferred embodiment, when the gas water heater is in the normal water use mode, after receiving a signal that the user shuts off the hot water use, the gas water heater is controlled to enter the internal circulation state.

[0047] In a preferred embodiment, when the gas water heating device is in the normal water use mode and in the internal circulation state, when the gas water heating device receives one of the following signals, the gas water heating device is controlled to stop the internal circulation: when the water temperature in the internal circulation water path is greater than or equal to a third preset temperature; when the temperature difference between two predetermined positions in the internal circulation water path is within a first preset temperature difference range;

[0048] within a first predetermined time after the user shuts off the water use, when the gas water heating device obtains a signal that the user uses hot water again.

[0049] In a preferred embodiment, the temperatures of the two predetermined positions are the water temperature between the primary heat exchanger and the secondary heat exchanger and the water temperature in the inner cavity of the housing, or the water temperature between the primary heat exchanger and the secondary heat exchanger and the water temperature in the bypass water path, or the water temperature in the inner cavity of the housing and the water temperature in the bypass water path.

[0050] In a preferred embodiment, when the gas water heating device is in the kitchen water use mode, when the preset entry conditions are met, the gas water heating device is controlled to enter the internal circulation state, and the preset entry conditions include: the water temperature in the internal circulation water path or the water temperature at a predetermined position in the internal circulation water path is lower than or equal to a fourth preset temperature.

[0051] In a preferred embodiment, the fourth preset temperature is the set outlet water temperature in the kitchen water use mode or the set outlet water temperature in the kitchen water use mode minus a first difference.

[0052] In a preferred embodiment, when the gas water heating device is operating in the internal circulation state, the water pump is controlled to be in the operating state and the burner is in the working state.

[0053] In a preferred embodiment, when the gas water heating device is in the kitchen water use mode and in the internal circulation state, when the gas water heating device receives one of the following signals, the gas water heating device is controlled to stop the internal circulation: when the water temperature in the internal circulation water path is greater than or equal to a fifth preset temperature; when the temperature difference between two predetermined positions in the internal circulation water path is within a second preset temperature difference range; when the gas water heating device obtains a signal that the user turns on the hot water use.

[0054] In a preferred embodiment, the fifth preset temperature is the set outlet water temperature in the kitchen water use mode or the set outlet water temperature in the kitchen water use mode plus a second difference.

[0055] In a preferred embodiment, the temperatures at the two predetermined positions are the water temperature between the primary heat exchanger and the secondary heat exchanger and the water temperature in the inner cavity of the housing, or the water temperature between the primary heat exchanger and the secondary heat exchanger and the water temperature in the bypass water path, or the water temperature in the inner cavity of the housing and the water temperature in the bypass water path.

[0056] The technical solution of the present invention has the following remarkable beneficial effects:

[0057] In the embodiment provided in the present application, the gas water heater can ensure that the heat in the flue gas is fully absorbed by the water in the heat exchanger by arranging the primary heat exchanger and the secondary heat exchanger successively along the flow direction of the flue gas, so as to ensure that the gas water heater has high energy efficiency. At the same time, it can also ensure that the discharged flue gas has a lower temperature, achieving the purpose of energy conservation and environmental protection; further, by setting the secondary heat exchanger in the form of a housing with a predetermined volume capable of accommodating water and a heat exchange tube passing through the inner cavity of the housing, wherein the flue gas flowing into the heat exchange tube can exchange heat with the water in the housing, the heat exchange efficiency between the secondary heat exchanger and the flue gas can be further improved, so that the heat in the flue gas can be further absorbed by the water in the heat exchanger, that is, the energy efficiency of the gas water heater is further improved, and at the same time, the temperature of the discharged flue gas can be further reduced.

[0058] In addition, on the basis of the above, a bypass water path is arranged in parallel with the heat exchanger in the gas water heater. By setting the bypass water path, the inner cavity of the housing, the primary heat exchanger and the bypass water path can cooperate to form an internal circulation water path. When the water pump is started, under the action of the water pump, the water in the internal circulation water path can be circulated. By using this internal circulation water path, when the burner is not started, the water temperature inside the gas water heater can be homogenized, and the temperature difference at each position can be controlled within a small fluctuation range, ensuring that the water temperature does not show sudden cold and hot temperature fluctuations when the user uses water again; when the burner is started, the water temperature inside the gas water heater can be raised to the preset temperature required by the user, so that when the user turns on the gas water heater, hot water with a water temperature meeting the requirements can be used, thereby achieving the purpose of improving the user experience from different angles.

[0059] Referring to the following description and drawings, specific embodiments of the present invention are disclosed in detail, indicating the ways in which the principles of the present invention can be adopted. It should be understood that the embodiments of the present invention are not limited thereby in scope. Within the spirit and terms of the appended claims, the embodiments of the present invention include many changes, modifications and equivalents. Features described and / or illustrated for one embodiment can be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or replace features in other embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] The accompanying drawings described herein are for illustrative purposes only and are not intended to limit the scope of the disclosure of the present invention in any way. Additionally, the shapes and proportional dimensions of the components in the figures are only schematic and are used to assist in understanding the present invention, rather than specifically defining the shapes and proportional dimensions of the components of the present invention. Those skilled in the art can, under the teachings of the present invention, select various possible shapes and proportional dimensions according to specific circumstances to implement the present invention.

[0061] Figure 1 It is a schematic structural diagram of a gas water heating device provided in an embodiment of the present application;

[0062] Figure 2 It is a schematic diagram showing the water flow direction in the internal circulation water path of a gas water heating device provided in an embodiment of the present application Figure 1 ;

[0063] Figure 3 It is a schematic diagram showing the water flow direction in the internal circulation water path of a gas water heating device provided in an embodiment of the present application Figure 2 ;

[0064] Figure 4 It is a schematic structural diagram of another gas water heating device provided in an embodiment of the present application;

[0065] Figure 5 It is a schematic structural diagram of yet another gas water heating device provided in an embodiment of the present application;

[0066] Figure 6 It is a schematic structural diagram of yet another gas water heating device provided in an embodiment of the present application;

[0067] Figure 7 It is a schematic diagram of the application scenario of a gas water heating device provided in an embodiment of the present application.

[0068] Reference numerals of the present application:

[0069] 1, Burner;

[0070] 21, Primary heat exchanger;

[0071] 22, Secondary heat exchanger;

[0072] 220, Housing;

[0073] 221, Heat exchange tube;

[0074] 222, Thermal insulation structure;

[0075] 23, Connecting pipe;

[0076] 24, Exhaust pipe;

[0077] 25, Wind guard;

[0078] 3. Fan

[0079] 4. Inlet pipe

[0080] 5. Outlet pipe

[0081] 6. Bypass pipe

[0082] 7. Water pump

[0083] 81. On - off valve

[0084] 82. Three - way valve

[0085] 821. First interface

[0086] 822. Second interface

[0087] 823. Third interface

[0088] 83. Check valve

[0089] 84. Electric water valve

[0090] 91. First temperature sensor

[0091] 92. Second temperature sensor

[0092] 93. Third temperature sensor

[0093] 94. Fourth temperature sensor Detailed implementation manners

[0094] The technical solutions of the present invention will be described in detail below in combination with the accompanying drawings and specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. After reading the present invention, various equivalent modifications made by those skilled in the art to the present invention fall within the scope defined by the appended claims of this application.

[0095] It should be noted that when an element is referred to as being "disposed on" another element, it can be directly on the other element or there can also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used herein are only for the purpose of illustration and do not represent the only implementation manner.

[0096] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terms used in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0097] The present invention provides a gas water heating device and a control method thereof, which can improve the comprehensive user experience while achieving energy conservation and environmental protection.

[0098] Please refer comprehensively to Figures 1 to 6 , in the embodiments of the specification of this application, a gas water heating device is provided, and the gas water heating device may include main components such as a burner 1, a heat exchanger, and a blower 3.

[0099] The water flowing into the heat exchanger exchanges heat with the flue gas generated by the burner 1 and then flows out of the heat exchanger. The heat exchanger includes a primary heat exchanger 21 and a secondary heat exchanger 22, and the primary heat exchanger 21 and the secondary heat exchanger 22 are arranged in sequence along the flow direction of the flue gas. The secondary heat exchanger 22 includes a housing 220 having a predetermined volume for accommodating water and a heat exchange tube 221 passing through the inner cavity of the housing 220. The inside of the heat exchange tube 221 is used for the flue gas to flow through, and the flue gas entering the heat exchange tube 221 exchanges heat with the water accommodated in the inner cavity of the housing 220 through the heat exchange tube 221. The gas water heating device further includes a bypass water path, and the bypass water path is arranged in parallel with the heat exchanger. An internal circulation water path can be formed inside the gas water heating device, and a water pump 7 is arranged in the internal circulation water path. The internal circulation water path includes the inner cavity of the housing 220, the primary heat exchanger 21, and the bypass water path; under the action of the water pump 7, the water in the internal circulation water path can circulate.

[0100] The gas water heating device provided in the embodiments of this application can ensure that the heat in the flue gas is fully absorbed by the water in the heat exchanger by arranging the primary heat exchanger 21 and the secondary heat exchanger 22 in sequence along the flow direction of the flue gas, thereby ensuring that the gas water heating device has high energy efficiency and at the same time can also ensure that the discharged flue gas has a low temperature, achieving the purpose of energy conservation and environmental protection; further, by setting the secondary heat exchanger 22 in the form of a housing 220 having a predetermined volume for accommodating water and a heat exchange tube 221 passing through the inner cavity of the housing 220, wherein the flue gas flowing into the heat exchange tube 221 can exchange heat with the water in the housing 220, the heat exchange efficiency between the secondary heat exchanger 22 and the flue gas can be further improved, so that the heat in the flue gas can be further absorbed by the water in the heat exchanger, that is, the energy efficiency of the gas water heating device is further improved, and at the same time the temperature of the discharged flue gas can be further reduced.

[0101] In addition, on the basis of the above, a bypass water circuit is provided in the gas water heating device in parallel with the heat exchanger. By providing this bypass water circuit, the inner cavity of the housing 220, the primary heat exchanger 21 and the bypass water circuit cooperate to form an internal circulation water circuit. When the water pump 7 is started, under the action of the water pump 7, the water in the internal circulation water circuit can be circulated. By using this internal circulation water circuit, when the burner 1 is not started, the water temperature inside the gas water heating device can be equalized, and the water temperature difference at each position can be controlled within a small fluctuation range, ensuring that the water temperature does not fluctuate suddenly when the user uses water again. When the burner 1 is started, the water temperature inside the gas water heating device can be raised to the preset temperature required by the user, so that when the user turns on the gas water heating device, hot water with a water temperature meeting the requirements can be used, thereby achieving the purpose of improving the user experience from different perspectives.

[0102] The following will describe the present application in detail with specific drawings and embodiments.

[0103] In an embodiment of the present application, the gas water heating device mainly includes: a burner 1, a heat exchanger (a primary heat exchanger 21 and a secondary heat exchanger 22), a blower 3, a water pump 7, a bypass water circuit, etc. In addition, the gas water heating device further includes a water inlet pipe 4 and a water outlet pipe 5 communicated with the heat exchanger. The water flowing through the water inlet pipe 4 flows into the heat exchanger, exchanges heat with the flue gas generated by the burner 1, and then flows out of the heat exchanger and into the water outlet pipe 5.

[0104] Among them, the heat generated by the burner 1 burning gas is used to heat the fluid flowing through the heat exchanger. Specifically, the burner 1 can be in the form of a burner with adjustable power.

[0105] The heat exchanger is used for circulating the water to be heated. The heat exchanger heats the fluid flowing through its interior by the heat generated by the burner 1 burning gas. Generally, the fluid can be water, but it does not exclude that it can also be a mixture of water and steam, or other forms of fluid. In the following embodiments, the fluid is described by taking water as an example, and other fluid forms can be analogously referred to. Specifically, the present application will not elaborate here.

[0106] The heat exchanger may include a primary heat exchanger 21 and a secondary heat exchanger 22. The primary heat exchanger 21 and the secondary heat exchanger 22 are arranged in sequence along the flow direction of the flue gas. Among them, the primary heat exchanger 21 is a heat exchanger relatively closer to the flue gas generation source (burner 1), and it serves as the main heat exchanger of the gas water heating device. The specific form of the primary heat exchanger 21 can be a finned heat exchanger, a plate heat exchanger, a tubular heat exchanger, etc. Of course, the shape, structure, etc. of the primary heat exchanger 21 can be different according to different actual use scenarios, and the present application does not make specific limitations here.

[0107] The secondary heat exchanger 22 can be arranged downstream of the primary heat exchanger 21 along the flue gas flow direction. After most of the high-temperature flue gas generated by the combustion of the burner 1 exchanges heat with the primary heat exchanger 21, it can flow through the secondary heat exchanger 22 and continue to exchange heat with the secondary heat exchanger 22. In an embodiment of the present application, the secondary heat exchanger 22 may include a hollow housing 220 and heat exchange tubes 221 passing through the inner cavity of the housing 220. Among them, the inside of the heat exchange tube 221 is used for the flue gas to flow through. When the flue gas flows through the heat exchange tube 221, it can efficiently exchange heat with the water contained in the inner cavity of the housing 220, and does not occupy too much internal space of the gas water heater.

[0108] In addition, in an embodiment of the present application, an embodiment in which the heat exchange tubes 221 of the secondary heat exchanger 22 do not exchange heat with the water contained in the inner cavity of the housing 220 is not excluded. For example, the heat exchange tubes 221 are only used to pass through the inner cavity of the housing 220 and do not contact the water contained in the inner cavity of the housing 220. Or, the heat exchange tubes 221 may have other cooperation relationships with the housing 220. Furthermore, the secondary heat exchanger 22 may also have other shapes and structures.

[0109] The housing 220 of the secondary heat exchanger 22 has a predetermined volume. The inner cavity of the housing 220 contains water, and the volume of the inner cavity of the housing 220 can be about 1L - 2L. Further, the ratio range of the volume of the heat exchange tubes 221 passing through the inner cavity of the housing 220 to the volume of the inner cavity of the housing 220 can be from 1 / 3 to 1 / 2, so as to ensure that the water of this volume is in full contact with the heat exchange tubes 221, realize the secondary full utilization of the flue gas energy, ensure a high heat exchange efficiency between the flue gas and the water, and at the same time, by reasonably controlling the sizes and ratios of the volumes of the heat exchange tubes 221 and the housing 220, it will not occupy too much internal space of the gas water heater and affect the volume of the gas water heater.

[0110] Among them, the housing 220 can be a hollow water tank structure. The specific shape and structure of the housing 220 can be adaptively set according to the internal space of the gas water heater, etc. The present application does not make specific limitations here. The heat exchange tubes 221 can be in the form of circular flue tubes with a certain diameter. Of course, it is not excluded that the heat exchange tubes 221 have other shapes and structures, and the present application does not make specific limitations here either.

[0111] The inner cavity of the housing 220 is communicated with the primary heat exchanger 21, and the water heated in the inner cavity of the housing 220 and the primary heat exchanger 21 can both be output to the user. Specifically, in the water flow direction, the inner cavity of the housing 220 can be arranged in series or in parallel with the primary heat exchanger 21.

[0112] The gas water heating device may further include a bypass water path, which is arranged in parallel with the heat exchanger. Specifically, the bypass water path may be in the form of a bypass pipe 6. Of course, the bypass water path may also be an internal flow path formed in the water path module, or the bypass water path may have other forms. Specifically, the form of the bypass water path is not uniquely defined in this application.

[0113] In an embodiment of the present application, an internal circulation water path can be formed inside the gas water heating device. The internal circulation water path includes the inner cavity of the housing 220, the primary heat exchanger 21, and the bypass water path. A water pump 7 is arranged in the internal circulation water path. The water pump 7 is used to provide driving force for the water flow. Under the action of the water pump 7, the water in the internal circulation water path can circulate. Among them, the water pump 7 can utilize an existing water pump 7 in the gas water heating device or can be separately arranged.

[0114] For the above form where the internal circulation water path includes the inner cavity of the housing 220, the primary heat exchanger 21, and the bypass water path, both ends of the bypass water path can be respectively connected to both ends of the heat exchanger to form a water path closed loop.

[0115] Further, for the gas water heating device, it may include a water inlet pipe 4 and a water outlet pipe 5 communicated with the heat exchanger. The water flowing through the water inlet pipe 4 flows into the heat exchanger, exchanges heat with the flue gas generated by the burner 1, and then flows out of the heat exchanger and into the water outlet pipe 5.

[0116] Among them, the water inlet pipe 4 can be communicated with an external water source to supply water to be heated to the gas water heating device. The water outlet pipe 5 can be communicated with a user's water using terminal to supply the heated water of the gas water heating device to the water using terminal. In addition, as Figure 6 shown, for a gas water heating device with a zero cold water function, the water inlet pipe 4 and the water outlet pipe 5 can be used as components of the entire zero cold water circulation. In an embodiment of the present application, a part of the water inlet pipe 4 and a part of the water outlet pipe 5 can be used as components of the internal circulation.

[0117] In an embodiment of the present application, mainly taking the bypass water path including the bypass pipe 6 as an example for illustration. One end of the bypass pipe 6 can be connected to the water outlet pipe 5 and the other end of the bypass pipe 6 can be connected to the water inlet pipe 4.

[0118] An internal circulation water path can be formed inside the gas water heating device. The internal circulation water path may include the inner cavity of the housing 220, the primary heat exchanger 21, a part of the water outlet pipe 5, the bypass water path, and a part of the water inlet pipe 4; under the action of the water pump 7, the water in the internal circulation water path can circulate.

[0119] As Figure 2As shown, in some embodiments, in the water flow direction, the inner cavity of the housing 220 is connected in series with the primary heat exchanger 21. Under the action of the water pump 7, the water in the internal circulation water path can circulate through the inner cavity of the housing 220, the primary heat exchanger 21, and the bypass water path in sequence.

[0120] In these embodiments, taking Figure 2 the counterclockwise water flow direction as an example, when the water pump 7 is started, the water flow successively passes through the primary heat exchanger 21, a part of the outlet pipe 5, the bypass pipe 6, a part of the inlet pipe 4, the inner cavity of the housing 220, and returns to the primary heat exchanger 21, forming an internal circulation water path.

[0121] Or, as Figure 3 shown, in the water flow direction, the inner cavity of the housing 220 is connected in series with the primary heat exchanger 21. Under the action of the water pump 7, the water in the internal circulation water path can circulate through the primary heat exchanger 21, the inner cavity of the housing 220, and the bypass water path in sequence.

[0122] In these embodiments, taking Figure 3 the clockwise water flow direction as an example, when the water pump 7 is started, the water flow successively passes through the primary heat exchanger 21, the inner cavity of the housing 220, a part of the inlet pipe 4, the bypass water path, a part of the outlet pipe 5, and returns to the primary heat exchanger 21.

[0123] Or, in some other embodiments, the primary heat exchanger 21 and the inner cavity of the housing 220 are arranged in parallel, and the water flowing into the inlet pipe 4 enters the primary heat exchanger 21 and the inner cavity of the housing 220 respectively and then flows into the outlet pipe 5.

[0124] As Figure 3 shown, in some embodiments, the water pump 7 can be arranged on the outlet pipe 5 and is located upstream of the connection between the bypass pipe 6 and the outlet pipe 5 along the water flow direction. Or, as Figure 2 shown, the water pump 7 can be arranged on the inlet pipe 4 and is located downstream of the connection between the bypass pipe 6 and the inlet pipe 4 along the water flow direction.

[0125] When the water pump 7 is arranged at the above positions, the water pump 7 can provide driving force for the water in the internal circulation water path. In addition, the water pump 7 can also provide driving force for the water in the external circulation water path, and the water pump 7 can also provide driving force for the water flow in the normal water use state of the user.

[0126] In the embodiments of the present application, the on-off of the internal circulation water path can be controlled by setting valve elements.

[0127] As Figure 1As shown, in some embodiments, a switching valve 81 may further be provided on the bypass pipe 6. When the water in the internal circulation water path circulates, the switching valve 81 is in a closed state so that the water in the bypass pipe 6 can flow. When water is used to flow out of the gas water heater from the outlet pipe 5, that is, when the user has a water demand, the switching valve 81 is in an open state so that the water in the bypass pipe 6 does not flow.

[0128] Alternatively, as Figure 2 shown, a three-way valve 82 is provided at the connection between the outlet pipe 5 and the bypass pipe 6. When the water in the internal circulation water path circulates, the three-way valve 82 connects the outlet pipe 5 and the bypass pipe 6.

[0129] In a specific embodiment, a three-way valve 82 is provided at the connection between the outlet pipe 5 and the bypass pipe 6. The three-way valve 82 includes a first interface 821 and a second interface 822 connected to the outlet pipe 5, and a third interface 823 connected to the bypass pipe 6; the first interface 821 is located upstream of the second interface 822; when water is used to flow out of the gas water heater from the outlet pipe 5, the first interface 821 and the second interface 822 are connected; when the water in the internal circulation water path circulates, the first interface 821 and the third interface 823 are connected.

[0130] Alternatively, as Figure 4 shown, a three-way valve 82 is provided at the connection between the inlet pipe 4 and the bypass pipe 6. When the water in the internal circulation water path circulates, the three-way valve 82 connects the bypass pipe 6 and the inlet pipe 4.

[0131] In a specific embodiment, a three-way valve 82 is provided at the connection between the inlet pipe 4 and the bypass pipe 6. The three-way valve 82 includes a first interface 821 and a second interface 822 connected to the inlet pipe 4, and a third interface 823 connected to the bypass pipe 6; the first interface 821 is located upstream of the second interface 822; when water is used to flow into the gas water heater from the inlet pipe 4, the first interface 821 and the second interface 822 are connected; when the water in the internal circulation water path circulates, the second interface 822 and the third interface 823 are connected.

[0132] Please refer to Figure 5 . When the valve element provided in the internal circulation water path is in the form of a three-way valve 82, the three-way valve 82 may specifically be a flow-adjustable three-way valve 82.

[0133] When the valve element is the flow - adjustable three - way valve 82, the flow - adjustable three - way valve 82 can mix the hot water flowing out of the heat exchanger and the cold water flowing in through the bypass pipe 6 in a suitable proportion, so as to directly output water meeting the predetermined temperature requirement to the user, which can prevent the output temperature of the water that has been heated again after passing through the internal circulation water path from being too high. Subsequently, when using water at the terminal, more cold water needs to be mixed in, and the amount of cold water to be mixed is uncertain. Especially when multiple users use water simultaneously, it is easy to cause the phenomenon of unstable water outlet temperature.

[0134] Please refer to Figure 5 , in some embodiments, an electric water valve 84 for adjusting the water flow in the bypass pipe 6 is provided on the bypass pipe 6.

[0135] In this embodiment, by providing the electric water valve 84 on the bypass pipe 6, the water flow rate in the bypass pipe 6 can be adjusted. The electric water valve 84 can specifically be in the form of an electric regulating valve capable of stepless flow regulation. The electric water valve 84 can be electrically connected to the controller and adjust the opening degree of the electric water valve 84 according to the control signal of the controller, so as to realize the flow regulation of the water in the bypass pipe 6. Specifically, the specific form, shape, structure, etc. of the electric water valve 84 are not specifically limited in this application.

[0136] For example, when the water in the internal circulation water path circulates, the electric water valve 84 has a first opening degree to allow the water in the bypass pipe 6 to flow through.

[0137] When the water in the internal circulation water path circulates, since the bypass pipe 6 forms a part of the internal circulation water path, water with a predetermined flow rate will flow through the bypass pipe 6. Among them, by controlling the opening degree of the electric water valve 84, the water flow rate through the bypass pipe 6 can reach the predetermined flow rate. The first opening degree can specifically be the maximum opening degree of the electric water valve 84, or can also be an intermediate opening degree between the maximum opening degree and the minimum opening degree (at this time, the electric water valve 84 is in a completely closed non - over - flow state). Specifically, the value of the first opening degree is not specifically limited in this application.

[0138] When water flows out of the gas water heater from the outlet pipe 5, the electric water valve 84 has a second opening degree smaller than the first opening degree, so that the water in the bypass pipe 6 does not flow, or so that part of the water entering the gas water heater from the inlet pipe 4 flows into the bypass pipe 6 and part flows into the inner cavity of the housing 220 of the secondary heat exchanger 22.

[0139] When water in the gas water heating device flows out from the water outlet pipe 5, the electric water valve 84 has a second opening degree, and the second opening degree can be a relatively small opening degree. Specifically, the second opening degree can be smaller than the first opening degree. For example, when the second opening degree is the minimum opening degree of the electric water valve 84 (at this time, the electric water valve 84 is in a fully closed non-overflow state), the water in the bypass pipe 6 does not flow; or, the second opening degree can be a relatively small opening degree value, so as to generate a relatively large pipe resistance in the bypass pipe 6, so that part of the water entering the gas water heating device from the water inlet pipe 4 flows into the bypass pipe 6, and part flows into the inner cavity of the housing 220 of the secondary heat exchanger 22.

[0140] As Figure 6 shown, a second temperature sensor 92 can be provided on the water outlet pipe 5 of the gas water heating device and upstream of the connection position between the bypass pipe 6 and the water outlet pipe 5, and a fourth temperature sensor 94 can be provided on the water outlet pipe 5 and downstream of the connection position between the bypass pipe 6 and the water outlet pipe 5. Both the second temperature sensor 92 and the fourth temperature sensor 94 can be electrically connected to the controller. Among them, the target water outlet temperature set by the user can be stored in the controller.

[0141] When water in the gas water heating device flows out from the water outlet pipe 5, the opening degree of the electric water valve 84 can be specifically determined based on the water temperature detected by the second temperature sensor 92 and the target water outlet temperature set by the user. In addition, the water temperature signal detected by the fourth temperature sensor 94 can be used to determine whether the water supplied to the user reaches the target water outlet temperature. If the target water outlet temperature is not reached, parameters such as the opening degree of the electric water valve 84 and the combustion load can be adjusted.

[0142] Please refer to Figure 7 together. When the amount of tap water supplied externally is certain and the user uses water at multiple points, cold water needs to be output to different user terminals simultaneously, and also needs to be supplied to the gas water heating device. When the above-mentioned flow adjustable three-way valve 82 is used to ensure stable hot water output on the side of the gas water heating device, the amount of cold water that needs to be mixed in each user terminal can be greatly reduced, and the fluctuation of the amount of cold water mixed in is also within a relatively small controllable range, so as to ensure the stable water outlet temperature at the water using terminal.

[0143] As Figure 3 shown, further, a check valve 83 can be provided on the bypass pipe 6, and the check valve 83 is used to make water flow only unidirectionally from the end of the bypass pipe 6 connected to the water outlet pipe 5 to the end of the bypass pipe 6 connected to the water inlet pipe 4, which can prevent external cold water from entering the inner circulation water path through the bypass pipe 6 during the inner circulation process.

[0144] As Figure 2 or Figure 3or Figure 4 As shown, in some embodiments, the secondary heat exchanger 22 further has a heat insulation structure 222, and the heat insulation structure 222 is used to insulate the inner cavity of the housing 220. By providing this heat insulation structure 222, the water in the inner cavity of the housing 220 can be insulated.

[0145] In a specific embodiment, the heat insulation structure 222 can be a heat insulation layer surrounding the outside of the housing 220. When the heat insulation structure 222 is in the form of a heat insulation layer, the heat insulation layer can surround the outer surface of the housing 220, and the material of the heat insulation layer can be selected from heat-resistant heat insulation materials, such as heat insulation cotton, etc. Among them, the specific material of the heat insulation layer is not specifically limited in this application.

[0146] In another specific embodiment, the heat insulation structure 222 can be a cavity provided outside the housing 220, and the cavity can be formed by the gap between a sleeve provided outside the housing 220 and the housing 220.

[0147] When the heat insulation structure 222 is in the form of a cavity, the heat insulation structure 222 can include a sleeve provided outside the housing 220. After the sleeve is sleeved outside the housing 220, a gap is formed between the sleeve and the housing 220. By using the gap between the sleeve and the housing 220 to form the heat insulation structure 222, the housing 220 and the water inside it can be insulated. When the heat insulation structure 222 is in the above form of a sleeved relationship with the housing 220, a cavity is formed between the outside of the housing 220 and the sleeve, and the cavity outside the housing 220 can be communicated with the heat exchange tube 221. The flue gas flowing out of the heat exchange tube 221 flows into the cavity outside the housing 220 and is then discharged outward through the smoke exhaust pipe 24. On the one hand, the housing 220 and the water in the housing 220 can be insulated, and on the other hand, it is also beneficial to further improve the heat exchange efficiency between the secondary heat exchanger 22 and the flue gas, so that the waste heat in the flue gas can be maximally utilized.

[0148] The fan 3 is used to provide the driving force for the airflow. Specifically, the structure of the fan 3 itself, its installation position and installation method can vary according to different actual use scenarios, and are not specifically limited in this application. For example, the fan 3 can specifically be a variable frequency fan 3. The rotation speed of the fan 3 can adaptively change with changes in conditions such as the combustion load.

[0149] In some embodiments, the primary heat exchanger 21, the fan 3, and the secondary heat exchanger 22 are arranged in sequence along the flow direction of the flue gas, and at least part of the flue gas discharged by the fan 3 can exchange heat with the water in the inner cavity of the housing 220 after entering the heat exchange tube 221.

[0150] Specifically, the fan 3 can be provided with an air inlet and an air outlet. Among them, the air inlet can be opposite to the primary heat exchanger 21, and the air outlet can be communicated with the heat exchange tubes 221 of the secondary heat exchanger 22. Along the flow direction of the flue gas, the primary heat exchanger 21, the fan 3, and the secondary heat exchanger 22 are arranged in sequence. The flue gas generated by the combustion of the burner 1 can first exchange heat with the primary heat exchanger 21. The flue gas after exchanging heat with the primary heat exchanger 21 enters the fan 3, and then enters the heat exchange tubes 221 of the secondary heat exchanger 22 to exchange heat with the water in the housing 220, and finally is discharged outward through the exhaust pipe 24, so as to ensure that the gas water heating device has a high heat exchange efficiency and achieve an ideal energy-saving and environmental protection effect.

[0151] Further, the fan 3 is arranged above the primary heat exchanger 21, and the secondary heat exchanger 22 is arranged obliquely above the primary heat exchanger 21.

[0152] In this embodiment, the gas water heating device can specifically be an up-draft gas water heating device. Among them, the gas water heating device is provided with a housing. As a whole, the burner 1, the primary heat exchanger 21, and the fan 3 are arranged in sequence along the height direction inside the housing. An opening for installing an exhaust port is provided at the top of the housing. Considering the installation positions of the burner 1, the primary heat exchanger 21, and the fan 3, as well as the relative arrangement of the air inlet and air outlet of the fan 3 and the arrangement relationship of the primary heat exchanger 21, the fan 3, and the secondary heat exchanger 22 along the flow direction of the flue gas, the primary heat exchanger 21 can be arranged obliquely above the secondary heat exchanger 22, close to the position where the exhaust port is set. On the one hand, the limited space inside the housing of the gas water heating device can be effectively utilized. On the other hand, the arrangement of the fan 3, the primary heat exchanger 21, and the secondary heat exchanger 22 is also reasonably set according to the flow direction of the flue gas, which is beneficial to the efficient heat exchange between the flue gas and the heat exchanger.

[0153] In some embodiments, the gas water heating device may further include a controller, a first temperature sensor 91 for detecting the water temperature in the inner cavity of the housing 220, a second temperature sensor 92 for detecting the water temperature flowing out of the primary heat exchanger 21, and a third temperature sensor 93 for detecting the water temperature between the inner cavity of the housing 220 and the primary heat exchanger 21. The controller is electrically connected to the first temperature sensor 91, the second temperature sensor 92, and the third temperature sensor 93.

[0154] In this embodiment, in order to obtain the water temperature and temperature difference in the internal circulation water path, a temperature sensor electrically connected to the controller can be set. The controller can judge the water temperature and temperature difference in the internal circulation water path according to the temperature signal obtained by the temperature sensor.

[0155] Specifically, the temperature sensor may include: a first temperature sensor 91 for detecting the water temperature entering the inner cavity of the housing 220, a second temperature sensor 92 for detecting the water temperature flowing out of the first-stage heat exchanger 21, and a third temperature sensor 93 for detecting the water temperature between the inner cavity of the housing 220 and the first-stage heat exchanger 21.

[0156] Among them, the first temperature sensor 91 may be disposed on the water inlet pipe 4, for example, at the position where the water inlet pipe 4 is connected to the bypass pipe 6. The second temperature sensor 92 may be disposed on the connecting pipe 23 between the inner cavity of the housing 220 and the first-stage heat exchanger 21. The third temperature sensor 93 may be disposed on the water outlet pipe 5, for example, at the position where the water outlet pipe 5 is connected to the bypass pipe 6.

[0157] Of course, the number and positions of the temperature sensors are not limited to the above description. Those skilled in the art may make other changes under the inspiration of the technical essence of this application. However, as long as the functions and effects achieved are the same or similar to those of this application, they should all be covered within the protection scope of this application.

[0158] In some embodiments, the gas water heating device may further include a controller and a flow sensor in the internal circulation water path. The controller is electrically connected to the flow sensor.

[0159] In this embodiment, in order to obtain the flow condition in the internal circulation water path, a flow sensor may be set. The flow sensor is electrically connected to the controller. The controller may judge the flow condition in the internal circulation water path according to the flow signal obtained by the flow sensor.

[0160] Based on the gas water heating device provided in the above embodiments, a control method for a gas water heating device is further provided in the embodiments of this application. The control method is applied to any of the above-mentioned gas water heating devices. The gas water heating device has an internal circulation state. The control method includes:

[0161] When the gas water heating device operates in the internal circulation state, control the water pump 7 to work so that the water in the internal circulation water path can circulate through the inner cavity of the housing 220, the first-stage heat exchanger 21, and the bypass water path.

[0162] In the embodiments of this application, the gas water heating device has an internal circulation state. Specifically, the internal circulation state means that under the driving action of the water pump 7, the water in the internal circulation water path of the above-mentioned gas water heating device can circulate.

[0163] For example, when the internal circulation water path includes the inner cavity of the housing 220, the primary heat exchanger 21, and the bypass water path, the water in the internal circulation water path can circulate through the inner cavity of the housing 220, the primary heat exchanger 21, and the bypass water path. Further, when the internal circulation water path further includes a partial water inlet pipe 4 and a partial water outlet pipe 5, the water in the internal circulation water path can circulate through the partial water inlet pipe 4, the inner cavity of the housing 220, the primary heat exchanger 21, the partial water outlet pipe 5, and the bypass water path.

[0164] When the water in the internal circulation circulates, the burner 1 can be started or not started according to different scenarios.

[0165] In some embodiments, when the gas water heater operates in the internal circulation state, the burner 1 can be controlled to be in the working state. When the gas water heater operates in the internal circulation state and the burner 1 is controlled to be in the working state, the water in the internal circulation can be heated.

[0166] Further, when the gas water heater operates in the internal circulation state, after the preset combustion conditions are met, the burner 1 of the gas water heater is controlled to be in the working state.

[0167] Among them, the burner 1 can be started after the preset combustion conditions are met to avoid all or partial overheating of the water in the internal circulation caused by mis-starting of the burner 1.

[0168] Specifically, the preset combustion conditions can include any one or a combination of the following: the water pump 7 works for a preset time; the preset combustion condition can be that the temperature of the water in the internal circulation water path is less than the first preset temperature before the burner 1 is turned on.

[0169] When the preset combustion condition includes that the water pump 7 works for a preset time, the gas water heater is provided with a controller, and the water pump 7 and the burner 1 can be electrically connected to the controller. After the water pump 7 works for the preset time, the controller then controls the burner 1 to start working. Among them, the specific value of the preset time is not specifically limited in this application.

[0170] When the water pump 7 works for a preset time, first, it can ensure the stable flow of water in the internal circulation water circuit. After the water in the internal circulation water circuit flows stably, the burner 1 can be started, which can prevent the burner 1 from heating the local water and causing the problem of overheating. Second, assuming that the water in the internal circulation water circuit has uneven temperature, the water pump 7 can be started first to homogenize the water in the internal circulation water circuit. Generally, when the water in the internal circulation water circuit has uneven temperature, the area with higher temperature occurs in the area of the primary heat exchanger 21. If the water pump 7 is not started first and the burner 1 is directly started, after the burner 1 is started, the area that heats up first is also the area of the primary heat exchanger 21. In this application, by starting the water pump 7 first to homogenize the water in the internal circulation water circuit and then starting the burner 1 after the water in the internal circulation water circuit flows stably, the water in the internal circulation water circuit can be heated evenly, preventing the phenomenon of local overheating.

[0171] When the preset combustion condition includes that the temperature of the water in the internal circulation water circuit is less than the first preset temperature before the burner 1 is turned on, the first preset temperature can be the target outlet water temperature that the user expects to output when the gas water heater is turned on. If the temperature of the water in the internal circulation water circuit does not reach the first preset temperature, the burner 1 can be started to raise the water temperature in the internal circulation water circuit to at least reach the first preset temperature, so that the water temperature that meets the user's needs can be output when starting up.

[0172] Of course, the preset combustion condition is not limited to the above description. Those skilled in the art may make other changes under the inspiration of the technical essence of this application, but as long as the functions and effects achieved are the same or similar to those of this application, they should be covered within the protection scope of this application.

[0173] As Figure 1 shown, in some embodiments, the gas water heater may further include an exhaust pipe 24 for discharging the flue gas after heat exchange with the heat exchanger from the gas water heater, and the exhaust pipe 24 is provided with a wind guard 25; the control method further includes: before the burner 1 is started, the wind guard 25 is in a closed state; after the burner 1 is started, the wind guard 25 is in an open state.

[0174] In this embodiment, the gas water heating device may be provided with an exhaust pipe 24. The exhaust pipe 24 is located at the most downstream along the flue gas flow direction and can be used to discharge the flue gas after heat exchange by the heat exchanger from the gas water heating device. Specifically, the exhaust pipe 24 may be installed at the top of the housing of the gas water heating device. One end of the exhaust pipe 24 may be communicated with the heat exchanger, and the other end of the exhaust pipe 24 extends out of the housing and is connected to the outside. A wind guard 25 may be provided at the end of the exhaust pipe 24 located outside. The wind guard 25 may be electrically connected to the controller. When the burner 1 is in a non-start state, the wind guard 25 is in a closed state to prevent strong external wind from flowing back into the interior of the gas water heating device, causing indoor air pollution. Especially when the environmental temperature is low, the extremely low temperature brought in may freeze and crack the housing 220 containing water, etc. When the burner 1 is in a start state, the wind guard 25 is in an open state to ensure that the exhaust pipe 24 can reliably discharge the flue gas to the outside.

[0175] In some embodiments, when controlling the operation of the water pump 7, the burner 1 is simultaneously controlled to be in an operating state.

[0176] In this embodiment, when controlling the operation of the water pump 7, the burner 1 can be simultaneously controlled to be in an operating state. The above control of the simultaneous operation of the water pump 7 and the burner 1 is particularly applicable to the following situations: when the gas water heating device has not been used for more than a period of time, the water temperature in the internal circulation water path is relatively low, and it is not easy to have problems such as over-temperature of the average water temperature and local over-temperature; or the water temperature at each position in the internal circulation water path is relatively uniform, there is no large temperature difference, and it is not easy to have problems of local over-temperature.

[0177] In some embodiments, the combustion load of the burner 1 in the internal circulation state is a preset load, and the preset load is between 2KW and 20KW.

[0178] In this embodiment, in the internal circulation state, the combustion load of the burner 1 can be between 2 kilowatts and 20 kilowatts. When the volume of the internal circulation water path is determined, the combustion load of the burner 1 can be comprehensively determined according to the inlet water temperature, the set outlet water temperature, the combustion time of the burner 1, and the heat preservation requirement, etc.

[0179] For example, when the inlet water temperature is low in winter and the temperature difference between the set outlet water temperature and the inlet water temperature is large, at this time, it is necessary to achieve the effect of rapid preheating circulation and provide water that meets the set outlet water temperature to the user in a short combustion time. At this time, the burner 1 can operate at a high load.

[0180] When the inlet water temperature is relatively high in summer and the temperature difference between the set outlet water temperature and the inlet water temperature is small, the burner 1 can operate at a low load, that is, it can provide water that meets the set outlet water temperature to the user within a short combustion time. At this time, the noise generated by the operation of the burner 1 is relatively low, which is conducive to ensuring the user experience.

[0181] In some embodiments, after the preset stop condition is satisfied, the burner 1 is controlled to stop working, or both the burner 1 and the water pump 7 are controlled to stop working.

[0182] In this embodiment, after the gas water heating device reaches the preset stop condition, it means that the water in the current internal circulation does not need to be further circulated and heated. At this time, the burner 1 can be controlled to stop working, and then the water pump 7 stops working; or, both the burner 1 and the water pump 7 are controlled to stop working.

[0183] Wherein, the preset stop condition may include any one or a combination of the following: the burner 1 works for a preset duration, and the water temperature between the primary heat exchanger 21 and the secondary heat exchanger 22 reaches a second preset temperature.

[0184] For example, when the preset stop condition includes that the burner 1 works for a preset duration, after the burner 1 works for the preset duration, the increased temperature of the water in the current internal circulation water path can be determined. According to the increased temperature of the water in the internal circulation water path and the water temperature in the internal circulation water path before starting the burner 1, the water temperature in the current internal circulation water path can be determined. This water temperature can be compared with a preset target temperature. If the water temperature in the current internal circulation water path reaches the preset target temperature, the burner 1 can be controlled to stop working. The preset target temperature can be the outlet water temperature set by the user or a preset temperature stored in the controller.

[0185] Or, the preset stop condition may include: the water temperature between the primary heat exchanger 21 and the secondary heat exchanger 22 reaches a second preset temperature. Since in the entire internal circulation water path, the water in the primary heat exchanger 21 can be heated by the burner 1 first, the water temperature in the primary heat exchanger 21 is relatively high. And it is located at the position where the water temperature in the internal circulation water path is relatively the lowest. Taking the connecting pipe 23 between the primary heat exchanger 21 and the secondary heat exchanger 22 shown as an example, Figure 2 assuming that the water temperature between the primary heat exchanger 21 and the secondary heat exchanger 22 has reached the second preset temperature, which is generally less than but relatively close to the first preset temperature, that is, close to the target outlet water temperature set by the user, it can indicate that the average water temperature of the entire internal circulation water path has been able to reach the first preset temperature. At this time, if the burner 1 stops burning and the water pump 7 is maintained for a certain period of time, the water temperature in the entire internal circulation water path can reach the first preset temperature.

[0186] Of course, in the embodiments of the present application, the preset temperature, such as the first preset temperature, the second preset temperature, etc., can specifically be a fluctuating value within a range. Moreover, the specific numerical range can vary slightly according to different factors such as actual user requirements and the internal structure of the gas water heating device. The present application does not make specific limitations here.

[0187] Furthermore, the preset duration for the burner 1 to operate can be determined according to the working load of the burner 1, the water temperature of the internal circulation water path when the burner 1 starts, and the user-set temperature.

[0188] Since the volume in the entire internal circulation water path is constant, when the water temperature of the internal circulation water path and the user-set temperature are known conditions, the preset duration for the burner 1 to operate can be determined according to the working load of the burner 1 without considering the volume (mass) parameter of the water.

[0189] In some other embodiments, when the gas water heating device operates in the internal circulation state, the burner 1 is controlled to be in a non-operating state.

[0190] In these embodiments, when the gas water heating device operates in the internal circulation state, the burner 1 is controlled to be in a non-operating state, that is, only the water pump 7 is kept in an operating state, so that the water in the internal circulation water path circulates, thereby making the water temperature at each position in the internal circulation water path uniform, and there will be no situation where the temperature difference at different positions is large. For example, when the user pauses using hot water and uses water again within a short period of time, since the internal circulation water path inside the gas water heating device equalizes the water temperature, there will be no phenomenon of sudden cold and sudden heat.

[0191] In the embodiments of the present application, the gas water heating device has a kitchen water use mode and a normal water use mode. Among them, in both the kitchen water use mode and the normal water use mode, the gas water heating device can enter the internal circulation state.

[0192] In this kitchen water use mode, when starting the internal circulation, the burner 1 starts, thereby heating the water in the internal circulation water path to make the water in the internal circulation water path reach the preset target outlet water temperature. In the normal water use mode, the burner 1 can start working or not. When the burner 1 does not start working in the normal water use mode, only the water pump 7 can be used to work to circulate the water in the internal circulation water path, so that the water temperature difference in the internal circulation water path is controlled within a small range.

[0193] For example, in some embodiments, when the gas water heating device is in the normal water use mode and a signal that the user shuts off the hot water use is obtained, the gas water heating device is controlled to enter the internal circulation state.

[0194] When the gas water heating device is in the normal water use mode, during the water use process by the user, there may be operations to temporarily cut off the hot water supply. For example, when taking a shower, the user may temporarily cut off the water supply to use bath products and then turn on the water supply again. Another example is that in winter, when the user is hand-washing clothes or other items, during the entire cleaning process, it may be necessary to perform the operations of temporarily cutting off the hot water supply and then turning it on multiple times. Or there may be other scenarios where the hot water supply needs to be temporarily cut off. After temporarily cutting off the hot water supply, if the water inside the housing of the gas water heating device does not circulate, it is likely to cause the water temperature near the primary heat exchanger 21 to be too high, and the water temperature far from the primary heat exchanger 21 to be too low in the water flow direction. When discharging water, when outputting this section of the water path with uneven temperature to the user, it is likely to cause the problem of uneven hot and cold water output temperature at the user terminal, thus affecting the user experience.

[0195] In the present application, in the normal water use mode, when a signal indicating that the user cuts off the hot water supply is obtained, the gas water heating device can be controlled to enter the internal circulation state, and the water in the internal circulation water path is circulated under the drive of the water pump 7, so that the water temperature in the internal circulation water path is uniform, and the temperature difference is controlled within a small range, avoiding the problem of large fluctuations in the water output temperature when the user temporarily hangs up the hot water supply and then turns on the water supply again.

[0196] Further, when the gas water heating device is in the normal water use mode and in the internal circulation state, when the gas water heating device receives one of the following signals, it controls the gas water heating device to stop the internal circulation.

[0197] When the water temperature of the internal circulation water path is greater than or equal to the third preset temperature;

[0198] When the temperature difference between two predetermined positions in the internal circulation water path is within the first preset temperature difference range;

[0199] Within the first predetermined time after the user cuts off the water supply, when the gas water heating device obtains a signal that the user uses hot water again.

[0200] In this embodiment, when the gas water heating device is in the normal water use mode and in the internal circulation state, it can stop the internal circulation when the water temperature of the internal circulation water path reaches the third preset temperature, or when the temperature difference between two predetermined positions in the internal circulation water path is within the first preset temperature difference range, or when a water use signal indicating that the user uses hot water again is obtained within the first predetermined time after the user cuts off the water supply.

[0201] Of course, when the gas water heating device is in the normal water use mode and in the internal circulation state, the specific conditions for stopping the internal circulation can also be other conditions, not limited to the above description. Those skilled in the art may make other changes under the inspiration of the technical essence of this application. However, as long as the functions and effects achieved are the same as or similar to those of this application, they should all be covered by the protection scope of this application.

[0202] Among them, in the normal water use mode, taking the non-starting of the burner 1 as an example for illustration, assume that the target water outlet temperature set by the user is A. When the user pauses using water, the gas water heating device enters the internal circulation state. After internal circulation for a period of time, the water temperature in the internal circulation water path tends to the third preset temperature, that is, the average temperature of the internal circulation water path, such as A - X. If the water temperature at the theoretically lowest temperature position in this internal circulation water path reaches or approaches this average temperature, it can indicate that the water temperature in the current internal circulation water path has become uniform, and the temperature difference between any two positions is within a small range. Among them, taking Figure 2 as an example, before entering the internal circulation state, the temperature at the first heat exchanger is relatively high, and the temperature at the connecting pipe 23 between the first heat exchanger and the housing 220 is relatively low. When making a judgment, the water temperature at the connecting pipe 23 can be checked. When the water temperature at this place reaches the third preset temperature, it indicates that the water temperature in the current internal circulation water path has become uniform and the temperature difference is small.

[0203] Among them, the temperatures at the two predetermined positions are the water temperature between the primary heat exchanger 21 and the secondary heat exchanger 22 and the water temperature inside the housing 220 cavity, or the water temperature between the primary heat exchanger 21 and the secondary heat exchanger 22 and the water temperature of the bypass water path, or the water temperature inside the housing 220 cavity and the water temperature of the bypass water path.

[0204] In this embodiment, two completely adjacent and / or non-heat-exchanging positions in the internal circulation water path need to be excluded. Except for the above situations, as long as there is a temperature difference between any two positions in the internal circulation water path, they can be selected as the predetermined positions.

[0205] For example, these two predetermined positions can be respectively between the primary heat exchanger 21 and the secondary heat exchanger 22 and inside the housing 220 cavity, between the primary heat exchanger 21 and the secondary heat exchanger 22 and the bypass water path, inside the housing 220 cavity and the bypass water path. Of course, the above two predetermined positions are only an example, and they can also be selected accordingly according to different structures and the like in the internal circulation water path. This application does not make specific limitations here.

[0206] When the temperature difference between the water temperatures at two predetermined positions is within the first preset temperature difference range, it can indicate that the water temperature in the internal circulation water path is uniform. Herein, the specific value of the first preset temperature difference range is not specifically limited in this application, and the first preset temperature difference range can be set according to the user's perceived needs. For example, when the temperature difference between two predetermined positions is within the first preset temperature difference range, when the user uses water again, the water temperature fluctuation output by the gas water heater is within the first preset temperature difference range, and the user can accept it perceptually without obvious hot and cold experiences.

[0207] In addition, within the first predetermined time after the user shuts off the water supply, when the gas water heater receives a signal that the user uses hot water again, it indicates that the user currently has a water usage demand, and at this time, the internal circulation can be stopped. Herein, the first predetermined time can be comprehensively determined in combination with the user's water usage habits, etc., and a reasonable duration is set. Within this duration, it is possible that the user will use water again. After exceeding this duration, the user has currently completed using water. The specific value of the first predetermined time is not specifically limited in this application either, and it can be a relatively short duration, such as within 10 minutes, etc.

[0208] In some embodiments, when the gas water heater is in the kitchen water usage mode, when the preset entry condition is met, the gas water heater is controlled to enter the internal circulation state. The preset entry condition includes: the water temperature of the internal circulation water path or the water temperature at a predetermined position of the internal circulation water path is lower than or equal to the fourth preset temperature.

[0209] In this embodiment, the gas water heater can be provided with a kitchen water usage mode. The kitchen water usage mode can be entered by the user on demand or on time after operating the APP. Of course, the kitchen water usage mode can also be automatically entered by the controller by learning the user's water usage habits. In addition, a corresponding operation part can be set on the control panel of the gas water heater. When the user operates the operation part, the kitchen water usage mode can be entered.

[0210] Among them, in the kitchen water usage mode, when the preset entry condition is met, the gas water heater enters the internal circulation state. When the gas water heater is operating in the internal circulation state, the water pump 7 can be controlled to be in the operating state, and the burner 1 is in the working state.

[0211] Among them, the preset entry condition may include the water temperature condition in the internal circulation waterway. For example, when the water temperature in the internal circulation waterway or the water temperature at a predetermined position in the internal circulation waterway is lower than or equal to the fourth preset temperature, it indicates that the water temperature in the current internal circulation waterway is too low, and the burner 1 needs to be started for heating to reach the set outlet water temperature in the kitchen water use mode. Among them, the water temperature in the internal circulation waterway may be the average water temperature in the internal circulation waterway. When specifically detecting the water temperature, the water pump 7 can be started first to circulate the water in the internal circulation waterway to equalize the water temperature, and then the temperature at any position can be detected later, which can represent the water temperature in the internal circulation waterway. In addition, according to the characteristics of the water temperature distribution in the internal circulation waterway, the water temperature at a relatively high temperature position can be detected. For example, the water temperature of the primary heat exchanger 21 or the position downstream of the primary heat exchanger 21 can be detected. If the water temperature at the above-mentioned predetermined position is also lower than the fourth preset temperature, it indicates that the water temperature in the current internal circulation waterway is on the low side and the burner 1 needs to be started for heating.

[0212] Among them, the fourth preset temperature may be the set outlet water temperature in the kitchen water use mode or the set outlet water temperature in the kitchen water use mode minus the first difference.

[0213] When the fourth preset temperature is the set outlet water temperature in the kitchen water use mode, this temperature can be pre-stored in the controller and can be adjusted according to the actual needs of the user later. Specifically, the value of the preset outlet water temperature is not uniquely limited in this application. In addition, in order to prevent the gas water heater from frequently entering the internal circulation state and frequently starting the burner 1 to work in the kitchen water use mode, the fourth preset temperature can be set to the set outlet water temperature in the kitchen water use mode minus the first difference. The first difference can be comprehensively determined according to the user's body feeling temperature range, the load of the burner 1, the inlet water temperature, etc. Specifically, the value of it is not uniquely limited in this application either.

[0214] Furthermore, when the gas water heater is in the kitchen water use mode and in the internal circulation state, when the gas water heater receives one of the following signals, it controls the gas water heater to stop the internal circulation.

[0215] When the water temperature of the internal circulation waterway is greater than or equal to the fifth preset temperature;

[0216] When the temperature difference between two predetermined positions in the internal circulation waterway is within the second preset temperature difference range;

[0217] When the gas water heater obtains a signal that the user turns on the hot water use.

[0218] In this embodiment, when the gas water heater is in the kitchen water use mode and in the internal circulation state, the internal circulation can be stopped when the water temperature in the internal circulation water circuit reaches the fifth preset temperature, or when the temperature difference between two predetermined positions in the internal circulation water circuit is within the range of the second preset temperature difference, or when a signal to start using hot water is issued by the user when using hot water again, the internal circulation is stopped.

[0219] Of course, when the gas water heater is in the kitchen water use mode and in the internal circulation state, the specific conditions for stopping the internal circulation can also be other conditions, not limited to the above description. Those skilled in the art may make other changes under the inspiration of the technical essence of this application, but as long as the functions and effects achieved are the same or similar to those of this application, they should all be covered by the protection scope of this application.

[0220] Among them, when the conditions for stopping the internal circulation include: when the water temperature in the internal circulation water circuit is greater than or equal to the fifth preset temperature, the fifth preset temperature can be the set outlet water temperature in the kitchen water use mode or the set outlet water temperature in the kitchen water use mode plus the second difference.

[0221] For the kitchen water use mode, it can be set with an outlet water temperature. Before the water in the internal circulation water circuit is heated by the burner 1 to this set outlet water temperature, the gas water heater continuously maintains the internal circulation state. When this set outlet water temperature is reached, the gas water heater can exit the internal circulation state, that is, stop the internal circulation.

[0222] Considering the actual water use situation of the user, for example, when the water in the gas water heater is heated to the set outlet water temperature, the user may not use the water immediately at this time. Although the water heated to the set outlet water temperature can be insulated by the insulation structure 222, there may inevitably be a certain temperature drop. When the fifth preset temperature is the set outlet water temperature plus the second difference, the temperature drop generated before the user uses the water can be compensated. The specific value of this second difference is not specifically limited in this application either.

[0223] In addition, it is also considered that when the three-way valve 82 in the gas water heater is a flow-adjustable three-way valve 82, when the water temperature in the internal circulation water circuit is slightly higher, for example, higher than the set outlet water temperature, and the user uses water immediately after the gas water heater stops the internal circulation, a small amount of cold water can be mixed into the hot water through this adjustable three-way valve 82, so that the water temperature output by the gas water heater meets the set outlet water temperature.

[0224] In this embodiment, when the gas water heater is in the kitchen water use mode and in the internal circulation state, the temperatures at the two predetermined positions detected can specifically be the water temperature between the primary heat exchanger 21 and the secondary heat exchanger 22 and the water temperature inside the cavity of the housing 220, or the water temperature between the primary heat exchanger 21 and the secondary heat exchanger 22 and the water temperature of the bypass water path, or the water temperature inside the cavity of the housing 220 and the water temperature of the bypass water path. Among them, the selection principle of the above two predetermined positions can refer to the specific description of the gas water heater in the normal water use mode and in the internal circulation state, which will not be elaborated in this application.

[0225] When an internal circulation water path is established in the gas water heater and it can enter the internal circulation state, in different scenarios, it can solve different technical problems.

[0226] For example, in the first scenario, for a scenario where the water use point is close to the gas water heater, taking the kitchen as an example, the user hopes that when water is needed, turning on the gas water heater will immediately output water that meets the preset temperature requirement.

[0227] The gas water heater provided in this application has a kitchen water use mode, and this kitchen water use mode can be equivalent to the gas water heater having a preheating function for the water in the internal circulation water path.

[0228] In the kitchen water use mode, it can enter the internal circulation state. After starting the water pump 7 to form an internal circulation water path and starting the burner 1, the water in the internal circulation state can be heated to the preset temperature. When the user needs water, opening the water use point, water that meets the temperature requirement can be output to the user.

[0229] Considering the common situation of short-term and small-volume water use in kitchen water use, after the preheating step of the kitchen water use mode is completed, the water reaching the preset temperature in the internal circulation water circuit can meet the hot water use demand of a certain amount of water for users. In particular, the gas water heater provided in the embodiment of the present application is provided with a secondary heat exchanger 22. The secondary heat exchanger 22 is provided with a housing 220 of a predetermined volume, and the heat exchange tube 221 passes through the housing 220. The water in the housing 220 also reaches the preset temperature after the preheating step is completed. The above structure makes the gas water heater provided in the present application have a larger water supply capacity compared with the existing gas water heaters. After the gas water heater is preheated, it can provide more hot water to users, so as to ensure that the demand for short-term and small-volume water use of users can be met before the burner 1 is not started, and thus the frequent ignition and start of the burner 1 of the gas water heater can be avoided. This not only helps to extend the service life of the gas water heater, but also can avoid the noise generated by the frequent start of the gas water heater and the problems such as the relatively concentrated heating position and uneven heating water temperature, which is beneficial to improving the comprehensive use experience of users. In addition, since the heat exchange tube 221 passes through the housing 220 to exchange heat with the water in the housing 220, the heat exchange efficiency between the secondary heat exchanger 22 and the flue gas can be further improved, so that the heat in the flue gas can be further absorbed by the water in the heat exchanger, that is, the energy efficiency of the gas water heater is further improved, achieving the purpose of energy conservation and environmental protection.

[0230] When the preheating step of the kitchen water use mode is completed, the user may need to use water. Here, it should be noted that the user's water use location can be in the kitchen near the installation location of the gas water heater, or it can be other locations, such as the balcony, the bathroom, etc. When the user is using water, if it is detected that the outlet water temperature has dropped by a predetermined temperature based on the preset temperature, or the difference in the outlet water temperature reaches a predetermined temperature difference, the burner 1 can be started at this time for ignition heating.

[0231] For example, in the second scenario, when the gas water heater is in the normal water use mode and the user is using water, the burner 1 in the gas water heater will start and burn normally.

[0232] Subsequently, if the user pauses using water during the water use process, the internal circulation can be started at this time, at least making the water pump 7 enter the working state to circulate the water in the internal circulation water circuit, so that the water temperature in the internal circulation water circuit is uniform.

[0233] When the subsequent user turns on the water-using terminal again to use water, since the water temperature in the internal circulation waterway is uniform, the user will not experience the situation of sudden cold and sudden heat at the beginning of continuous water use. In addition, after the water temperature in the internal circulation waterway reaches a stable and uniform state, if it is detected that the water temperature in the internal circulation waterway is relatively low during the process of the user pausing water use, the burner 1 can also be started to heat the water in the internal circulation waterway to make it reach the preset temperature. Of course, during the internal circulation process, if the signal that the user turns on hot water use is obtained again, the internal circulation can be exited.

[0234] It should be noted that in the description of the present application, the terms "first", "second", etc. are only used for descriptive purposes and to distinguish similar objects, and there is no sequence between them, nor can it be understood as indicating or implying relative importance. In addition, in the description of the present application, unless otherwise specified, the meaning of "a plurality" is two or more.

[0235] The above various embodiments in this specification are all described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments.

[0236] The above are only several embodiments of the present invention. Although the disclosed embodiments of the present invention are as above, the content is only an embodiment adopted for the convenience of understanding the present invention and is not used to limit the present invention. Any person skilled in the art in the technical field to which the present invention pertains, without departing from the spirit and scope disclosed by the present invention, can make any modifications and changes in the form and details of the embodiments, but the patent protection scope of the present invention shall still be subject to the scope defined by the appended claims.

Claims

1. A gas water heating device, characterized in that, The gas water heating device includes: a burner, a heat exchanger, and a blower. The water flowing into the heat exchanger exchanges heat with the flue gas generated by the burner and then flows out of the heat exchanger. The heat exchanger includes a primary heat exchanger and a secondary heat exchanger, and the primary heat exchanger and the secondary heat exchanger are arranged in sequence along the flow direction of the flue gas. The secondary heat exchanger includes a housing capable of accommodating water with a predetermined volume and heat exchange tubes passing through the inner cavity of the housing. The inside of the heat exchange tubes is used for the flow of flue gas, and the flue gas entering the heat exchange tubes exchanges heat with the water accommodated in the inner cavity of the housing through the heat exchange tubes. The gas water heating device further includes a bypass water path, and the bypass water path is arranged in parallel with the heat exchanger. An internal circulation water path can be formed inside the gas water heating device. A water pump is provided in the internal circulation water path. The internal circulation water path includes the inner cavity of the housing, the primary heat exchanger, and the bypass water path. Under the action of the water pump, the water in the internal circulation water path can circulate.

2. The gas water heating device according to claim 1, characterized in that, The secondary heat exchanger further has a heat preservation structure, and the heat preservation structure is used for heat preservation of the inner cavity of the housing.

3. The gas water heating device according to claim 2, wherein The heat preservation structure is a heat preservation layer arranged around the outside of the housing.

4. The gas water heating device according to claim 2, wherein The heat preservation structure is a cavity arranged outside the housing, and the cavity is formed by the gap between a casing arranged outside the housing and the housing.

5. The gas water heating device according to claim 4, wherein The cavity outside the housing is communicated with the heat exchange tubes, and the flue gas flowing out of the heat exchange tubes flows into the cavity outside the housing.

6. The gas water heating device according to claim 1, wherein, In the water flow direction, the inner cavity of the housing and the primary heat exchanger are arranged in series or in parallel.

7. The gas water heating device according to claim 1, characterized in that, The gas water heating device further includes a water inlet pipe and a water outlet pipe communicated with the heat exchanger. The water flowing through the water inlet pipe flows into the heat exchanger, exchanges heat with the flue gas generated by the burner, then flows out of the heat exchanger and into the water outlet pipe. The bypass water path includes a bypass pipe, one end of the bypass pipe is connected to the water outlet pipe, and the other end of the bypass pipe is connected to the water inlet pipe.

8. The gas water heating device according to claim 6, characterized in that, In the water flow direction, the inner cavity of the housing and the primary heat exchanger are connected in series. Under the action of the water pump, the water in the internal circulation water path can sequentially circulate through the inner cavity of the housing, the primary heat exchanger, and the bypass water path.

9. The gas water heating device according to claim 6, characterized in that, In the water flow direction, the inner cavity of the housing and the primary heat exchanger are connected in series. Under the action of the water pump, the water in the internal circulation water path can sequentially circulate through the primary heat exchanger, the inner cavity of the housing, and the bypass water path.

10. The gas water heating device according to claim 7, wherein the water pump is arranged on the water outlet pipe and is located upstream of the connection between the bypass pipe and the water outlet pipe along the water flow direction, or the water pump is arranged on the water inlet pipe and is located downstream of the connection between the bypass pipe and the water inlet pipe along the water flow direction.

11. The gas water heating device according to claim 7, wherein a switching valve is further arranged on the bypass pipe. When the water in the internal circulation water path circulates, the switching valve is in a closed state so that the water in the bypass pipe can circulate. Alternatively, a three-way valve is provided at the connection between the outlet pipe and the bypass pipe. When the water in the internal circulation water path circulates, the three-way valve connects the outlet pipe and the bypass pipe. Alternatively, a three-way valve is provided at the connection between the inlet pipe and the bypass pipe. When the water in the internal circulation water path circulates, the three-way valve connects the bypass pipe and the inlet pipe.

12. The gas water heating device according to claim 11, characterized in that, The three-way valve is a flow-adjustable three-way valve.

13. The gas water heating device according to claim 11, wherein, A switch valve is provided on the bypass pipe. When water flows out of the gas water heater from the outlet pipe, the switch valve is in an off state so that the water in the bypass pipe does not flow.

14. The gas water heating device according to claim 10, wherein, An electric water valve for adjusting the flow rate of the water in the bypass pipe is provided on the bypass pipe.

15. The gas water heating device according to claim 14, characterized in that, When the water in the internal circulation water path circulates, the electric water valve has a first opening degree so that the water in the bypass pipe circulates.

16. The gas water heating device according to claim 15, wherein, When water flows out of the gas water heater from the outlet pipe, the electric water valve has a second opening degree smaller than the first opening degree so that the water in the bypass pipe does not flow, or so that part of the water entering the gas water heater from the inlet pipe flows into the bypass pipe and part flows into the inner cavity of the secondary heat exchanger.

17. The gas water heating device according to claim 15, wherein, When water flows out of the gas water heater from the outlet pipe, the electric water valve has a second opening degree so that the water in the bypass pipe does not flow, or so that part of the water entering the gas water heater from the inlet pipe flows into the bypass pipe and part flows into the inner cavity of the secondary heat exchanger.

18. The gas water heating device according to claim 11, characterized in that, A three-way valve is provided at the connection between the outlet pipe and the bypass pipe. The three-way valve includes a first interface and a second interface connected to the outlet pipe, and a third interface connected to the bypass pipe; the first interface is located upstream of the second interface. When water flows out of the gas water heater from the outlet pipe, the first interface and the second interface are connected; when the water in the internal circulation water path circulates, the first interface and the third interface are connected.

19. The gas water heating device according to claim 11, wherein, A three-way valve is provided at the connection between the inlet pipe and the bypass pipe. The three-way valve includes a first interface and a second interface connected to the inlet pipe, and a third interface connected to the bypass pipe; the first interface is located upstream of the second interface. When water flows into the gas water heater from the inlet pipe, the first interface and the second interface are connected; when the water in the internal circulation water path circulates, the second interface and the third interface are connected.

20. The gas water heating device according to claim 11, characterized in that, A one-way valve is provided on the bypass pipe. The one-way valve is used to make water flow unidirectionally only from the end of the bypass pipe connected to the outlet pipe to the end of the bypass pipe connected to the inlet pipe.

21. The gas water heating device according to claim 1, wherein The primary heat exchanger, the blower, and the secondary heat exchanger are arranged in sequence along the flow direction of the flue gas. At least part of the flue gas discharged by the blower can exchange heat with the water in the inner cavity of the shell after entering the heat exchange tube.

22. The gas water heating device according to claim 21, wherein The blower is arranged above the primary heat exchanger, and the secondary heat exchanger is arranged obliquely above the primary heat exchanger.

23. The gas water heater according to claim 1, wherein The ratio of the volume of the heat exchange tubes passing through the inner cavity of the shell to the volume of the inner cavity of the shell ranges from 1 / 3 to 1 / 2.

24. The gas water heating device according to any one of claims 7-9, characterized in that, The gas water heating device further includes a controller, a first temperature sensor for detecting the water temperature entering the inner cavity of the shell, a second temperature sensor for detecting the water temperature flowing out of the first-stage heat exchanger, and a third temperature sensor for detecting the water temperature between the inner cavity of the shell and the first-stage heat exchanger. The controller is electrically connected to the first temperature sensor, the second temperature sensor, and the third temperature sensor.

25. The gas water heating device according to any one of claims 7-9, characterized in that, The gas water heating device further includes a controller and a flow sensor in the internal circulation water path. The controller is electrically connected to the flow sensor.

26. The gas water heating device according to claim 6, wherein, The first-stage heat exchanger and the inner cavity of the shell are arranged in parallel. The water flowing into the water inlet pipe enters the first-stage heat exchanger and the inner cavity of the shell respectively and then flows into the water outlet pipe.

27. A control method for a gas water heating device, characterized in that The control method is applied to the gas water heating device according to any one of claims 1 to 26. The gas water heating device has an internal circulation state. The control method includes: When the gas water heating device operates in the internal circulation state, control the water pump to work so that the water in the internal circulation water path can circulate through the inner cavity of the shell, the first-stage heat exchanger, and the bypass water path.

28. The control method according to claim 27, wherein When the gas water heating device operates in the internal circulation state, control the burner to be in the working state.

29. The control method according to claim 28, characterized in that, When the gas water heating device operates in the internal circulation state, when the preset combustion condition is satisfied, control the burner of the gas water heating device to be in the working state.

30. The control method according to claim 29, wherein, The preset combustion condition is that the water pump works for a preset time; Or, the preset combustion condition is that the temperature of the water in the internal circulation water path is less than the first preset temperature before the burner is turned on.

31. The control method according to claim 29, wherein The gas water heating device further includes a smoke exhaust pipe for exhausting the flue gas heat-exchanged with the heat exchanger from the gas water heating device. The smoke exhaust pipe is provided with a windproof cap. The control method further includes: Before the burner is started, the windproof cap is in the closed state; After the burner is started, the windproof cap is in the open state.

32. The control method according to claim 28, wherein When controlling the water pump to work, simultaneously control the burner to be in the working state.

33. The control method according to claim 28, wherein The combustion load of the burner in the internal circulation state is a preset load, and the preset load is between 2KW and 20KW.

34. The control method according to claim 28, characterized in that, When the preset stop condition is satisfied, control the burner to stop working, or control both the burner and the water pump to stop working.

35. The control method according to claim 34, characterized in that, The preset stop condition includes that the burner works for a preset duration, or the water temperature between the first-stage heat exchanger and the second-stage heat exchanger reaches the second preset temperature.

36. The control method according to claim 35, wherein The preset duration of the burner working is determined according to the working load of the burner, the water temperature of the internal circulation water path when the burner is started, and the user-set temperature.

37. The control method according to claim 27, wherein When the gas water heating device operates in the internal circulation state, control the burner to be in the non-working state.

38. The control method according to claim 27, wherein The gas water heating device has a kitchen water use mode and a normal water use mode.

39. The control method according to claim 38, characterized in that, When the gas water heating device is in the normal water use mode, after receiving the signal that the user turns off the hot water use, control the gas water heating device to enter the internal circulation state.

40. The control method according to claim 39, wherein When the gas water heating device is in the normal water use mode and in the internal circulation state, when the gas water heating device receives one of the following signals, control the gas water heating device to stop the internal circulation. When the water temperature of the internal circulation water path is greater than or equal to the third preset temperature; When the temperature difference between two predetermined positions in the internal circulation water path is within the first preset temperature difference range; Within the first predetermined time after the user turns off the water use, when the gas water heating device receives the signal that the user uses hot water again.

41. The control method according to claim 40, wherein, The temperatures of the two predetermined positions are the water temperature between the primary heat exchanger and the secondary heat exchanger and the water temperature of the inner cavity of the housing, or the water temperature between the primary heat exchanger and the secondary heat exchanger and the water temperature of the bypass water path, or the water temperature of the inner cavity of the housing and the water temperature of the bypass water path.

42. The control method according to claim 38, wherein, When the gas water heating device is in the kitchen water use mode, when the preset entry conditions are met, control the gas water heating device to enter the internal circulation state, and the preset entry conditions include: the water temperature of the internal circulation water path or the water temperature of a predetermined position in the internal circulation water path is lower than or equal to the fourth preset temperature.

43. The control method according to claim 42, characterized in that, The fourth preset temperature is the set outlet water temperature of the kitchen water use mode or the set outlet water temperature of the kitchen water use mode minus the first difference.

44. The control method according to claim 42, wherein, When the gas water heating device is operating in the internal circulation state, control the water pump to be in the operating state and the burner to be in the working state.

45. The control method according to claim 42, characterized in that, When the gas water heating device is in the kitchen water use mode and in the internal circulation state, when the gas water heating device receives one of the following signals, control the gas water heating device to stop the internal circulation. When the water temperature of the internal circulation water path is greater than or equal to the fifth preset temperature; When the temperature difference between two predetermined positions in the internal circulation water path is within the second preset temperature difference range; When the gas water heating device receives the signal that the user turns on the hot water use.

46. The control method according to claim 45, wherein The fifth preset temperature is the set outlet water temperature of the kitchen water use mode or the set outlet water temperature of the kitchen water use mode plus the second difference.

47. The control method according to claim 45, wherein The temperatures of the two predetermined positions are the water temperature between the primary heat exchanger and the secondary heat exchanger and the water temperature of the inner cavity of the housing, or the water temperature between the primary heat exchanger and the secondary heat exchanger and the water temperature of the bypass water path, or the water temperature of the inner cavity of the housing and the water temperature of the bypass water path.

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