Gas water heater and operation method thereof

Abstract

The invention discloses a gas water heater and an operation method thereof. The gas water heater comprises a shell, a heat exchanger, a heat exchange pipe, a water inlet pipe, a water outlet pipe, a water pump, a water flow sensing device, a water inlet temperature probe, a gas control valve, a bypass pipe and a bypass control valve. The first end of the bypass pipe is connected with the water inlet end of the water inlet pipe, the second end of the bypass pipe is connected with the water outlet end of the water outlet pipe, the bypass electromagnetic valve is arranged on the bypass pipe and used for controlling on-off of the bypass pipe, and a microcirculation loop is formed among the water inlet pipe, the heat exchange pipe, the water outlet pipe and the bypass pipe. According to the gas water heater and the operation method thereof, the microcirculation loop solves the problem that when a user boils water again, a section of water flow which is suddenly cold and suddenly hot appears in the outlet water of the gas water heater.

Description

Technical Field

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

[0002] When using a conventional gas water heater, if you turn off the water and then turn it on again, the water will flow out in a sudden burst of hot and cold water, directly affecting the bathing experience. To avoid scalding and cold, when turning the water on again, users usually wait until the previous hot water has drained out and then test the water temperature by hand to see if it is suitable before using it, which increases the waiting time for hot water and wastes water.

[0003] Because after the conventional gas water heater is turned off, the heat exchanger of the gas water heater transfers the remaining heat to heat the water in the heat exchange tube, making the water temperature in the heat exchange tube higher than the user's preset temperature. When the water is turned on again, the first section of high-temperature water flows out first, and then the cold water that has not been heated in time flows out, causing the water temperature to be hot first and then cold. The greater the tap water flow or the lower the tap water temperature, the greater the temperature drop of the hot water will be. In severe cases, the temperature drop can be as high as 10°C or more, seriously affecting the user's bathing experience.

[0004] Therefore, a gas water heater is urgently needed to solve the above problems. Summary of the invention

[0005] The present invention aims to solve at least one of the problems existing in the existing related technologies to a certain extent. To this end, the present invention proposes a gas water heater that can solve the problem of the water flow from the gas water heater suddenly cooling or heating when the user turns on the water again.

[0006] The above purpose is achieved through the following technical solutions:

[0007] A gas water heater, comprising:

[0008] shell;

[0009] a heat exchanger disposed in the housing;

[0010] A heat exchange tube passing through the heat exchanger;

[0011] A water inlet pipe, whose water inlet end is connected to the external water supply pipe of the gas water heater, and whose water outlet end extends into the shell and is connected to the water inlet end of the heat exchange tube;

[0012] A water outlet pipe, whose water outlet end is connected to a hot water supply pipe at a water point outside the water heater, and whose water inlet end extends into the shell and is connected to the water outlet end of the heat exchange pipe;

[0013] A water pump, installed on the water inlet pipe;

[0014] A water flow sensing device, installed on the water inlet pipe, for detecting the water flow of the water inlet pipe;

[0015] An inlet water temperature probe, arranged on the inlet water pipe, for detecting the water temperature in the inlet water pipe;

[0016] An outlet water temperature probe, arranged on the outlet water pipe, for detecting the water temperature in the outlet water pipe;

[0017] A gas control valve, disposed between the heat exchanger and an external gas supply pipeline of the gas water heater, for controlling the gas supply amount of the heat exchanger;

[0018] A bypass pipe, a first end of which is connected to the water inlet end of the water inlet pipe, and a second end of which is connected to the water outlet end of the water outlet pipe;

[0019] A bypass solenoid valve, arranged on the bypass pipe, for controlling the on-off of the bypass pipe;

[0020] A microcirculation loop is formed among the water inlet pipe, the heat exchange pipe, the water outlet pipe and the bypass pipe.

[0021] Optionally, a cold water supply pipe for a water use point is also provided outside the gas water heater, the water inlet end of the water inlet pipe is connected to the cold water supply pipe for a water use point outside the gas water heater, a one-way valve is provided between the hot water supply pipe for the water use point and the cold water supply pipe for the water use point, and a preheating circulation loop is formed between the water inlet pipe, the heat exchange pipe, the water outlet pipe, the hot water supply pipe for the water use point and the cold water supply pipe for the water use point.

[0022] Optionally, it also includes a controller and an operation display arranged on the shell, and the operation display, the water pump, the water flow sensing device, the water inlet temperature probe, the water outlet temperature probe, the gas control valve and the bypass solenoid valve are all communicatively connected to the controller.

[0023] Another aspect of the present invention further provides an operating method of the gas water heater as described above, comprising the following steps:

[0024] S1: The gas water heater is in the bathing standby mode;

[0025] S2: Close the bypass solenoid valve;

[0026] S3: Determine whether the water flow rate is greater than the startup flow rate. If so, open the gas control valve, start the ignition, and execute the shower mode. If not, return to S1;

[0027] S4: Determine whether the water flow rate is greater than the startup flow rate. If so, return to S3; if not, enter S5;

[0028] S5: Close the gas control valve, shut down the machine, and turn on the water pump and bypass solenoid valve;

[0029] S6: Determine whether the water flow rate is greater than the startup flow rate. If so, proceed to S7;

[0030] S7: Enter the microcirculation heating and heat exchange mode.

[0031] Optionally, the S7 specifically includes:

[0032] S71: Open the gas control valve, start the ignition, and enter the micro-circulation heating mode;

[0033] S72: Determine whether the microcirculation flameout condition is met, if so, proceed to S73, if not, repeat S72;

[0034] S73: Close the gas control valve, shut down the machine and enter the micro-circulation heat exchange mode;

[0035] S74: Determine whether the microcirculation water pump shut-down condition is met, if so, proceed to S75, if not, repeat S74;

[0036] S75: Turn off the water pump and bypass solenoid valve, exit the microcirculation mode and return to S1.

[0037] Optionally, the microcirculation flameout condition is: the cumulative heating time is greater than the microcirculation heating time t preset by the program 加热 .

[0038] Optionally, the microcirculation heating time t 加热 is the heating temperature rise △T 加热 Matching value, matching microcirculation heating time t 加热 and heating temperature rise △T 加热 Has a proportional linear relationship, △T 加热 =T 设 -T 进 , where T 设 is the preset temperature, T 进 is the inlet water temperature, and when △T 加热 When it is negative, △T 加热 The value is 0℃.

[0039] Optionally, when △T 加热 ≤△T 加热min When theating = t 加热min ;

[0040] When △T 加热min <△T 加热 <△T 加热max When theating = (t 加热max -t 加热min )×(△T 加热 -△T 加热min ) / (△T 加热max -△T 加热min)+t 加热min ;

[0041] When △T 加热 ≥△T 加热min When t 加热 =t 加热max ;

[0042] Among them, △T 加热max is the maximum heating temperature rise, t 加热max is the longest microcirculation heating time, △T 加热min is the minimum heating temperature rise, t 加热min It is the shortest microcirculation heating time.

[0043] Optionally, the microcirculation flameout condition is: the cumulative gas consumption is greater than the microcirculation gas consumption V preset by the program 气 The program presets the microcirculation gas volume V 气 is the microcirculation target temperature rise △T 目标 The program presets the microcirculation gas consumption V 气 and microcirculation target temperature rise △T 目标 Has the following proportional linear relationship:

[0044] V 气 =(V 管 ×C×△T 目标 ) / (Q×η);

[0045] Where C is the specific heat capacity of water, Q is the calorific value of gas, η is the thermal efficiency, V 管 It is the total volume of the heat exchange tube, the water inlet pipe, the water outlet pipe and the bypass pipe.

[0046] Optionally, the microcirculation water pump shut-off condition is that the cumulative heat exchange time is greater than the microcirculation heat exchange time t preset by the program. 换热 .

[0047] Optionally, the program presets the microcirculation heat exchange time t 换热 is the circulation flow rate L measured by the water flow sensing device in the microcirculation mode 循环 The program presets the microcirculation heat exchange time t 换热 The calculation formula is:

[0048] t 换热 =K×V 管 / L 循环 ;

[0049] Among them, V 管 is the total volume of the heat exchange tube, the water inlet pipe, the water outlet pipe and the bypass pipe, and K is the number of cycles.

[0050] Optionally, in S6, if the water flow rate is ≤ the startup flow rate, a circulation system failure alarm is issued, the water pump and the bypass solenoid valve are turned off, and the process returns to S1.

[0051] Compared with the prior art, the present invention has at least the following beneficial effects:

[0052] The gas water heater provided by the present invention comprises a shell, a heat exchanger, a heat exchange tube, a water inlet pipe, a water outlet pipe, a water pump, a water flow sensing device, a water inlet temperature probe, a gas control valve, a bypass pipe, and a bypass control valve. The heat exchanger is arranged in the shell. The heat exchange tube passes through the heat exchanger. The water inlet end of the water inlet pipe is connected to the external water supply pipe of the gas water heater, and the water outlet end extends into the shell and is connected to the water inlet end of the heat exchange tube. The water outlet end of the water outlet pipe is connected to the hot water supply pipeline of the water use point outside the water heater, and the water inlet end extends into the shell and is connected to the water outlet end of the heat exchange tube. The water pump is installed on the water inlet pipe. The water flow sensing device is installed on the water inlet pipe for detecting the water flow of the water inlet pipe. The water inlet temperature probe is arranged on the water inlet pipe for detecting the water temperature in the water inlet pipe. The water outlet temperature probe is arranged on the water outlet pipe for detecting the water temperature in the water outlet pipe. The gas control valve is arranged between the heat exchanger and the external gas supply pipeline of the gas water heater, and is used to control the gas supply of the heat exchanger; the first end of the bypass pipe is connected to the water inlet end of the water inlet pipe, and the second end is connected to the water outlet end of the water outlet pipe. The bypass solenoid valve is arranged on the bypass pipe, and is used to control the on and off of the bypass pipe. A microcirculation loop is formed between the water inlet pipe, the heat exchange pipe, the water outlet pipe and the bypass pipe. Specifically, when the user uses water, the bypass solenoid valve is closed, the bypass pipe is disconnected, and the gas water heater normally executes the shower mode. When the user turns off the water, the bypass solenoid valve is opened, the bypass pipe is opened, and the water pump is running to form a microcirculation loop. The water in the microcirculation loop can continue to be heated and heat-exchanged, ensuring that the water temperature in the microcirculation loop can be close to the user's water temperature requirements, thereby solving the problem of a section of water flow that suddenly cools and heats when the user turns on the water again. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 is a schematic diagram of the structure of a gas water heater provided in a specific embodiment of the present invention (in shower mode);

[0054] Figure 2 It is a structural schematic diagram of a gas water heater provided in a specific embodiment of the present invention (in a micro-circulation heating and heat exchange mode);

[0055] Figure 3 It is a diagram of the operation steps of the gas water heater provided by a specific embodiment of the present invention;

[0056] Figure 4 It is a structural schematic diagram of a gas water heater provided by a specific embodiment of the present invention (with a water mixing tank);

[0057] Figure 5It is a curve diagram showing that the micro-circulation heating time of the gas water heater provided by the specific embodiment of the present invention is proportional to the heating temperature rise;

[0058] Figure 6 It is a water temperature variation curve diagram of a gas water heater that is shut off and restarted midway provided by a specific embodiment of the present invention.

[0059] In the figure:

[0060] 1. Shell; 11. Heat exchanger; 12. Water inlet interface; 13. Water outlet interface; 14. Water inlet pipe; 15. Heat exchange pipe; 16. Water outlet pipe; 17. Bypass pipe; 18. Water mixing tank;

[0061] 2. Water pump;

[0062] 3. Water flow sensing device;

[0063] 4. Inlet water temperature probe;

[0064] 5. Water outlet temperature probe;

[0065] 6. Gas control valve;

[0066] 7. Bypass solenoid valve;

[0067] 8. Operate the display;

[0068] 9. Controller;

[0069] 10. Check valve;

[0070] 101. Hot water supply pipes at water use points; 102. Cold water supply pipes at water use points. DETAILED DESCRIPTION

[0071] The following examples illustrate the present invention, but the present invention is not limited to these examples. Modifications to the specific embodiments of the present invention or equivalent replacement of some technical features without departing from the spirit of the present invention should be included in the scope of the technical solution claimed by the present invention.

[0072] Please refer to Figure 1-Figure 3The present invention provides a gas water heater, comprising a housing 1, a heat exchanger 11, a heat exchange tube 15, a water inlet pipe 14, a water outlet pipe 16, a water pump 2, a water flow sensing device 3, a water inlet temperature probe 4, a gas control valve 6, a bypass pipe 17, and a bypass solenoid valve 7. The heat exchanger 11 is arranged in the housing 1. The heat exchange tube 15 passes through the heat exchanger 11. The water inlet end of the water inlet pipe 14 is connected to the external water supply pipe of the gas water heater, and the water outlet end extends into the housing 1 and is connected to the water inlet end of the heat exchange tube 15. The water outlet end of the water outlet pipe 16 is connected to the hot water supply pipe 101 of the water use point outside the water heater, and the water inlet end extends into the housing 1 and is connected to the water outlet end of the heat exchange tube 15. The water pump 2 is installed on the water inlet pipe 14. The water flow sensing device 3 is installed on the water inlet pipe 14, and is used to detect the water flow of the water inlet pipe 14. The water inlet temperature probe 4 is arranged on the water inlet pipe 14, and is used to detect the water temperature in the water inlet pipe 14. The outlet water temperature probe 5 is arranged on the outlet water pipe 16, and is used to detect the water temperature in the outlet water pipe 16. The gas control valve 6 is arranged between the heat exchanger 11 and the external gas supply pipeline of the gas water heater, and is used to control the gas supply of the heat exchanger 11; the first end of the bypass pipe 17 is connected to the water inlet end of the water inlet pipe 14, and the second end is connected to the water outlet end of the outlet water pipe 16. The bypass solenoid valve 7 is arranged on the bypass pipe 17, and is used to control the on-off of the bypass pipe 17. A microcirculation loop is formed between the water inlet pipe 14, the heat exchange pipe 15, the outlet water pipe 16 and the bypass pipe 17. Specifically, when the user uses water, the bypass solenoid valve 7 is closed, the bypass pipe 17 is disconnected, and the gas water heater normally executes the shower mode. When the user turns off the water, the bypass solenoid valve 7 is opened, the bypass pipe 17 is opened, and the water pump 2 runs to form a microcirculation loop. The water in the microcirculation loop can continue to be heated and heat-exchanged, ensuring that the water temperature in the microcirculation loop can be close to the user's water temperature requirements, thereby solving the problem of a sudden cold and hot water flow in the gas water heater when the user turns on the water again.

[0073] Optionally, a water inlet interface 12 is provided at the water inlet end of the water inlet pipe 14, and the water inlet interface 12 is connected to an external water supply pipe of the gas water heater.

[0074] Optionally, a water outlet interface 13 is provided at the water outlet end of the water outlet pipe 16, and the water outlet interface 13 is connected to a hot water supply pipeline 101 at a water use point outside the water heater.

[0075] Optionally, a cold water supply pipe 102 for a water point is further provided outside the gas water heater, the water inlet end of the water inlet pipe 14 is connected to the cold water supply pipe 102 for a water point outside the gas water heater, a one-way valve 10 is provided between the hot water supply pipe 101 for a water point and the cold water supply pipe 102 for a water point, and a preheating circulation loop is formed between the water inlet pipe 14, the heat exchange pipe 15, the water outlet pipe 16, the hot water supply pipe 101 for a water point and the cold water supply pipe 102 for a water point. In this way, by only providing one water pump 2, the microcirculation loop, the preheating loop and the normal shower mode can all be realized, the structure is simple and the cost is low.

[0076] Optionally, the bypass solenoid valve 7 is a normally closed direct-acting solenoid valve, which does not need to be powered on in a standby state to save power consumption.

[0077] Optionally, it also includes a controller 9 and an operation display 8 arranged on the shell 1, and the operation display 8, water pump 2, water flow sensing device 3, water inlet temperature probe 4, water outlet temperature probe 5, gas control valve 6 and bypass solenoid valve 7 are all communicatively connected to the controller 9.

[0078] Optionally, the operation display 8 includes an operation panel and a display screen. The user selects the operation mode and water temperature of the gas water heater through the operation panel. The display screen is used to display the current temperature, the set temperature and one or more of the operation modes selected by the user.

[0079] Please refer to Figure 4 Optionally, a water mixing tank 18 is further included, and the water mixing tank 18 is arranged at the water outlet end of the water outlet pipe 16, and the second end of the bypass pipe 17 is connected to the water mixing tank 18. By providing the water mixing tank 18, it is helpful to improve the constant temperature performance and further reduce the hot water temperature drop of the secondary boiling water.

[0080] Please refer to Figure 1-Figure 3 On the other hand, the present invention also provides an operating method of the gas water heater as described above, comprising the following steps:

[0081] S1: The gas water heater is in the bathing standby mode;

[0082] S2: Close the bypass solenoid valve 7;

[0083] S3: Determine whether the water flow rate is greater than the startup flow rate. If so, open the gas control valve 6, start the ignition, and execute the shower mode (the water flow direction is as follows Figure 1 If not, return to S1;

[0084] S4: Determine whether the water flow rate is greater than the startup flow rate. If so, return to S3; if not, enter S5;

[0085] S5: Close the gas control valve 6, shut down the machine and turn on the water pump 2 and the bypass solenoid valve 7;

[0086] S6: Determine whether the water flow rate is greater than the startup flow rate. If so, proceed to S7;

[0087] S7: Enter the micro-circulation heating mode (the water flow direction is as follows Figure 2 (indicated by arrow B in the middle).

[0088] Optionally, S7 specifically includes:

[0089] S71: Open the gas control valve 6, start the ignition, and enter the micro-circulation heating mode;

[0090] S72: Determine whether the microcirculation flameout condition is met, if so, proceed to S73, if not, repeat S72;

[0091] S73: close the gas control valve 6, shut down the machine and turn off the flame, and enter the micro-circulation heat exchange mode;

[0092] S74: Determine whether the microcirculation water pump shut-down condition is met, if so, proceed to S75, if not, repeat S74;

[0093] S75: Turn off water pump 2 and bypass solenoid valve 7, exit microcirculation mode and return to S1.

[0094] Optionally, the microcirculation flameout condition is: the accumulated heating time is greater than the microcirculation heating time theating preset by the program.

[0095] Optionally, the microcirculation heating time theating is 5s-15s.

[0096] Alternatively, if Figure 5 As shown, the microcirculation heating time theating is a value that matches the heating temperature rise △Theating. The matched microcirculation heating time theating and the heating temperature rise △Theating have a positive proportional linear relationship, △Theating = Tset-Tin, wherein Tset is a preset temperature, Tin is the water inlet temperature, and when △Theating is a negative value, △Theating takes a value of 0°C.

[0097] Optionally, when ΔTheating ≤ ΔTheating min, theating = theating min;

[0098] When △T heating min<△T heating<△T heating max, t heating=(t heating max-t heating min)×(△T heating-△T heating min) / (△T heating max-△T heating min)+t heating min;

[0099] When △Theating ≥ △Theating min, theating = theating max;

[0100] Among them, △Theatingmax is the maximum heating temperature rise, theatingmax is the longest microcirculation heating time, △Theatingmin is the minimum heating temperature rise, and theatingmin is the shortest microcirculation heating time.

[0101] Specifically, the longest microcirculation heating time theatingmax, the shortest microcirculation heating time theatingmin, the maximum heating temperature rise △Theatingmax and the minimum heating temperature rise △Theatingmin are all fixed values ​​and are derived from experimental experience values. In winter, the temperature is low, the tap water temperature is low, the user preset temperature is high, and the heating temperature rise △Theating becomes larger, then the microcirculation heating time theating following of the microcirculation heating mode becomes longer, the water temperature in the pipes inside the machine is increased, and the temperature drop of hot water is reduced when boiling water. In summer, the temperature is high, the tap water temperature is high, the user preset temperature is low, and the heating temperature rise △Theating becomes smaller, then the microcirculation heating time theating following of the microcirculation heating mode becomes smaller, which can prevent the water temperature in the pipes inside the machine from being too high.

[0102] Exemplarily, in this embodiment, the longest microcirculation heating time theatingmax is 15s, the shortest microcirculation heating time theatingmin is 5s, the maximum heating temperature rise ΔTheatingmax is 40°C, and the minimum heating temperature rise ΔTheatingmin is 0°C.

[0103] Optionally, the microcirculation flameout condition is: the cumulative gas consumption is greater than the microcirculation gas consumption Vgas preset by the program, the microcirculation gas consumption Vgas preset by the program is a value matching the microcirculation target temperature rise △Ttarget, and the microcirculation gas consumption Vgas preset by the program and the microcirculation target temperature rise △Ttarget have the following positive proportional linear relationship:

[0104] V 气 =(V 管 ×C×△T 目标 ) / (Q×η);

[0105] Where C is the specific heat capacity of water, Q is the calorific value of gas, η is the thermal efficiency, V 管 It is the total volume of the heat exchange tube 15 , the water inlet pipe 14 , the water outlet pipe 16 and the bypass pipe 17 .

[0106] Optionally, the condition for shutting down the water pump 2 in the microcirculation is that the accumulated heat exchange time is greater than the microcirculation heat exchange time theat exchange preset by the program.

[0107] Optionally, the program presets the microcirculation heat exchange time theatexchange to be 5s-15s.

[0108] Optionally, the program presets the microcirculation heat exchange time theat exchange as a value matching the circulation flow Lcirculation measured by the water flow sensing device 3 in the microcirculation mode, and the calculation formula of the program preset microcirculation heat exchange time theat exchange is:

[0109] t 换热 =K×V 管 / L 循环 ;

[0110] Among them, V 管 is the total volume of the heat exchange tube 15, the water inlet pipe 14, the water outlet pipe 16 and the bypass pipe 17, and K is the number of cycles.

[0111] Optionally, K is 2 to further even out the water temperatures of the heat exchange tube 15 , the water inlet pipe 14 , the water outlet pipe 16 and the bypass pipe 17 .

[0112] Optionally, in S6, if the water flow rate is ≤ the startup flow rate, a circulation system failure alarm is issued, the water pump 2 and the bypass solenoid valve 7 are turned off, and the process returns to S1.

[0113] Please refer to Figure 6 In the microcirculation heating stage, the hot water in the water outlet pipe 16 circulates into the water inlet pipe 14, and the water temperature in the water inlet pipe 14 is significantly increased; in the microcirculation heat exchange stage, after the flameout, the water in the microcirculation loop circulates for heat exchange, and the inlet water temperature is close to the outlet water temperature; after the boiling water is restarted, the water temperature quickly rises to the user's preset temperature, and there is no obvious water temperature fluctuation.

[0114] By adopting the method of the present invention to control the water temperature after the water is turned off midway, preferably, the temperature drop of the hot water can be controlled within 1° C., which can meet the needs of users.

[0115] The above are only some embodiments of the present invention. For those skilled in the art, several modifications and improvements can be made without departing from the creative concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A gas water heater, characterized in that: include: Housing (1); A heat exchanger (11) is arranged in the housing (1); A heat exchange tube (15) passing through the heat exchanger (11); A water inlet pipe (14), the water inlet end of which is connected to an external water supply pipe of the gas water heater, and the water outlet end of which extends into the shell (1) and is connected to the water inlet end of the heat exchange tube (15); A water outlet pipe (16), whose water outlet end is connected to a hot water supply pipe (101) at a water use point outside the water heater, and whose water inlet end extends into the shell (1) and is connected to the water outlet end of the heat exchange pipe (15); A water pump (2) installed on the water inlet pipe (14); A water flow sensing device (3), installed on the water inlet pipe (14), and used to detect the water flow rate of the water inlet pipe (14); An inlet water temperature probe (4) is arranged on the inlet water pipe (14) and is used to detect the water temperature in the inlet water pipe (14); An outlet water temperature probe (5) is arranged on the outlet water pipe (16) and is used to detect the water temperature in the outlet water pipe (16); A gas control valve (6) is arranged between the heat exchanger (11) and an external gas supply pipeline of the gas water heater, and is used to control the gas supply amount of the heat exchanger (11); a bypass pipe (17), a first end of which is connected to the water inlet end of the water inlet pipe (14), and a second end of which is connected to the water outlet end of the water outlet pipe (16); A bypass solenoid valve (7), arranged on the bypass pipe (17) and used for controlling the on-off of the bypass pipe (17); A microcirculation loop is formed between the water inlet pipe (14), the heat exchange pipe (15), the water outlet pipe (16) and the bypass pipe (17).

2. The gas water heater according to claim 1, characterized in that: A water point cold water supply pipe (102) is also provided outside the gas water heater, and a water inlet end of the water inlet pipe (14) is connected to the water point cold water supply pipe (102) outside the gas water heater, a one-way valve (10) is provided between the water point hot water supply pipe (101) and the water point cold water supply pipe (102), and a preheating circulation loop is formed between the water inlet pipe (14), the heat exchange pipe (15), the water outlet pipe (16), the water point hot water supply pipe (101) and the water point cold water supply pipe (102).

3. The gas water heater according to claim 1, characterized in that: It also includes a controller (9) and an operation display (8) arranged on the housing (1); the operation display (8), the water pump (2), the water flow sensing device (3), the water inlet temperature probe (4), the water outlet temperature probe (5), the gas control valve (6) and the bypass solenoid valve (7) are all connected to the controller (9) in a communication manner.

4. A method for operating a gas water heater according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1: The gas water heater is in the bathing standby mode; S2: Close the bypass solenoid valve; S3: Determine whether the water flow rate is greater than the startup flow rate. If so, open the gas control valve, start the ignition, and execute the shower mode. If not, return to S1; S4: Determine whether the water flow rate is greater than the startup flow rate. If so, return to S3; if not, enter S5; S5: Close the gas control valve, shut down the machine, and turn on the water pump and bypass solenoid valve; S6: Determine whether the water flow rate is greater than the startup flow rate. If so, proceed to S7; S7: Enter the microcirculation heating and heat exchange mode.

5. The operating method of the gas water heater according to claim 4, characterized in that: The S7 specifically includes: S71: Open the gas control valve, start the ignition, and enter the micro-circulation heating mode; S72: Determine whether the microcirculation flameout condition is met, if so, proceed to S73, if not, repeat S72; S73: Close the gas control valve, shut down the machine and enter the micro-circulation heat exchange mode; S74: Determine whether the microcirculation water pump shut-down condition is met, if so, proceed to S75, if not, repeat S74; S75: Turn off the water pump and bypass solenoid valve, exit the microcirculation mode and return to S1.

6. The operating method of the gas water heater according to claim 5, characterized in that: The microcirculation flameout condition is: the cumulative heating time is greater than the microcirculation heating time t preset by the program 加热 .

7. The operating method of the gas water heater according to claim 6, characterized in that: The microcirculation heating time t 加热 is the heating temperature rise △T 加热 Matching value, matching microcirculation heating time t 加热 and heating temperature rise △T 加热 Has a proportional linear relationship, △T 加热 =T 设 -T 进 , where T 设 is the preset temperature, T 进 is the inlet water temperature, and when △T 加热 When it is negative, △T 加热 The value is 0℃.

8. The operating method of the gas water heater according to claim 7, characterized in that: When △T 加热 ≤△T 加热min When theating = t 加热min ; When △T 加热min <△T 加热 <△T 加热max When theating = (t 加热max -t 加热min )×(△T 加热 -△T 加热min ) / (△T 加热max -△T 加热min )+t 加热min ; When △T 加热 ≥△T 加热min When t 加热 =t 加热max ; Among them, △T 加热max is the maximum heating temperature rise, t 加热max is the longest microcirculation heating time, △T 加热min is the minimum heating temperature rise, t 加热min It is the shortest microcirculation heating time.

9. The operating method of the gas water heater according to claim 4, characterized in that: The microcirculation flameout condition is: the cumulative gas consumption is greater than the microcirculation gas consumption V preset by the program 气 The program presets the microcirculation gas volume V 气 is the microcirculation target temperature rise △T 目标 The program presets the microcirculation gas consumption V 气 and microcirculation target temperature rise △T 目标 Has the following proportional linear relationship: V 气 =(V 管 ×C×△T 目标 ) / (Q×η); Where C is the specific heat capacity of water, Q is the calorific value of gas, η is the thermal efficiency, V 管 It is the total volume of the heat exchange tube, the water inlet pipe, the water outlet pipe and the bypass pipe.

10. The operating method of the gas water heater according to claim 4, characterized in that: The microcirculation water pump shut-down condition is that the cumulative heat exchange time is greater than the microcirculation heat exchange time t preset by the program 换热 .

11. The operating method of the gas water heater according to claim 10, characterized in that: The program presets the microcirculation heat exchange time t 换热 is the circulation flow rate L measured by the water flow sensing device in the microcirculation mode 循环 The program presets the microcirculation heat exchange time t 换热 The calculation formula is: t 换热 =K×V 管 / L 循环 ; Among them, V 管 is the total volume of the heat exchange tube, the water inlet pipe, the water outlet pipe and the bypass pipe, and K is the number of cycles.

12. The operating method of the gas water heater according to claim 5, characterized in that: In S6, if the water flow rate is less than or equal to the startup flow rate, a circulation system failure alarm is issued, the water pump and the bypass solenoid valve are turned off, and the process returns to S1.

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