Gas water heater, preheating cycle control method thereof, and readable storage medium

Abstract

The present invention provides a gas water heater and its preheating cycle control method and readable storage medium. The preheating cycle control method includes: obtaining the average circulating water flow rate when the circulating water pump is running in the preheating cycle mode; calculating the return water and outlet water temperature difference limit value based on the minimum input load of the equipment and the average circulating water flow rate, and the return water and outlet water temperature difference limit value is the difference between the outlet water temperature threshold value and the return water temperature threshold value; obtaining the return water temperature threshold value based on the return water and outlet water temperature difference limit value and the predetermined outlet water temperature threshold value; monitoring the return water temperature and the outlet water temperature, and stopping the combustion when the return water temperature is greater than or equal to the return water temperature threshold value, or the outlet water temperature is greater than or equal to the predetermined outlet water temperature threshold value. Adaptively adjusting the return water temperature threshold value according to the circulating water flow rate can alleviate the frequent start and stop of the equipment during the preheating process, and at the same time make the preheating in the circulation pipeline more sufficient and the temperature distribution more uniform.

Description

Technical Field

[0001] The present disclosure relates to the field of gas water heater control, and in particular to a gas water heater and a control method for a preheating cycle thereof. Background Art

[0002] Gas water heaters typically include gas water heaters and gas boilers. Gas water heaters are used to supply hot water for drinking, bathing, and other domestic needs, while gas boilers, in addition to providing domestic hot water, can also be connected to indoor radiators to provide central heating.

[0003] Usually, when users need domestic hot water, they will turn on the mixing tap, and the gas water heater will start up. In the period after the equipment is started, the cold water stored in the water pipe will be discharged first, which will affect the user experience. In order to avoid this problem, current gas water heaters usually have a preheating circulation mode to circulate the cold water in the preheating water pipe when the user is not using hot water, so that the user can use hot water after turning it on. However, after long-term use, the water flow in the circulation pipeline will decrease due to increased water resistance. When the equipment is operating at this minimum input load and the circulating water flow is small, the outlet water temperature of the equipment will rise rapidly and reach the temperature threshold at which the preheating cycle stops running. At this time, the equipment will stop working. However, at this time, the water temperature in the circulating water circuit does not evenly reach the set temperature for the circulation preheating. For example, the water temperature at the water inlet / return outlet of the equipment is low. As the water temperature drops, the preheating cycle will be triggered again soon, and this cycle will cause the burner assembly and circulating water pump of the equipment to start frequently, which will obviously affect the life of the equipment and will also cause the water in the circulating water circuit to be unevenly heated, causing users to feel hot and cold when using hot water, resulting in a decrease in comfort. Summary of the Invention

[0004] In order to overcome the problems existing in the background technology, the present disclosure provides a gas water heater, a preheating cycle control method thereof, and a readable storage medium.

[0005] A first aspect of an embodiment of the present disclosure provides a preheating cycle control method for a gas water heater, comprising: obtaining an average circulating water flow rate when a circulating water pump is running in a preheating cycle mode; calculating a return water and outlet water temperature difference limit value based on a minimum input load of the equipment and the average circulating water flow rate, wherein the return water and outlet water temperature difference limit value is the difference between an outlet water temperature threshold value and a return water temperature threshold value; obtaining a return water temperature threshold value based on the return water and outlet water temperature difference limit value and a predetermined outlet water temperature threshold value; monitoring the return water temperature and the outlet water temperature, and stopping combustion when the return water temperature is greater than or equal to the return water temperature threshold value, or the outlet water temperature is greater than or equal to the predetermined outlet water temperature threshold value.

[0006] In some embodiments, the step of obtaining the return water temperature threshold includes: calculating the return water temperature threshold based on the return water and outlet water temperature difference limit and the predetermined outlet water temperature threshold; when the calculated return water temperature threshold is less than the predetermined minimum allowable return water temperature threshold, the above-mentioned predetermined minimum allowable return water temperature threshold is set as the return water temperature threshold; otherwise, the calculated return water temperature threshold is maintained.

[0007] In some embodiments, the preheating cycle control method further includes, when the return water temperature is greater than or equal to the return water temperature threshold, or the outlet water temperature is greater than or equal to the outlet water temperature threshold, the circulating water pump continues to operate for a predetermined period of time and then stops working.

[0008] In some embodiments, the predetermined outlet water temperature threshold is predetermined according to a preheating cycle set temperature.

[0009] A second aspect of an embodiment of the present disclosure provides a computer-readable storage medium having instructions stored thereon, which implement the above-mentioned method steps when executed by a processor.

[0010] A third aspect of the embodiments of the present disclosure provides a gas water heater, comprising a burner assembly, a flow sensor, a return water temperature sensor, an outlet water temperature sensor, a circulating water pump, and a controller. The controller is configured to: obtain an average circulating water flow rate when the circulating water pump is operating in a preheating circulation mode via the flow sensor; calculate a return water and outlet water temperature difference limit based on the minimum input load of the device and the average circulating water flow rate, wherein the return water and outlet water temperature difference limit is the difference between an outlet water temperature threshold and a return water temperature threshold; obtain a return water temperature threshold based on the return water and outlet water temperature difference limit and a predetermined outlet water temperature threshold; monitor the return water temperature and outlet water temperature respectively via the return water temperature sensor and the outlet water temperature sensor; and stop the burner assembly when the return water temperature is greater than or equal to the return water temperature threshold, or when the outlet water temperature is greater than or equal to the predetermined outlet water temperature threshold.

[0011] In some embodiments, the control of the return water temperature threshold obtained by the above-mentioned controller includes: calculating the return water temperature threshold based on the return water and outlet water temperature difference limit and the predetermined outlet water temperature threshold; when the calculated return water temperature threshold is less than the predetermined minimum allowable return water temperature threshold, the above-mentioned predetermined minimum allowable return water temperature threshold is set as the return water temperature threshold; otherwise, the calculated return water temperature threshold is maintained.

[0012] In some embodiments, the controller is further configured to control the circulating water pump to continue running for a predetermined period of time and then stop working when the return water temperature is greater than or equal to the return water temperature threshold, or the outlet water temperature is greater than or equal to the outlet water temperature threshold.

[0013] In some embodiments, the predetermined outlet water temperature threshold is predetermined according to a preheating cycle set temperature.

[0014] The technical solutions provided by one or more embodiments of the present disclosure can provide the following beneficial effects: adaptively adjusting the return water temperature threshold based on the circulating water flow rate can alleviate frequent starts and stops during the preheating process, while also ensuring more complete preheating and more uniform temperature distribution within the circulating pipeline. Furthermore, by presetting a minimum allowable return water temperature threshold, the adjusted return water temperature threshold can be adjusted to a value that is too low, resulting in excessively low circulating water temperatures and thus impacting user comfort. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0016] Figure 1 This is a block diagram of a gas water heater connected to a hot water system in one embodiment of the present disclosure;

[0017] Figure 2 This is a principle block diagram of another embodiment of the present disclosure in which a gas water heater is connected to a hot water system;

[0018] Figure 3 This is a flow chart of a method for controlling a circulating water pump of a gas water heater in one embodiment when the gas water heater operates in a preheating circulation mode;

[0019] Figure 4 is a flow chart of a control method for stopping a preheating cycle of a gas water heater in one embodiment;

[0020] Figure 5 is a flow chart of a control method for performing preheating cycle control on a gas water heater in another embodiment;

[0021] Figure 6 yes Figure 5 A variable embodiment discloses a flow chart of another control method for preheating cycle control of a gas water heater. DETAILED DESCRIPTION

[0022] The following will describe in detail the various embodiments shown in conjunction with the accompanying drawings. However, these embodiments do not represent all embodiments consistent with the present disclosure, and any structural, methodological, or functional modifications made by those skilled in the art based on these embodiments are included within the scope of protection requested by the appended claims.

[0023] Gas water heaters use combustible gases as fuel, such as natural gas, city gas, liquefied gas, biogas, etc., and provide heat by burning combustible gases to meet the user's living needs. For example, gas water heaters provide domestic hot water, or gas boilers can provide domestic hot water and heating needs at the same time.

[0024] like Figure 1 The hot water system 100 shown in one embodiment of the present disclosure comprises a gas water heater, which is connected to a water point (e.g., a mixing valve) 70 via a cold water line 51 and a hot water line 52. Furthermore, a return pipe 53 is connected between the gas water heater and the hot water line 52. The pipes can be formed by connecting multiple water pipes to form a water flow path. There can be multiple water points, each connected to a cold water line and a hot water line. In this embodiment, water point 70 is the one that is farthest or relatively far from the gas water heater. When the gas water heater is operating in bathroom mode, i.e., supplying domestic hot water, cold water and hot water are supplied to water point 70 via the cold water line 51 and the hot water line 52, respectively, and mixed before being output. When the gas water heater is operating in preheating circulation mode, the hot water output by the appliance flows back into the appliance via the hot water line 52 and the return pipe 53 for reheating. In some embodiments, a one-way valve 54 is further provided on the return pipe 53 to limit the water flow to only flow from the hot water pipeline 52 through the return pipe 53 into the gas water heater.

[0025] The gas water heater includes a housing 10, which houses the burner assembly, heat exchanger 13, and smoke exhaust system. The housing 10 can be constructed from several panels assembled to create a space within which to accommodate the various components. A water inlet pipe 111 is located within the housing 10. Extending from the bottom of the housing 10 are a water outlet pipe 112 and a gas supply line 113. The water inlet pipe 111 connects to the cold water line 51 via a first section 1111 and to the return line 53 via a second section 1112. The water outlet pipe 112 is directly connected to the hot water line 52.

[0026] The burner assembly typically includes a gas distribution frame (not shown) and a burner 12. A gas valve 15 is provided on the gas supply line 113. This gas valve 15 can be an electrically controllable valve used to connect or disconnect the gas supply channel and control the amount of gas supplied to the gas distribution frame. In some embodiments, the burner 12 includes several combustion units arranged side by side in a longitudinal direction. Each combustion unit is flat and plate-shaped, typically fixed upright in the burner frame. It has an air inlet at its bottom, several flame holes at its top, and a gas-air mixing channel connecting the air inlet and the several flame holes. Gas flowing through the gas valve 15 enters the air inlet of each combustion unit through distribution from the gas distribution frame. Gas is mixed with the primary air entering simultaneously in the gas-air mixing channel and then transferred to the flame holes located at the top of the fire row for combustion, generating hot flue gas. The burner assembly also includes an ignition device 121 for igniting the gas-air mixture and a flame detection device 122 for detecting the presence of a flame. In some embodiments, the ignition device 121 includes a pair of ignition electrodes extending above the flame hole of the combustion unit. The flame detection device 122 includes a flame detection electrode extending above the flame hole of the combustion unit.

[0027] The heat generated by the burner 12 passes through the heat exchanger 13. The heat exchanger 13 is typically located above the burner 12. In some embodiments, the heat exchanger may be a fin-and-tube heat exchanger, i.e., a plurality of fins are disposed within the heat exchanger housing, and a heat exchange water pipe winds through these fins, with its two ends connected to an inlet pipe 111 located upstream of the water flow direction and an outlet pipe 112 located downstream of the water flow direction, respectively. The heat generated by the combustion of the gas-air mixture is absorbed by the fins and further transferred to the water flowing through the heat exchange water pipe. The heated water is then transferred to the hot water pipe 52 via the outlet pipe 112, thereby providing users with hot water for drinking, bathing, and other domestic purposes.

[0028] In some embodiments, a fan 16 may be provided below the burner 12 to drive air flow, thereby providing the air required for combustion and causing the smoke generated by combustion to be collected by the smoke hood of the smoke exhaust device and then discharged through a smoke exhaust pipe (not shown) connected to the smoke hood. An inlet water temperature sensor 171 is provided at the water inlet pipe 111 (e.g., on the outer wall of the water inlet pipe) to detect the temperature of the water flowing through the water inlet pipe. In the preheating cycle mode, the inlet water temperature sensor 171 is used to detect the return water temperature flowing into the water inlet pipe 111 through the return water pipe 54 and the second pipe section 1112, so it is used as a return water temperature sensor at this time; in the bathroom mode, the temperature sensor 171 is used to detect the temperature of the cold water flowing into the water inlet pipe 111 through the first pipe section 1111. An outlet water temperature sensor 172 is provided at the outlet water pipe 112 (e.g., on the outer wall of the outlet water pipe) to detect the outlet water temperature passing through the outlet water pipe. The temperature sensor can be a thermistor, such as a positive temperature coefficient thermistor (PTC). In some embodiments, the temperature sensor can also be a negative temperature coefficient (NTC) temperature sensor. A flow sensor 14 is arranged in the water circuit for detecting the water flow. In some embodiments, the flow sensor can be installed at the first pipe section 1111 to detect the cold water inlet flow flowing in through the cold water pipe 51. The flow sensor 14 can include a rotor assembly with a magnet and a Hall element. When water flows through the detection device, the rotor assembly is driven to rotate, thereby utilizing the Hall effect of the Hall element to measure the magnetic physical quantity. A circulating water pump 18 is arranged in the water circuit for driving or promoting water flow. In this embodiment, the circulating water pump 18 is connected to the water inlet pipe 111. In other embodiments, the circulating water pump 18 can also be connected to the second pipe section 1112.

[0029] A controller 20 is disposed within the housing 10 and is used to monitor and control the operation of various components and circuit devices within the gas water heater. In some embodiments, the controller 20 may be a control circuit comprising a processor, memory, and several electronic components connected according to a specific wiring scheme. The processor may be a central processing unit (CPU), other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or any conventional processor. In this embodiment, the processor is the control center of the gas water heater, connecting various components of the device using various interfaces and circuits. For example, the controller 20 is electrically connected to the gas valve 15, fan 16, return water temperature sensor 171, outlet water temperature sensor 172, flow sensor 14, and circulating water pump 18, either by wired or wireless communication.

[0030] The memory can be used to store instructions for any application or method running on the controller's processor, as well as various types of data. The processor implements the various functions of the gas water heater by running or executing the programs or instructions stored in the memory, and calling the data stored in the memory. The memory can include any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (PROM), magnetic memory, flash memory, solid-state memory, magnetic disk, or optical disk, etc.

[0031] Figure 2 Shown is another embodiment of a hot water system 200, which is Figure 1The heating system 100 shown in FIG is similar to the heating system 100 shown in FIG, with the main difference being that the return pipe 63 is connected between the cold water pipe 51 and the hot water pipe 52 near the water point 70 through two three-way joints 61 and 62. In this way, even if the user does not pre-lay the return pipe when decorating the home, the return pipe can be connected between the cold and hot water pipes at the water point far from the gas water heater (such as under the basin) to achieve the preheating circulation function. Similarly, a one-way valve 64 is also provided on the return pipe 63 to limit the water flow to only flow from the hot water pipe 52 through the return pipe 63 into the cold water pipe 51 in one direction, and further flow back to the gas water heater through the water inlet pipe 111. In addition, in this embodiment, the water inlet pipe 111 is directly connected to the cold water pipe 51, and the flow sensor 14 is provided on the water inlet pipe 111.

[0032] Figure 3 The diagram shows the steps of a method for controlling a circulating water pump of a gas water heater in a preheating circulation mode in one embodiment. The following also describes in detail how the controller 20 executes these method steps.

[0033] Step 301: Preheating cycle mode is triggered.

[0034] In some embodiments, the preheat cycle mode can be activated during a fixed time period, such as between 4:00 PM and 6:00 PM. The start time of the fixed time period can be arbitrarily set by the user through the device's control panel or an associated mobile phone application. In other embodiments, the preheat cycle mode can be always active or can be turned on and off at any time using a separate function button.

[0035] Step 302: Obtain the return water and outlet water temperature difference limit ΔT.

[0036] The return water and outlet water temperature difference limit ΔT is the difference between the outlet water temperature threshold Tol and the return water temperature threshold Til, i.e., ΔT = Tol - Til. In some embodiments, ΔT is pre-set and stored in a storage medium. In other embodiments, the outlet water temperature threshold Tol and the return water temperature threshold Til are pre-set and stored in a storage medium. The return water and outlet water temperature difference limit ΔT is then calculated using the difference between the outlet water temperature threshold and the return water temperature threshold Tol - Til. In other embodiments, the outlet water temperature threshold Tol and the return water temperature threshold Til can also be pre-determined based on the preheating cycle set temperature Ts. For example, the preheating cycle set temperature Ts is first obtained. This can be set by the user, i.e., the temperature the user desires the circulating water in the preheating circulation system to reach. Of course, if the user-set circulation temperature Ts is too high or too low, such as exceeding an upper limit of 43°C or falling below a lower limit of 37°C, the upper limit or lower limit will be set as the preheating cycle temperature Ts. Then, the outlet water temperature threshold Tol and return water temperature threshold Til are determined based on the preheat cycle set temperature Ts. The outlet water temperature threshold Tol is the preheat cycle set temperature Ts plus a temperature difference T1, i.e., Tol = Ts + T1, for example, T1 = 6°C. The return water temperature threshold Til is the preheat cycle set temperature Ts minus a temperature difference T2, i.e., Til = Ts - T2, for example, T2 = 5°C. The return water temperature difference limit ΔT is then calculated using the difference between the outlet and return water temperature thresholds, Tol - Til.

[0037] Step 303: Calculate the target circulating water flow rate Qt.

[0038] Calculate the target circulating water flow rate, Qt, based on the equipment's minimum input load, Pmin, and the return-to-outlet temperature difference limit, ΔT. For example, the target circulating water flow rate, Qt, can be calculated using the formula Qt = Pmin / (c × ΔT), where c is the specific heat capacity of water.

[0039] Step 304: Start the circulating water pump and obtain the current water flow Qc.

[0040] In the preheating circulation mode, when the circulating water pump 18 is running, the controller 20 can obtain the current water flow Qc in real time through the flow sensor 14. In some embodiments, the controller 20 can also obtain the current water flow data through the flow sensor 14 at fixed intervals, such as 0.1 seconds.

[0041] Step 305: Compare the current water flow Qc with the target circulating water flow Qt. If the current water flow Qc is greater than or equal to the target circulating water flow Qt, execute step 310; if the current water flow Qc is less than the target circulating water flow Qt, execute step 306.

[0042] Step 306: Increase the water pump speed.

[0043] If the current water flow rate Qc is less than the target circulating water flow rate Qt, the speed of the circulating water pump 18 is continuously increased until the current water flow rate Qc is greater than or equal to the target circulating water flow rate Qt. In some embodiments, the current water flow rate Qc and the target circulating water flow rate Qt can be used as inputs to adjust the speed of the circulating water pump 18 using a PID (Proportion-Integral-Differential) control module.

[0044] Step 307: Determine whether the water flow rate Qmax when the water pump runs at the maximum speed is still less than the target circulating water flow rate Qt.

[0045] As the speed of the circulating water pump 18 increases, if the water flow rate Qmax when the water pump runs at the maximum speed still does not reach the target circulating water flow rate Qt, step 308 is executed; conversely, if the current water flow rate can reach the target circulating water flow rate Qt during the process of increasing the water pump speed, step 309 is executed.

[0046] Step 308: The controller 20 enables the circulating water pump 18 to maintain running at the maximum speed.

[0047] Step 309: The controller 20 enables the circulating water pump 18 to maintain its rotation speed corresponding to the target circulating water flow rate Qt.

[0048] Step 310: The controller 20 enables the circulating water pump 18 to maintain the current speed;

[0049] Step 311: Ignition and combustion.

[0050] After the speed of the circulating water pump 18 is stabilized, the controller 20 controls the air valve 15 to open to a suitable opening, controls the fan 16 to run at a certain speed, and controls the burner assembly to ignite and burn.

[0051] By ensuring a large circulating water flow during the preheating cycle, frequent start and stop of the equipment due to excessively rapid local temperature rise in the preheating circulation pipeline can be avoided. At the same time, the preheating in the circulation pipeline can be more sufficient and the temperature distribution can be more uniform.

[0052] Figure 4 The diagram shows the steps of a method for controlling a gas water heater to stop a preheating cycle in one embodiment. The following also describes in detail how the controller 20 executes these steps.

[0053] During the operation of the preheating circulation mode (step 401), the controller 20 monitors the return water temperature and the outlet water temperature respectively through the return water temperature sensor 171 and the outlet water temperature sensor 172, and determines whether the collected return water temperature Ti is greater than or equal to the return water temperature threshold Til, or whether the outlet water temperature To is greater than or equal to the outlet water temperature threshold Tol (step 402); if so, the burner assembly is controlled to stop working (step 403), and the circulating water pump 18 is controlled to continue to operate for a predetermined period of time and then stop working (step 404), so that the water temperature distribution in the circulation pipeline is more uniform.

[0054] Figure 5 The figures show the steps of a control method for controlling a preheating cycle of a gas water heater in one embodiment. The following also describes in detail how the controller 20 executes these method steps.

[0055] Step 801: Preheating cycle mode is triggered.

[0056] In some embodiments, the preheat cycle mode can be activated during a fixed time period, such as between 4:00 PM and 6:00 PM. The start time of the fixed time period can be arbitrarily set by the user through the device's control panel or an associated mobile phone application. In other embodiments, the preheat cycle mode can be always active or can be turned on and off at any time using a separate function button.

[0057] Step 802: Start the circulating water pump and obtain the average circulating water flow rate Qav.

[0058] In the preheating circulation mode, while the circulating water pump 18 is operating, the controller 20 can obtain the average circulating water flow rate Qav through the flow sensor 14. In some embodiments, the controller 20 can also obtain and store the current water flow data through the flow sensor 14 at fixed intervals, i.e., sampling periods, such as 0.1 seconds. During stable operation of the water pump, the controller 20 calculates the average of the flow values ​​obtained during the most recent (e.g., 10) consecutive sampling periods to obtain the average circulating water flow rate Qav.

[0059] Step 803: Calculate the return water and outlet water temperature difference limit ΔT.

[0060] The return-water-outlet temperature difference limit ΔT is the difference between the outlet temperature threshold Tol and the return-water temperature threshold Til, i.e., ΔT = Tol - Til. This limit can be calculated using the equipment's minimum input load Pmin and the average circulating water flow rate Qav. For example, the return-water-outlet temperature difference limit ΔT can be calculated using the formula ΔT = Pmin / (c × Qav), where c is the specific heat capacity of water.

[0061] Step 804: Obtain the return water temperature threshold Til.

[0062] In some embodiments, the return water temperature threshold Til can be calculated based on the return water and outlet water temperature difference limit ΔT and the predetermined outlet water temperature threshold Tol, that is, Til = Tol - ΔT. The outlet water temperature threshold Tol can be pre-set and stored in a storage medium. In some other embodiments, the outlet water temperature threshold Tol can also be predetermined based on the preheating cycle set temperature Ts. For example, the preheating cycle set temperature Ts is first obtained, which can be set by the user, that is, the temperature that the user wants the circulating water in the preheating circulation pipeline to reach; of course, if the user-set circulation temperature Ts is too high or too low, such as exceeding an upper limit of 43°C or below a lower limit of 37°C, the upper limit or lower limit will be set as the preheating cycle temperature Ts. Then, the outlet water temperature threshold Tol is determined based on the preheating cycle set temperature Ts. For example, the outlet water temperature threshold Tol is the preheating cycle set temperature Ts superimposed with a temperature difference T1, that is, Tol = Ts + T1, such as T1 = 6°C.

[0063] Step 805: Ignition and combustion.

[0064] The controller 20 controls the gas valve 15 to open to a suitable opening, controls the fan 16 to run at a certain speed, and controls the burner assembly to ignite and burn.

[0065] Step 806: Determine whether the preheating cycle stop condition is met.

[0066] In the preheating cycle mode, the controller 20 monitors the return water temperature and the outlet water temperature respectively through the return water temperature sensor 171 and the outlet water temperature sensor 172, and determines whether the collected return water temperature Ti is greater than or equal to the return water temperature threshold Til, or whether the outlet water temperature To is greater than or equal to the outlet water temperature threshold Tol; if so, execute step 807.

[0067] Step 807: Stop combustion, that is, the controller 20 controls the burner assembly to stop working, closes the gas valve 15 and stops the fan 16 from running.

[0068] Step 808: The controller 20 further controls the circulating water pump 18 to continue operating for a predetermined period of time and then stop operating, so that the water temperature in the circulating pipeline is more evenly distributed.

[0069] Figure 6 The figures show the steps of a control method for controlling a preheating cycle of a gas water heater in another embodiment. The following also describes in detail how the controller 20 executes these method steps.

[0070] Step 811: Preheat cycle mode is triggered.

[0071] In some embodiments, the preheat cycle mode can be activated during a fixed time period, such as between 4:00 PM and 6:00 PM. The start time of the fixed time period can be arbitrarily set by the user through the device's control panel or an associated mobile phone application. In other embodiments, the preheat cycle mode can be always active or can be turned on and off at any time using a separate function button.

[0072] Step 812: Start the circulating water pump and obtain the average circulating water flow rate Qav.

[0073] In the preheating circulation mode, while the circulating water pump 18 is operating, the controller 20 can obtain the average circulating water flow rate Qav through the flow sensor 14. In some embodiments, the controller 20 can also obtain and store the current water flow data through the flow sensor 14 at fixed intervals, i.e., sampling periods, such as 0.1 seconds. During stable operation of the water pump, the controller 20 calculates the average of the flow values ​​obtained during the most recent (e.g., 10) consecutive sampling periods to obtain the average circulating water flow rate Qav.

[0074] Step 813: Calculate the return water and outlet water temperature difference limit ΔT.

[0075] The return-water-outlet temperature difference limit ΔT is the difference between the outlet temperature threshold Tol and the return-water temperature threshold Til, i.e., ΔT = Tol - Til. This limit can be calculated using the equipment's minimum input load Pmin and the average circulating water flow rate Qav. For example, the return-water-outlet temperature difference limit ΔT can be calculated using the formula ΔT = Pmin / (c × Qav), where c is the specific heat capacity of water.

[0076] Step 814: Calculate the return water temperature threshold Til.

[0077] In some embodiments, the return water temperature threshold Til can be calculated based on the return water and outlet water temperature difference limit ΔT and the predetermined outlet water temperature threshold Tol, that is, Til = Tol - ΔT. The outlet water temperature threshold Tol can be pre-set and stored in a storage medium. In some other embodiments, the outlet water temperature threshold Tol can also be predetermined based on the preheating cycle set temperature Ts. For example, the preheating cycle set temperature Ts is first obtained, which can be set by the user, that is, the temperature that the user wants the circulating water in the preheating circulation pipeline to reach; of course, if the user-set circulation temperature Ts is too high or too low, such as exceeding an upper limit of 43°C or below a lower limit of 37°C, the upper limit or lower limit will be set as the preheating cycle temperature Ts. Then, the outlet water temperature threshold Tol is determined based on the preheating cycle set temperature Ts. For example, the outlet water temperature threshold Tol is the preheating cycle set temperature Ts superimposed with a temperature difference T1, that is, Tol = Ts + T1, such as T1 = 6°C.

[0078] Step 815: Determine whether the calculated return water temperature threshold Til is greater than or equal to the predetermined minimum allowable return water temperature threshold Talo. If so, the calculated return water temperature threshold is maintained and step 817 is executed. If the calculated return water temperature threshold Til is less than the predetermined minimum allowable return water temperature threshold Talo, step 816 is executed.

[0079] Step 816: If the calculated return water temperature threshold Til is less than the predetermined minimum allowable return water temperature threshold Talo, the predetermined minimum allowable return water temperature threshold Talo is set as the return water temperature threshold Til, and step 817 is executed. The minimum allowable return water temperature threshold Talo is pre-set to prevent the calculated return water temperature threshold Til from being too low, thereby affecting user comfort.

[0080] Step 817: Ignition and combustion.

[0081] The controller 20 controls the gas valve 15 to open to a suitable opening, controls the fan 16 to run at a certain speed, and controls the burner assembly to ignite and burn.

[0082] Step 818: Determine whether the preheating cycle stop condition is met.

[0083] In the preheating cycle mode, the controller 20 monitors the return water temperature and the outlet water temperature respectively through the return water temperature sensor 171 and the outlet water temperature sensor 172, and determines whether the collected return water temperature Ti is greater than or equal to the return water temperature threshold Til, or whether the outlet water temperature To is greater than or equal to the outlet water temperature threshold Tol; if so, execute step 807.

[0084] Step 819: Stop combustion, that is, the controller 20 controls the burner assembly to stop working, closes the gas valve 15 and stops the fan 16 from running.

[0085] Step 820: The controller 20 further controls the circulating water pump 18 to continue operating for a predetermined period of time and then stop operating, so that the water temperature in the circulating pipeline is more evenly distributed.

[0086] After long-term use, the circulating water circuit in a user's home may experience increased water resistance, leading to a decrease in circulating water flow. In the above embodiment, adaptively adjusting the return water temperature threshold based on the circulating water flow can alleviate frequent starts and stops during the preheating process, while also ensuring more complete preheating and more uniform temperature distribution within the circulating pipes. Furthermore, by presetting a minimum allowable return water temperature threshold, the adjusted return water temperature threshold can be adjusted too low, resulting in excessively low circulating water temperatures and thus affecting user comfort.

[0087] All or part of the steps in the method of the above disclosed embodiment can be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium, and when the computer program is executed by a processor, it can implement the steps of the above-mentioned various method embodiments. Among them, the computer program includes computer program code, which can be in source code form, object code form, executable file or some intermediate form. The readable storage medium can include any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (PROM), magnetic memory, flash memory, solid-state memory, magnetic disk or optical disk, etc.

[0088] It should be understood that the methods and devices disclosed in the above disclosure can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of units in the controller is only a division of logical functions. There may be other division methods in actual implementation. For example, multiple units can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the connection between the components, elements, and units discussed above can be electrical, mechanical, or other connection forms; it can be a direct connection or an indirect connection through some interfaces; it can be a wired connection or a wireless communication.

[0089] In addition, the units described above as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; some or all of the units may be selected according to actual needs to achieve the purpose of the disclosed embodiment. In addition, the functional units in the above embodiments may be integrated into a processing unit, or each unit may exist physically separately, or two or more units may be integrated into a single unit. The above integrated units may be implemented in the form of hardware or in the form of hardware plus software functional units.

[0090] It should be understood that although this specification is described according to embodiments, not every embodiment contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.

Claims

1. A preheating cycle control method for a gas water heater, characterized in that: The method includes: Get the average circulating water flow Qav when the circulating water pump is running in the preheating circulation mode; Based on the minimum input load Pmin of the equipment and the average circulating water flow rate Qav, the return water and outlet water temperature difference limit ΔT is calculated, that is, ΔT = Pmin / (c×Qav), where c is the specific heat capacity of water; the return water and outlet water temperature difference limit ΔT is the difference between the outlet water temperature threshold Tol and the return water temperature threshold Til, that is, ΔT = Tol-Til; Obtaining a return water temperature threshold value according to the return water and outlet water temperature difference limit and a predetermined outlet water temperature threshold value; Monitor the return water temperature and the outlet water temperature, and stop the combustion when the return water temperature is greater than or equal to the return water temperature threshold, or the outlet water temperature is greater than or equal to the predetermined outlet water temperature threshold.

2. The preheating cycle control method of a gas water heater according to claim 1, characterized in that: The step of obtaining the return water temperature threshold comprises: Calculating a return water temperature threshold value based on the return water and outlet water temperature difference limit and a predetermined outlet water temperature threshold value; When the calculated return water temperature threshold is less than the predetermined minimum allowable return water temperature threshold, the predetermined minimum allowable return water temperature threshold is set as the return water temperature threshold; otherwise, the calculated return water temperature threshold is maintained.

3. The preheating cycle control method of a gas water heater according to claim 1, characterized in that: The method also includes, when the return water temperature is greater than or equal to the return water temperature threshold, or the outlet water temperature is greater than or equal to the outlet water temperature threshold, the circulating water pump continues to operate for a predetermined period of time and then stops working.

4. The preheating cycle control method of a gas water heater according to claim 1, characterized in that: The predetermined outlet water temperature threshold is predetermined according to the preheating cycle set temperature.

5. A computer-readable storage medium having instructions stored thereon, characterized in that: When the instructions are executed by a processor, the method according to any one of claims 1 to 4 is implemented.

6. A gas water heater, characterized by: The device includes a burner assembly, a flow sensor, a return water temperature sensor, a water outlet temperature sensor, a circulating water pump and a controller; wherein the controller is configured to The average circulating water flow Qav of the circulating water pump when it is running in the preheating circulation mode is obtained through the flow sensor; Based on the minimum input load Pmin of the equipment and the average circulating water flow rate Qav, the return water and outlet water temperature difference limit ΔT is calculated, that is, ΔT = Pmin / (c×Qav), where c is the specific heat capacity of water; the return water and outlet water temperature difference limit ΔT is the difference between the outlet water temperature threshold Tol and the return water temperature threshold Til, that is, ΔT = Tol-Til; Obtaining a return water temperature threshold value according to the return water and outlet water temperature difference limit and a predetermined outlet water temperature threshold value; The return water temperature and the outlet water temperature are monitored respectively by the return water temperature sensor and the outlet water temperature sensor; When the return water temperature is greater than or equal to the return water temperature threshold, or the outlet water temperature is greater than or equal to the predetermined outlet water temperature threshold, the burner assembly is stopped.

7. The gas water heater according to claim 6, characterized in that: The controller obtains the return water temperature threshold value by: Calculating a return water temperature threshold value based on the return water and outlet water temperature difference limit and a predetermined outlet water temperature threshold value; When the calculated return water temperature threshold is less than the predetermined minimum allowable return water temperature threshold, the predetermined minimum allowable return water temperature threshold is set as the return water temperature threshold; otherwise, the calculated return water temperature threshold is maintained.

8. The gas water heater according to claim 6, characterized in that: The controller is further configured to control the circulating water pump to continue running for a predetermined period of time and then stop working when the return water temperature is greater than or equal to the return water temperature threshold, or the outlet water temperature is greater than or equal to the outlet water temperature threshold.

9. The gas water heater according to claim 6, characterized in that: The predetermined outlet water temperature threshold is predetermined according to the preheating cycle set temperature.

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