Gas-fired hot water equipment and its circulating water pump control method and readable storage medium

Abstract

This invention provides a gas-fired hot water device, its circulating water pump control method, and a readable storage medium. The circulating water pump control method includes: acquiring a return water to outlet water temperature difference limit, which is the difference between an outlet water temperature threshold and a return water temperature threshold; calculating a target circulating water flow rate based on the device's minimum input load and the return water to outlet water temperature difference limit; acquiring the current water flow rate of the circulating water pump during preheating circulation mode and comparing it with the target circulating water flow rate; if the current water flow rate is greater than or equal to the target circulating water flow rate, the circulating water pump maintains its current speed; if the current water flow rate is less than the target circulating water flow rate, the pump speed is increased. By ensuring a large circulating water flow rate during preheating circulation, frequent start-stop cycles during the preheating process can be avoided.

Description

Technical Field

[0001] This disclosure relates to the field of gas-fired water heating equipment control, and in particular to a control method for a gas-fired water heating equipment and its circulating water pump in a preheating cycle. Background Technology

[0002] Gas-fired water heating systems typically include gas water heaters and gas boilers. Gas water heaters are used to supply domestic hot water for drinking and bathing; while gas boilers, in addition to providing domestic hot water, can also be connected to radiators installed indoors to provide central heating.

[0003] Typically, users turn on the mixing tap when they need hot water, which activates the gas water heater. For a short period after startup, cold water stored in the pipes is discharged, affecting the user experience. To avoid this, current gas water heaters usually have a preheating circulation mode. This mode circulates the cold water in the preheating pipes when the user is not using hot water, ensuring hot water is available immediately upon startup. However, over time, increased water resistance in the circulation pipes reduces water flow. When the unit operates at its minimum input load with low circulation flow, the outlet water temperature rises rapidly, reaching the temperature threshold that stops the preheating circulation. At this point, the unit stops operating. However, the water temperature in the circulation circuit has not yet uniformly reached the set preheating temperature. For example, if the water temperature at the inlet / outlet of the equipment is low, the preheating cycle will be triggered again as the water temperature drops. This cycle repeats, causing the burner components and circulating water pump of the equipment to start frequently. This will obviously affect the lifespan of the equipment and will also cause uneven heating and cooling of the water in the circulating water circuit, making users feel hot and cold when using hot water, resulting in a decrease in comfort. Summary of the Invention

[0004] To overcome the problems existing in the prior art, this disclosure provides a gas-fired hot water equipment, a circulating water pump control method thereon, and a readable storage medium.

[0005] A first aspect of this disclosure provides a method for controlling a circulating water pump in a gas-fired water heater, comprising: acquiring a temperature difference limit between the return water and the outlet water, wherein the temperature difference limit is the difference between an outlet water temperature threshold and a return water temperature threshold; calculating a target circulating water flow rate based on the minimum input load of the equipment and the temperature difference limit between the return water and the outlet water; acquiring the current water flow rate of the circulating water pump during operation in a preheating circulation mode and comparing it with the target circulating water flow rate; if the current water flow rate is greater than or equal to the target circulating water flow rate, then the circulating water pump maintains its current speed; if the current water flow rate is less than the target circulating water flow rate, then the pump speed is increased.

[0006] In some embodiments, the method further includes: as the pump speed increases, when the current water flow reaches the target circulating water flow, the circulating water pump maintains the corresponding speed at this time.

[0007] In some embodiments, the method further includes: when the pump speed increases to the maximum speed but the current water flow still does not reach the target water flow, the circulating pump maintains the maximum speed.

[0008] In some embodiments, the step of obtaining the temperature difference limit between the return water and the outlet water includes: obtaining the preheating cycle set temperature; determining the outlet water temperature threshold and the return water temperature threshold based on the preheating cycle set temperature; and calculating the temperature difference limit between the return water and the outlet water by the difference between the outlet water temperature threshold and the return water temperature threshold.

[0009] A second aspect of this disclosure provides a computer-readable storage medium having instructions stored thereon that, when executed by a processor, implement the method steps described above.

[0010] A third aspect of this disclosure provides a gas-fired water heating device, comprising a burner assembly, a flow sensor, a circulating water pump, and a controller. The controller is configured to: acquire a return water to outlet water temperature difference limit, the return water to outlet water temperature difference limit being the difference between an outlet water temperature threshold and a return water temperature threshold; calculate a target circulating water flow rate based on the device's minimum input load and the return water to outlet water temperature difference limit; acquire the current water flow rate of the circulating water pump during preheating circulation mode via the flow sensor and compare it with the target circulating water flow rate; if the current water flow rate is greater than or equal to the target circulating water flow rate, maintain the circulating water pump at its current speed; if the current water flow rate is less than the target circulating water flow rate, increase the pump speed.

[0011] In some embodiments, the controller is further configured to maintain the corresponding operating speed of the circulating water pump when the current water flow rate reaches the target circulating water flow rate, as the pump speed increases.

[0012] In some embodiments, the controller is also configured to keep the circulating water pump running at its maximum speed when the current water flow rate has not yet reached the target water flow rate when the pump speed increases to the maximum speed.

[0013] In some embodiments, the control of the controller to obtain the temperature difference limit between the return water and the outlet water includes: obtaining the preheating cycle set temperature; determining the outlet water temperature threshold and the return water temperature threshold based on the preheating cycle set temperature; and calculating the temperature difference limit between the return water and the outlet water by the difference between the outlet water temperature threshold and the return water temperature threshold.

[0014] In some embodiments, the device further includes a return water temperature sensor and an outlet water temperature sensor. The controller is also configured to: monitor the return water temperature and the outlet water temperature respectively via the return water temperature sensor and the outlet water temperature sensor; when the return water temperature is greater than or equal to a return water temperature threshold, or the outlet water temperature is greater than or equal to an outlet water temperature threshold, control the burner assembly to stop working, and control the circulating water pump to continue operating for a predetermined time before stopping working.

[0015] The technical solutions provided by one or more embodiments of this disclosure may include the following beneficial effects: by ensuring a large circulating water flow during preheating circulation, frequent start-ups and shutdowns of equipment caused by excessively rapid local temperature rise in the preheating circulation pipeline can be avoided, while making the preheating in the circulation pipeline more thorough and the temperature distribution more uniform. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this disclosure or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic block diagram of a gas-fired water heater connected to a hot water system according to one embodiment of the present disclosure;

[0018] Figure 2 This is a schematic block diagram of a gas-fired water heater connected to a hot water system in another embodiment of this disclosure;

[0019] Figure 3 This is a flowchart of a method for controlling the circulating water pump of a gas-fired hot water equipment when it is operating in preheating circulation mode in one embodiment.

[0020] Figure 4 This is a flowchart of a control method for stopping the preheating cycle in one embodiment of a gas-fired hot water equipment;

[0021] Figure 5 This is a flowchart of a control method for preheating cycle control in another embodiment of a gas-fired water heater;

[0022] Figure 6 yes Figure 5 A variable embodiment of the present invention discloses a flowchart of another control method for preheating cycle control of a gas-fired water heater. Detailed Implementation

[0023] The embodiments shown will now be described in detail with reference to the accompanying drawings. However, these embodiments do not represent all embodiments consistent with this 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 claimed in the appended claims.

[0024] Gas-fired water heating equipment uses combustible gases as fuel, such as natural gas, city gas, liquefied petroleum gas, and biogas, to provide heat to meet users' living needs. Examples include gas water heaters that provide domestic hot water, or gas boilers that can provide both domestic hot water and heating.

[0025] like Figure 1 The hot water system 100 shown in one embodiment of this disclosure includes a gas-fired water heater, which is connected to a water point (such as a mixing valve faucet) 70 via a cold water pipe 51 and a hot water pipe 52. A return water pipe 53 connects the gas-fired water heater and the hot water pipe 52. The pipes can be a water flow path formed by connecting several water pipes. There can be multiple water points, each connected to the cold water pipe and the hot water pipe. In this embodiment, water point 70 is the water point furthest or relatively farthest from the gas-fired water heater among several water points. When the gas-fired water heater operates in bathroom mode, i.e., supplying domestic hot water, cold water and hot water are supplied to water point 70 via the cold water pipe 51 and the hot water pipe 52 respectively, mixed, and then output. When the gas-fired water heater operates in preheating circulation mode, the hot water output by the device flows back into the device via the hot water pipe 52 and the return water pipe 53 for reheating. In some embodiments, a one-way valve 54 is also provided on the return water pipe 53 to limit the water flow to flow only from the hot water pipe 52 through the return water pipe 53 into the gas water heater.

[0026] The gas-fired water heater includes a housing 10, which houses a burner assembly, a heat exchanger 13, and a flue gas exhaust system. The housing 10 can be assembled from several panels to form an internal space to accommodate the components. An inlet pipe 111 is provided inside the housing 10, and an outlet pipe 112 and a gas supply pipe 113 extend from the bottom of the housing 10. The inlet pipe 111 is connected to a cold water pipe 51 via a first pipe section 1111 and to a return water pipe 53 via a second pipe section 1112, while the outlet pipe 112 is directly connected to a hot water pipe 52.

[0027] The burner assembly typically includes a gas distributor (not shown) and a burner 12. A gas valve 15 is provided on the gas supply line 113. This gas valve 15 may be an electrically controllable valve for connecting or disconnecting the gas supply passage and controlling the amount of gas supplied to the gas distributor. In some embodiments, the burner 12 includes a plurality of combustion units arranged side by side along a longitudinal direction. Each combustion unit is flat and plate-shaped, typically vertically fixed in the burner frame, with an air inlet at the bottom, a plurality of flame holes at the top, and a gas-air mixing passage connecting the air inlet and the flame holes. Gas supplied via the gas valve 15 enters the air inlet of each combustion unit through the gas distributor, mixes with simultaneously entering primary air in the gas-air mixing passage, and is delivered to the flame holes located at the top of the burner plate for combustion to generate 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 port of the combustion unit. The flame detection device 122 includes a flame detection electrode extending above the flame port of the combustion unit.

[0028] The heat generated by combustion in burner 12 passes through heat exchanger 13. Heat exchanger 13 is typically positioned above burner 12. In some embodiments, the heat exchanger may be a finned tube heat exchanger, wherein multiple fins are provided within the heat exchanger housing, and a heat exchange water pipe meanders through these fins, with its two ends connected to an inlet pipe 111 located upstream in the water flow direction and an outlet pipe 112 located downstream in the water flow direction, respectively. The heat generated by 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 hot water pipe 52 through outlet pipe 112, thereby providing users with domestic hot water for drinking, bathing, and other purposes.

[0029] In some embodiments, a fan 16 may be disposed below the burner 12 to drive airflow, thereby providing the air required for combustion and causing the flue gas generated by combustion to be collected by the smoke hood of the exhaust device, and then discharged through an exhaust pipe (not shown) connected to the smoke hood. A water inlet temperature sensor 171 is disposed 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 circulation mode, the water inlet temperature sensor 171 is used to detect the temperature of the return water 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; while 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. A water outlet temperature sensor 172 is disposed at the water outlet pipe 112 (e.g., on the outer wall of the water outlet pipe) to detect the temperature of the water flowing out through the water outlet pipe. The temperature sensor can be a thermistor, such as a positive temperature coefficient (PTC) thermistor. In some embodiments, the temperature sensor can also be a negative temperature coefficient (NTC) temperature sensor. A flow sensor 14 is disposed in the water path to detect water flow rate. In some embodiments, the flow sensor can be installed at the first pipe section 1111 to detect the flow rate of cold water entering 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 rotated, thereby utilizing the Hall effect of the Hall element to measure magnetic physical quantities. A circulating water pump 18 is disposed in the water path to drive or promote water flow. In this embodiment, the circulating water pump 18 is connected in the inlet pipe 111. In other embodiments, the circulating water pump 18 can also be connected in the second pipe section 1112.

[0030] A controller 20 is disposed within the housing 10 for detecting and controlling the operation of various components and circuit devices within the gas-fired water heater. In some embodiments, the controller 20 may be a control circuit comprising a processor, a memory, and several electronic components connected in a specific wiring configuration. The processor may be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. The general-purpose processor may be a microprocessor or any conventional processor. In this embodiment, the processor is the control center of the gas-fired water heater, connecting various parts of the device via various interfaces and lines. For example, the controller 20 is wired or wirelessly connected to the gas valve 15, the fan 16, the return water temperature sensor 171, the outlet water temperature sensor 172, the flow sensor 14, and the circulating water pump 18.

[0031] The memory can be used to store instructions for any application or method that operates on the processor of the controller, as well as various types of data. The processor implements the various functions of the gas-fired water heater by running or executing programs or instructions stored in the memory and by calling data stored in the memory. The memory can contain 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 storage, flash memory, solid-state memory, magnetic disks, or optical disks, etc.

[0032] Figure 2 The illustration shows another embodiment of the hot water system 200, which is similar to... Figure 1The heating system 100 shown is similar, 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 via two T-joints 61 and 62. In this way, even if the user did not pre-lay a return pipe during home renovation, a preheating circulation function can be achieved by connecting the return pipe between the cold and hot water pipes at a water point far from the gas water heater (such as under the sink). Similarly, the return pipe 63 is also equipped with a one-way valve 64 to limit the water flow only from the hot water pipe 52 to the cold water pipe 51 via the return pipe 63, and further back to the gas water heater via the inlet pipe 111. Furthermore, in this embodiment, the inlet pipe 111 is directly connected to the cold water pipe 51, and the flow sensor 14 is installed on the inlet pipe 111.

[0033] Figure 3 The following describes the steps of the circulating water pump control method of a gas-fired water heater in the preheating circulation mode in one embodiment. The controller 20 will also perform these steps in detail below.

[0034] Step 301: Preheating cycle mode triggered.

[0035] In some embodiments, the preheating cycle mode may be activated during a fixed time period, such as between 4 PM and 6 PM. The start time of the fixed time period can be arbitrarily set by the user through the device's control panel or the associated mobile application. In other embodiments, the preheating cycle mode may always be active, or it may be turned on and off at any time via a separate function button.

[0036] Step 302: Obtain the temperature difference limit ΔT between return water and outlet water.

[0037] The temperature difference limit ΔT between the outlet and return water is the difference between the outlet temperature threshold Tol and the return water temperature threshold Til, i.e., ΔT = Tol - Til. In some embodiments, ΔT is preset and stored in a storage medium. In other embodiments, the outlet temperature threshold Tol and the return water temperature threshold Til are preset and stored in a storage medium, and then the temperature difference limit ΔT between the outlet and return water is calculated using the difference Tol - Til. In still other embodiments, the outlet temperature threshold Tol and the return water temperature threshold Til 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, i.e., the temperature that the user wants the circulating water in the preheating cycle system to reach; of course, if the user-set cycle 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, then that upper or lower limit will be set as the preheating cycle temperature Ts. Then, the outlet water temperature threshold Tol and the return water temperature threshold Til are determined based on the preheating cycle set temperature Ts. The outlet water temperature threshold Tol is the preheating cycle set temperature Ts plus a temperature difference T1, i.e., Tol = Ts + T1, such as T1 = 6℃; the return water temperature threshold Til is the preheating cycle set temperature Ts minus a temperature difference T2, i.e., Til = Ts - T2, such as T2 = 5℃. Finally, the temperature difference limit ΔT between the outlet and return water is calculated using the difference Tol - Til between the outlet and return water temperature thresholds.

[0038] Step 303: Calculate the target circulating water flow rate Qt.

[0039] The target circulating water flow rate Qt is calculated based on the minimum input load Pmin of the equipment and the temperature difference limit between the return water and the outlet water 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.

[0040] Step 304: Start the circulating water pump and obtain the current water flow rate Qc.

[0041] In the preheating circulation mode, during the operation of the circulating water pump 18, the controller 20 can obtain the current water flow rate Qc in real time through the flow sensor 14. In some embodiments, the controller 20 can also obtain the current water flow rate data through the flow sensor 14 at fixed intervals, such as 0.1 seconds.

[0042] Step 305: Compare the current water flow rate Qc with the target circulating water flow rate Qt. If the current water flow rate Qc is greater than or equal to the target circulating water flow rate Qt, proceed to step 310; if the current water flow rate Qc is less than the target circulating water flow rate Qt, proceed to step 306.

[0043] Step 306: Increase the water pump speed.

[0044] 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, and the speed of the circulating water pump 18 can be adjusted using a PID (Proportion-Integral-Differential) control module.

[0045] Step 307: Determine whether the water flow rate Qmax when the water pump is running at its maximum speed is still less than the target circulating water flow rate Qt.

[0046] If the water flow rate Qmax when the pump is running at its maximum speed still does not reach the target circulating water flow rate Qt, then step 308 is executed; otherwise, if the current water flow rate can reach the target circulating water flow rate Qt during the process of increasing the pump speed, then step 309 is executed.

[0047] Step 308: Controller 20 keeps circulating water pump 18 running at maximum speed.

[0048] Step 309: Controller 20 keeps the circulating water pump 18 running at the speed corresponding to the target circulating water flow rate Qt.

[0049] Step 310: Controller 20 keeps circulating water pump 18 running at its current speed;

[0050] Step 311: Ignition and combustion.

[0051] After the circulating water pump 18 reaches a stable speed, the controller 20 controls the gas valve 15 to open to a suitable degree, controls the fan 16 to run at a certain speed, and controls the burner assembly to ignite and burn.

[0052] By ensuring a large circulating water flow during preheating circulation, frequent equipment start-ups and shutdowns can be avoided due to excessively rapid local temperature rise in the preheating circulation pipeline. At the same time, it ensures more thorough preheating and more uniform temperature distribution in the circulation pipeline.

[0053] Figure 4 The following describes the steps of a control method for stopping the preheating cycle of a gas-fired water heater in one embodiment. The execution of these steps by the controller 20 will also be described in detail below.

[0054] During the preheating circulation mode operation (step 401), the controller 20 monitors the return water temperature and the outlet water temperature through the return water temperature sensor 171 and the outlet water temperature sensor 172 respectively, 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 Tool (step 402); if so, the controller controls the burner assembly to stop working (step 403), and controls the circulating water pump 18 to continue running for a predetermined time before stopping working (step 404), so that the water temperature distribution in the circulation pipeline is more uniform.

[0055] Figure 5 The diagram illustrates the steps of a control method for preheating circulation control of a gas-fired water heater in one embodiment. The following describes in detail the execution of these steps by the controller 20.

[0056] Step 801: Preheating cycle mode triggered.

[0057] In some embodiments, the preheating cycle mode may be activated during a fixed time period, such as between 4 PM and 6 PM. The start time of the fixed time period can be arbitrarily set by the user through the device's control panel or the associated mobile application. In other embodiments, the preheating cycle mode may always be active, or it may be turned on and off at any time via a separate function button.

[0058] Step 802: Start the circulating water pump and obtain the average circulating water flow rate Qav.

[0059] In the preheating circulation mode, during the operation of the circulating water pump 18, 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 rate data through the flow sensor 14 at fixed intervals, i.e., sampling periods, such as 0.1 seconds; during the stable operation of the water pump, the average value is calculated based on several flow rates obtained from the most recent (e.g., 10) consecutive sampling periods, i.e., the average circulating water flow rate Qav is obtained.

[0060] Step 803: Calculate the temperature difference limit ΔT between return water and outlet water.

[0061] The temperature difference limit ΔT between the return water and the outlet water is the difference between the outlet water temperature threshold Tol and the return water temperature threshold Til, i.e., ΔT = Tol - Til. It can be calculated using the minimum input load Pmin and the average circulating water flow rate Qav. For example, the temperature difference limit ΔT between the return water and the outlet water can be calculated using the formula ΔT = Pmin / (c × Qav), where c is the specific heat capacity of water.

[0062] Step 804: Obtain the return water temperature threshold Til.

[0063] 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 a predetermined outlet water temperature threshold Tol, i.e., Til = Tol - ΔT. The outlet water temperature threshold Tol can be preset and stored in a storage medium. In 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, i.e., the temperature that the user wants the circulating water in the preheating cycle 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 falling below a lower limit of 37°C, then the upper 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, such as the outlet water temperature threshold Tol being the preheating cycle set temperature Ts plus a temperature difference T1, i.e., Tol = Ts + T1, such as T1 = 6°C.

[0064] Step 805: Ignition and combustion.

[0065] The controller 20 controls the gas valve 15 to open to a suitable degree, controls the fan 16 to run at a certain speed, and controls the burner assembly to ignite and burn.

[0066] Step 806: Determine whether the preheating cycle stop condition has been met.

[0067] In the preheating cycle mode, the controller 20 monitors the return water temperature and the outlet water temperature through the return water temperature sensor 171 and the outlet water temperature sensor 172 respectively, 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 Tool; if so, step 807 is executed.

[0068] Step 807: Stop combustion, that is, the controller 20 controls the burner assembly to stop working, and closes the gas valve 15 and stops the fan 16 from running.

[0069] Step 808: The controller 20 further controls the circulating water pump 18 to continue running for a predetermined time and then stop working, so as to make the water temperature distribution in the circulation pipeline more uniform.

[0070] Figure 6 The following describes the steps of a control method for preheating circulation control of a gas-fired water heater in another embodiment. The controller 20 will also perform these steps in detail below.

[0071] Step 811: Preheating cycle mode triggered.

[0072] In some embodiments, the preheating cycle mode may be activated during a fixed time period, such as between 4 PM and 6 PM. The start time of the fixed time period can be arbitrarily set by the user through the device's control panel or the associated mobile application. In other embodiments, the preheating cycle mode may always be active, or it may be turned on and off at any time via a separate function button.

[0073] Step 812: Start the circulating water pump and obtain the average circulating water flow rate Qav.

[0074] In the preheating circulation mode, during the operation of the circulating water pump 18, 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 rate data through the flow sensor 14 at fixed intervals, i.e., sampling periods, such as 0.1 seconds; during the stable operation of the water pump, the average value is calculated based on several flow rates obtained from the most recent (e.g., 10) consecutive sampling periods, i.e., the average circulating water flow rate Qav is obtained.

[0075] Step 813: Calculate the temperature difference limit ΔT between return water and outlet water.

[0076] The temperature difference limit ΔT between the return water and the outlet water is the difference between the outlet water temperature threshold Tol and the return water temperature threshold Til, i.e., ΔT = Tol - Til. It can be calculated using the minimum input load Pmin and the average circulating water flow rate Qav. For example, the temperature difference limit ΔT between the return water and the outlet water can be calculated using the formula ΔT = Pmin / (c × Qav), where c is the specific heat capacity of water.

[0077] Step 814: Calculate the return water temperature threshold Til.

[0078] 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 a predetermined outlet water temperature threshold Tol, i.e., Til = Tol - ΔT. The outlet water temperature threshold Tol can be preset and stored in a storage medium. In 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, i.e., the temperature that the user wants the circulating water in the preheating cycle 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 falling below a lower limit of 37°C, then the upper 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, such as the outlet water temperature threshold Tol being the preheating cycle set temperature Ts plus a temperature difference T1, i.e., Tol = Ts + T1, such as T1 = 6°C.

[0079] 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, keep the calculated return water temperature threshold and proceed to step 817; if the calculated return water temperature threshold Til is less than the predetermined minimum allowable return water temperature threshold Talo, proceed to step 816.

[0080] Step 816: When 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 preset to avoid the calculated return water temperature threshold Til being too low and affecting the user's comfort.

[0081] Step 817: Ignition and combustion.

[0082] The controller 20 controls the gas valve 15 to open to a suitable degree, controls the fan 16 to run at a certain speed, and controls the burner assembly to ignite and burn.

[0083] Step 818: Determine whether the preheating cycle stop condition has been met.

[0084] In the preheating cycle mode, the controller 20 monitors the return water temperature and the outlet water temperature through the return water temperature sensor 171 and the outlet water temperature sensor 172 respectively, 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 Tool; if so, step 807 is executed.

[0085] Step 819: Stop combustion, that is, the controller 20 controls the burner assembly to stop working, and closes the gas valve 15 and stops the fan 16 from running.

[0086] Step 820: The controller 20 further controls the circulating water pump 18 to continue running for a predetermined time and then stop working, so as to make the water temperature distribution in the circulation pipeline more uniform.

[0087] Over time, the circulating water system in a user's home may experience reduced flow due to increased water resistance. The above embodiment adaptively adjusts the return water temperature threshold based on the circulating water flow, which can alleviate frequent start-ups and shutdowns during the preheating process and ensure more thorough preheating and more uniform temperature distribution in the circulation pipeline. Furthermore, by pre-setting a minimum permissible return water temperature threshold, it is possible to prevent the adjusted return water temperature threshold from being too low, which could lead to excessively low circulating water temperatures and affect user comfort.

[0088] All or part of the steps in the methods of the above-disclosed embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable files, or some intermediate form. The readable storage medium can contain 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 storage, flash memory, solid-state memory, magnetic disk, or optical disk, etc.

[0089] It should be understood that the methods and apparatus disclosed above can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative. The division of units in the controller is only a logical functional division; in actual implementation, there may be other division methods. For example, multiple units may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the connections between the components, parts, and units discussed above can be electrical, mechanical, or other forms of connection; they can be direct connections or indirect connections through interfaces, etc.; they can be wired connections or wireless connections.

[0090] Furthermore, 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 can be selected to achieve the purpose of the disclosed embodiments according to actual needs. Additionally, the functional units in the above embodiments can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated units described above can be implemented in hardware or in a combination of hardware and software functional units.

[0091] It should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This way of describing the specification is only for 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 method for controlling the circulating water pump of a gas-fired hot water equipment, characterized in that, The method includes: Obtain the temperature difference limit ΔT between the return water and the outlet water. The temperature difference limit ΔT between the return water and the outlet water is the difference between the outlet water temperature threshold Tol and the return water temperature threshold Til, that is, ΔT = Tol - Til. Based on the minimum input load Pmin of the equipment and the temperature difference limit between the return water and the outlet water ΔT, the target circulating water flow rate Qt is calculated, i.e., Qt=Pmin / (c×ΔT), where c is the specific heat capacity of water; Obtain the current water flow rate of the circulating water pump during preheating circulation mode and compare it with the target circulating water flow rate; If the current water flow rate is greater than or equal to the target circulating water flow rate, the circulating water pump will maintain its current speed; if the current water flow rate is less than the target circulating water flow rate, the pump speed will be increased.

2. The circulating water pump control method for a gas-fired hot water equipment according to claim 1, characterized in that: The method also includes maintaining the corresponding speed of the circulating water pump as the pump speed increases, when the current water flow reaches the target circulating water flow.

3. The circulating water pump control method for a gas-fired hot water equipment according to claim 1, characterized in that: The method also includes the following: when the pump speed increases to the maximum speed but the current water flow still does not reach the target water flow, the circulating water pump will continue to operate at the maximum speed.

4. The circulating water pump control method for a gas-fired hot water equipment according to claim 1, characterized in that: The step of obtaining the temperature difference limit between the return water and the outlet water includes: Obtain the preheating cycle set temperature; Determine the outlet water temperature threshold and return water temperature threshold based on the preheating cycle set temperature; The temperature difference limit between the return water and the outlet water is calculated by the difference between the outlet water temperature threshold and the return water temperature threshold.

5. A computer-readable storage medium having instructions stored thereon, characterized in that: When the instructions are executed by the processor, they implement the method as described in any one of claims 1-4.

6. A gas-fired hot water device, characterized in that: The device includes a burner assembly, a flow sensor, a circulating water pump, and a controller; wherein the controller is configured to... Obtain the temperature difference limit ΔT between the return water and the outlet water. The temperature difference limit ΔT between the return water and the outlet water is the difference between the outlet water temperature threshold Tol and the return water temperature threshold Til, that is, ΔT = Tol - Til. Based on the minimum input load Pmin of the equipment and the temperature difference limit between the return water and the outlet water ΔT, the target circulating water flow rate Qt is calculated, i.e., Qt=Pmin / (c×ΔT), where c is the specific heat capacity of water; The current water flow rate of the circulating water pump in the preheating circulation mode is obtained by a flow sensor and compared with the target circulating water flow rate. If the current water flow rate is greater than or equal to the target circulating water flow rate, the circulating water pump will maintain its current speed; if the current water flow rate is less than the target circulating water flow rate, the pump speed will be increased.

7. The gas-fired hot water equipment according to claim 6, characterized in that: The controller is also configured to maintain the corresponding operating speed of the circulating water pump when the current water flow reaches the target circulating water flow as the pump speed increases.

8. The gas-fired hot water equipment according to claim 6, characterized in that: The controller is also configured to keep the circulating water pump running at its maximum speed when the current water flow rate has not yet reached the target water flow rate when the pump speed increases to the maximum speed.

9. The gas-fired hot water equipment according to claim 6, characterized in that: The controller's control for obtaining the temperature difference limit between the return water and the outlet water includes... Obtain the preheating cycle set temperature; Determine the outlet water temperature threshold and return water temperature threshold based on the preheating cycle set temperature; The temperature difference limit between the return water and the outlet water is calculated by the difference between the outlet water temperature threshold and the return water temperature threshold.

10. The gas-fired hot water equipment according to any one of claims 6 to 9, characterized in that: The device also includes a return water temperature sensor and an outlet water temperature sensor; the controller is further configured to, The return water temperature and the outlet water temperature are monitored by a return water temperature sensor and an outlet water temperature sensor, respectively. 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 burner assembly is controlled to stop working, and the circulating water pump is controlled to continue running for a predetermined time before stopping.

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