A method for constant temperature control of a water heater and a water heater

Abstract

The present application relates to a kind of thermostatic control methods of water heater, the water heater includes inlet pipe, heat exchanger, burner and outlet pipe, the inlet pipe is connected with the water inlet of heat exchanger, outlet pipe is connected with the water outlet of heat exchanger, the burner is set up for heating the water of heat exchanger for corresponding heat exchanger, it is characterized by: water heater is closed, control continues to heat by increasing the heating load of burner, so that the water temperature in outlet pipe, heat exchanger is higher than the set outlet temperature T0.This thermostatic control method, energy consumption is low, can improve the thermostatic property of outlet temperature.The present application also relates to the water heater using the thermostatic control method, the water heater does not need to set up heating device additionally, reduce cost, while not waste excessive energy consumption, outlet temperature stability is good when closing water and opening water again.

Description

TECHNICAL FIELD

[0001] The present application relates to a constant temperature control method of a water heater, and also relates to a water heater applying the constant temperature control method. BACKGROUND

[0002] When the water heater is turned off and then turned on again, the heating energy cannot be instantly increased from the ignition energy to the target load, and there is also a process of pre-cleaning the fan before ignition. During this process, the fan rotates to exhaust waste gas. At this time, the water in the pipeline is flowing, but has not been ignited. These two points cause the water temperature to drop sharply, and ultimately the user at the water end will feel that the water temperature is hot and cold, especially in winter. Based on this, the existing technology mainly uses the following two technical means to solve this problem.

[0003] The first is to set up a circulating pipeline, which starts the water circulation work after the water heater is turned off, so that the water heater is in a continuous working state, thereby ensuring that the water temperature is maintained at a constant temperature. For example, the Chinese patent application for invention with publication number CN113124571A (application number 201911426187.0) “Control method of water heater system and water heater system” discloses a water heater system. When the preheating function of the gas water heater is turned on, the water preheated by the gas water heater is circulated in the preheating circulation loop composed of the hot water pipe, the backwater device, the water pipe and the water heater to perform cycle preheating. A water again signal is obtained. Before the electric control valve is closed, the water heater system starts the preheating function, obtains a signal that the gas water heater first starts the preheating function, detects the backwater temperature of the water inlet end of the water inlet pipe of the gas water heater, confirms that the backwater temperature of the water inlet end reaches a first preset temperature, controls the gas water heater to stop preheating, and obtains the first preheating time of the gas water heater. According to the first preheating time, the cycle preheating time of the water heater is confirmed. The gas water heater obtains a signal that the preheating function is started again, and controls the water heater to perform cycle preheating according to the cycle preheating time of the gas water heater. This water heater cannot completely solve the problem of constant water temperature, and also has the problems of high energy consumption and slow first heating.

[0004] The second is to solve the problem by setting an additional heating device. For example, a hot water heater disclosed in a Chinese patent for invention with publication number CN112443984B (application number 202011348327.X) "Hot water heater and its water outlet control system and water supply system" additionally sets a heat pool for storing water, and a heating module is arranged in the heat pool. The water in the heat pool is heated to a set temperature range by the heating module. After the water is turned off and then turned on, a small amount of cold water output by the hot water heater is neutralized by mixing to ensure the constant temperature of the output water. A Chinese patent application for invention with publication number CN113154689A (application number 202110443048.X) "Control method of gas hot water heater and gas hot water heater" discloses a hot water heater provided with an additional electric heating module. After the water is turned off and then turned on, the electric heating module is used for auxiliary heating to reduce the temperature fluctuation range. The hot water heater with such a structure has high structure cost, high energy consumption and slow initial heating. SUMMARY

[0005] The first technical problem to be solved by the present application is to provide a constant temperature control method for a hot water heater that can adjust the post-cleaning work parameters for short water-off and water-on situations, eliminate the pre-cleaning process, and thus increase the water outlet temperature in a short time, thereby reducing the water temperature drop during water stoppage.

[0006] The second technical problem to be solved by the present application is to provide a hot water heater that can avoid excessive temperature drop during water-off and water-on.

[0007] The technical solution adopted by the present application to solve the above-mentioned first technical problem is a constant temperature control method for a hot water heater, characterized in that: after the hot water heater is turned off, the post-cleaning time t is extended, and when the hot water heater is turned on again, the pre-cleaning process is omitted, and the burner is directly ignited for heating.

[0008] Alternatively, after the hot water heater is turned off, the post-cleaning time is extended to one of the hot water heater being turned on again and the upper limit time threshold tmax.

[0009] Alternatively, the post-cleaning time t is calculated according to the temperature difference AT between the current water flow Q, the target water outlet temperature and the water inlet temperature, and the post-cleaning rotation speed R is calculated according to the set total cleaning air volume X and the calculated post-cleaning time t.

[0010] As an improvement, the calculation formula of the post-cleaning time t is t=k1*Q*AT, wherein k1 is a first calculation coefficient adjusted according to the water inlet temperature;

[0011] The calculation formula of the post-cleaning rotation speed R is R=k2*X / t, wherein k2 is a second calculation coefficient adjusted according to the water inlet temperature.

[0012] As an improvement, when the water heater turns on the water again, the heating load is controlled to be increased to P when the water is turned on again.

[0013] As an improvement, the heating load P when the water heater turns on again is calculated based on the post-cleaning time t and the set initial heating load P0. The calculation formula for the heating load P when the water heater turns on again is P=k3*t*P0, where k3 is the third calculation coefficient adjusted according to the inlet water temperature.

[0014] As an improvement, the current water inlet temperature T is obtained and compared with the set temperature threshold T0; if T<T0, after the water heater is turned off, the post-cleaning time is controlled to be extended compared with the standard post-cleaning time t0 in the standard working parameters of the water heater; when the water heater is turned on again, the pre-cleaning work is omitted and the burner is controlled to directly ignite for heating.

[0015] As an improvement, if T≥T0, the water heater is controlled to operate according to the standard operating parameters of the water heater; or

[0016] The post-cleaning time is shortened compared to the post-cleaning time t corresponding to the time T<T0, and the post-cleaning speed is increased compared to the post-cleaning speed corresponding to the time T<T0.

[0017] The technical solution adopted by the present invention to solve the above-mentioned second technical problem is: a water heater, including a water inlet pipe, a heat exchanger, a burner and a water outlet pipe, the water inlet pipe is connected to the water inlet of the heat exchanger, the water outlet pipe is connected to the water outlet of the heat exchanger, the burner is arranged corresponding to the heat exchanger and is used to heat the water flowing through the heat exchanger, the water heater also includes a memory and a processor, and is characterized in that: the memory also stores a program for implementing the constant temperature control method as mentioned above, and the processor can call and execute the program in the memory.

[0018] In order to achieve further water mixing in the early stage of re-opening the water so that the temperature of the output water is closer to the target water outlet temperature, a water tank is further provided on the water outlet pipe.

[0019] Compared with the prior art, the advantages of the present invention are: the constant temperature control method of the water heater in the present invention, after the water heater is turned off, by extending the post-cleaning time, so that under the premise of ensuring cleaning safety and reliable ignition, the pre-cleaning time when the water heater is turned on again can be set to 0, that is, the pre-cleaning work is omitted and the ignition is directly ignited for heating, which can quickly increase the outlet water temperature, so that the outlet water temperature can reach the target outlet water temperature at the fastest speed, thereby achieving the purpose of reducing the excessive temperature drop when the water is shut off and improving the user experience.

[0020] For water heaters that use this method, the outlet water temperature is stable when the water is turned off and then on again. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Flowchart of a constant temperature control method for a water heater in an embodiment of the present invention. DETAILED DESCRIPTION

[0022] The present invention will be described in further detail below with reference to the accompanying drawings and embodiments.

[0023] The water heater in this embodiment includes a water inlet pipe, a heat exchanger, a burner, and a water outlet pipe. The water inlet pipe is connected to the water inlet of the heat exchanger, and the water outlet pipe is connected to the water outlet of the heat exchanger. The burner in this embodiment is a gas burner. Depending on the specific type of water heater, the burner can also be a other type of heating device or a burner using other fuels. The burner is configured to correspond to the heat exchanger and is used to heat the water flowing through the heat exchanger. During operation, water from the water source is supplied to the water inlet pipe. As the water in the water inlet pipe flows through the heat exchanger, the burner heats the water in the heat exchanger.

[0024] In addition, a water tank can be installed on the water outlet pipe. After the water heater is turned off, the heat output by the burner can raise the temperature of the water in the heat exchanger, the water outlet pipe, and the water tank. In this way, when the water heater is turned off and then turned on again, the water in the water tank will flow out slowly. In the early stage of turning on again, the water that has just entered the water inlet pipe will be heated by the heat exchanger and flow into the water tank. This part of the lower temperature water will mix with the higher temperature water in the water tank, reducing the fluctuation of the output water temperature, making the output water temperature closer to the target water outlet temperature, and improving the constant temperature performance of the water heater.

[0025] The water heater also includes a memory and a processor. The memory also stores a program for implementing the constant temperature control method described below. The processor can retrieve and execute the program in the memory.

[0026] When using a water heater, it is common to encounter the situation where the water is turned off and then turned on again within a short period of time, such as when washing dishes or taking a shower. This situation usually occurs within 3 minutes. When the water heater is turned off and then turned on again, the water heater re-ignites, and the heating energy cannot be instantly increased from the ignition energy to the target load. At the same time, there is a fan cleaning process before ignition. During this process, the fan rotates to discharge the exhaust gas. At this time, the water in the pipe is flowing, but it has not yet been ignited. These two points cause the water temperature to drop sharply, and ultimately cause users to experience the water temperature fluctuating between hot and cold, which is a very poor user experience, especially in winter.

[0027] Based on this situation, Figure 1 As shown, the constant temperature control method of the water heater in this embodiment is specifically as follows.

[0028] After the water heater is shut off, the post-cleaning parameters are adjusted. This ensures that post-cleaning is safe and ignition is reliable. When the water heater is turned back on, pre-cleaning is omitted and the burner is controlled to ignite directly for heating. This heats the cold water flowing through the heat exchanger at the fastest speed, rapidly raising the water temperature and reducing the temperature drop during water shutoff. The post-cleaning parameters specifically include post-cleaning time t and post-cleaning speed R. By extending the post-cleaning time, pre-cleaning can be omitted when the water heater is turned back on. At the same time, the coordination of post-cleaning speed R and post-cleaning time t ensures a clean cleaning process.

[0029] The method of extending the post-cleaning time can adopt either of the following two methods.

[0030] One method for extending the post-cleaning time is to extend it to either the time the water heater is turned off or the upper time threshold, tmax. Setting the upper time threshold prevents the post-cleaning process from continuing even when the user is not using the water heater. Typically, the interval between a short water shut-off and water restart does not exceed tmax. For example, tmax can be between 3 and 5 minutes.

[0031] Another method is to calculate the post-cleaning time t based on the current water flow rate Q and the temperature difference ΔT between the target outlet and inlet water temperatures, and to calculate the post-cleaning speed R based on the set total cleaning air volume X and the calculated post-cleaning time t. This method is used in this embodiment to achieve more precise control of the water heater.

[0032] In this embodiment, after the water heater is turned off, the post-cleaning time t is calculated based on the current water flow rate Q and the temperature difference ΔT between the target water outlet temperature and the water inlet temperature; and the post-cleaning speed R is calculated based on the set total cleaning air volume X and the calculated post-cleaning time t to ensure that the water can be cleaned thoroughly within the post-cleaning time t and ensure safe use.

[0033] Specifically, the calculation formula for the post-cleaning time t is t=k1*Q*ΔT, where k1 is the first calculation coefficient adjusted according to the inlet water temperature, and k1 can be obtained through experimental tests. ΔT=Ts-T, where Ts is the target outlet water temperature and T is the inlet water temperature. The calculation formula for the post-cleaning speed R is R=k2*X / t, where k2 is the second calculation coefficient adjusted according to the inlet water temperature, and k2 can be obtained through experimental tests. It can be seen that the post-cleaning time t is positively correlated with the inlet water flow rate Q and the temperature difference ΔT. That is, the greater the inlet water flow rate and the greater the temperature difference between the inlet water temperature and the target temperature, the longer the required cleaning time will be. In order to ensure that the cleaning is thorough, the post-cleaning speed R is negatively correlated with the post-cleaning time t. The total cleaning air volume X can also be obtained through multiple experimental tests. Based on the total cleaning air volume X, the safety of post-cleaning can be guaranteed, and it will not affect re-ignition. When re-igniting, there will be no deflagration, flame separation, or other working conditions that affect flame stability.

[0034] In addition, based on the fact that the post-cleaning time is extended so that the ignition can be directly started when the water is turned on again, thereby achieving a rapid increase in the outlet water temperature, the outlet water temperature can also be rapidly increased by adjusting the heating load P when the water heater turns on again. In this embodiment, when the water heater turns on again, the heating load when the water is turned on again is controlled to be P. Specifically, the heating load P when the water heater turns on again can be calculated based on the post-cleaning time t and the set initial heating load P0. The calculation formula for the heating load P when the water heater turns on again is P=k3*t*P0, where k3 is the third calculation coefficient adjusted according to the inlet water temperature, and the third calculation coefficient can be obtained based on experimental tests. For example, in the aforementioned cases of T≥T0 and T<T0, different third calculation coefficients k3 are used respectively. In this way, when the water heater turns on again, the heating load when the water is turned on again is controlled to be P.

[0035] When the water heater is in use, the difference in water inlet temperature between summer and winter is quite large. In summer, the water inlet temperature usually exceeds 20°C. When the external ambient temperature is high, the user is relatively less sensitive to the temperature drop when the water heater is turned off and then turned on again. In winter, the water inlet temperature is usually below 10°C, and the user is highly sensitive to the temperature drop when the water heater is turned off and then turned on again. At the same time, due to the lower water inlet temperature, the requirement for a rapid increase in water temperature is higher.

[0036] Based on this, in this embodiment, the current inlet water temperature T is obtained and compared with the set temperature threshold T0. The temperature threshold T0 is usually set to a relatively moderate temperature data, such as a temperature data within the range of 18°C ​​to 25°C.

[0037] If T < T0, it indicates that the ambient temperature is low and the user is relatively sensitive to the temperature drop when the water heater is turned off and then turned back on. Therefore, it is necessary to minimize the temperature drop when the water heater is turned back on. In this embodiment, the post-cleaning time is extended compared to the standard post-cleaning time t0 in the water heater's standard operating parameters, and the post-cleaning speed is reduced compared to the standard post-cleaning speed R0 in the water heater's standard operating parameters. Extending the post-cleaning time allows for a short period of re-ignition during the post-cleaning process, allowing for direct ignition, thereby reducing the water temperature drop. After the post-cleaning time is extended, the post-cleaning speed can be appropriately reduced to minimize disturbance to the user while still achieving the desired cleaning result.

[0038] If T ≥ T0, the ambient temperature is considered relatively high, and the user is relatively less sensitive to the temperature drop when the water heater is turned off and then on again. This allows the water heater to operate according to standard operating parameters, or the post-cleaning time t to be shortened compared to the corresponding post-cleaning time when T < T0, minimizing disruption to the user while the fan is running and saving energy. Furthermore, the post-cleaning speed can be increased compared to the corresponding post-cleaning speed when T < T0 to ensure a thorough post-cleaning process.

[0039] If T ≥ T0 and the post-cleaning time is shortened, the post-cleaning process may have stopped for a while during the brief water shut-off and restart. Therefore, if necessary, the pre-cleaning process can be performed before the burner ignition to ensure safe use. However, if T ≥ T0, the temperature drop during the brief water shut-off and restart period is relatively low, and users are less sensitive to temperature drops, so this adjustment will have little impact on users. Alternatively, to increase the outlet water temperature's rise rate, the heating load P can be further increased to quickly raise the outlet water temperature.

[0040] The constant temperature control method of the water heater in the present invention extends the post-cleaning time after the water heater is turned off, so that under the premise of ensuring cleaning safety and reliable ignition, the pre-cleaning time when the water heater is turned on again can be set to 0, that is, the pre-cleaning work is omitted and the ignition is directly ignited for heating, which can quickly increase the outlet water temperature, so that the outlet water temperature can reach the target outlet water temperature at the fastest speed, thereby achieving the purpose of reducing the excessive temperature drop when the water is stopped and improving the user experience.

[0041] For water heaters that use this method, the outlet water temperature is stable when the water is turned off and then on again.

Claims

1. A constant temperature control method for a water heater, characterized by: After the water heater is turned off, the post-cleaning time t is extended. When the water heater is turned on again, the pre-cleaning work is omitted and the burner is controlled to ignite directly for heating; Obtain the current water inlet temperature T and compare it with the set temperature threshold T0. If T < T0, after the water heater is turned off, the post-cleaning time is extended compared to the standard post-cleaning time t0 in the water heater's standard operating parameters. When the water heater is turned on again, the pre-cleaning work is omitted and the burner is controlled to ignite directly for heating. If T≥T0, control the water heater to operate according to the standard operating parameters of the water heater; or The post-cleaning time is shortened compared to the post-cleaning time t corresponding to the time T<T0, and the post-cleaning speed is increased compared to the post-cleaning speed corresponding to the time T<T0.

2. The constant temperature control method for a water heater according to claim 1, characterized in that: After the water heater is turned off, the post-cleaning time is extended to one of the time when the water heater is turned on again or the upper limit time threshold tmax.

3. The constant temperature control method for a water heater according to claim 1, characterized in that: The post-cleaning time t is calculated based on the current water flow rate Q and the temperature difference ΔT between the target water outlet temperature and the water inlet temperature, and the post-cleaning speed R is calculated based on the set total cleaning air volume X and the calculated post-cleaning time t.

4. The constant temperature control method for a water heater according to claim 3, characterized in that: The calculation formula of the post-cleaning time t is t = k1*Q*ΔT, where k1 is the first calculation coefficient adjusted according to the inlet water temperature; The calculation formula of the post-cleaning speed R is R=k2*X / t, where k2 is the second calculation coefficient adjusted according to the inlet water temperature.

5. The constant temperature control method for a water heater according to claim 1, characterized in that: When the water heater is turned on again, the heating load is controlled to be increased to P.

6. The constant temperature control method for a water heater according to claim 5, characterized in that: The heating load P when the water heater turns on again is calculated based on the post-cleaning time t and the set initial heating load P0. The calculation formula for the heating load P when the water heater turns on again is P=k3*t*P0, where k3 is the third calculation coefficient adjusted according to the inlet water temperature.

7. A water heater comprising a water inlet pipe, a heat exchanger, a burner, and a water outlet pipe, wherein the water inlet pipe is connected to the water inlet of the heat exchanger, the water outlet pipe is connected to the water outlet of the heat exchanger, the burner is arranged corresponding to the heat exchanger and is used to heat water flowing through the heat exchanger, and the water heater further comprises a memory and a processor, characterized in that: The memory also stores a program for implementing the constant temperature control method according to any one of claims 1 to 6, and the processor can call and execute the program in the memory.

8. The water heater according to claim 7, characterized in that: A water tank is also provided on the water outlet pipe.

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