JP2015503724A - Hot water supply apparatus and hot water supply method - Google Patents

Abstract

A hot water supply apparatus and a hot water supply method are provided. The hot water supply device includes: a heater that heats inflowed water by a heater heating capacity; a water discharge valve that adjusts an amount of water discharged from the heater; a temperature sensor that measures a water discharge temperature of the discharged water; And a control unit that controls the degree of opening of the water discharge valve in proportion to the difference in target temperature. The said control part calculates the variation | change_quantity of the said water discharge temperature value, and adjusts the open degree of the said water discharge valve according to the said temperature variation calculated. [Selection] Figure 1

Description

  The present invention relates to a hot water supply apparatus and a hot water supply method, and more particularly to a direct water type hot water supply apparatus and a direct water type hot water supply method capable of quickly distributing hot water.

  A hot water supply device used for a water purifier or the like includes a water tank type hot water supply device in which a heater is installed in a water tank, and a direct water type hot water supply device that heats water by using a heater as necessary. Can be classified.

  A water tank type hot water supply device obtains purified water suitable for drinking by filtering normal temperature water supplied from the water supply with a filter, etc., heats the purified water stored in the water tank, and supplies the heated water to the user. Supply. In this case, the water tank type hot water supply device includes a purified water tank that stores the filtered purified water in a room temperature state, and a hot water tank that stores the heated water heated to a predetermined temperature. It can also be configured such that purified water is supplied to a hot water tank and heated by a heater installed in the hot water tank to form hot water.

  However, in the hot water supply device of the water tank type, regardless of whether hot water is used or not, it consumes standby power because the temperature of the hot water must be maintained at a predetermined temperature in the water tank, Since a separate hot water tank must be provided, sufficient space must be secured. Further, due to the characteristic of water having a high specific heat, a waiting time of several tens of seconds to several minutes is required.

  Therefore, recently, a direct water type hot water supply device that supplies hot water by instantaneously heating in response to a request for supply of hot water from a user has been used. However, it is not possible to provide hot water at a target temperature desired by the user in the initial stage of discharging hot water.

  An object of the present invention is to provide a direct water type hot water supply apparatus and a direct water type hot water supply method for quickly distributing hot water.

  The hot water supply apparatus of the present invention includes a heater that heats inflowed water by a heater heating capacity, a water discharge valve that adjusts the amount of water discharged from the heater, and a temperature sensor that measures a water discharge temperature of the water discharged. And a controller that controls the degree of opening of the water discharge valve in proportion to the temperature difference between the water temperature and the target temperature.

  Here, the control unit can calculate a change amount of the water discharge temperature and adjust an opening degree of the water discharge valve according to the calculated change amount.

  Here, the hot water supply device further includes a voltage detection unit that detects a supply voltage supplied from a power source, and the control unit calculates the heater heating capacity using the supply voltage, and the heater heating capacity And the opening degree of the water discharge valve can be set using the temperature difference between the water discharge temperature and the target temperature.

  Here, the voltage detection unit can detect the supply voltage when a hot water distribution signal for requesting hot water distribution is input or when a preset time interval elapses.

  Here, the voltage detection unit can convert the supply voltage input by alternating current into a direct current voltage, quantize the converted direct current voltage, and detect the magnitude of the supply voltage.

  Here, the control unit can set a proportionality constant corresponding to the heater heating capacity, and can set the degree of opening of the water discharge valve in proportion to the temperature difference between the water discharge temperature and the target temperature.

  Here, when the temperature difference between the outlet temperature and the target temperature is equal to or greater than a preset value and the calculated change amount is equal to or greater than a first reference change amount, the control unit The degree of opening of the water discharge valve at the time when the amount of change is calculated can be maintained for a first set time.

  Here, when the temperature difference between the outlet temperature and the target temperature is less than a preset value, and the calculated change amount is less than a second reference change amount, the control unit The degree of opening of the water discharge valve at the time when the amount of change is calculated can be maintained for a second set time.

  In the hot water supply method of the present invention, when a hot water supply signal is input, an initial opening degree of the water discharge valve that adjusts the amount of water discharged from the heater is set, and the water discharge valve is set to the set opening degree. An initial water discharge operation that opens, and a water discharge control operation that controls the degree of opening of the water discharge valve in proportion to the temperature difference between the water discharge temperature and the target temperature.

  The initial water discharge operation may further include a heater heating capacity calculation operation of measuring a supply voltage supplied from a power source and calculating a heater heating capacity of the heater using the supply voltage.

  In the heater heating capacity calculation operation, when a warm water distribution signal for requesting warm water distribution is input or when a preset time interval elapses, the heater heating capacity is calculated by measuring the supply voltage. it can.

  In the heater heating capacity calculation operation, an AC supply voltage supplied from the power source is converted into a DC voltage, and the converted DC voltage is quantized to measure the magnitude of the supply voltage. it can.

  Here, the amount of change in the water discharge temperature can be calculated by the water discharge control operation, and the degree of opening of the water discharge valve can be adjusted according to the calculated amount of change.

  Here, in the water discharge control operation, when the temperature difference between the water discharge temperature and the target temperature is equal to or greater than a preset value, and the calculated change amount is equal to or greater than a first reference change amount, The degree of opening of the water discharge valve at the time when the amount of change is calculated can be maintained for a first set time.

  Here, in the water discharge control operation, when the temperature difference between the water discharge temperature and the target temperature is less than a preset value, and the calculated change amount is equal to or greater than a second reference change amount, The degree of opening of the water discharge valve at the time when the amount of change is calculated can be maintained for a second set time.

  According to the hot water supply device and the hot water supply method according to the embodiment of the present invention, hot water having a target temperature desired by the user can be provided from the initial water discharge.

  In addition, since the control operation for extracting the target temperature is minimized, the energy required for the hot water extraction can be reduced.

  Moreover, since warm water is generated in consideration of changes in the heater heating capacity due to voltage fluctuations of the commercial AC power supply, it is possible to distribute hot water having an accurate target temperature. In addition, since the heater heating capacity is calculated by directly measuring the voltage applied to the heater, it is possible to provide hot water having a target temperature desired by the user even in foreign countries where the magnitude of the voltage of the commercial AC power supply is different. .

It is the block diagram which showed the hot water supply apparatus of one Embodiment of this invention.

It is the flowchart which showed the warm water supply method of one Embodiment of this invention.

It is the flowchart which showed the initial water discharge operation of the warm water supply method of one Embodiment of this invention.

It is the graph which showed the discharge temperature of the warm water discharged | emitted from the warm water supply apparatus of one Embodiment of this invention. It is the graph which showed the discharge temperature of the warm water discharged | emitted from the warm water supply apparatus of one Embodiment of this invention.

  Hereinafter, embodiments will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains can easily implement the present invention. However, in the description of the present invention, if it is considered that the description of related known functions or structures will unnecessarily change the gist of the present invention, such description is omitted, but will be understood by those skilled in the art. That would be true. Throughout the specification, the same reference numerals are used for the same parts.

  When a component is “connected” to another component, it is not only directly connected to the other component, but also indirectly connected via an intervening component. This includes cases where In contrast, when a component is “directly connected” to another component, there are no intervening components. In addition, unless clearly stated, the words “comprise”, “comprises”, “comprising”, etc. mean that the constituent elements described are included. It will be understood that it does not exclude any of the components, but means that other components can be further included.

  FIG. 1 is a block diagram showing an embodiment of the hot water supply apparatus of the present invention.

  Referring to FIG. 1, the hot water supply apparatus according to an embodiment of the present invention may include a heater 10, a water outlet valve 20, a temperature sensor 31, a water incoming temperature sensor 32, and a control unit 40.

  Hereinafter, a hot water supply apparatus according to an embodiment of the present invention will be described with reference to FIG.

  The heater 10 heats the introduced water with a heater heating capacity. The heater heating capacity is related to the power consumption of the heater 10 and can be expressed in watts (w). The heater 10 can uniformly heat the inflowing water with a preset heater heating capacity.

  The amount of heat that the inflowing water receives from the heater 10 can be proportional to the heater heating capacity and the time (or period) when the water is heated by the heater 10. Therefore, if the heater heating capacity of the heater 10 is kept constant, the amount of heat that the inflowing water receives from the heater 10 can be proportional to the time during which the water is heated by the heater 10. Here, the time during which the inflowing water is heated by the heater 10 can be determined according to the time it takes for the inflowing water to flow out of the heater through the water outlet valve 20, and therefore the heating time is determined by the water outlet valve. It can be adjusted according to the opening degree of 20.

  The heater 10 can be turned on and off by the control unit 40. When a warm water distribution signal is input, the control unit 40 turns on the heater 10 and heats the inflowed water with the heater heating capacity. Can do.

  However, when the voltage or current supplied to the heater 10 is not constant, the heater heating capacity cannot be kept constant. The heater heating capacity can be calculated by using at least two of the heater current V, the heater current I, and the heater resistance R (P = V * I = I ^ 2 / R = I ^ 2). * R), the commercial AC power supplied to the heater 10 actually has a voltage change of approximately 15%. Therefore, the voltage distributed to the heater 10 also fluctuates due to the voltage fluctuation of the commercial AC power supply, and the heater heating capacity fluctuates.

  In general, voltage fluctuations in commercial AC power supply are recognized as an allowable error range, and therefore, it is not necessary to consider the difference in heater heating capacity due to voltage change. However, when the heating and heating time is short and it is necessary to supply hot water having an accurate target temperature as in the case of a direct water type hot water supply apparatus, it is necessary to consider an error due to voltage fluctuation of the commercial AC power supply. Therefore, a commercial AC power source, that is, a voltage detection unit for detecting the magnitude of the voltage supplied by the power source can be further configured. That is, in consideration of the heater heating capacity based on the magnitude of the supply voltage measured by the voltage detection unit, the time for heating the water flowing into the heater 10 can be set.

  Specifically, the voltage detection unit performs half-wave rectification, smoothing, voltage drop, and conversion to a DC voltage from an AC voltage supplied from a power source, and converts an analog value of the DC voltage by an analog-to-digital converter (ADC). The supply voltage value can be obtained by quantization. For example, when the AC 200V commercial AC power supply is used, the voltage supplied from the power supply may fluctuate from 198V to 253V. Therefore, the voltage detection unit divides the supply voltage by 200V intervals at 200V, 210V, It can be measured at any one of 220V, 230V, 240V, and 250V. Therefore, the control unit 40 can calculate the heater heating capacity based on each measured supply voltage, and can set the opening / closing degree of the water discharge valve 20.

  However, in order to prevent power consumption by voltage detection, the voltage detection unit can detect voltage supply only at preset intervals or only when a hot water distribution signal is input.

  Furthermore, when the magnitude of either the current or voltage supplied from the power source is known, the heater heating capacity can be calculated, so that the current supplied from the power source can be calculated instead of the voltage detection unit. A current detection unit for detection can also be used.

  The water discharge valve 20 can adjust the amount of water discharged from the heater 10. As described above, by adjusting the amount of water discharged from the heater 10, the time during which the water that has flowed into the heater 10 is heated in the heater 10 can be adjusted. Specifically, when the opening degree of the water outlet valve 20 is increased, the time during which the introduced water is heated by the heater 10 can be shortened, and when the opening degree of the water outlet valve 20 is reduced, the introduced water is heated by the heater. The time heated by 10 can be lengthened. Therefore, the control unit 40 can control the temperature of the water discharged from the heater 10 to the target temperature by adjusting the opening degree of the water discharge valve.

  Here, the water discharge valve 20 adjusts the degree of opening of the water discharge valve 20 by adjusting the opening time of the water discharge valve 20 or the size of the cross-sectional area of the open flow path flow in accordance with a control signal from the control unit 40. be able to.

  Here, the water discharge valve 20 can include a flow path blocking unit such as a disk that blocks all or part of the flow path along the flow path for distributing water from the heater 10. Here, the amount of water discharged from the heater 10 per unit area can be adjusted by adjusting the size of the cross-sectional area of the flow path blocked by the flow path blocking unit.

  Further, the water discharge valve 20 can adjust the amount of water discharged from the heater 10 per unit time by periodically opening and closing the water discharge valve 20 in a short time. Can be implemented by pulse width modulation (PWM). For example, the water discharge valve 20 receives a control signal in a pulse form with a constant period transmitted by the control unit 40, and opens the water discharge valve 20 when the pulse is high, and closes the water discharge valve 20 when the pulse is low. Can do. Here, when the number of high pulses among the pulses transmitted by the controller 40 increases, the water discharge valve 20 can discharge a larger amount of water from the heater 10 per unit time.

  Therefore, by using the water discharge valve 20, it is possible to determine the amount of water discharged per unit time, that is, the water discharge speed of the water that has flowed into the heater 10. When the water discharge speed is increased, the time for heating the water that has flowed into the heater 10 in the heater 10 is reduced, so that the temperature of the water discharged from the heater 10 can be lowered. On the other hand, when the water discharge speed decreases, the time that the water that has flowed into the heater 10 stays in the heater 10 increases, so the time that the water that has flowed in is heated by the heater 10 increases, and the temperature of water obtained from the heater 10 Rises.

  Here, the degree of opening of the water discharge valve 20 can be continuously adjusted from fully opened to completely shut off, and the degree of opening can be set in accordance with a preset number of steps. For example, the degree of opening can be divided into four stages from fully open to complete shut-off. That is, the first stage can be completely shut off, the second stage can be opened by 1/3, the third stage can be opened by 2/3, and the fourth stage can be fully opened. In this case, by using the stepping motor, the water discharge valve 20 can be set to a predetermined number of opening degrees.

  Here, the water discharge valve 20 can have an initial opening degree set so as to control the water discharge temperature so as to reach the target temperature in the initial stage of water discharge. That is, the initial opening degree of the water discharge valve 20 can be set by the control unit 40 in order to discharge water at the target temperature from the time when water starts to be discharged from the heater 10.

  The temperature sensor 31 can measure the temperature of the discharged water. Any temperature sensor 31 can be used as long as it can measure the temperature of water. As shown in FIG. 1, the temperature sensor 31 can be provided between the water outlet valve 20 and the heater 10. Therefore, when the water outlet valve 20 is completely shut off, the water outlet temperature measured by the temperature sensor 31 becomes the temperature of the water stored in the heater 10.

  The hot water supply apparatus in the embodiment of the present invention can further include an incoming water temperature sensor 32. The incoming water temperature sensor 32 can measure the temperature of the water flowing into the heater 10. The measured inflow temperature can then be used to set the initial opening degree of the water discharge valve 20.

  When the warm water distribution signal is input, the control unit 40 can operate the heater 10, and the control unit 4 sets the initial opening degree of the water discharge valve 20 in order to start discharging water at the target temperature from the initial water discharge. can do.

  As described above, the water temperature measured by the temperature sensor 31 is equal to the temperature of the water stored in the heater 10. Therefore, the most appropriate opening degree of the water discharge valve 20 can be experimentally determined by varying the initial opening degree of the water discharge valve 20 depending on the water discharge temperature at the time of initial water discharge. That is, the degree of opening preset by the measured outlet temperature can be set as the initial opening degree of the outlet valve 20, so that water close to the target temperature can be discharged from the initial outlet.

  Here, the control unit 40 measures the use waiting time between when the water is finally discharged and when the water is discharged next, and sets the initial opening degree of the water discharge valve 20 based on the use waiting time and the discharge temperature. . That is, the control unit 40 can set the initial opening degree in consideration of the use standby time in the same manner as the water temperature.

  Further, the control unit 40 can receive the inflow temperature of water injected into the heater 10 and calculate the amount of water discharged from the heater using the received inflow temperature, heater heating capacity, and target temperature. it can. Thereby, the control part 40 can set the initial opening degree of the water discharge valve 20 with the calculated water discharge amount.

を使用することによりヒータ１０から出水される水の初期出水量を計算することができ、計算された初期出水量により出水弁２０の初期開放度を設定することができる。
すなわち、制御部４０は、入水温度センサ３２からの入水温度を受け取って、より正確に出水弁２０の初期開放度を設定することができる。ここで、Ｖは出水される水の容積、ｗはヒータ１０のヒータ加熱容量、ｃは水の比熱、ρは水の密度、Δｔは加熱時間、Ｔ_１は目標温度、Ｔ_２は流入温度である。 For example, the control unit 40 has the following formula:

The initial water discharge amount of water discharged from the heater 10 can be calculated, and the initial opening degree of the water discharge valve 20 can be set based on the calculated initial water discharge amount.
That is, the control unit 40 can receive the incoming water temperature from the incoming water temperature sensor 32 and set the initial opening degree of the water outlet valve 20 more accurately. Here, the volume of water V is a flood, w is a heater heating capacity of the heater 10, c is the specific heat of water, [rho is the density of water, Delta] t is the heating time, T ₁ is the target temperature, T ₂ in the inlet temperature is there.

  After the initial water discharge, the control unit 40 controls the degree of opening of the water discharge valve 20 in accordance with fluctuations in the value of the water discharge temperature.

  As described above, the temperature of the water flowing into the heater 10 can be increased in proportion to the heater heating capacity and the heating time by the heater 10.

  In general, since the heater heating capacity is kept constant, the controller 40 can control the heating time for heating the inflowing water by the heater 10 by adjusting the opening degree of the water outlet valve 20. Therefore, the control unit 40 can control the temperature of the water discharged from the heater 10 to the target temperature by adjusting the degree of opening of the water discharge valve 20 based on the water discharge temperature measured by the temperature sensor 31.

  Specifically, the control unit 40 can determine the difference between the water discharge temperature and the target temperature and control the degree of opening of the water discharge valve 20 so as to be proportional to the difference. That is, when the outlet temperature is higher than the target temperature, the control unit 40 can open the outlet valve in proportion to the difference between the outlet temperature and the target temperature, and the outlet temperature is higher than the target temperature. When it is low, the control unit 40 can close the water discharge valve in proportion to the difference between the water discharge temperature and the target temperature. Here, in the adjustment of the opening degree of the water discharge valve 20, by using a proportional expression based on the difference between the water discharge temperature and the target temperature, or by using a table created experimentally based on the water discharge temperature, Openness can be set.

  However, as described above, the heater heating capacity of the heater 10 may fluctuate due to voltage fluctuation of the commercial AC power supply. Therefore, in order to adjust the temperature more accurately, it is desirable to set the initial opening degree of the water discharge valve 20 in consideration of the change in the heater heating capacity due to the voltage fluctuation of the commercial AC power supply.

  As a result, the heater 10 can further include a voltage detection unit that detects the supply voltage from the power source, and the control unit 40 can obtain the heater heating capacity from the supply voltage. Specifically, the heater voltage value actually supplied to the heater 10 can be obtained from the applied voltage, and the actual heater heating capacity of the heater 10 can be calculated by using the heater voltage. it can. That is, the control unit 40 can calculate the actual heater heating capacity by substituting the heater voltage and resistance value of the heater 10 into P = V * I = V ^ 2 / R.

  First, in order to set the initial opening degree of the water discharge valve 20 corresponding to the water discharge temperature, the control unit 40 can use the actual calculated heater heating capacity. That is, even if the water discharge temperature is the same, if the heater heating capacity is different, the initial opening degree is different, and the most appropriate opening degree of the water discharge valve 10 is tested based on the water discharge temperature at the beginning of the water discharge time and the measured heater heating capacity. Can be obtained. Therefore, the setting of the degree of openness based on the measured water discharge temperature and the heater heating capacity can be set as the initial degree of openness of the water discharge valve 20, whereby water close to the target temperature can be discharged from the initial water discharge. .

において、実際に計算されたヒータ加熱容量を式のヒータ加熱容量ｗに代入することにより、ヒータ１０から出水される水の初期出水量Ｖを計算することができる。この場合、出水弁２０の初期開放度の調整に基づいて、ヒータ１０に実際に印可される電圧に基づいてヒータ加熱容量を計算することができることから、温度をより正確に調整することができる。 When the inflow temperature of the water that has entered the heater 10 is received,

Then, by substituting the actually calculated heater heating capacity into the heater heating capacity w in the equation, the initial amount V of water discharged from the heater 10 can be calculated. In this case, since the heater heating capacity can be calculated based on the voltage actually applied to the heater 10 based on the adjustment of the initial opening degree of the water discharge valve 20, the temperature can be adjusted more accurately.

  After the initial water discharge, the control unit 40 can use the heater heating capacity that is actually calculated in order to adjust the opening degree of the water discharge valve 20 according to the change in the value of the water discharge temperature. Specifically, a proportional coefficient proportional to the heater heating capacity can be set, and the degree of opening of the water discharge valve 40 can be set in proportion to the difference between the water discharge temperature and the target temperature. In the adjustment of the opening degree of the water discharge valve 20, a table created experimentally by using a proportional expression generated by the difference between the water discharge temperature and the target temperature and the target temperature or by the heater heating capacity and the water discharge temperature is used. By using it, the degree of opening of the water discharge valve 20 can be set.

  For example, the supply voltage measured by the voltage detection unit may be quantized into 200V, 210V, 220V, 230V, 240V, and 250V, and there may be a proportionality factor preset by each supply voltage value. Therefore, the opening degree of the water discharge valve 20 can be adjusted using the proportionality coefficient and the water discharge temperature. Here, the proportionality coefficient can be obtained experimentally.

  Here, since the control unit 40 directly calculates the heater heating capacity based on the supply voltage measured by the voltage detection unit, the control can be performed according to the voltage fluctuation of the commercial AC power supply. Therefore, even in foreign countries where the voltage range of the commercial AC power supply is different, hot water having a target temperature desired by the user can be provided without performing a setup process. That is, consistency can be provided even overseas where the voltage range of the commercial AC power supply is different.

  However, the hot water supply device is a direct water type hot water supply device, but even if the initial opening degree of the water discharge valve 20 is set according to the water discharge temperature, there is a possibility that the heated water may not be heated sufficiently, Hot water that has not reached the temperature may be supplied. However, since the user discharges water with the expectation that the hot water supply device will provide water at the target temperature, it is essential for the hot water supply device to provide water at the target temperature even at the early stage of the water discharge.

  Therefore, when the temperature of the water stored in the heater 10 is lower than the preheating reference temperature, the control unit 40 can operate the heater 10 during the preheating time before the water outlet valve 20 is opened.

  That is, before the water stored in the heater 10 is discharged, the water stored in the heater 10 is heated and preheated to increase the temperature, and then water can be discharged. In this case, there is a possibility that the response time may be delayed depending on the time required for preheating after the user inputs the warm water distribution signal for requesting the hot water supply. be able to.

  Here, there may be a case where hot water is supplied again immediately after the hot water supply device supplies hot water. In this case, since the temperature of the water existing in the heater 10 is already close to the target temperature, it is not necessary to preheat. Conversely, there may be a case where hot water is supplied after a long time has elapsed since the hot water supply device supplied hot water to the user. For example, there may be a case where hot water is supplied two hours after the hot water supply device first supplies hot water. In this case, the water present in the heater 10 is already cooled, and there can be a large difference from the target temperature.

  Therefore, the control unit 40 can check the temperature of the stored water using the temperature sensor 31 only when the temperature of the stored water is lower than the preheating reference temperature, for example, 60 degrees or less.

  Moreover, the control part 40 can set preheating time long, so that the temperature of the water stored in the heater 10, ie, the water discharge temperature, is low. Since the difference between the water discharge temperature and the target temperature becomes large, the preheating time can be set long in order to sufficiently heat the water stored in the heater 10. Conversely, when the water discharge temperature is high, the temperature is close to the target temperature, so that even if the water stored in the heater 1 is heated in a short time, the target temperature can be sufficiently reached.

  In addition to this, the control unit 40 measures the waiting time for use between the last water discharge and the next water discharge, and the preheating time and the degree of opening of the water discharge valve 20 according to the measured water discharge temperature. Can be set.

  When the input of the hot water distribution signal is stopped, the hot water supply device can completely close the water discharge valve 20 to stop the supply of hot water, and heats the water stored in the heater 10 to the target temperature. Can be maintained in a state. In this case, however, if the hot water supply device does not operate, the temperature of the water stored in the heater 10 decreases with the passage of time. Accordingly, the degree of opening of the water discharge valve 20 can be set in consideration of the use waiting time as well as the difference between the target temperature and the water discharge temperature.

  Furthermore, in order to quickly distribute the water at the target temperature, the control unit 40 can adjust the degree of opening of the water discharge valve 20 according to a change in the water discharge temperature value. A specific operation related to the operation of the control unit 40 will be described with reference to FIGS.

  Fig.4 (a) is the graph which showed the water discharge temperature in the case of the 1st water discharge. That is, FIG. 4A shows a graph in the case where warm water is discharged after a predetermined time has elapsed since water was finally discharged. Referring to FIG. 4A, the water discharge temperature has converged to the target temperature, and this convergence can be obtained by controlling the degree of opening of the water discharge valve as described above.

  In this case, however, as shown in FIG. 4 (a), in the process where the outlet water temperature converges to the target temperature, the outlet water temperature rises or falls based on the target temperature and fluctuates. Due to fluctuations, users may be suddenly supplied with hot or cold water. In addition, it may take a long time to stabilize the outlet temperature to the target temperature. Therefore, it is necessary to control the water discharge valve 20 in order to minimize the fluctuation of the water discharge temperature curve.

  FIG.4 (b) has shown the water temperature in the case of discharging water continuously. Since the hot water is continuously distributed, as shown in FIG. 4B, the water temperature does not rise rapidly at the initial stage, but the water temperature curve varies. Therefore, it is necessary to control the water discharge valve 20 in order to minimize fluctuations.

  Therefore, the control part 40 can calculate the variation | change_quantity of a water discharge temperature value, adjust the open degree of the water discharge valve 20 according to this calculated variation | change_quantity, and can suppress a fluctuation | variation to the minimum.

  First, the control unit 40 calculates the difference between the water temperature and the target temperature, and determines whether the hot water distribution is the first water discharge or the continuous water discharge from the value of this difference. be able to.

  For example, when the difference between the water temperature and the target temperature is equal to or greater than a preset value, the control unit 40 determines that the hot water water is the first water discharge, and between the water temperature and the target temperature. When the difference is less than a preset value, the control unit 40 can determine that the warm water discharge is a continuous discharge.

  Here, the difference between the water temperature and the target temperature can be determined at an initial time point when the hot water is distributed. In this case, the first water discharge and the continuous water discharge can be clearly distinguished.

  That is, in the case of the first water discharge, the temperature of the water stored in the heater 10 can be brought close to normal temperature (approximately 26 ° C.), but in the case of continuous water discharge, it is already heated. The temperature of the water stored in the heater 10 can approach the target temperature (85 ° C.).

  Therefore, it is possible to determine the first water discharge and the continuous water discharge based on the difference between the water discharge temperature and the target temperature, and if the water discharge valve 20 is different according to the first water discharge and the continuous water discharge. Can be controlled.

  When the warm water is discharged for the first time, the control unit 40 can calculate the amount of change in the water output temperature, and can adjust the degree of opening of the water discharge valve 20 according to the change in the water output temperature.

  The amount of change in the water temperature can be obtained by measuring the water temperature value at each preset time interval and calculating the difference between the measured water temperature values. Here, when the calculated change in the water temperature is equal to or greater than the first reference change, it is considered that the water temperature has increased rapidly. In this case, the fluctuation number and fluctuation amplitude of the curve of the water temperature graph. May become large.

  Therefore, if it is determined that the fluctuation increases rapidly, the opening degree of the water discharge valve 20 can be fixed to the opening degree when the change amount is calculated, and the opening degree is fixed for the first set time. Can be maintained during. That is, in order to reduce the amount of change in the water discharge temperature, the control of the degree of opening of the water discharge valve 20 can be interrupted for the first set time according to the water discharge temperature. Thereby, the fluctuation | variation of the water temperature can be reduced as shown in FIG.

  Referring to (a) of FIG. 4, even in the case of the first water discharge, the water discharge temperature can be gradually increased as time elapses, and the temperature difference between the water discharge temperature and the target temperature is set higher than a preset value. Can be reduced. Therefore, in this case, the control unit 40 can control the degree of opening of the water discharge valve 20 in the same manner as continuous water discharge. Below, operation | movement of the control part 40 in the case of continuous water discharge is demonstrated.

  If it is determined that the warm water is continuously discharged, as described above, it is possible to calculate whether or not the change amount of the discharge temperature is equal to or greater than the second reference fluctuation amount. The second reference change amount can be smaller than the first reference change amount. When the amount of change is equal to or greater than the second reference amount of change, it can be considered that the water discharge temperature is gradually rising.

  When the water temperature rises slowly, it can be expected that the number of fluctuations and the fluctuation amplitude of the curve in the water temperature graph will increase, and therefore the degree of opening of the water outlet valve 20 is fixed to the degree of opening when the fluctuation is calculated. be able to. Here, the fixed time point can be a second set time point that is shorter than the first set time point, and the fluctuation of the water discharge temperature can be reduced by interrupting the control of the water discharge valve 20.

  Therefore, by adjusting the degree of opening of the water outlet valve 20 according to the amount of change in the water outlet temperature, the water outlet temperature can be quickly converged to the target temperature, and by reducing the control time of the water outlet valve 20, The consumption of energy for controlling the water discharge valve 20 can be reduced.

  Although not shown in the figure, the water purifier can include a hot water supply device. The water purifier can include a water purification filter that filters the tap water supplied from the water supply, and the water purified by the water purification filter can flow into the heater 10. Thereafter, the purified water is heated in the heater 10, discharged through the outlet valve 20, and provided to the user. Here, the control unit 40 can control the degree of opening of the water discharge valve 20 to adjust the temperature of the extracted water to the target temperature. Similarly, the control unit 40 controls the opening degree of the water discharge valve 20 by using the temperature sensor 31 and the inflow temperature sensor 32 and controls the heater 10 and the water discharge valve 20 to flow into the heater 10. Can preheat water.

  FIG. 2 is a flowchart illustrating a hot water supply method according to an embodiment of the present invention, and FIG. 3 is a flowchart illustrating an initial water discharge operation (stage) of the hot water supply method according to an embodiment of the present invention. is there.

  2 and 3, the hot water supply method according to the embodiment of the present invention may include an initial water discharge operation (stage) (S10) and a water discharge control operation (stage) (S20). The initial water discharge operation (S10) can include an initial opening control operation (S11), a preheating step (S12), and an initial opening step (S13).

  Hereinafter, a hot water supply method according to an embodiment of the present invention will be described with reference to FIGS. 2 and 3.

  In the initial water discharge operation (S10), when a warm water supply signal is input, an initial opening degree of the water discharging valve for adjusting the amount of water discharged from the heater is set, and the water discharging valve in which the opening degree is set in advance. The water outlet valve can be opened. In the initial water discharge operation (S10), heating is started by inputting a warm water supply signal. In this operation, in order to start extracting water at the target temperature from the initial water discharge, the initial opening degree of the water discharge valve can be set.

  Specifically, the initial water discharge operation (S10) can include an initial opening setting operation (S11) and a preheating operation (S13).

  In the initial opening setting operation (S11), a preset opening degree can be set as the initial opening degree of the water discharge valve according to the water discharge temperature.

  The water temperature can be measured by using a temperature sensor disposed between the heater and the water valve. Before opening the water outlet valve, the temperature of the water stored in the heater can be set as the water outlet temperature. Therefore, the temperature of the water stored in the heater can be measured using the water temperature before opening the water valve, and the initial opening degree of the water valve can be set according to the measured water temperature. it can.

  Specifically, since the temperature of the water stored in the heater depends on how much time has passed since the last water discharge, it is necessary to change the initial opening degree according to the temperature of the water stored in the heater.

  For example, when one minute has passed since the last water discharge, the temperature of the stored water can be brought close to the target temperature, so that it is not necessary to heat the water for a long time, and therefore the initial operation is to discharge a relatively large amount of water. Openness can be set.

  On the other hand, when two hours have passed since the last water discharge, the temperature of the stored water may be greatly different from the target temperature, so it is necessary to heat the water with a heater for a long time. In this case, the initial opening degree can be set so that the amount of water flowing out is relatively small.

  Here, the initial opening degree according to the water discharge temperature can be experimentally obtained as the most appropriate initial opening degree by the fluctuation of the initial opening degree of the water discharge valve according to the measured water discharge temperature. The initial opening degree of the corresponding water discharge valve can be set in advance.

  Furthermore, as described above, the amount of water stored in the heater depends on the degree of time that has elapsed since the last water discharge, that is, the use waiting time between the last water discharge and the next water discharge. The temperature can be varied. Therefore, in the initial opening degree setting operation (S11), by measuring the use waiting time between the last water discharge and the next water discharge, and using the measured use standby time and the water discharge temperature, The initial opening degree of the water discharge valve can be set.

  In the initial opening degree setting operation (S11), in addition to the outlet water temperature, the inflow temperature of the water flowing into the heater is received, and the initial opening degree of the outlet valve can be set based on the inflow temperature.

を用いることにより計算することができ、そして、計算されたヒータの初期出水量に応じて出水弁の初期開放度を設定することができる。すなわち、流入温度を受けることにより、出水弁の初期開放度をより正確に設定することができる。ここで、Ｖは出水される水の容積、ｗはヒータ１０のヒータ加熱容量、ｃは水の比熱、ρは水の密度、Δｔは加熱時間、Ｔ_１は目標温度、Ｔ_２は流入温度である。 Specifically, the initial water discharge amount of the heater required to discharge water having the target temperature is

The initial opening degree of the water discharge valve can be set according to the calculated initial water discharge amount of the heater. That is, the initial opening degree of the water discharge valve can be set more accurately by receiving the inflow temperature. Here, the volume of water V is a flood, w is a heater heating capacity of the heater 10, c is the specific heat of water, [rho is the density of water, Delta] t is the heating time, T ₁ is the target temperature, T ₂ in the inlet temperature is there.

  In this case, however, the initial opening degree is set on the assumption that the heater heating capacity of the heater is constant. In practice, however, the heater heating of the heater depends on the voltage fluctuation of the commercial AC power supplied to the heater. Capacity can also vary. Therefore, in order to set the initial opening degree of the water discharge valve more accurately, it is necessary to consider the change in the heater heating capacity.

  For this reason, the initial opening degree setting operation (S10) can further include a heater heating capacity calculation step (not shown), and supply supplied from the power source in the heater heating capacity calculation step. The heater heating capacity can be calculated by measuring the voltage and using this supply voltage.

Specifically, in the heater heating capacity calculation operation, an AC supply voltage supplied from a power source is converted into a DC voltage, and the converted DC voltage is quantized to detect the supply voltage. That is, the AC voltage supplied from the power source is half-wave rectified, smoothed, dropped to convert it to a DC voltage, and the converted DC voltage is quantized by an analog-digital converter, The supply voltage can be measured. Therefore, when a 220V commercial AC power supply that varies from 198V to 253V is supplied,
This power can be measured as one of 200V, 210V, 220V, 23V, 240V, and 250V divided at 10V intervals. Since the resistance value of the heater is constant, when the supply voltage is measured, the heater voltage applied to the heater can be obtained, and by using P = V * I = V ^ 2 / R, the heater heating of the heater The capacity can be calculated easily.

  Thereafter, in the initial opening degree setting operation (S11), the opening degree of the water discharge valve can be set by using the heater heating capacity calculated in the heater heating capacity calculation operation. Specifically, in the initial opening degree setting operation (S11), even if the water temperature is constant, the opening degree of the water outlet valve can be changed when the calculated heater heating capacity is different. The most appropriate opening degree of the water discharge valve can be experimentally determined according to the measured heater heating capacity. Therefore, the preset opening degree can be set to the initial opening degree of the water discharge valve according to the water discharge temperature at the time of initial water discharge and the measured heater heating capacity.

のヒータ加熱容量ｗに実際に測定されたヒータ加熱容量を代入することによってヒータ１０から出水される水の初期出水量Ｖを計算することができる。この場合、出水弁２０の初期開放度を調整するための基礎となるヒータ加熱容量を、ヒータ１０に実際に印可される電圧に基づいて計算することができる。 When the inflow temperature flowing into the heater is received,

By substituting the heater heating capacity actually measured for the heater heating capacity w, the initial amount V of water discharged from the heater 10 can be calculated. In this case, the heater heating capacity that is the basis for adjusting the initial opening degree of the water discharge valve 20 can be calculated based on the voltage that is actually applied to the heater 10.

  Further, in the heater heating capacity calculation operation, the voltage supplied from the power source, that is, the supply voltage can be measured at preset time intervals or when the hot water k distribution signal is supplied. This is to reduce the power consumption required for measuring the supply voltage.

  In the initial opening degree setting operation (S11), the initial opening degree of the water outlet valve for allocating water having the target temperature has already been set, but when the temperature of the water stored in the heater is extremely low, the distribution is performed. Water that is being heated may not be sufficiently heated, and thus water that does not have a target temperature may be provided.

  Therefore, the initial water discharge operation S10 can further include a preheating operation (S12). If the measured outlet water temperature is lower than the preheat reference temperature, the heater can be operated to heat the water stored in the heater during the preheat time. When the water stored in the heater is lower than the preheating reference temperature, the water is preheated before the water is discharged. Therefore, when water is discharged after the preheating operation (S12), water having the target temperature can be discharged from the initial water discharge.

  Specifically, when the measured outlet temperature is lower than 60 ° C., the preheating operation (S12) can be performed, and when the measured outlet temperature is low, the heater is set to extend the time and Fully preheat.

  Here, the initial opening setting operation (S11) and the preheating operation (S12) can be performed at the same time. Also, the preheating operation (S12) is performed first, and the initial opening setting operation S11 and the preheating operation (S12). The initial opening degree of the water discharge valve can be set in consideration of the temperature of the preheated water.

  In the initial opening operation (S13), the water discharge valve can be opened according to a preset opening degree of the water discharge valve. Water having the target temperature can be provided by the initial opening degree setting operation (S11) and the preheating operation (S12), and then the water is discharged to provide water having the target temperature continuously even during the water discharge. Control operation S20 can be performed.

  In the water discharge control operation S20, the water discharged from the heater can be adjusted to have a target temperature by controlling the degree of opening of the water discharge valve.

  Here, the opening degree of the water discharge valve can be adjusted according to the change in the value of the water discharge temperature. Specifically, when the outlet temperature is higher than the target temperature, the outlet valve is opened in proportion to the difference between the outlet temperature and the target temperature, and when the outlet temperature is lower than the target temperature, The outlet valve can be closed in proportion to the difference between the outlet temperature and the target temperature.

  When the heater heating capacity of the heater is constant, the temperature of the water discharged from the heater can be increased in proportion to the time for heating the water by the heater. The larger the outlet valve is opened, the greater the amount of water discharged per hour, and the shorter the time for heating the water with the heater. On the other hand, when the water discharge valve is closed, the amount of water discharged per hour decreases, and the time for heating the water with the heater becomes longer.

  Therefore, in the water discharge control operation S20, the temperature of the water discharged from the heater can be adjusted by adjusting the degree of opening of the water discharge valve so that the temperature of the water discharged from the heater reaches the target temperature. .

  Further, in the water discharge control operation S20, the inflow temperature of the water flowing into the heater can be received, and the opening degree of the water discharge valve is adjusted by using the inflow temperature, the heater heating capacity of the heater, and the target temperature. Can do.

  Specifically, by using the inflow temperature, the heater heating capacity of the heater, and the target temperature, it is possible to calculate the amount of water required to discharge the water that transports the target temperature. The degree of opening of the water discharge valve can be adjusted based on the above.

を用いて計算することができ、この計算された出水量に応じて出水弁の開放度を設定することができる。すなわち、流入温度を受けて出水弁の開放度をより正確に設定することができる。ここで、Ｖは出水される水の容積、ｗはヒータ１０のヒータ加熱容量、ｃは水の比熱、ρは水の密度、Δｔは加熱時間、Ｔ_１は目標温度、Ｔ_２は流入温度である。 For example, the amount of heater water required to discharge water with the target temperature is

The degree of opening of the water discharge valve can be set according to the calculated water discharge amount. That is, the degree of opening of the water discharge valve can be set more accurately in response to the inflow temperature. Here, the volume of water V is a flood, w is a heater heating capacity of the heater 10, c is the specific heat of water, [rho is the density of water, Delta] t is the heating time, T ₁ is the target temperature, T ₂ in the inlet temperature is there.

  In this case, as described above, since the heater heating capacity may fluctuate, in order to control the temperature more accurately, by using the actual heater heating capacity of the heater measured by the heater heating capacity calculation operation, The degree of opening of the water discharge valve can be adjusted.

  Specifically, a proportional constant proportional to the heater heating capacity can be set, and the degree of opening of the water discharge valve proportional to the difference between the water discharge temperature and the target temperature can be set. As a result, the proportional formula generated according to the difference between the water discharge temperature and the target temperature and the heater heating capacity can be used, and the table created experimentally according to the heater heating capacity and the water discharge temperature is used. Can also be used.

のヒータ加熱容量（ｗ）に実際計算したヒータ加熱容量を代入することにより、ヒータの出水量を計算することができる。 When the temperature of water flowing into the heater is input,

By substituting the heater heating capacity actually calculated for the heater heating capacity (w), the amount of water discharged from the heater can be calculated.

  In the water discharge control operation (S20), in order to quickly distribute the water having the target temperature, the degree of opening of the water discharge valve can be adjusted using the amount of change in the value of the water discharge temperature.

  Fig.4 (a) is the graph which showed the water discharge temperature in the case of the 1st water discharge. That is, FIG. 4A shows a graph in the case where warm water is discharged after a predetermined time has elapsed since water was finally discharged. Referring to FIG. 4A, the water discharge temperature has converged to the target temperature, and this convergence can be obtained by controlling the degree of opening of the water discharge valve as described above.

  In this case, however, as shown in FIG. 4 (a), in the process where the outlet water temperature converges to the target temperature, the outlet water temperature rises or falls based on the target temperature and fluctuates. Due to fluctuations, users may be suddenly supplied with hot or cold water. In addition, it may take a long time to stabilize the outlet temperature to the target temperature. Therefore, it is necessary to control the water discharge valve 20 in order to minimize the fluctuation of the water discharge temperature curve.

  FIG.4 (b) has shown the water temperature in the case of discharging water continuously. Since the hot water is continuously distributed, as shown in FIG. 4B, the water temperature does not rise rapidly at the initial stage, but the water temperature curve varies. Therefore, it is necessary to control the water discharge valve 20 in order to minimize fluctuations.

  Therefore, in the water discharge control operation (S20), the amount of change of the water discharge temperature value is calculated, and the degree of opening of the water discharge valve is adjusted according to the calculated amount of change, thereby minimizing fluctuations.

  First, in the water discharge control operation (S20), the difference between the water discharge temperature and the target temperature is calculated, and whether the warm water distribution is the first water discharge or the continuous water discharge from the value of this difference. Can be determined.

  If the difference between the water temperature and the target temperature is greater than or equal to a preset value, it can be determined that the warm water water is the first water discharge, and the difference between the water temperature and the target temperature is preset. When the value is less than the determined value, it can be determined that the warm water discharge is a continuous discharge.

  Here, the difference between the water temperature and the target temperature can be determined at an initial time point when the hot water is distributed. In this case, the first water discharge and the continuous water discharge can be clearly distinguished.

  That is, in the case of the first water discharge, the temperature of the water stored in the heater can be brought close to normal temperature (approximately 26 ° C.), but in the case of continuous water discharge, the heater has already been heated. The temperature of the water stored in 10 can approach the target temperature (85 ° C.).

  Therefore, it is possible to determine the first water discharge and the continuous water discharge based on the difference between the water discharge temperature and the target temperature, and if the water discharge valve 20 is different according to the first water discharge and the continuous water discharge. Can be controlled.

  When the warm water is discharged for the first time, the control unit 40 can calculate the amount of change in the water output temperature, and can adjust the degree of opening of the water discharge valve 20 according to the change in the water output temperature.

  The amount of change in the water temperature can be obtained by measuring the water temperature value at each preset time interval and calculating the difference between the measured water temperature values. Here, when the calculated change in the water temperature is equal to or greater than the first reference change, it is considered that the water temperature has increased rapidly. In this case, the fluctuation number and fluctuation amplitude of the curve of the water temperature graph. May become large.

  Therefore, if it is determined that the fluctuation increases rapidly, the opening degree of the water discharge valve 20 can be fixed to the opening degree when the change amount is calculated, and the opening degree is fixed for the first set time. Can be maintained during. That is, in order to reduce the amount of change in the water discharge temperature, the control of the degree of opening of the water discharge valve 20 can be interrupted for the first set time according to the water discharge temperature. Thereby, the fluctuation | variation of the water temperature can be reduced as shown in FIG.

  Referring to (a) of FIG. 4, even in the case of the first water discharge, the water discharge temperature can be gradually increased as time elapses, and the temperature difference between the water discharge temperature and the target temperature is set higher than a preset value. Can be reduced. Therefore, in this case, the control unit 40 can control the degree of opening of the water discharge valve 20 in the same manner as continuous water discharge. Below, operation | movement of the control part 40 in the case of continuous water discharge is demonstrated.

  If it is determined that the warm water is continuously discharged, as described above, it is possible to calculate whether or not the change amount of the discharge temperature is equal to or greater than the second reference fluctuation amount. The second reference change amount can be smaller than the first reference change amount. When the amount of change is equal to or greater than the second reference amount of change, it can be considered that the water discharge temperature is gradually rising.

  When the water temperature rises slowly, it can be expected that the number of fluctuations and the fluctuation amplitude of the curve in the water temperature graph will increase, and therefore the degree of opening of the water outlet valve 20 is fixed to the degree of opening when the fluctuation is calculated. be able to. Here, the fixed time point can be a second set time point that is shorter than the first set time point, and the fluctuation of the water discharge temperature can be reduced by interrupting the control of the water discharge valve 20.

  Therefore, by adjusting the degree of opening of the water outlet valve 20 according to the amount of change in the water outlet temperature, the water outlet temperature can be quickly converged to the target temperature, and by reducing the control time of the water outlet valve 20, The consumption of energy for controlling the water discharge valve 20 can be reduced.

  Although the embodiment of the present invention has been described in detail above, the scope of the right of the present invention is not limited to this, and various modifications and modifications can be made without departing from the technical idea of the present invention described in the claims. It will be apparent to those of ordinary skill in the art that variations are possible.

    10 heater, 20 water discharge valve, 31 temperature sensor, 32 water temperature sensor, 40 control unit, S10 initial water discharge stage, S11 initial opening setting process, S12 preheating process, S13 initial opening process, S20 water discharge control stage

Claims (15)

A heater that heats inflowed water by a heater heating capacity;
A water discharge valve for adjusting the amount of water discharged from the heater;
A temperature sensor for measuring the temperature of the discharged water;
A control unit that controls the degree of opening of the water discharge valve in proportion to the temperature difference between the water temperature and the target temperature;
Hot water supply device with   The hot water supply device according to claim 1, wherein the control unit calculates a change amount of the water discharge temperature and adjusts an opening degree of the water discharge valve according to the calculated change amount.   Furthermore, a voltage detection unit for detecting a supply voltage supplied from a power source is provided, and the control unit calculates the heater heating capacity using the supply voltage, and calculates the heater heating capacity, the outlet temperature, and the target temperature. The hot water supply device according to claim 1, wherein an opening degree of the water discharge valve is set using a temperature difference between the two.   The hot water supply apparatus according to claim 3, wherein the voltage detection unit detects the supply voltage when a hot water distribution signal for requesting hot water distribution is input or when a preset time interval elapses.   The hot water supply device according to claim 3, wherein the voltage detection unit converts the supply voltage input by alternating current into a direct current voltage, and quantizes the converted direct current voltage to detect the magnitude of the supply voltage. .   The said control part sets the proportionality constant corresponding to the said heater heating capacity, and sets the open degree of the said water discharge valve in proportion to the temperature difference between the said water discharge temperature and target temperature. Hot water supply device.   When the temperature difference between the outlet temperature and the target temperature is equal to or greater than a preset value and the calculated change amount is equal to or greater than a first reference change amount, the control unit calculates the change amount. The hot water supply device according to claim 2, wherein the opening degree of the water discharge valve at the calculated time point is maintained for a first set time.   When the temperature difference between the outlet temperature and the target temperature is less than a preset value and the calculated change amount is less than a second reference change amount, the control unit calculates the change amount. The hot water supply device according to claim 2, wherein the opening degree of the water discharge valve at the calculated time point is maintained for a second set time. When a warm water supply signal is input, an initial opening degree of a water discharge valve that adjusts the amount of water discharged from the heater is set, and an initial water discharge operation that opens the water discharge valve by the set opening degree;
A hot water supply method including a water discharge control operation for controlling an opening degree of the water discharge valve in proportion to a temperature difference between the water discharge temperature and a target temperature.   The hot water supply method according to claim 9, wherein the initial water discharge operation further includes a heater heating capacity calculation operation of measuring a supply voltage supplied from a power source and calculating a heater heating capacity of the heater using the supply voltage. .   The heater heating capacity calculation operation calculates the heater heating capacity by measuring the supply voltage when a warm water distribution signal for requesting hot water distribution is input or when a preset time interval elapses. Item 11. The hot water supply method according to Item 10.   11. The magnitude of the supply voltage is measured by converting the AC supply voltage supplied from the power source into a DC voltage, and quantizing the converted DC voltage in the heater heating capacity calculation operation. Hot water supply method.   The hot water supply method according to claim 9, wherein the amount of change in the water discharge temperature is calculated by the water discharge control operation, and the degree of opening of the water discharge valve is adjusted according to the calculated amount of change.   In the water discharge control operation, when the temperature difference between the water discharge temperature and the target temperature is not less than a preset value and the calculated change amount is not less than a first reference change amount, the change amount The hot water supply method according to claim 13, wherein the degree of opening of the water discharge valve at the time of calculating is maintained for a first set time.   In the water discharge control operation, when the temperature difference between the water discharge temperature and the target temperature is less than a preset value, and the calculated change amount is greater than or equal to a second reference change amount, the change amount The hot water supply method according to claim 13, wherein the degree of opening of the water discharge valve at the time of calculating is maintained for a second set time.

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