JP2018031574A - Hot water supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology capable of enhancing COP in executing boiling-up operation, and also suppressing hot water with lower temperature than a hot water supply setting temperature from being supplied to a hot water utilization place.SOLUTION: Control means is configured to: cause a temperature sensor to measure a first hot water storage temperature, which is a temperature of hot water in a tank at the time when a hot water storage amount in the tank is less than a predetermined hot water storage amount after execution of first boiling-up operation; and when the first hot water storage temperature is higher than a first reference temperature, set a temperature obtained by subtracting an absolute value of the differential between the first hot water storage temperature and the first reference temperature from a first boiling-up temperature, as tomorrow's first boiling-up temperature, while when the first hot water storage temperature is lower than a second reference temperature, set a temperature obtained by adding an absolute value of the differential between the first hot water storage temperature and the second reference temperature to the first boiling-up temperature, as the tomorrow's first boiling-up temperature, to execute tomorrow's first boiling-up operation.SELECTED DRAWING: Figure 3

Description

  The technology disclosed in this specification relates to a hot water supply system.

  The hot water supply system disclosed in Patent Document 1 includes a heat pump that absorbs heat from the outside air to boil water, a tank that stores hot water boiled by the heat pump, and a supply path that supplies hot water in the tank to a hot water use location And a setting means capable of setting the hot water supply set temperature at the hot water use location, and a control means. The control means can execute a boiling operation in which water in the tank is heated to a boiling temperature by a heat pump. Hot water boiled by the heat pump is stored in a tank. Thereafter, the temperature of the hot water in the tank decreases with the passage of time due to natural heat dissipation.

Japanese Patent Laid-Open No. 2015-038397

  In the hot water supply system, when the boiling operation is performed at the low temperature, the COP (Coefficient Of Performance) in the heat pump can be made higher than when the boiling operation is performed at the high temperature. Therefore, it is preferable to perform the boiling operation at the lowest possible temperature.

  On the other hand, if the boiling temperature is too low, the temperature of the hot water stored in the tank will be low, and when supplying the hot water in the tank to the hot water use location, the hot water at the hot water supply set temperature can be supplied to the hot water use location. It may disappear. In particular, when the temperature of the hot water in the tank decreases with time due to natural heat dissipation, it may not be possible to supply the hot water at the hot water supply set temperature to the hot water use location. Therefore, the present specification provides a technique capable of suppressing the supply of hot water having a temperature lower than the hot water supply set temperature to the hot water use location while increasing the COP when performing the boiling operation.

  A hot water supply system disclosed in the present specification includes a heat pump that absorbs heat from outside air to boil water, a tank that stores hot water boiled by the heat pump, a temperature sensor that measures the temperature of hot water stored in the tank, and A supply path for supplying the hot water in the tank to the hot water use location, a setting means capable of setting the hot water supply set temperature at the hot water use location, and a control means are provided. The control means can execute a first boiling operation in which water in the tank is heated to a first boiling temperature by a heat pump at a predetermined first boiling time. In addition, the control means measures the first hot water storage temperature, which is the temperature of the hot water in the tank when the hot water storage amount in the tank becomes smaller than the predetermined hot water storage amount after executing the first boiling operation, using the temperature sensor. When the first hot water storage temperature is higher than the first reference temperature higher than the hot water supply set temperature, the first boiling temperature of the next day is lowered, and the first hot water storage temperature is higher than the hot water supply set temperature and lower than the first reference temperature. When the temperature is lower than the reference temperature, the first boiling temperature on the next day is raised and the first boiling operation on the next day is executed.

  According to such a configuration, when the control means executes the first boiling operation, the heat pump raises the water in the tank to the first boiling temperature. Hot water boiled by the heat pump is stored in a tank. Hot water at the first boiling temperature is stored in the tank. Thereafter, when the hot water in the tank is supplied to the hot water use location, the amount of hot water stored in the tank decreases. Moreover, the temperature of the hot water in a tank falls with time passage by natural heat radiation. The control means measures the temperature of the hot water in the tank (that is, the first hot water storage temperature) when the amount of hot water stored in the tank becomes less than a predetermined amount of hot water stored. When the measured first hot water storage temperature is higher than the first reference temperature, the control means lowers the first boiling temperature on the next day. Moreover, a control means raises the 1st boiling temperature on the next day, when the measured 1st hot water storage temperature is lower than 2nd reference temperature. And a control means performs a 1st boiling operation at the predetermined 1st boiling time of the following day at the 1st boiling temperature lowered | hung above or the raised 1st boiling temperature.

  According to said structure, when the temperature (1st hot water storage temperature) of the warm water which remains in a tank just before using up the warm water boiled by 1st boiling operation is higher than 1st reference temperature, 1 Lower boiling temperature. As a result, on the next day, the first boiling temperature can be lowered while maintaining the temperature of the hot water remaining in the tank at or above the hot water supply set temperature just before the hot water boiled in the first boiling operation is used up. it can. Thus, when the 1st hot water storage temperature is high, in order to lower the 1st hot water temperature of the next day, since the 1st boiling temperature of the next day is lowered, the 1st boiling temperature at the time of performing the 1st boiling operation is set. COP can be raised by lowering.

  If the temperature of the hot water remaining in the tank (first hot water storage temperature) is lower than the second reference temperature immediately before the hot water boiled in the first boiling operation is used up, the first boiling temperature of the next day is set. increase. Thus, on the next day, it is possible to reliably prevent the temperature of the hot water remaining in the tank from falling below the hot water supply set temperature immediately before the hot water boiled in the first boiling operation is used up. Thus, when the 1st hot water storage temperature is low, since the 1st hot water temperature of the next day can be raised, when supplying the hot water in a tank to a hot water use location, hot water lower than hot water supply preset temperature is a hot water use location. Can be suppressed.

  In the above hot water supply system, when the first hot water storage temperature is higher than the first reference temperature higher than the hot water supply set temperature, the temperature obtained by subtracting the absolute value of the difference between the first hot water storage temperature and the first reference temperature from the first boiling temperature is set. When the first boiling temperature is the next day and the first hot water temperature is lower than the second reference temperature that is higher than the hot water set temperature and lower than the first reference temperature, the absolute value of the difference between the first hot water temperature and the second reference temperature is The first boiling operation on the next day may be executed with the temperature added to the 1 boiling temperature as the first boiling temperature on the next day.

  According to such a configuration, when lowering the first boiling temperature on the next day, the temperature obtained by subtracting the absolute value of the difference between the first hot water temperature and the first reference temperature from the first boiling temperature is set to the first boiling temperature on the next day. By setting it as raising temperature, it can suppress that the 1st boiling temperature on the next day becomes low too much. As a result, it is possible to suppress the temperature of the hot water remaining in the tank (the first hot water storage temperature on the next day) from becoming too low immediately before the hot water boiled in the first boiling operation on the next day is used up. On the other hand, when raising the first boiling temperature on the next day, the temperature obtained by adding the absolute value of the difference between the first hot water storage temperature and the second reference temperature to the first boiling temperature is set as the first boiling temperature on the next day. The first boiling temperature on the next day can be suppressed from becoming too high. As a result, the first hot water storage temperature on the next day can be prevented from becoming too high. Thereby, the 1st hot water storage temperature of the next day can be closely approached to the temperature close | similar to hot water supply preset temperature.

  Another hot water supply system disclosed in the present specification includes a heat pump that absorbs heat from outside air to boil water, a tank that stores hot water boiled by the heat pump, and a temperature that measures the temperature of the hot water stored in the tank. A sensor, a supply path for supplying hot water in the tank to the hot water use location, a setting means capable of setting a hot water supply set temperature at the hot water use location, and a control means are provided. The control means can execute a second boiling operation in which water in the tank is heated to a second boiling temperature by a heat pump at a second boiling time which is the last boiling time of the day. Further, the control means uses a temperature sensor to determine the second hot water storage temperature, which is the temperature of the hot water in the tank when the hot water in the tank is supplied to the hot water use location at the end of the day after the second boiling operation is performed. When the second hot water storage temperature is higher than the third reference temperature higher than the hot water supply set temperature, the second boiling temperature is lowered on the next day, and the second hot water storage temperature is higher than the hot water supply set temperature and lower than the third reference temperature. When the temperature is lower than 4 reference temperature, the second boiling temperature on the next day is raised and the second boiling operation on the next day is executed.

  According to such a configuration, when the control means executes the second boiling operation, the heat pump raises the water in the tank to the second boiling temperature. Hot water boiled by the heat pump is stored in a tank. Hot water at the second boiling temperature is stored in the tank. Thereafter, when the hot water in the tank is supplied to the hot water use location, the amount of hot water stored in the tank decreases. Moreover, the temperature of the hot water in a tank falls with time passage by natural heat radiation. A control means measures the temperature (namely, 2nd hot water storage temperature) of the warm water in a tank when the warm water in a tank is supplied to the hot water utilization location at the end of the day. When the measured second hot water storage temperature is higher than the third reference temperature, the control means lowers the second boiling temperature on the next day. Moreover, a control means raises the 2nd boiling temperature on the next day, when the measured 2nd hot water storage temperature is lower than 4th reference temperature. And a control means performs a 2nd boiling operation with the 2nd boiling temperature lowered | hung above or the 2nd boiling temperature raised at the 2nd boiling time which is the last boiling time of the next day.

  According to the above configuration, when the temperature of the hot water remaining in the tank at the end of the day (second hot water temperature) is higher than the third reference temperature after boiling in the second boiling operation, the next day Lower the second boiling temperature. Thus, on the next day, the second boiling temperature can be lowered while maintaining the temperature of the hot water remaining in the tank at the end of the day at or above the hot water supply set temperature. In this way, when the second hot water storage temperature is high, the second boiling temperature is lowered on the next day in order to lower the second hot water temperature on the next day, so the second boiling temperature at the time of executing the second boiling operation is reduced. COP can be raised by lowering.

  In addition, when the temperature of the hot water remaining in the tank at the end of the day (second hot water storage temperature) is lower than the fourth reference temperature after boiling in the second boiling operation, the second boiling is performed on the next day. Increase the temperature. Accordingly, it is possible to reliably prevent the temperature of the hot water remaining in the tank at the end of the day from falling below the hot water supply set temperature on the next day. Thus, when the 2nd hot water storage temperature is low, the 2nd hot water storage temperature of the next day can be raised, so when supplying the hot water in the tank to the hot water use location, the hot water having a temperature lower than the hot water supply set temperature is used. Can be suppressed.

  In the above hot water supply system, when the second hot water storage temperature is higher than the third reference temperature higher than the hot water supply set temperature, a temperature obtained by subtracting the absolute value of the difference between the second hot water storage temperature and the third reference temperature from the second boiling temperature is set. When the second boiling temperature is the next day's second boiling temperature and the second hot water storage temperature is lower than the fourth reference temperature higher than the hot water supply set temperature and lower than the third reference temperature, the absolute value of the difference between the second hot water storage temperature and the fourth reference temperature is The second boiling operation on the next day may be executed with the temperature added to the two boiling temperatures as the second boiling temperature on the next day.

  According to such a configuration, when lowering the second boiling temperature of the next day, the temperature obtained by subtracting the absolute value of the difference between the second hot water storage temperature and the third reference temperature from the second boiling temperature is set to the second boiling temperature of the next day. By setting it as raising temperature, it can suppress that the 2nd boiling temperature on the next day becomes low too much. As a result, the temperature of the hot water remaining in the tank at the end of the first day of the next day (the second hot water storage temperature of the next day) can be suppressed from becoming too low. On the other hand, when raising the second boiling temperature on the next day, the temperature obtained by adding the absolute value of the difference between the second hot water storage temperature and the fourth reference temperature to the second boiling temperature is set as the second boiling temperature on the next day. The second boiling temperature on the next day can be suppressed from becoming too high. As a result, it is possible to suppress the second hot water storage temperature on the next day from becoming too high. Thereby, the second hot water storage temperature of the next day can be accurately brought close to a temperature close to the hot water supply set temperature.

  Still another hot water supply system disclosed in the present specification is a heat pump that absorbs heat from outside air to boil water, a tank that stores hot water boiled by the heat pump, and a temperature of the hot water stored in the tank. A temperature sensor, a supply path for supplying hot water in the tank to the hot water use location, a setting means capable of setting a hot water supply set temperature at the hot water use location, and a control means are provided. The control means performs a first boiling operation in which water in the tank is heated to a first boiling temperature by a heat pump at a predetermined first boiling time, and a second boiling time that is the last boiling time of the day. The water in the tank is heated to the third boiling temperature by the heat pump between the second boiling operation in which the water in the tank is heated to the second boiling temperature by the heat pump, and the first boiling operation and the second boiling operation. It is possible to execute the third boiling operation to be raised. In addition, the control means measures the first hot water storage temperature, which is the temperature of the hot water in the tank when the hot water storage amount in the tank becomes smaller than the predetermined hot water storage amount after executing the first boiling operation, using the temperature sensor. When the first hot water storage temperature is higher than the first reference temperature higher than the hot water supply set temperature, the first boiling temperature of the next day is lowered, and the first hot water storage temperature is higher than the hot water supply set temperature and lower than the first reference temperature. When the temperature is lower than the reference temperature, the first boiling temperature on the next day is raised and the first boiling operation on the next day is executed. Further, the control means uses a temperature sensor to determine the second hot water storage temperature, which is the temperature of the hot water in the tank when the hot water in the tank is supplied to the hot water use location at the end of the day after the second boiling operation is performed. When the second hot water storage temperature is higher than the third reference temperature higher than the hot water supply set temperature, the second boiling temperature is lowered on the next day, and the second hot water storage temperature is higher than the hot water supply set temperature and lower than the third reference temperature. When the temperature is lower than 4 reference temperature, the second boiling temperature on the next day is raised and the second boiling operation on the next day is executed. Further, the control means sets the temperature between the first boiling temperature on the next day and the second boiling temperature on the next day to the third boiling point on the next day between the first boiling operation on the next day and the second boiling operation on the next day. As the raised temperature, the third boiling operation on the next day is executed.

  According to such a configuration, with respect to the first boiling operation on the next day, hot water having a temperature lower than the hot water supply set temperature is increased while increasing the COP when performing the boiling operation by lowering the first boiling temperature as much as possible. While being able to suppress the supply to the hot water use location, with respect to the second boiling operation on the next day, the hot water supply set temperature while increasing the COP when performing the boiling operation by lowering the second boiling temperature as much as possible It can suppress that cooler warm water is supplied to a warm water utilization location.

  Moreover, according to said structure, the 3rd boiling temperature in the 3rd boiling operation performed between a 1st boiling operation and a 2nd boiling operation is made into the 1st boiling temperature and the 2nd boiling temperature. The temperature is between. If the third boiling temperature is extremely lower than the first boiling temperature and the second boiling temperature, the temperature of the hot water remaining in the tank during the third boiling operation is changed to the third boiling temperature. There is a possibility that the temperature stratification in the tank is reversed because the temperature is higher than the raised temperature. Conversely, if the third boiling temperature is made extremely higher than the first boiling temperature and the second boiling temperature, the temperature of the hot water remaining in the tank during the second boiling operation becomes the second temperature. There is a possibility that the temperature stratification in the tank is reversed because the temperature is higher than the boiling temperature. As described above, by setting the third boiling temperature between the first boiling temperature and the second boiling temperature, the temperature stratification in the tank is performed during the third boiling operation and the second boiling operation. Can be prevented from reversing.

  As described above, according to the hot water supply system disclosed in the present specification, it is possible to suppress the supply of hot water having a temperature lower than the hot water supply set temperature to the hot water use location while increasing the COP when performing the boiling operation.

  In the above hot water supply system, when the first hot water storage temperature is higher than the first reference temperature higher than the hot water supply set temperature, the temperature obtained by subtracting the absolute value of the difference between the first hot water storage temperature and the first reference temperature from the first boiling temperature is set. When the first boiling temperature is the next day and the first hot water temperature is lower than the second reference temperature that is higher than the hot water set temperature and lower than the first reference temperature, the absolute value of the difference between the first hot water temperature and the second reference temperature is The first boiling operation on the next day may be executed with the temperature added to the 1 boiling temperature as the first boiling temperature on the next day. Further, when the second hot water storage temperature is higher than the third reference temperature higher than the hot water supply set temperature, the temperature obtained by subtracting the absolute value of the difference between the second hot water storage temperature and the third reference temperature from the second boiling temperature is the second day of the next day. When the second hot water temperature is lower than the fourth reference temperature which is higher than the hot water supply set temperature and lower than the third reference temperature, the absolute value of the difference between the second hot water temperature and the fourth reference temperature is set as the second boiling temperature. The second heating operation on the next day may be executed with the temperature added to the second heating temperature on the next day.

  According to such a configuration, regarding the first boiling operation on the next day, the temperature of the hot water remaining in the tank immediately before the hot water boiled in the first boiling operation on the next day is used up (the first hot water storage temperature on the next day). ) Can be accurately approached to a temperature close to the hot water supply set temperature. Further, regarding the second boiling operation on the next day, the temperature of the hot water remaining in the tank at the end of the day (the second hot water storage temperature on the next day) can be accurately brought close to the temperature close to the hot water supply set temperature.

The figure which shows typically the structure of the hot water supply system 2 which concerns on an Example. The graph which shows the relationship between the time regarding a 1st boiling operation, and the amount of hot water storage in the tank. The flowchart (1) which shows the control processing regarding a 1st boiling operation. The graph which shows the relationship between the time regarding 1st boiling operation, and the temperature of the warm water in the tank. The flowchart (2-1) which shows the control processing regarding a 1st boiling operation. The flowchart (2-2) which shows the control processing regarding a 1st boiling operation. The graph which shows the relationship between the time regarding the 2nd boiling operation, and the amount of hot water stored in the tank. The flowchart (1) which shows the control processing regarding a 2nd boiling operation. The graph which shows the relationship between the time regarding the 2nd boiling operation, and the temperature of the hot water in the tank. The flowchart (2-1) which shows the control processing regarding a 2nd boiling operation. The flowchart (2-2) which shows the control processing regarding a 2nd boiling operation. The graph which shows the relationship between the time regarding a 3rd boiling operation, and the amount of hot water storage in the tank. The flowchart (1) which shows the control processing regarding a 3rd boiling operation. The flowchart (2) which shows the control processing regarding a 3rd boiling operation. The flowchart which shows the method of calculating the amount of hot water storage in a tank.

  The main features of the embodiments described below are listed. The technical elements described below are independent technical elements and exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Absent.

  (Characteristic 1) The hot water supply system may further include an auxiliary heater that heats the hot water supplied from the tank to the hot water use location by combustion of fuel.

  When the hot water source is only the heat pump, hot water supply at the hot water supply set temperature becomes impossible if the temperature of the hot water in the tank becomes lower than the hot water supply set temperature. For this reason, in a hot water supply system in which the heat source is only a heat pump, the first reference temperature and the second reference temperature and / or the third reference temperature and the fourth reference temperature are set higher, It is necessary to keep the boiling temperature in the raising operation at a certain level. In contrast to this, when the auxiliary heater is provided in addition to the heat pump as the heating source for hot water as in the hot water supply system described above, the temperature of the hot water in the tank has become lower than the set hot water temperature. Even in this case, hot water can be supplied at a hot water supply set temperature by heating the hot water using an auxiliary heater. Therefore, according to the hot water supply system described above, the first reference temperature and the second reference temperature and / or the third reference temperature and the fourth reference temperature are set to lower temperatures, and the boiling temperature in the heating operation is set. Lower temperatures can be achieved. Therefore, COP in the boiling operation can be further increased.

(Example)
FIG. 1 shows a configuration of a hot water supply system 2 according to the present embodiment. As shown in FIG. 1, the hot water supply system 2 according to this embodiment includes a tank 10, a tank water circulation path 20, a water supply path 30, a supply path 40, a heat pump 50, a burner heating device 60, and a controller 100. .

  The heat pump 50 is a heat source that absorbs heat from the outside air and heats the water in the tank water circulation path 20. The heat pump 50 is a device for boiling water in the tank 10. Although not shown, the heat pump 50 has a heat medium circulation path for circulating a heat medium (for example, R32), an evaporator for exchanging heat between the outside air and the heat medium, and compresses the heat medium to high temperature and high pressure. A compressor, a condenser that exchanges heat between the water in the tank water circulation path 20 and the high-temperature and high-pressure heat medium, an expansion valve that depressurizes the heat medium after the heat exchange is finished, and lowers the temperature to low pressure; It has.

  The tank 10 stores hot water boiled by the heat pump 50. The tank 10 is a hermetically sealed type, and the outside is covered with a heat insulating material. Water is stored in the tank 10 until it is full. In this embodiment, the capacity of the tank 10 is 100L. The thermistors 12, 14, 16, and 18 are attached to the tank 10 at predetermined intervals in the height direction of the tank 10. Each thermistor 12, 14, 16, 18 measures the temperature of water at its mounting position. For example, each of the thermistors 12, 14, 16, and 18 measures the temperature of water at positions 6L, 12L, 30L, and 50L from the top of the tank 10, respectively. The thermistor 11 (an example of a temperature sensor) is attached to the tank 10. The thermistor 11 is attached to the upper part of the tank 10 and measures the temperature of the water stored in the upper part of the tank 10. The thermistor 11 measures the temperature of water just before being discharged from the tank 10.

  The tank water circulation path 20 has an upstream end connected to the lower part of the tank 10 and a downstream end connected to the upper part of the tank 10. A circulation pump 22 is interposed in the tank water circulation path 20. The circulation pump 22 sends the water in the tank water circulation path 20 from the upstream side to the downstream side. Further, the tank water circulation path 20 passes through a condenser (not shown) of the heat pump 50. Therefore, when the heat pump 50 is operated, the water in the tank water circulation path 20 is heated by the condenser of the heat pump 50. Therefore, when the circulation pump 22 and the heat pump 50 are operated, the water in the lower part of the tank 10 is heated by the heat pump 50, and the heated water is returned to the upper part of the tank 10. That is, the tank water circulation path 20 is a water path for storing heat in the tank 10. A thermistor 24 is interposed on the upstream side of the heat pump 50 in the tank water circulation path 20. The thermistor 24 is derived from the lower part of the tank 10 and measures the temperature of water before passing through the heat pump 50.

  An upstream end of the water supply channel 30 is connected to a tap water supply source 31. The water supply channel 30 supplies tap water to the tank 10. A thermistor 32 is interposed in the water supply channel 30. The thermistor 32 measures the tap water supply temperature. The downstream side of the water supply passage 30 branches into a first introduction passage 30a and a second introduction passage 30b. The downstream end of the first introduction path 30 a is connected to the lower part of the tank 10. The downstream end of the second introduction path 30b is connected to a supply path 40 described later. A mixing valve 42 is provided at a connection portion between the downstream end of the second introduction path 30 b and the supply path 40. The mixing valve 42 adjusts the amount by which the water in the second introduction path 30 b is mixed with the hot water flowing in the supply path 40.

  The upstream end of the supply path 40 is connected to the upper part of the tank 10. As described above, in the middle of the supply path 40, the second introduction path 30b of the water supply path 30 is connected, and the mixing valve 42 is provided at the connection portion. A thermistor 43 is interposed in the supply path 40 upstream from the mixing valve 42. The thermistor 43 measures the temperature of the hot water supplied from the tank 10 to the supply path 40. A burner heating device 60 (an example of an auxiliary heater) is interposed in the supply passage 40 on the downstream side of the connection portion with the second introduction passage 30b. A thermistor 44 is interposed in the supply path 40 on the downstream side of the burner heating device 60. The thermistor 44 measures the temperature of the hot water supplied to the hot water use location. The burner heating device 60 heats the water in the supply path 40 so that the temperature of the hot water measured by the thermistor 44 matches the hot water supply set temperature. The burner heating device 60 heats water by burning fuel (for example, gas). The downstream end of the supply path 40 is connected to a hot water use location (for example, a kitchen, a bathtub, etc.).

  The controller 100 (an example of a control unit) is electrically connected to each component and controls the operation of each component. Connected to the controller 100 is a remote controller 104 (an example of a setting unit) having an operation unit that allows a user to input various instructions and a display unit that can display various information. The remote controller 104 can set the hot water supply set temperature at the location where hot water is used. The controller 100 also includes a memory 102 (an example of a storage unit). The memory 102 can store various information.

  Next, the operation of the hot water supply system 2 of the present embodiment will be described. The hot water supply system 2 can perform a boiling operation and a hot water supply operation. Hereinafter, each operation will be described.

(Boiling operation)
The boiling operation is an operation in which water in the tank 10 is heated by the heat pump 50. When execution of the boiling operation is instructed by the controller 100, the heat pump 50 starts its operation and the circulation pump 22 rotates.

  When the heat pump 50 operates, the heat medium circulates in the heat medium circulation path. Further, when the circulation pump 22 rotates, the water in the tank 10 circulates in the tank water circulation path 20. That is, the water existing in the lower part of the tank 10 is introduced into the tank water circulation path 20, and when the introduced water passes through the condenser, it is heated and heated by the heat of the heat medium in the heat medium circulation path. Water is returned to the top of the tank 10. Thereby, hot water is stored in the tank 10. In the upper part of the tank 10, a temperature stratification is formed in which a high-temperature water layer is laminated on a low-temperature water layer.

(Hot water operation)
The hot water supply operation is an operation in which the water in the tank 10 is supplied to the hot water use location. The hot water supply operation can also be executed during the above-described boiling operation. When the hot water tap at the location where the hot water is used is opened, tap water flows into the lower part of the tank 10 from the water supply channel 30 (first introduction channel 30a) due to the water pressure from the tap water supply source 31. At the same time, the hot water in the upper part of the tank 10 is supplied to the hot water use location via the supply path 40.

  When the temperature of the water supplied from the tank 10 to the supply path 40 (that is, the measured temperature of the thermistor 43) is higher than the hot water supply set temperature, the controller 100 opens the mixing valve 42 and supplies it from the second introduction path 30b. Tap water is introduced into the road 40. In this case, the water supplied from the tank 10 and the tap water supplied from the second introduction path 30 b are mixed in the supply path 40. The controller 100 adjusts the opening degree of the mixing valve 42 so that the temperature of the hot water supplied to the hot water use location matches the hot water supply set temperature. On the other hand, the controller 100 operates the burner heating device 60 when the temperature of the hot water supplied from the tank 10 to the supply path 40 is lower than the hot water supply set temperature. In this case, the hot water passing through the supply path 40 is heated by the burner heating device 60. The controller 100 controls the output of the burner heating device 60 so that the temperature of the hot water supplied to the hot water usage location matches the hot water supply set temperature.

(First boiling operation)
Next, control processing in the hot water supply system 2 will be described. First, a control process related to the first boiling operation will be described. In order to explain this, first, it is assumed that the hot water supply set temperature Ta at the hot water use location is set to 40 ° C. by the user operating the remote controller 104. Further, as shown in FIG. 2, it is assumed that hot water is stored in the tank 10 at a certain time (for example, 18:00) on a certain day (for example, August 1). Hot water boiled by the heat pump 50 is stored in the tank 10. It is assumed that the amount of hot water stored in the tank 10 at 18:00 is 30 L (liters) or less.

  In this situation, as shown in FIG. 3, in S9, the controller 100 determines whether or not the current time is the first boiling time. The 1st boiling time is set by the learning process based on the past boiling time, for example, is 18:00. If the current time is the first boiling time, the controller 100 determines Yes in S9 and proceeds to S10. On the other hand, if the current time is not the first boiling time, the controller 100 determines No in S9 and waits.

  In subsequent S <b> 10, the controller 100 determines whether or not a boiling operation for boiling water in the tank 10 by the heat pump 50 is being executed. When the boiling operation is being executed, the controller 100 determines Yes in S10, skips S11, and proceeds to S12. On the other hand, when the boiling operation is not being executed, the controller 100 determines No in S10 and proceeds to S11.

  In subsequent S11, the controller 100 determines whether or not the amount of hot water stored in the tank 10 is 30 L or less. If the amount of hot water stored in the tank 10 is 30 L or less, the controller 100 determines Yes in S11 and proceeds to S12. On the other hand, if the amount of hot water stored in the tank 10 is not 30L or less (more than 30L), the controller 100 determines No in S11 and waits. Whether or not the amount of hot water stored in the tank 10 is 30 L or less can be determined based on the measured temperature of the thermistor 16 attached to the 30 L position of the tank 10. When the measured temperature of the thermistor 16 is not more than a predetermined temperature, it can be determined that the amount of hot water stored in the tank 10 is 30 L or less. The predetermined temperature serving as a reference for determination is, for example, a hot water supply set temperature Ta− (minus) 5 ° C.

  In subsequent S12, the controller 100 permits the first boiling operation. When the controller 100 permits the first boiling operation, the first boiling operation is started. As described above, when the current time is the first boiling time (18:00) and the amount of hot water stored in the tank 10 is equal to or less than the predetermined amount (30 L), the first boiling operation is started. The In addition, when the boiling operation is already being performed, the boiling operation is switched to the first boiling operation. When the first boiling operation is started, water in the tank 10 is boiled by the heat pump 50. The hot water boiled by the heat pump 50 is stored in the tank 10. Therefore, as shown in FIG. 2, the amount of hot water stored in the tank 10 increases after the first boiling time (18:00).

  When the controller 100 performs the first boiling operation, the controller 100 performs the first boiling operation so that the hot water in the tank 10 becomes the first boiling temperature Tw1. The first boiling temperature Tw1 is initially set, and is 45 ° C., for example. Alternatively, the first boiling temperature Tw1 may be set by a learning process based on the past boiling temperature. The heat pump 50 raises the water in the tank 10 to the first boiling temperature Tw1. Hot water having the first boiling temperature Tw1 is stored in the tank 10.

  In subsequent S13, the controller 100 determines whether or not the amount of hot water stored in the tank 10 is 100 L or more. If the amount of hot water stored in the tank 10 is 100 L or more, the controller 100 determines Yes in S13 and proceeds to S14. On the other hand, when the amount of hot water stored in the tank 10 is not 100L or more (less than 100L), the controller 100 determines No in S13 and waits. Whether or not the amount of hot water stored in the tank 10 is 100 L or more can be determined based on the measured temperature of the thermistor 24 interposed upstream of the heat pump 50. When the measured temperature of the thermistor 24 is equal to or higher than a predetermined temperature, it can be determined that the amount of hot water stored in the tank 10 is 100 L or higher. The predetermined temperature serving as a reference for determination is, for example, the first boiling temperature− (minus) 5 ° C.

  In subsequent S14, the controller 100 ends the first boiling operation. For example, as shown in FIG. 2, the amount of hot water stored in the tank 10 becomes 100 L or more at 19:00, and the controller 100 ends the first boiling operation based on that.

  When the hot water supply operation is executed after the first boiling operation is completed, the hot water in the tank 10 is supplied from the tank 10 to the hot water use location, and the amount of hot water stored in the tank 10 decreases. For example, the amount of hot water stored in the tank 10 decreases by filling a bathtub (an example of a hot water use location) with hot water. It is assumed that the amount of hot water stored in the tank 10 becomes 12 L or less at 20:00.

  As shown in FIG. 3, in subsequent S15, the controller 100 determines whether or not the amount of hot water stored in the tank 10 is 12L or less. If the amount of hot water stored in the tank 10 is 12 L or less, the controller 100 determines Yes in S15 and proceeds to S16. On the other hand, if the amount of hot water stored in the tank 10 is not 12L or less (more than 12L), the controller 100 determines No in S15 and waits. Whether or not the amount of hot water stored in the tank 10 is 12 L or less can be determined based on the measured temperature of the thermistor 14 attached to the 12 L position of the tank 10. When the measured temperature of the thermistor 14 is a predetermined temperature or lower, it can be determined that the amount of hot water stored in the tank 10 is 12 L or lower. The predetermined temperature serving as a reference for determination is, for example, a hot water supply set temperature Ta− (minus) 5 ° C.

  In subsequent S <b> 16, the controller 100 measures the first hot water storage temperature Tb <b> 1 that is the temperature of the hot water in the tank 10. The first hot water storage temperature Tb1 is measured by the thermistor 11 attached to the upper part of the tank 10. The measured temperature of the thermistor 11 is transmitted to the controller 100, and the controller 100 receives it. When the amount of hot water stored in the tank 10 is 6 L or less, the controller 100 determines that the tank 10 is out of hot water. Therefore, the controller 100 measures the first hot water storage temperature Tb1 when the amount of hot water stored in the tank 10 is 12L or less and more than 6L. The amount of hot water stored in the tank 10 at this time can be regarded as the minimum amount of hot water stored in one day. The 1st hot water storage temperature Tb1 is the temperature of the warm water just before the tank 10 becomes a hot water out state. That is, the first hot water storage temperature Tb1 is the temperature of the hot water remaining in the tank 10 immediately before the hot water boiled in the first boiling operation is used up.

  As shown in FIG. 4, the temperature of the hot water in the tank 10 is the first boiling temperature Tw1 (for example, 45 ° C.) at 19:00 immediately after the first boiling operation is completed. Thereafter, with the passage of time, the temperature of the hot water in the tank 10 decreases due to natural heat dissipation. Therefore, when the amount of hot water stored in the tank 10 becomes 12 L or less at 20:00, the temperature of the hot water in the tank 10 is lower than the first boiling temperature Tw1. That is, the first hot water storage temperature Tb1 measured by the thermistor 11 is lower than the first boiling temperature Tw1. The first hot water storage temperature Tb1 varies depending on how the temperature of the hot water in the tank 10 decreases. The 1st hot water storage temperature Tb1 is 43 degreeC, 40 degreeC, etc., for example.

  As shown in FIG. 3, in subsequent S <b> 17, the controller 100 stores the measured first hot water storage temperature Tb <b> 1 in the memory 102. Thereafter, the controller 100 ends the process related to the first boiling operation on that day (August 1). The first hot water storage temperature Tb1 on that day (August 1) is used to calculate the first boiling temperature Tw1 in the first boiling operation on the next day (August 2).

  Next, the operation on the next day (August 2) will be described. Also on the next day (August 2), it is assumed that the hot water supply set temperature Ta at the hot water use location is set to 40 ° C. as in the previous day (August 1). Further, it is assumed that the amount of hot water stored in the tank 10 at a certain time (18:00) is 30 L (liters) or less. In the present specification, the next day is assumed to be August 2, and the previous day is assumed to be August 1. The next day (August 2) in this case is the next day relative to the previous day (August 1).

  In this situation, as shown in FIG. 5A, in S19, the controller 100 determines whether or not the current time is the first boiling time. The 1st boiling time is set by the learning process based on the past boiling time, for example, is 18:00. If the current time is the first boiling time, the controller 100 determines Yes in S19 and proceeds to S20. On the other hand, if the current time is not the first boiling time, the controller 100 determines No in S19 and waits.

  In subsequent S <b> 20, the controller 100 determines whether or not a boiling operation for boiling water in the tank 10 by the heat pump 50 is being executed. If the boiling operation is being executed, the controller 100 determines Yes in S20, skips S21, and proceeds to S22. On the other hand, when the boiling operation is not being executed, the controller 100 determines No in S20 and proceeds to S21.

  In subsequent S <b> 21, the controller 100 determines whether or not the amount of hot water stored in the tank 10 is 30 L or less. If the amount of hot water stored in the tank 10 is 30 L or less, the controller 100 determines Yes in S21 and proceeds to S22. On the other hand, if the amount of hot water stored in the tank 10 is not 30L or less (more than 30L), the controller 100 determines No in S21 and waits. Whether or not the amount of hot water stored in the tank 10 is 30 L or less can be determined based on the measured temperature of the thermistor 16 attached to the 30 L position of the tank 10. When the measured temperature of the thermistor 16 is not more than a predetermined temperature, it can be determined that the amount of hot water stored in the tank 10 is 30 L or less. The predetermined temperature serving as a reference for determination is, for example, a hot water supply set temperature Ta− (minus) 5 ° C.

  In continuing S22, the controller 100 acquires 1st hot water storage temperature Tb1 after performing the 1st boiling operation of the previous day (August 1st). The first hot water storage temperature Tb1 of the previous day is stored in the memory 102.

  In subsequent S23, the controller 100 acquires the first boiling temperature Tw1 when the first boiling operation on the previous day (August 1) is executed. The first boiling temperature Tw1 of the previous day is stored in the memory 102.

  As shown in FIG. 5B, in subsequent S24, the controller 100 determines whether or not the first hot water storage temperature Tb1 of the previous day is higher than the hot water supply set temperature Ta + ΔT1. ΔT1 is a preset temperature, for example, 2 ° C. If the first hot water storage temperature Tb1 of the previous day is higher than the hot water supply set temperature Ta + ΔT1, the controller 100 determines Yes in S24 and proceeds to S25. For example, when the first hot water storage temperature Tb1 of the previous day is 43 ° C., the first hot water storage temperature Tb1 (43 ° C.)> The hot water supply set temperature Ta (40 ° C.) + ΔT1 (2 ° C.), and the controller 100 determines Yes in S24. to decide. The hot water supply set temperature Ta + ΔT1 is an example of a first reference temperature. The first reference temperature is a temperature that is higher by ΔT1 than the hot water supply set temperature Ta.

  In subsequent S25, the controller 100 calculates the first boiling temperature Tw1 for the next day (August 2). Specifically, the first boiling temperature Tw1 of the next day = the first boiling temperature Tw1− | the previous day's first boiling temperature Tb1− (the hot water supply set temperature Ta + ΔT1) | That is, the temperature obtained by subtracting the absolute value of the difference between the first hot water storage temperature Tb1 of the previous day and the first reference temperature (hot water supply set temperature Ta + ΔT1) from the first boiling temperature Tw1 of the previous day is set as the first boiling temperature Tw1 of the next day. . Accordingly, the first boiling temperature Tw1 of the next day is lower than the first boiling temperature Tw1 of the previous day.

  On the other hand, in S26 after determining No in S24, the controller 100 determines whether or not the first hot water storage temperature Tb1 of the previous day is lower than the hot water supply set temperature Ta + ΔT2. ΔT2 is a preset temperature, for example, 1 ° C. ΔT2 is a temperature lower than ΔT1 (small value). If the first hot water storage temperature Tb1 of the previous day is lower than the hot water supply set temperature Ta + ΔT2, the controller 100 determines Yes in S26 and proceeds to S27. For example, when the first hot water storage temperature Tb1 of the previous day is 40 ° C., the first hot water storage temperature Tb1 (40 ° C.) <The hot water supply set temperature Ta (40 ° C.) + ΔT2 (1 ° C.), and the controller 100 determines Yes in S26. to decide. The hot water supply set temperature Ta + ΔT2 is an example of a second reference temperature. The second reference temperature is a temperature higher by ΔT2 than the hot water supply set temperature Ta. Further, the second reference temperature is a temperature lower than the first reference temperature.

  In subsequent S27, the controller 100 calculates the first boiling temperature Tw1 for the next day (August 2). Specifically, the first boiling temperature Tw1 of the next day = the first boiling temperature Tw1 + | the previous day's first boiling temperature Tb1− (the hot water supply set temperature Ta + ΔT2) | That is, the temperature obtained by adding the absolute value of the difference between the first hot water storage temperature Tb1 of the previous day and the second reference temperature (hot water supply set temperature Ta + ΔT2) to the first boiling temperature Tw1 of the previous day is defined as the first boiling temperature Tw1 of the next day. . Accordingly, the first boiling temperature Tw1 of the next day is higher than the first boiling temperature Tw1 of the previous day.

  On the other hand, in S28 after determining No in S26, the controller 100 sets the first boiling temperature Tw1 on the next day (August 2) to the same temperature as the first boiling temperature Tw1 on the previous day (August 1). And Accordingly, the first boiling temperature Tw1 does not change.

  In S29, the controller 100 permits the first boiling operation. When the controller 100 permits the first boiling operation, the first boiling operation is started. As described above, when the current time is the first boiling time (18:00) and the amount of hot water stored in the tank 10 is equal to or less than the predetermined amount (30 L), the first boiling operation is started. The In addition, when the boiling operation is already being performed, the boiling operation is switched to the first boiling operation.

  When executing the first boiling operation on the next day (August 2), the controller 100 executes the first boiling operation based on the first boiling temperature Tw1 calculated on the next day as described above. The controller 100 performs the first boiling operation so that the warm water in the tank 10 becomes the first boiling temperature Tw1 calculated on the next day. The heat pump 50 raises the water in the tank 10 to the first boiling temperature Tw1 on the next day. The hot water boiled by the heat pump 50 is stored in the tank 10. The hot water at the first boiling temperature Tw1 of the next day is stored in the tank 10, and the amount of hot water stored in the tank 10 increases.

  Thereafter, in S30, the controller 100 determines whether or not the amount of hot water stored in the tank 10 is 100 L or more. If the amount of hot water stored in the tank 10 is 100 L or more, the controller 100 determines Yes in S30 and proceeds to S31. On the other hand, if the amount of hot water stored in the tank 10 is not 100L or more (less than 100L), the controller 100 determines No in S30 and waits. Whether or not the amount of hot water stored in the tank 10 is 100 L or more can be determined based on the measured temperature of the thermistor 24 interposed upstream of the heat pump 50. When the measured temperature of the thermistor 24 is equal to or higher than a predetermined temperature, it can be determined that the amount of hot water stored in the tank 10 is 100 L or higher. The predetermined temperature that is a criterion for determination is, for example, the first boiling temperature of the next day— (minus) 5 ° C.

  In subsequent S31, the controller 100 ends the first boiling operation. As described above, the first boiling operation on the next day is performed.

  The first boiling operation has been described above. As is apparent from the above description, the hot water supply system 2 includes a heat pump 50 that absorbs heat from the outside air to boil water, a tank 10 that stores hot water boiled by the heat pump 50, and hot water that is stored in the tank 10. A thermistor 11 for measuring the temperature of the water, a supply path 40 for supplying the hot water in the tank 10 to the hot water use location, a remote controller 104 capable of setting the hot water supply set temperature Ta at the hot water use location, and a controller 100. The controller 100 can execute a first boiling operation in which the water in the tank 10 is heated to the first boiling temperature Tw1 by the heat pump 50 at a predetermined first boiling time. Further, the controller 100 calculates the first hot water storage temperature Tb1, which is the temperature of the hot water in the tank 10 when the hot water storage amount in the tank 10 becomes smaller than a predetermined hot water storage amount after executing the first boiling operation. 11 to measure. Thereafter, when the measured first hot water storage temperature Tb1 is higher than the first reference temperature (Ta + ΔT1) higher than the hot water supply set temperature Ta, the controller 100 lowers the first boiling temperature Tw1 of the next day. Specifically, the controller 100 sets the temperature obtained by subtracting the absolute value of the difference between the first hot water storage temperature Tb1 and the first reference temperature (Ta + ΔT1) from the first boiling temperature Tw1 as the first boiling temperature Tw1 on the next day. In addition, when the measured first hot water storage temperature Tb1 is lower than the second reference temperature (Ta + ΔT2) that is higher than the hot water supply set temperature Ta and lower than the first reference temperature, the controller 100 increases the first boiling temperature Tw1 on the next day. Specifically, the controller 100 sets the temperature obtained by adding the absolute value of the difference between the first hot water storage temperature Tb1 and the second reference temperature (Ta + ΔT2) to the first boiling temperature Tw1 as the first boiling temperature Tw1 on the next day. Then, the controller 100 executes the first boiling operation on the next day at the calculated first boiling temperature Tw1 on the next day. That is, the controller 100 lowers or raises the first boiling temperature Tw1 of the next day and executes the first boiling operation of the next day.

  According to such a configuration, the temperature of the hot water remaining in the tank 10 (first hot water storage temperature Tb1) immediately before the hot water boiled in the first boiling operation is used up is higher than the first reference temperature (Ta + ΔT1). In the case, the first boiling temperature Tw1 of the next day is lowered. Thus, on the next day, the first boiling temperature Tw1 is lowered while maintaining the temperature of the hot water remaining in the tank 10 at the hot water supply set temperature Ta or more immediately before the hot water boiled in the first boiling operation is used up. can do. Thus, when the 1st hot water storage temperature Tb1 is high, in order to lower the 1st hot water storage temperature Tb1 of the next day, since the 1st boiling temperature Tw1 of the next day is lowered, the 1st boiling at the time of performing 1st boiling operation is performed. The COP can be increased by lowering the raised temperature Tw1. This is because the hot water supply system 2 can increase the COP by performing the boiling operation at the lowest possible temperature.

  In addition, when the temperature of the hot water remaining in the tank 10 (first hot water storage temperature Tb1) is lower than the second reference temperature (Ta + ΔT2) immediately before the hot water boiled in the first boiling operation is used up, 1 Raise boiling temperature Tw1. Thus, on the next day, the temperature of the hot water remaining in the tank 10 immediately before the hot water boiled up in the first boiling operation is used up can be reliably prevented from falling below the hot water supply set temperature Ta. Thus, when the 1st hot water storage temperature Tb1 is low, the 1st hot water storage temperature Tb1 on the next day can be raised, Therefore When supplying the hot water in the tank 10 to a hot water use location, hot water lower than the hot water supply preset temperature Ta Can be prevented from being supplied to the hot water use location.

  In the above configuration, when lowering the first boiling temperature Tw1 on the next day, the temperature obtained by subtracting the absolute value of the difference between the first hot water storage temperature Tb1 and the first reference temperature (Ta + ΔT1) from the first boiling temperature Tw1 is used. The first boiling temperature Tw1 is set for the next day. Thereby, it can suppress that the 1st boiling temperature Tw1 of the next day becomes low too much. As a result, it is possible to suppress the temperature of the hot water remaining in the tank 10 (the first hot water storage temperature Tb1 on the next day) from becoming too low immediately before the hot water boiled in the first boiling operation on the next day is used up. On the other hand, in the above configuration, when the first boiling temperature Tw1 of the next day is raised, the temperature obtained by adding the absolute value of the difference between the first hot water storage temperature Tb1 and the second reference temperature (Ta + ΔT2) to the first boiling temperature Tw1. The first boiling temperature Tw1 is set for the next day. Thereby, it can suppress that the 1st boiling temperature Tw1 on the next day becomes high too much. As a result, the first hot water storage temperature Tb1 of the next day can be prevented from becoming too high. Since it can suppress that the 1st hot water storage temperature Tb1 of the following day becomes too low and becomes too high, the 1st hot water storage temperature Tb1 of the next day can be closely approached to the temperature close | similar to the hot water supply preset temperature Ta.

  The hot water supply system 2 further includes a burner heating device 60 that heats the hot water supplied from the tank 10 to the location where the hot water is used by burning fuel (for example, gas).

  When the hot water heating source is only the heat pump 50, hot water supply at the hot water supply set temperature Ta becomes impossible if the temperature of the hot water in the tank 10 becomes lower than the hot water supply set temperature Ta. For this reason, in the hot water supply system in which the heating source of the hot water is only the heat pump 50, the first reference temperature and the second reference temperature are set high, and the boiling temperature in the boiling operation is kept high to some extent. It is necessary to keep. In contrast to this, when the burner heating device 60 is provided in addition to the heat pump 50 as a hot water heating source as in the hot water supply system 2 described above, the temperature of the hot water in the tank 10 is temporarily higher than the hot water supply set temperature Ta. Even when the temperature is lowered, hot water can be supplied at the hot water supply set temperature Ta by heating the hot water using the burner heating device 60. Therefore, according to the hot water supply system 2 described above, the first reference temperature and the second reference temperature can be set to lower temperatures, and the boiling temperature in the boiling operation can be lowered. Therefore, COP in the boiling operation can be further increased.

(Second boiling operation)
Next, a control process related to the second boiling operation will be described. In order to explain this, first, it is assumed that the hot water supply set temperature Ta at the hot water use location is set to 40 ° C. by the user operating the remote controller 104. As shown in FIG. 6, it is assumed that hot water is stored in the tank 10 at a certain time (for example, 21:00) on a certain day (for example, August 1). Hot water boiled by the heat pump 50 is stored in the tank 10. It is assumed that the amount of hot water stored in the tank 10 at 22:00 is 30 L (liters) or less.

  In this situation, as shown in FIG. 7, in S39, the controller 100 determines whether or not the current time is the second boiling time. The second boiling time is set by a learning process based on the past boiling time, and is 22:00, for example. The second boiling time (22:00) is a time after the first boiling time (18:00) in the first boiling operation. The second boiling time is the last boiling time of the day. When the current time is the second boiling time, the controller 100 determines Yes in S39 and proceeds to S40. On the other hand, if the current time is not the second boiling time, the controller 100 determines No in S39 and waits.

  In subsequent S <b> 40, the controller 100 determines whether or not a boiling operation for boiling water in the tank 10 by the heat pump 50 is being executed. If the boiling operation is being executed, the controller 100 determines Yes in S40, skips S41, and proceeds to S42. On the other hand, if the boiling operation is not being executed, the controller 100 determines No in S40 and proceeds to S41.

  In subsequent S41, the controller 100 determines whether or not the amount of hot water stored in the tank 10 is 30 L or less. If the amount of hot water stored in the tank 10 is 30 L or less, the controller 100 determines Yes in S41 and proceeds to S42. On the other hand, if the amount of hot water stored in the tank 10 is not 30L or less (more than 30L), the controller 100 determines No in S41 and waits. Whether or not the amount of hot water stored in the tank 10 is 30 L or less can be determined based on the measured temperature of the thermistor 16 attached to the 30 L position of the tank 10. When the measured temperature of the thermistor 16 is not more than a predetermined temperature, it can be determined that the amount of hot water stored in the tank 10 is 30 L or less. The predetermined temperature serving as a reference for determination is, for example, a hot water supply set temperature Ta− (minus) 5 ° C.

  In subsequent S42, the controller 100 permits the second boiling operation. When the controller 100 permits the second boiling operation, the second boiling operation is started. As described above, when the current time is the second boiling time (22:00) and the amount of hot water stored in the tank 10 is equal to or less than the predetermined amount (30 L), the second boiling operation is started. The Further, when the boiling operation is already being performed, the boiling operation is switched to the second boiling operation. When the second boiling operation is started, water in the tank 10 is boiled by the heat pump 50. The hot water boiled by the heat pump 50 is stored in the tank 10. Therefore, as shown in FIG. 6, the amount of hot water stored in the tank 10 increases after the second boiling time (22:00). The second boiling operation is executed after the first boiling operation. The second boiling operation is the last boiling operation of the day.

  When the controller 100 performs the second boiling operation, the controller 100 performs the second boiling operation so that the hot water in the tank 10 becomes the second boiling temperature Tw2. The second boiling temperature Tw2 is initially set, and is 45 ° C., for example. Alternatively, the second boiling temperature Tw2 may be set by a learning process based on the past boiling temperature. The heat pump 50 raises the water in the tank 10 to the second boiling temperature Tw2. Hot water having the second boiling temperature Tw2 is stored in the tank 10.

  In subsequent S43, the controller 100 determines whether or not the amount of hot water stored in the tank 10 is 100 L or more. If the amount of hot water stored in the tank 10 is 100 L or more, the controller 100 determines Yes in S43 and proceeds to S44. On the other hand, if the amount of hot water stored in the tank 10 is not 100L or more (less than 100L), the controller 100 determines No in S43 and waits. Whether or not the amount of hot water stored in the tank 10 is 100 L or more can be determined based on the measured temperature of the thermistor 24 interposed upstream of the heat pump 50. When the measured temperature of the thermistor 24 is equal to or higher than a predetermined temperature, it can be determined that the amount of hot water stored in the tank 10 is 100 L or higher. The predetermined temperature serving as a reference for determination is, for example, the second boiling temperature− (minus) 5 ° C.

  In subsequent S44, the controller 100 ends the second boiling operation. For example, as shown in FIG. 6, the amount of hot water stored in the tank 10 becomes 100 L or more at 23:00, and the controller 100 ends the second boiling operation based on that.

  When the hot water supply operation is performed after the second boiling operation is completed, the hot water in the tank 10 is supplied from the tank 10 to the hot water use location, and the amount of hot water stored in the tank 10 decreases. For example, the amount of hot water stored in the tank 10 decreases as hot water is used for brushing teeth or washing the face.

  As shown in FIG. 7, in subsequent S45, the controller 100 determines whether or not the last hot water supply operation of the day has been executed. When the last hot water supply operation of the day is executed, the controller 100 determines Yes in S45 and proceeds to S46. On the other hand, if the last hot water supply operation of the day has not been executed, the controller 100 determines No in S45 and waits. Whether or not the last hot water supply operation of the day has been executed is determined by, for example, storing the time at which the hot water supply operation of the day (August 1) was executed in the memory 102, on that day (August 1). Can be determined after the completion of When the last hot water supply operation of the day is executed, the amount of hot water stored in the tank 10 does not decrease. For example, if the last hot water supply operation of the day is executed at 23:50 on that day (August 1), the amount of hot water stored in the tank 10 after 23:50 is constant as shown in FIG. Become.

  In subsequent S46, the controller 100 measures the second hot water storage temperature Tb2, which is the temperature of the hot water in the tank 10. The second hot water storage temperature Tb <b> 2 is measured by the thermistor 11 attached to the upper part of the tank 10. The measured temperature of the thermistor 11 is transmitted to the controller 100, and the controller 100 receives it. The 2nd hot water storage temperature Tb2 is the temperature of the hot water in the tank 10 when the last hot water supply operation of the day is performed. That is, the second hot water storage temperature Tb2 is the temperature of the hot water in the tank 10 when the hot water in the tank is supplied to the hot water use location at the end of the day. The second hot water storage temperature Tb2 is the temperature of the hot water remaining in the tank 10 at the end of the day after boiling in the second boiling operation.

  As shown in FIG. 8, the temperature of the hot water in the tank 10 is the second boiling temperature Tw2 (for example, 45 ° C.) at 23:00 immediately after the second boiling operation is completed. Thereafter, with the passage of time, the temperature of the hot water in the tank 10 decreases due to natural heat dissipation. Therefore, when the last hot water supply operation of the day is executed at 23:50, the temperature of the hot water in the tank 10 is lower than the second boiling temperature Tw2. That is, the second hot water storage temperature Tb2 measured by the thermistor 11 is lower than the second boiling temperature Tw2. The second hot water storage temperature Tb2 varies depending on how the temperature of the hot water in the tank 10 decreases. The 2nd hot water storage temperature Tb2 is 43 degreeC, 40 degreeC, etc., for example.

  As shown in FIG. 7, in subsequent S <b> 47, the controller 100 stores the measured second hot water storage temperature Tb <b> 2 in the memory 102. Thereafter, the controller 100 ends the process related to the second boiling operation on that day (August 1). The second hot water storage temperature Tb2 on that day (August 1) is used to calculate the second boiling temperature Tw2 in the second boiling operation on the next day (August 2).

  Next, the operation on the next day (August 2) will be described. Also on the next day (August 2), it is assumed that the hot water supply set temperature Ta at the hot water use location is set to 40 ° C. as in the previous day (August 1). Further, it is assumed that the amount of hot water stored in the tank 10 at a certain time (22:00) is 30 L (liters) or less.

  In this situation, as shown in FIG. 9A, in S49, the controller 100 determines whether or not the current time is the second boiling time. The second boiling time is set by a learning process based on the past boiling time, and is 22:00, for example. If the current time is the second boiling time, the controller 100 determines Yes in S49 and proceeds to S50. On the other hand, if the current time is not the second boiling time, the controller 100 determines No in S49 and waits.

  In subsequent S50, the controller 100 determines whether or not a boiling operation for boiling water in the tank 10 by the heat pump 50 is being executed. If the boiling operation is being executed, the controller 100 determines Yes in S50, skips S51, and proceeds to S52. On the other hand, if the boiling operation is not being executed, the controller 100 determines No in S50 and proceeds to S51.

  In subsequent S51, the controller 100 determines whether or not the amount of hot water stored in the tank 10 is 30L or less. If the amount of hot water stored in the tank 10 is 30 L or less, the controller 100 determines Yes in S51 and proceeds to S52. On the other hand, if the amount of hot water stored in the tank 10 is not 30L or less (more than 30L), the controller 100 determines No in S51 and waits. Whether or not the amount of hot water stored in the tank 10 is 30 L or less can be determined based on the measured temperature of the thermistor 16 attached to the 30 L position of the tank 10. When the measured temperature of the thermistor 16 is not more than a predetermined temperature, it can be determined that the amount of hot water stored in the tank 10 is 30 L or less. The predetermined temperature serving as a reference for determination is, for example, a hot water supply set temperature Ta− (minus) 5 ° C.

  In continuing S52, the controller 100 acquires 2nd hot water storage temperature Tb2 after performing the 2nd heating operation of the previous day (August 1st). The second hot water storage temperature Tb2 of the previous day is stored in the memory 102.

  In subsequent S53, the controller 100 acquires the second boiling temperature Tw2 when the second boiling operation on the previous day (August 1) is executed. The second boiling temperature Tw2 of the previous day is stored in the memory 102.

  As shown in FIG. 9B, in subsequent S54, the controller 100 determines whether or not the second hot water storage temperature Tb2 of the previous day is higher than the hot water supply set temperature Ta + ΔT3. ΔT3 is a preset temperature, for example, 2 ° C. When the second hot water storage temperature Tb2 of the previous day is higher than the hot water supply set temperature Ta + ΔT3, the controller 100 determines Yes in S54 and proceeds to S55. For example, when the second hot water storage temperature Tb2 of the previous day is 43 ° C., the second hot water storage temperature Tb2 (43 ° C.)> The hot water supply set temperature Ta (40 ° C.) + ΔT3 (2 ° C.), and the controller 100 determines Yes in S54. to decide. The hot water supply set temperature Ta + ΔT3 is an example of a third reference temperature. The third reference temperature is a temperature that is higher by ΔT3 than the hot water supply set temperature Ta.

  In subsequent S55, the controller 100 calculates the second boiling temperature Tw2 for the next day (August 2). Specifically, the second boiling temperature Tw2 on the next day = the second boiling temperature Tw2− | the previous day's second hot water storage temperature Tb2− (the hot water supply set temperature Ta + ΔT3) |. That is, the temperature obtained by subtracting the absolute value of the difference between the second hot water storage temperature Tb2 of the previous day and the second reference temperature (hot water set temperature Ta + ΔT3) from the second boiling temperature Tw2 of the previous day is set as the second boiling temperature Tw2 of the next day. . Therefore, the second boiling temperature Tw2 of the next day is lower than the second boiling temperature Tw2 of the previous day.

  On the other hand, in S56 after determining No in S54, the controller 100 determines whether or not the second hot water storage temperature Tb2 of the previous day is lower than the hot water supply set temperature Ta + ΔT4. ΔT4 is a preset temperature, for example, 1 ° C. ΔT4 is a temperature lower than ΔT3 (small value). If the second hot water storage temperature Tb2 of the previous day is lower than the hot water supply set temperature Ta + ΔT4, the controller 100 determines Yes in S56 and proceeds to S57. For example, when the second hot water storage temperature Tb2 of the previous day is 40 ° C., the second hot water storage temperature Tb2 (40 ° C.) <The hot water supply set temperature Ta (40 ° C.) + ΔT4 (1 ° C.), and the controller 100 determines Yes in S56. to decide. The hot water supply set temperature Ta + ΔT4 is an example of a fourth reference temperature. The fourth reference temperature is a temperature that is higher by ΔT4 than the hot water supply set temperature Ta. The fourth reference temperature is a temperature lower than the third reference temperature.

  In subsequent S57, the controller 100 calculates the second boiling temperature Tw2 of the next day (August 2). Specifically, the second boiling temperature Tw2 of the next day = the second boiling temperature Tw2 + of the previous day || the second hot water storage temperature Tb2− (the hot water supply set temperature Ta + ΔT4) | of the previous day. That is, the temperature obtained by adding the absolute value of the difference between the second hot water storage temperature Tb2 of the previous day and the fourth reference temperature (hot water supply set temperature Ta + ΔT4) to the second boiling temperature Tw2 of the previous day is defined as the second boiling temperature Tw2 of the next day. . Accordingly, the second boiling temperature Tw2 of the next day is higher than the second boiling temperature Tw2 of the previous day.

  On the other hand, in S58 after determining No in S56, the controller 100 sets the second boiling temperature Tw2 on the next day (August 2) to the same temperature as the second boiling temperature Tw2 on the previous day (August 1). And Therefore, the second boiling temperature Tw2 does not change.

  In subsequent S59, the controller 100 permits the second boiling operation. When the controller 100 permits the second boiling operation, the second boiling operation is started. As described above, when the current time is the second boiling time (22:00) and the amount of hot water stored in the tank 10 is equal to or less than the predetermined amount (30 L), the second boiling operation is started. The Further, when the boiling operation is already being performed, the boiling operation is switched to the second boiling operation.

  When executing the second boiling operation on the next day (August 2), the controller 100 executes the second boiling operation based on the second boiling temperature Tw2 calculated as described above. The controller 100 performs the second boiling operation so that the warm water in the tank 10 becomes the second boiling temperature Tw2 calculated on the next day. The heat pump 50 raises the water in the tank 10 to the second boiling temperature Tw2 of the next day. The hot water boiled by the heat pump 50 is stored in the tank 10. Hot water at the second boiling temperature Tw2 of the next day is stored in the tank 10, and the amount of hot water stored in the tank 10 increases.

  Thereafter, in S60, the controller 100 determines whether or not the amount of hot water stored in the tank 10 is 100 L or more. If the amount of hot water stored in the tank 10 is 100 L or more, the controller 100 determines Yes in S60 and proceeds to S61. On the other hand, if the amount of hot water stored in the tank 10 is not 100L or more (less than 100L), the controller 100 determines No in S60 and stands by. Whether or not the amount of hot water stored in the tank 10 is 100 L or more can be determined based on the measured temperature of the thermistor 24 interposed upstream of the heat pump 50. When the measured temperature of the thermistor 24 is equal to or higher than a predetermined temperature, it can be determined that the amount of hot water stored in the tank 10 is 100 L or higher. The predetermined temperature serving as a reference for determination is, for example, the second boiling temperature on the next day− (minus) 5 ° C.

  In subsequent S61, the controller 100 ends the second boiling operation. As described above, the second boiling operation on the next day is performed.

  The second boiling operation has been described above. As is apparent from the above description, the hot water supply system 2 includes a heat pump 50 that absorbs heat from the outside air to boil water, a tank 10 that stores hot water boiled by the heat pump 50, and hot water that is stored in the tank 10. A thermistor 11 for measuring the temperature of the water, a supply path 40 for supplying the hot water in the tank 10 to the hot water use location, a remote controller 104 capable of setting the hot water supply set temperature Ta at the hot water use location, and a controller 100. The controller 100 can execute a second boiling operation in which the water in the tank 10 is heated to the second boiling temperature Tw2 by the heat pump 50 at the second boiling time that is the last boiling time of the day. Moreover, the controller 100 measures the temperature of the hot water in the tank 10 when the last hot water supply operation of the day is executed after executing the second boiling operation with the thermistor 11. That is, the controller 100 sets the second hot water storage temperature Tb2 that is the temperature of the hot water in the tank 10 when the hot water in the tank 10 is supplied to the hot water use location at the end of the day after executing the second boiling operation. Measure with thermistor 11. Thereafter, when the measured second hot water storage temperature Tb2 is higher than a third reference temperature (Ta + ΔT3) higher than the hot water supply set temperature Ta, the controller 100 decreases the second boiling temperature Tw2 of the next day. Specifically, the controller 100 sets the temperature obtained by subtracting the absolute value of the difference between the second hot water storage temperature Tb2 and the third reference temperature (Ta + ΔT3) from the second boiling temperature Tw2 as the second boiling temperature Tw2 on the next day. In addition, when the measured second hot water storage temperature Tb2 is lower than the fourth reference temperature (Ta + ΔT4) that is higher than the hot water supply set temperature Ta and lower than the third reference temperature, the controller 100 increases the second boiling temperature Tw2 of the next day. Specifically, the controller 100 sets the temperature obtained by adding the absolute value of the difference between the second hot water storage temperature Tb2 and the fourth reference temperature (Ta + ΔT4) to the second boiling temperature Tw2 as the second boiling temperature Tw2 on the next day. Then, the controller 100 executes the second boiling operation on the next day at the calculated second boiling temperature Tw2 on the next day. That is, the controller 100 lowers or raises the second boiling temperature Tw2 of the next day and executes the second boiling operation of the next day.

  According to such a configuration, after boiling in the second boiling operation, the temperature of the hot water remaining in the tank 10 (second hot water storage temperature Tb2) at the end of the day is the third reference temperature (Ta + ΔT3). If higher, the second boiling temperature Tw2 of the next day is lowered. Thus, on the next day, the second boiling temperature Tw2 can be lowered while maintaining the temperature of the hot water remaining in the tank 10 at the end of the day at the hot water supply set temperature Ta or higher. In this way, when the second hot water storage temperature Tb2 is high, the second boiling water temperature Tw2 of the next day is lowered in order to lower the second hot water storage temperature Tb2 of the next day, so the second boiling when the second boiling operation is performed. COP can be increased by lowering the raised temperature Tw2.

  If the temperature of the hot water (second hot water storage temperature Tb2) remaining in the tank 10 at the end of the day after boiling in the second boiling operation is lower than the fourth reference temperature (Ta + ΔT4), the next day The second boiling temperature Tw2 is increased. Accordingly, it is possible to reliably prevent the temperature of the hot water remaining in the tank 10 at the end of the day from falling below the hot water supply set temperature Ta on the next day. Thus, when the 2nd hot water storage temperature Tb2 is low, since the 2nd hot water storage temperature Tb2 on the next day can be raised, when supplying the hot water in the tank 10 to a hot water utilization location, hot water lower than the hot water supply set temperature Ta Can be prevented from being supplied to the hot water use location.

  In the above configuration, when lowering the second boiling temperature Tw2 of the next day, a temperature obtained by subtracting the absolute value of the difference between the second hot water storage temperature Tb2 and the third reference temperature (Ta + ΔT3) from the second boiling temperature Tw2 is used. The second boiling temperature Tw2 is set for the next day. Thereby, it can suppress that the 2nd boiling temperature Tw2 of the next day becomes low too much. As a result, the temperature of the hot water remaining in the tank 10 at the end of the first day of the next day (the second hot water storage temperature Tb2 of the next day) can be suppressed from becoming too low. On the other hand, in the above configuration, when the second boiling temperature Tw2 of the next day is raised, the temperature obtained by adding the absolute value of the difference between the second hot water storage temperature Tb2 and the fourth reference temperature (Ta + ΔT4) to the second boiling temperature Tw2. The second boiling temperature Tw2 is set for the next day. Thereby, it can suppress that the 2nd boiling temperature Tw2 of the next day becomes too high. As a result, the second hot water storage temperature Tb2 of the next day can be suppressed from becoming too high. Since the second hot water storage temperature Tb2 of the next day can be suppressed from becoming too low and too high, the second hot water storage temperature Tb2 of the next day can be accurately brought close to a temperature close to the hot water supply set temperature Ta.

  The hot water supply system 2 includes a burner heating device 60 that heats the hot water supplied from the tank 10 to the hot water use location by combustion of fuel (for example, gas). According to such a configuration, hot water can be supplied at the hot water supply set temperature Ta by heating the hot water using the burner heating device 60 as in the case of the first boiling operation described above. Therefore, the third reference temperature and the fourth reference temperature can be set to lower temperatures, and the boiling temperature in the boiling operation can be set to a lower temperature. Therefore, COP in the boiling operation can be further increased.

(Third boiling operation)
Next, a control process related to the third boiling operation will be described. In order to explain this, first, it is assumed that the hot water supply set temperature Ta at the hot water use location is set to 40 ° C. by the user operating the remote controller 104. As shown in FIG. 10, it is assumed that hot water is stored in the tank 10 at a certain time (for example, 20:30) on a certain day (for example, August 1). Hot water boiled by the heat pump 50 is stored in the tank 10. The amount of hot water stored in the tank 10 at 20:30 is assumed to be 30 L (liters) or less.

  In this situation, as shown in FIG. 11, in S69, the controller 100 determines whether or not the current time is the third boiling time. The 3rd boiling time is set by the learning process based on the past boiling time, for example, is 20:30. The third boiling time (20:30) is the first boiling time (18:00) in the first boiling operation and the second boiling time (22:00) in the second boiling operation. It is time between. If the current time is the third boiling time, the controller 100 determines Yes in S69 and proceeds to S70. On the other hand, if the current time is not the third boiling time, the controller 100 determines No in S69 and waits.

  In subsequent S <b> 70, the controller 100 determines whether or not a boiling operation for boiling water in the tank 10 by the heat pump 50 is being executed. When the boiling operation is being executed, the controller 100 determines Yes in S70, skips S71, and proceeds to S72. On the other hand, if the boiling operation is not being executed, the controller 100 determines No in S70 and proceeds to S71.

  In subsequent S71, the controller 100 determines whether or not the amount of hot water stored in the tank 10 is 30L or less. If the amount of hot water stored in the tank 10 is 30 L or less, the controller 100 determines Yes in S71 and proceeds to S72. On the other hand, if the amount of hot water stored in the tank 10 is not 30L or less (more than 30L), the controller 100 determines No in S71 and waits. Whether or not the amount of hot water stored in the tank 10 is 30 L or less can be determined based on the measured temperature of the thermistor 16 attached to the 30 L position of the tank 10. When the measured temperature of the thermistor 16 is not more than a predetermined temperature, it can be determined that the amount of hot water stored in the tank 10 is 30 L or less. The predetermined temperature serving as a reference for determination is, for example, a hot water supply set temperature Ta− (minus) 5 ° C.

  In subsequent S72, the controller 100 permits the third boiling operation. When the controller 100 permits the third boiling operation, the third boiling operation is started. As described above, when the current time is the third boiling time (20:30) and the amount of hot water stored in the tank 10 is equal to or less than the predetermined amount (30L), the third boiling operation is started. The If the boiling operation is already being performed, the boiling operation is switched to the third boiling operation. When the third boiling operation is started, the water in the tank 10 is boiled by the heat pump 50. The hot water boiled by the heat pump 50 is stored in the tank 10. Therefore, as shown in FIG. 10, the amount of hot water stored in the tank 10 increases after the third boiling time (20:30). The third boiling operation is executed between the first boiling operation and the second boiling operation. The third boiling operation is executed between the first boiling time and the second boiling time.

  When the controller 100 performs the third boiling operation, the controller 100 performs the third boiling operation so that the hot water in the tank 10 becomes the third boiling temperature Tw3. The third boiling temperature Tw3 is initially set, and is 45 ° C., for example. Or 3rd boiling temperature Tw3 may be set by the learning process based on the past boiling temperature. The heat pump 50 raises the water in the tank 10 to the third boiling temperature Tw3. Hot water having the third boiling temperature Tw3 is stored in the tank 10.

  As shown in FIG. 11, in subsequent S73, the controller 100 determines whether or not the amount of hot water stored in the tank 10 is 100 L or more. If the amount of hot water stored in the tank 10 is 100 L or more, the controller 100 determines Yes in S73 and proceeds to S74. On the other hand, if the amount of hot water stored in the tank 10 is not 100L or more (less than 100L), the controller 100 determines No in S73 and waits. Whether or not the amount of hot water stored in the tank 10 is 100 L or more can be determined based on the measured temperature of the thermistor 24 interposed upstream of the heat pump 50. When the measured temperature of the thermistor 24 is equal to or higher than a predetermined temperature, it can be determined that the amount of hot water stored in the tank 10 is 100 L or higher. The predetermined temperature serving as a reference for determination is, for example, the third boiling temperature− (minus) 5 ° C.

  In subsequent S74, the controller 100 ends the third boiling operation. For example, as shown in FIG. 10, the amount of hot water stored in the tank 10 becomes 100 L or more at 21:30, and the controller 100 ends the third boiling operation based on that. When the hot water supply operation is executed after the completion of the third boiling operation, the hot water in the tank 10 is supplied from the tank 10 to the hot water use location, and the amount of hot water stored in the tank 10 decreases. Thereafter, the controller 100 ends the process related to the third boiling operation on that day (August 1).

  Next, the operation on the next day (August 2) will be described. Also on the next day (August 2), it is assumed that the hot water supply set temperature Ta at the hot water use location is set to 40 ° C. as in the previous day (August 1). Further, it is assumed that the amount of hot water stored in the tank 10 at a certain time (20:30) is 30 L (liters) or less.

  In this situation, as shown in FIG. 12, in S79, the controller 100 determines whether or not the current time is the third boiling time. The 3rd boiling time is set by the learning process based on the past boiling time, for example, is 20:30. If the current time is the third boiling time, the controller 100 determines Yes in S79 and proceeds to S80. On the other hand, if the current time is not the third boiling time, the controller 100 determines No in S79 and waits.

  In subsequent S80, the controller 100 determines whether or not a boiling operation for boiling water in the tank 10 by the heat pump 50 is being executed. If the boiling operation is being executed, the controller 100 determines Yes in S80, skips S81, and proceeds to S82. On the other hand, if the boiling operation is not being executed, the controller 100 determines No in S80 and proceeds to S81.

  In subsequent S81, the controller 100 determines whether or not the amount of hot water stored in the tank 10 is 30L or less. If the amount of hot water stored in the tank 10 is 30L or less, the controller 100 determines Yes in S81 and proceeds to S82. On the other hand, if the amount of hot water stored in the tank 10 is not 30L or less (more than 30L), the controller 100 determines No in S81 and waits. Whether or not the amount of hot water stored in the tank 10 is 30 L or less can be determined based on the measured temperature of the thermistor 16 attached to the 30 L position of the tank 10. When the measured temperature of the thermistor 16 is not more than a predetermined temperature, it can be determined that the amount of hot water stored in the tank 10 is 30 L or less. The predetermined temperature serving as a reference for determination is, for example, a hot water supply set temperature Ta− (minus) 5 ° C.

  In subsequent S82, the controller 100 performs the first boiling temperature Tw1 in the first boiling operation on the next day (August 2) and the second boiling temperature Tw2 in the second boiling operation on the next day (August 2). To get. As explained in the first boiling operation, the first boiling temperature Tw1 of the next day (August 2) is calculated based on the first hot water storage temperature Tb1 of the previous day (August 1). Further, as described in the second boiling operation, the second boiling temperature Tw2 of the next day (August 2) is calculated based on the second hot water storage temperature Tb2 of the previous day (August 1). .

  In subsequent S83, the controller 100 determines whether or not the first boiling temperature Tw1 of the next day (August 2) is equal to or higher than the second boiling temperature Tw2 + 3 ° C. of the next day (August 2). If the first boiling temperature Tw1 of the next day is equal to or higher than the second boiling temperature Tw2 + 3 ° C. of the next day, the controller 100 determines Yes in S83 and proceeds to S84. On the other hand, if the first boiling temperature Tw1 of the next day is not equal to or higher than the second boiling temperature Tw2 + 3 ° C of the next day (Tw1 is lower than Tw2 + 3 ° C), the controller 100 determines No in S83 and proceeds to S85.

  In S84 after determining Yes in S83, the controller 100 calculates the third boiling temperature Tw3 for the next day (August 2). Specifically, the third boiling temperature Tw3 of the next day = the first boiling temperature Tw1−ΔTx of the next day. That is, the temperature obtained by subtracting the predetermined temperature ΔTx from the first boiling temperature Tw1 of the next day is set as the third boiling temperature Tw3 of the next day. The predetermined temperature ΔTx is not particularly limited. Further, the predetermined temperature ΔTx may change over time. For example, ΔTx may be configured to increase by 1 ° C. every 20 minutes from the time when the first hot water storage temperature Tb1 is measured. Also, ΔTx <first day boiling temperature Tw1−second day second boiling temperature Tw2.

  On the other hand, in S85 after determining No in S83, the controller 100 sets the third boiling temperature Tw3 on the next day (August 2) to the same temperature as the second boiling temperature Tw2 on the next day. When the second boiling temperature Tw2 of the next day is higher than the first boiling temperature Tw1 of the next day, the third boiling temperature Tw3 of the next day is also higher than the first boiling temperature Tw1 of the next day. When the second boiling temperature Tw2 of the next day is lower than the first boiling temperature Tw1 of the next day, the third boiling temperature Tw3 of the next day is also lower than the first boiling temperature Tw1 of the next day.

  In subsequent S86, the controller 100 permits the third boiling operation. When the controller 100 permits the third boiling operation, the third boiling operation is started. As described above, when the current time is the third boiling time (20:30) and the amount of hot water stored in the tank 10 is equal to or less than the predetermined amount (30L), the third boiling operation is started. The If the boiling operation is already being performed, the boiling operation is switched to the third boiling operation.

  Thereafter, in S87, the controller 100 determines whether or not the amount of hot water stored in the tank 10 is 100L or more. If the amount of hot water stored in the tank 10 is 100 L or more, the controller 100 determines Yes in S87 and proceeds to S88. On the other hand, if the amount of hot water stored in the tank 10 is not 100L or more (less than 100L), the controller 100 determines No in S87 and waits. Whether or not the amount of hot water stored in the tank 10 is 100 L or more can be determined based on the measured temperature of the thermistor 24 interposed upstream of the heat pump 50. When the measured temperature of the thermistor 24 is equal to or higher than a predetermined temperature, it can be determined that the amount of hot water stored in the tank 10 is 100 L or higher. The predetermined temperature that is a criterion for determination is, for example, the third boiling temperature on the next day— (minus) 5 ° C.

  In subsequent S88, the controller 100 ends the third boiling operation. As described above, the third boiling operation on the next day is performed.

  The third boiling operation has been described above. As is apparent from the above description, the hot water supply system 2 includes a heat pump 50 that absorbs heat from the outside air to boil water, a tank 10 that stores hot water boiled by the heat pump 50, and hot water that is stored in the tank 10. A thermistor 11 for measuring the temperature of the water, a supply path 40 for supplying the hot water in the tank 10 to the hot water use location, a remote controller 104 capable of setting the hot water supply set temperature Ta at the hot water use location, and a controller 100. The controller 100 performs a first boiling operation in which water in the tank 10 is heated to the first boiling temperature Tw1 by the heat pump 50 at a predetermined first boiling time, and a second boiling that is the last boiling time of the day. It is possible to execute the second boiling operation in which the water in the tank 10 is heated to the second boiling temperature Tw2 by the heat pump 50 at the raising time. The first boiling operation and the second boiling operation have been described above. Further, the controller 100 can execute a third boiling operation in which water in the tank 10 is heated to the third boiling temperature Tw3 by the heat pump 50 between the first boiling operation and the second boiling operation. The controller 100 sets the third boiling temperature Tw3 of the next day to the temperature of the first boiling temperature Tw1−ΔTx of the next day. Alternatively, the controller 100 sets the third boiling temperature Tw3 of the next day to the same temperature as the second boiling temperature Tw2 of the next day. That is, the third boiling temperature Tw3 on the next day is a temperature between the first boiling temperature Tw1 on the next day and the second boiling temperature Tw2 on the next day. The controller 100 sets the temperature between the first boiling temperature Tw1 of the next day and the second boiling temperature Tw2 of the next day to the third boiling of the next day between the first boiling operation and the second boiling operation of the next day. The third boiling operation on the next day is executed as the raised temperature Tw3.

  According to such a configuration, regarding the first boiling operation on the next day, while lowering the first boiling temperature Tw1 as much as possible and increasing the COP when performing the boiling operation, the temperature is lower than the hot water supply set temperature Ta. While it is possible to suppress the supply of hot water to the hot water use location, and with respect to the second boiling operation on the next day, while lowering the second boiling temperature Tw2 as much as possible and increasing the COP when performing the boiling operation, It can suppress that warm water lower than hot water supply preset temperature Ta is supplied to a warm water utilization location. Further, regarding the first boiling operation on the next day, the first hot water storage temperature Tb1 on the next day can be accurately brought close to a temperature close to the hot water supply set temperature Ta. Further, regarding the second boiling operation on the next day, the second hot water storage temperature Tb2 on the next day can be accurately brought close to a temperature close to the hot water supply set temperature Ta.

  Moreover, according to said structure, 3rd boiling temperature Tw3 in the 3rd boiling operation performed between 1st boiling operation and 2nd boiling operation is made into 1st boiling temperature Tw1 and 2nd boiling up. The temperature is between the temperatures Tw2. If the third boiling temperature Tw3 is extremely lower than the first boiling temperature Tw1 and the second boiling temperature Tw2, the temperature of the hot water remaining in the tank 10 during the third boiling operation is assumed. Is higher than the third boiling temperature Tw3, and the temperature stratification in the tank 10 may be reversed. Conversely, if the third boiling temperature Tw3 is made extremely higher than the first boiling temperature Tw1 and the second boiling temperature Tw2, the hot water remaining in the tank 10 during the second boiling operation The temperature is higher than the second boiling temperature Tw2, and the temperature stratification in the tank 10 may be reversed. As described above, the third boiling temperature Tw3 is set to a temperature between the first boiling temperature Tw1 and the second boiling temperature Tw2, so that the tank 10 can be used during the third boiling operation or the second boiling operation. It is possible to prevent the inner temperature stratification from being reversed.

  Although one embodiment has been described above, the specific mode is not limited to the above embodiment.

  In the above embodiment, the first hot water storage temperature Tb1 of the previous day (August 1) is used to calculate the first boiling temperature Tw1 of the next day (August 2). However, the present invention is limited to this configuration. It is not a thing. In another embodiment, in order to calculate the first boiling temperature Tw1 of the next day (August 2), the average value of the first hot water storage temperature Tb1 over several days until the previous day (August 1) may be used. Good.

  In the above embodiment, the second hot water storage temperature Tb2 of the previous day (August 1) is used to calculate the second boiling temperature Tw2 of the next day (August 2). However, the present invention is limited to this configuration. Is not to be done. In another embodiment, in order to calculate the second boiling temperature Tw2 of the next day (August 2), the average value of the second hot water storage temperature Tb2 over several days until the previous day (August 1) may be used. Good.

  In the above embodiment, the hot water supply operation is started after the first boiling operation is completed. However, the present invention is not limited to this configuration. In another embodiment, the hot water supply operation may be started before the first boiling operation is finished. Therefore, the hot water in the tank 10 may be supplied to the hot water use location before the amount of hot water stored in the tank 10 reaches 100 L or more.

  In the above embodiment, the third boiling operation is performed once between the first boiling operation and the second boiling operation. However, the present invention is not limited to this configuration. In another embodiment, a plurality of third boiling operations may be performed.

  In the above embodiment, when the amount of hot water stored in the tank 10 is 12 L or less in S15, the first hot water storage temperature Tb1 is measured in S16. However, the present invention is not limited to this configuration. In another embodiment, when the amount of hot water stored in the tank 10 is 30 L or less or 50 L or less in S15, the first hot water storage temperature Tb1 may be measured in S16. That is, the predetermined amount of hot water stored as a reference when measuring the first hot water storage temperature Tb1 is not particularly limited.

  The predetermined hot water storage amount used as a reference when measuring the first hot water storage temperature Tb1 may be set based on the past hot water storage amount. For example, among the hot water storage amount on July 31 the day before August 1, the minimum hot water storage amount excluding the hot water condition can be set as the predetermined hot water storage amount. That is, the amount of hot water stored when the amount of hot water stored in the tank 10 becomes the smallest on a certain day in the past can be set as the predetermined amount of stored hot water. In addition, the minimum hot water storage amount excluding the hot water condition can be measured over the past several days, and the average value thereof can be used as the predetermined hot water storage amount. Further, the hot water storage amount near the minimum hot water storage amount can be set to a predetermined hot water storage amount. The temperature of the hot water immediately before the hot water in the tank 10 is used can be measured by setting the predetermined hot water storage amount as a reference when measuring the first hot water storage temperature Tb1 as small as possible.

  Moreover, the method of calculating | requiring the amount of hot water storage in the tank 10 is not specifically limited. In another embodiment, the amount of hot water stored in the tank 10 can be determined based on the measured temperatures of a plurality of thermistors attached to the tank 10. Specifically, as shown in FIG. 13, first, in S91, the controller 100 acquires the measured temperatures of the thermistors 12, 14, 16, and 18 attached to the positions of 6L, 12L, 30L, and 50L of the tank 10. .

  Subsequently, in S92, the controller 100 calculates the amount of hot water stored in the tank 10 by linear approximation based on the measured temperatures of the thermistors 12, 14, 16, and 18. For example, when the measured temperature of the thermistor 12 attached to the 6L position of the tank 10 is 39 ° C. and the measured temperature of the thermistor 14 attached to the 12L position of the tank 10 is 42 ° C., linear approximation Thus, it can be calculated that the amount of hot water stored at 40 ° C. or higher in the tank 10 is 8 L.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

2: Hot water supply system 10: Tank 11: Thermistor 12: Thermistor 14: Thermistor 16: Thermistor 18: Thermistor 20: Tank water circulation path 22: Circulation pump 24: Thermistor 30: Water supply path 30a: First introduction path 30b: Second introduction path 31: Tap water supply source 32: Thermistor 40: Supply path 42: Mixing valve 43: Thermistor 44: Thermistor 50: Heat pump 60: Burner heating device 100: Controller 102: Memory 104: Remote control

Claims (7)

A heat pump that absorbs heat from the outside air to boil water,
A tank for storing hot water boiled by the heat pump;
A temperature sensor for measuring the temperature of hot water stored in the tank;
A supply path for supplying hot water in the tank to a hot water use location;
Setting means capable of setting the hot water supply set temperature at the hot water use location;
Control means,
The control means can execute a first boiling operation in which water in the tank is heated to a first boiling temperature by the heat pump at a predetermined first boiling time, and after executing the first boiling operation The first hot water storage temperature, which is the temperature of the hot water in the tank when the hot water storage amount in the tank becomes less than a predetermined hot water storage amount, is measured by the temperature sensor, and the first hot water storage temperature is higher than the hot water supply set temperature. When the temperature is higher than the first reference temperature, the first boiling temperature of the next day is lowered, and when the first hot water storage temperature is lower than the second reference temperature that is higher than the hot water supply set temperature and lower than the first reference temperature, the first boiling of the next day is performed. A hot water supply system that raises the temperature and executes the first boiling operation on the next day.   When the first hot water storage temperature is higher than the first reference temperature, which is higher than the hot water supply set temperature, the temperature obtained by subtracting the absolute value of the difference between the first hot water temperature and the first reference temperature from the first boiling temperature is the first boiling on the next day. If the first hot water temperature is lower than the second reference temperature that is higher than the hot water supply set temperature and lower than the first reference temperature, the absolute value of the difference between the first hot water temperature and the second reference temperature is added to the first boiling temperature. The hot water supply system according to claim 1, wherein the first boiling operation on the next day is executed with the measured temperature as the first boiling temperature on the next day. A heat pump that absorbs heat from the outside air to boil water,
A tank for storing hot water boiled by the heat pump;
A temperature sensor for measuring the temperature of hot water stored in the tank;
A supply path for supplying hot water in the tank to a hot water use location;
Setting means capable of setting the hot water supply set temperature at the hot water use location;
Control means,
The control means can execute a second boiling operation in which water in the tank is heated to a second boiling temperature by the heat pump at a second boiling time which is the last boiling time of the day, A second hot water storage temperature, which is the temperature of the hot water in the tank when the hot water in the tank is supplied to the hot water use location at the end of the day after performing the two-boiling operation, is measured by the temperature sensor; When the second hot water storage temperature is higher than the third reference temperature higher than the hot water supply set temperature, the second boiling temperature of the next day is lowered, and the second hot water temperature is higher than the hot water supply set temperature and lower than the third reference temperature. When the temperature is lower, the hot water supply system increases the second boiling temperature on the next day and executes the second boiling operation on the next day.   When the second hot water storage temperature is higher than the third reference temperature higher than the hot water supply set temperature, the temperature obtained by subtracting the absolute value of the difference between the second hot water storage temperature and the third reference temperature from the second boiling temperature is the second boiling on the next day. When the second hot water temperature is lower than the fourth reference temperature which is higher than the set hot water temperature and lower than the third reference temperature, the absolute value of the difference between the second hot water temperature and the fourth reference temperature is added to the second boiling temperature. The hot water supply system according to claim 3, wherein the second boiling operation is performed on the next day, with the measured temperature as the second boiling temperature on the next day. A heat pump that absorbs heat from the outside air to boil water,
A tank for storing hot water boiled by the heat pump;
A temperature sensor for measuring the temperature of hot water stored in the tank;
A supply path for supplying hot water in the tank to a hot water use location;
Setting means capable of setting the hot water supply set temperature at the hot water use location;
Control means,
The control means includes a first boiling operation in which water in the tank is heated to a first boiling temperature by the heat pump at a predetermined first boiling time, and a second boiling that is the last boiling time of the day. The water in the tank is heated by the heat pump between the second boiling operation in which the water in the tank is heated to the second boiling temperature by the heat pump at the time of raising, and the first boiling operation and the second boiling operation. A third boiling operation for boiling to the third boiling temperature can be performed,
A first hot water storage temperature, which is a temperature of the hot water in the tank when the hot water storage amount in the tank becomes less than a predetermined hot water storage amount after performing the first boiling operation, is measured by the temperature sensor, When the 1 hot water storage temperature is higher than the first reference temperature higher than the hot water supply set temperature, the first boiling temperature of the next day is lowered, and the first hot water temperature is higher than the hot water supply set temperature and lower than the first reference temperature. If it is low, raise the first boiling temperature on the next day and execute the first boiling operation on the next day,
The second hot water storage temperature, which is the temperature of the hot water in the tank when the hot water in the tank is supplied to the hot water use location at the end of the day after performing the second boiling operation, is measured by the temperature sensor. When the second hot water storage temperature is higher than the third reference temperature higher than the hot water supply set temperature, the second boiling temperature of the next day is lowered, and the second hot water storage temperature is higher than the hot water supply set temperature and lower than the third reference temperature. If it is lower than the temperature, raise the second boiling temperature on the next day and execute the second boiling operation on the next day,
Between the first boiling operation on the next day and the second boiling operation on the next day, the temperature between the first boiling temperature on the next day and the second boiling temperature on the next day is set as the third boiling temperature on the next day, and the next day A hot water supply system that performs the third boiling operation. When the first hot water storage temperature is higher than the first reference temperature, which is higher than the hot water supply set temperature, the temperature obtained by subtracting the absolute value of the difference between the first hot water temperature and the first reference temperature from the first boiling temperature is the first boiling on the next day. If the first hot water temperature is lower than the second reference temperature that is higher than the hot water supply set temperature and lower than the first reference temperature, the absolute value of the difference between the first hot water temperature and the second reference temperature is added to the first boiling temperature. The first heating operation of the next day is executed with the temperature set as the first heating temperature of the next day,
When the second hot water storage temperature is higher than the third reference temperature higher than the hot water supply set temperature, the temperature obtained by subtracting the absolute value of the difference between the second hot water storage temperature and the third reference temperature from the second boiling temperature is the second boiling on the next day. When the second hot water temperature is lower than the fourth reference temperature which is higher than the set hot water temperature and lower than the third reference temperature, the absolute value of the difference between the second hot water temperature and the fourth reference temperature is added to the second boiling temperature. The hot water supply system according to claim 5, wherein the second boiling operation is performed on the next day, with the measured temperature as the second boiling temperature on the next day. The hot water supply system according to any one of claims 1 to 6, further comprising an auxiliary heater that heats the hot water supplied from the tank to the hot water use location by combustion of fuel.

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