Hot water supply system, control method, and program

Abstract

To provide a hot water supply system capable of performing a boiling operation at a timing when electricity charges are low until the boiling operation. [Solution] The control unit (100) performs a first operation to determine a third time (t3) at which the electricity rate for the hot water supply system is lowest or lower than a predetermined rate within a target period (ΔP) of a predetermined range from a first time (t1) after the end of a heating operation to a second time (t2) at which the next heating operation is required, and a second operation to execute the heating operation during a period including the third time (t3).

Description

[Technical Field]

[0001] The present disclosure relates to a hot water supply system, a control method, and a program. [Background technology]

[0002] Patent Document 1 discloses a system that controls a water heater in response to fluctuations in electricity rates. The control unit inputs information on time-varying electricity rates from an electric power company. When the electricity rate is lower than the base rate, the control unit activates the heating unit (heater) of the water heater. This reduces the electricity rate associated with operating the water heater. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2018-157615 Summary of the Invention [Problem to be solved by the invention]

[0004] In a hot water supply system, as in Patent Document 1, if heating operation is performed under the condition that the electricity rate is lower than a preset rate, there is a possibility that heating operation cannot be performed during a period of time when the electricity rate is lower between that point and the next heating operation.

[0005] An object of the present disclosure is to provide a hot water supply system that can perform a boiling operation at a timing when electricity rates are low before the boiling operation starts. [Means for solving the problem]

[0006] The first aspect is directed to a hot water supply system. The hot water supply system includes a tank (34) that stores water to be supplied to a user, a heating unit (35), and a control unit (100) that executes a water heating operation in which the water in the tank (34) is heated by the heating unit (35). The control unit (100) performs a first operation to determine a third time (t3) at which the electricity rate for the hot water supply system is lowest or lower than a predetermined rate within a target period (ΔP) of a predetermined range from a first time (t1) after the end of the water heating operation to a second time (t2) at which the next water heating operation is required, and a second operation to execute the water heating operation during a period including the third time (t3).

[0007] In the first aspect, the control unit (100) determines a third time (t3) at which the electricity rate will be low during a target period (ΔP) from a first time (t1) after the water heating operation to a second time (t2) at which the next water heating operation is required. The control unit (100) executes the water heating operation during a predetermined period including the third time (t3). In this manner, the control unit (100) takes into account the second time (t2) at which the next water heating operation is required, and executes the water heating operation during the target period (ΔP) prior to the second time (t2) at which the next water heating operation is required, at a timing at which the electricity rate will be low. Therefore, the water heating operation can be executed at a timing at which the electricity rate is low during the period leading up to the water heating operation.

[0008] In the second mode, in the first mode, the control unit (100) determines, in the first operation, the estimated time at which the temperature of the water in the tank (34) is estimated to reach the first reference temperature (Ts1) as the second time (t2).

[0009] In the second aspect, the control unit (100) can perform the water heating operation at a timing before the second time (t2) when it is estimated that the temperature of the water in the tank (34) will reach the first reference temperature (Ts1). Thus, the water heating operation can be performed at a timing when the electricity rate is low during the period until the estimated time when the water heating operation is to be performed so that there is no shortage of hot water in the tank (34).

[0010] In the third aspect, in the second aspect, the control unit (100) executes the first operation at a first time (t1) that is the time when the temperature of the water in the tank (34) reaches a second reference temperature (Ts2) after the end of the boiling operation.

[0011] In the third aspect, the control unit (100) executes the boiling operation after the first time (t1) when the temperature of the water in the tank (34) reaches the second reference temperature (Ts2). This makes it possible to suppress the execution of the boiling operation in a short period of time when the efficiency is low.

[0012] In a fourth aspect, in any one of the first to third aspects, the control unit (100) ends the boiling operation when the temperature of the water in the tank (34) reaches a third reference temperature (Ts3) during the boiling operation.

[0013] In the fourth mode, the water temperature in the tank (34) can be increased to the third reference temperature (Ts3) or higher by the boiling operation.

[0014] The fifth aspect further comprises an operation unit (121) for a user to set at least one of the first time (t1) and the second time (t2) as the set time.

[0015] In the fifth aspect, the user can set the first time (t1) and the second time (t2) by operating the operation unit (121). As a result, the water heating operation can be performed at a timing when the electricity rate is low during the target period (ΔP) desired by the user.

[0016] In a sixth aspect, in any one of the first to fifth aspects, the hot water supply system (1) is configured to perform a heating operation in which water heated by the heating section (35) is supplied to the heating device (5). The control section (100) determines a first period (ΔP1) during which the heating operation is required. When the third time (t3) determined in the first operation overlaps with the first period (ΔP1), the control section (100) determines a fourth time (t4) at which the electricity rate for the hot water supply system is the lowest or lower than a predetermined rate in a second period (ΔP2) of the target period (ΔP) excluding the first period (ΔP1). The control section (100) starts a boiling operation at the fourth time (t4).

[0017] In the sixth aspect, the heating operation can be started at a timing other than the first period (ΔP1) when a heating operation is required, so that the request for heating operation can be met. Since the fourth time (t4) is a timing when electricity rates are low, the electricity rate for the heating operation can be reduced.

[0018] In a seventh aspect, in any one of the first to fifth aspects, the hot water supply system (1) is configured to perform a heating operation in which water heated by the heating section (35) is supplied to the heating device (5). The control section (100) determines a first period (ΔP1) during which the heating operation is required. When a third time (t3) determined in the first operation overlaps with the first period (ΔP1), the control section (100) causes the water heating operation or the heating operation, whichever consumes more power, to be performed during the period including the third time (t3).

[0019] In the seventh aspect, the operation with the higher power consumption is performed when the electricity rate is low, so that the power consumption of the entire hot water supply system can be reduced.

[0020] An eighth aspect relates to a control method for a hot water supply system having a tank (34) that stores water to be supplied to a user and a heating unit (35). The control method includes a first operation of determining a third time (t3) at which the electricity rate for the hot water supply system is lowest or lower than a predetermined rate within a target period (ΔP) of a predetermined range from a first time (t1) after the end of a water heating operation in which water in the tank (34) is heated by the heating unit (35) to a second time (t2) at which the next water heating operation is required, and a second operation of executing the water heating operation during a period including the third time (t3).

[0021] A ninth aspect is a program for causing a computer to execute the control method of the eighth aspect. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a schematic piping diagram showing the overall configuration of a hot water supply system according to an embodiment. [Figure 2] FIG. 2 is a block diagram showing the main devices of the hot water supply system. [Figure 3] FIG. 3 is a flowchart of the first mode. [Figure 4] FIG. 4 is a flowchart of the second mode. [Figure 5] FIG. 5 is a time chart showing the relationship between the electricity fee, the detected temperature inside the tank, and the heating operation in the second mode. [Figure 6] FIG. 6 is a flowchart of the third mode according to the first modification. [Figure 7] FIG. 7 is a time chart showing the relationship between the electricity fee, the water heating operation, and the heating operation in the third mode. [Figure 8] FIG. 8 is a flowchart showing the main part of the fourth mode according to the second modification. DETAILED DESCRIPTION OF THE INVENTION

[0023] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The present disclosure is not limited to the embodiments shown below, and various modifications are possible within the scope of the technical concept of the present disclosure. Since the drawings are intended to conceptually explain the present disclosure, dimensions, ratios, or numbers may be exaggerated or simplified as necessary to facilitate understanding.

[0024] (1) Overall structure The hot water supply system (1) shown in FIG. 1 supplies hot water to a user. In this embodiment, the user includes a hot water supply target and a heating device (5). The hot water supply target is, for example, a faucet, a shower, or a bath. The hot water supply system (1) includes a heat source unit (10), a hot water supply unit (30), and a control unit (100). The heat source unit (10) is installed outdoors. The hot water supply unit (30) is installed indoors, for example. The heat source unit (10) includes a refrigerant circuit (11) that performs a refrigeration cycle. The hot water supply unit (30) includes a water circuit (31) through which water heated by a refrigerant circulates. The hot water supply system (1) includes a water heat exchanger (32) that exchanges heat between the refrigerant in the refrigerant circuit (11) and the water in the water circuit (31). In this embodiment, the water heat exchanger (32) is provided in the hot water supply unit (30), but may be provided in the heat source unit (10). The control unit (100) controls the components of the heat source unit (10) and the hot water supply unit (30).

[0025] (2) Heat source unit The heat source unit (10) has a refrigerant circuit (11) housed in an outdoor casing (not shown) and a fan (20) arranged in an air passage in the outdoor casing. The refrigerant circuit (11) has a compressor (12), an outdoor heat exchanger (13), an expansion valve (14), and a four-way selector valve (15). The compressor (12) compresses the refrigerant it has drawn in and discharges the compressed refrigerant. The outdoor heat exchanger (13) exchanges heat between the refrigerant and outdoor air transported by the fan (20). The expansion valve (14) reduces the pressure of the refrigerant.

[0026] The four-way selector valve (15) switches between a first state indicated by a solid line in FIG. 1 and a second state indicated by a dashed line in FIG. 1. The refrigeration cycle includes a first refrigeration cycle and a second refrigeration cycle. The first refrigeration cycle is a heating cycle for heating water in the water circuit (31). In the first refrigeration cycle, the four-way selector valve (15) is in the first state, and the refrigerant compressed by the compressor (12) releases heat to the water in the water circuit (31) in the water heat exchanger (32), is decompressed by the expansion valve (14), and evaporates in the outdoor heat exchanger (13). The second refrigeration cycle is a defrosting cycle for defrosting the outdoor heat exchanger (13). In the second refrigeration cycle, the four-way switching valve (15) is in the second state, and the refrigerant compressed by the compressor (12) dissipates heat to the air in the outdoor heat exchanger (13), is decompressed by the expansion valve (14), and evaporates in the outdoor heat exchanger (13).

[0027] (3) Hot water supply unit The hot water supply unit (30) includes a water heat exchanger (32), a pump (33), a tank (34), and an internal heat exchanger (35) accommodated in the tank (34).

[0028] The pump 33 circulates the water in the water circuit 31. In Figure 1, the arrows indicate the direction in which the water circulates in the water circuit 31.

[0029] The water heat exchanger (32) has a first flow path (32a) connected to the refrigerant circuit (11) and a second flow path (32b) connected to the water circuit (31). The water heat exchanger (32) exchanges heat between the refrigerant in the first flow path (32a) and the water in the second flow path (32b).

[0030] The tank (34) stores water (more precisely, hot water) to be supplied to a user. The tank (34) is a hollow container having a hot water storage space (S) formed therein. A water supply pipe (36) and a hot water outlet pipe (37) are connected to the tank (34). One end of the water supply pipe (36) is connected to the bottom of the tank (34), and the other end of the water supply pipe (36) is connected to a water main. When the water level in the tank (34) decreases, the water supply pipe (36) supplies low-temperature water from the water main into the tank (34). One end of the hot water outlet pipe (37) is connected to the top of the tank (34), and the other end of the hot water outlet pipe (37) is connected to a predetermined hot water supply object. The hot water outlet pipe (37) supplies high-temperature water from the tank (34) to a hot water supply object such as a faucet, shower, or bath.

[0031] The internal heat exchanger (35) is an example of a heating section that heats the water in the tank (34). The heating section of this embodiment directly heats the water in the tank (34). The internal heat exchanger (35) is disposed in the hot water storage space (S). The internal heat exchanger (35) of this embodiment is a heat transfer tube formed in a spiral shape. Hot water heated by the water heat exchanger (32) flows through the internal heat exchanger (35). The internal heat exchanger (35) exchanges heat between the water flowing therethrough and the surrounding water. As a result, the water in the hot water storage space (S) is heated by the internal heat exchanger (35).

[0032] The water circuit 31 is connected to a utilization-side heat exchanger 6 of the heating device 5. The utilization-side heat exchanger 6 heats the air in the target space (indoor space). The utilization-side heat exchanger 6 is configured as a fin-and-tube heat exchanger or a radiant panel that heats the air, or a heat exchanger for floor heating that heats the floor of the target space.

[0033] The water circuit (31) has a main flow path (40), a hot water supply side flow path (41), and a heating side flow path (42). A pump (33) and a second flow path (32b) of the water heat exchanger (32) are connected to the main flow path (40) in this order. In this embodiment, the pump (33) is disposed upstream of the water heat exchanger (32), but may be disposed downstream of the water heat exchanger (32). An internal heat exchanger (35) is connected to the hot water supply side flow path (41). A utilization side heat exchanger (6) is connected to the heating side flow path (42). An outlet end of the hot water supply side flow path (41) and an outlet end of the heating side flow path (42) are connected to an inlet end of the main flow path (40).

[0034] A three-way valve (43) is connected to the water circuit (31). The three-way valve (43) has a first port (P1), a second port (P2), and a third port (P3). The first port (P1) is connected to an outlet end of the main flow path (40), the second port (P2) is connected to an inlet end of the hot water supply side flow path (41), and the third port (P3) is connected to an inlet end of the heating side flow path (42). The three-way valve (43) is switched between a first state in which the first port (P1) and the second port (P2) communicate with each other, and a second state in which the first port (P1) and the third port (P3) communicate with each other.

[0035] (4) Other equipment (4-1) Sensor As shown in FIG. 1 , the hot water supply system (1) includes a temperature sensor that detects the water temperature in the tank (34). The temperature sensor in this embodiment includes a first temperature sensor (51) and a second temperature sensor (52). The first temperature sensor (51) and the second temperature sensor (52) are disposed in the hot water storage space (S). The first temperature sensor (51) is located higher than the second temperature sensor (52). In this embodiment, the first temperature sensor (51) is located in an upper part of the tank (34), and the second temperature sensor (52) is located in a lower part of the tank (34).

[0036] (4-2) Control Unit The control unit (100) shown in Fig. 2 controls each device of the hot water supply system (1). Specifically, the control unit (100) controls the start / stop of the compressor (12), the rotation speed of the compressor (12), the opening of the expansion valve (14), the state of the four-way selector valve (15), the start / stop of the fan (20), the rotation speed of the fan (20), the start / stop of the pump (33), and the state of the three-way valve (43). The control unit (100) receives input of the temperatures detected by the first temperature sensor (51) and the second temperature sensor (52).

[0037] The control unit (100) includes an MCU (Micro Control Unit), an electric circuit, and an electronic circuit. The MCU includes a CPU (Central Processing Unit), a memory, and a communication interface. The memory stores various programs to be executed by the CPU. The control unit (100) may be composed of one physically independent element, or may be composed of two or more physically separated elements.

[0038] The control unit (100) is connected to the network (N) via a wired or wireless connection. Specifically, the control unit (100) is connected to a server device (150) on the cloud via a router (101), which is an example of a communication interface, and the network (N). The server device (150) is a terminal on the side of the power supply company. Power supply companies include not only power companies but also intermediaries (so-called aggregators) between power companies and consumers. The control unit (100) acquires electricity rate information from the server device (150). Strictly speaking, the electricity rate information is time-varying electricity rate information. The electricity rate information includes, for example, data on the relationship between the time of day and the electricity rate. The control unit (100) acquires electricity rate information for the next day from the server device (150) at predetermined intervals (for example, every day). The actual electricity rate is accrued according to this electricity rate information.

[0039] The control unit (100) has a storage unit (102). The storage unit (102) is configured with, for example, a static random access memory (SRAM), a dynamic random access memory (DRAM), a flash memory, an electrically erasable programmable read-only memory (EEPROM), etc. The storage unit (102) appropriately stores the electricity rate information acquired by the control unit (100).

[0040] (4-3) Remote Controller The remote controller (120) is connected to the control unit (100) wirelessly or via a wire. The remote controller (120) has an operation unit (121) and a display unit (122). The operation unit (121) is used by a user to input various instructions to the hot water supply system (1). The operation unit (121) is configured with buttons, switches, a touch panel, or the like. The instructions referred to here include switching the hot water supply system (1) on / off, switching the operation mode of the hot water supply system (1), and changing various setting values.

[0041] The display unit (122) displays information relating to the state and operation of the hot water supply system (1), including the operation mode and set values ​​of the hot water supply system (1).

[0042] (5) Driving behavior The operation of the hot water supply system (1) will be described. The hot water supply system (1) operates in a first mode and a second mode. The first mode is a normal mode. The second mode is a saving mode that reduces the electricity charge for the operation of the hot water supply system (1).

[0043] (5-1) First mode In the first mode of this embodiment shown in Fig. 3, the control unit (100) determines whether to start or stop the boiling-up operation based on the temperature detected by the first temperature sensor (51), in other words, the temperature detected by one and the same temperature sensor. In the following description, the time when the boiling-up operation ends is used as the reference point.

[0044] After the water heating operation is completed in step ST11, the control unit (100) determines in step ST12 whether the temperature (first detected temperature (T1)) detected by the first temperature sensor (51) is equal to or lower than a first reference temperature (Ts1). The first reference temperature (Ts1) corresponds to a water temperature at which sufficient hot water cannot be supplied to a hot water supply target. If the first detected temperature (T1) is equal to or lower than the first reference temperature (Ts1) in step ST12, the control unit (100) starts the water heating operation in step ST13. In the water heating operation, the control unit (100) executes the first refrigeration cycle in the refrigerant circuit (11), operates the pump (33), and sets the three-way valve (43) to the first state. As a result, the hot water heated in the water heat exchanger (32) releases heat to the surroundings in the internal heat exchanger (35), and hot water is produced in the tank (34).

[0045] During the heating operation, in step ST14, the control unit (100) determines whether the first detected temperature (T1) is equal to or higher than a third reference temperature (Ts3). The third reference temperature (Ts3) corresponds to the water temperature in the tank (34) that is high enough to supply sufficient hot water to the hot water supply target. If, in step ST14, the first detected temperature (T1) is equal to or higher than the third reference temperature (Ts3), the control unit (100) ends the heating operation in step ST15.

[0046] In the first mode, the control unit (100) repeats these processes until an operation termination command is input to the control unit (100).

[0047] (5-2) Second mode The second mode will be described with reference to Figures 4 and 5. The second mode is a power saving mode for performing heating operation during periods when electricity rates are low. Here, if heating operation is performed only on the condition that the electricity rate is lower than a preset rate, there is a possibility that heating operation cannot be performed during a period when the electricity rate is low between that time and the next heating operation. In contrast, the second mode can solve this problem.

[0048] In the second mode of this embodiment, the control unit (100) determines whether to start or stop the boiling-up operation based on the temperature detected by the first temperature sensor (51), in other words, the temperature detected by one and the same temperature sensor. In the following description, the time when the boiling-up operation ends is used as the reference point.

[0049] After the water heating operation is completed in step ST21, the control unit (100) determines in step ST22 whether the first detected temperature (T1) is equal to or lower than the second reference temperature (Ts2). As shown in FIG. 5, the second reference temperature (Ts2) in this embodiment is lower than the third reference temperature (Ts3) that is the criterion for determining the end of the water heating operation in the first and second modes. The second reference temperature (Ts2) is higher than the first reference temperature (Ts1) that is the criterion for determining the start of the water heating operation in the first mode. The second reference temperature (Ts2) is determined taking into consideration the frequency of the water heating operation, the effect of reducing electricity charges, the efficiency of the refrigeration cycle of the refrigerant circuit (11), and the like.

[0050] In step ST22, if the first detected temperature (T1) is equal to or lower than the second reference temperature (Ts2), the control section (100) executes a first operation. The first operation is an operation for determining the start time of the boiling operation. The first operation includes the processes of steps ST23 to ST26.

[0051] In step ST23, the control unit (100) estimates a second time (t2), which is the time when the next water heating operation is required. In this embodiment, the second time (t2) is the estimated time when the temperature of the water in the tank (34) is estimated to reach the first reference temperature (Ts1). Specifically, the control unit (100) determines the estimated time when the first detected temperature (T1) will reach the first reference temperature (Ts1) based on the current first detected temperature (T1) and other data. The other data may include parameters such as the capacity of the tank (34) and the outside air temperature, and past operating history stored in the memory unit (102). The past operating history preferably includes, in particular, changes in the water temperature in the tank (34) while the water heating operation was stopped.

[0052] After the second time (t2) is determined in step ST23, the control unit (100) determines a target period (ΔP) in step ST24. The target period (ΔP) in this embodiment is the period from the first time (t1) to the second time (t2). The first time (t1) is the time when the first operation starts, in other words, the time when the first detected temperature (T1) becomes equal to or lower than the second reference temperature (Ts2).

[0053] After the target period (ΔP) is determined, in step ST25, the control unit (100) reads the electricity rate information stored in the storage unit (102).

[0054] Next, in step ST26, the control unit (100) determines a third time (t3) at which the electricity rate is lowest during the target period (ΔP). In Fig. 5, the third time (t3) corresponds to point A3 at which the electricity rate is lowest.

[0055] Thereafter, in step ST27, the control unit (100) performs a second operation to execute the water heating operation during a period including the third time (t3). As a result, the water heating operation is executed at the time when the electricity rate is lowest, thereby reducing the actual electricity rate. In the second operation of this embodiment, the control unit (100) starts the water heating operation at the third time (t3).

[0056] During the boiling operation, in step ST28, the control unit (100) determines whether the first detected temperature (T1) is equal to or higher than the third reference temperature (Ts3). If the first detected temperature (T1) is equal to or higher than the third reference temperature (Ts3) in step ST28, the control unit (100) ends the boiling operation in step ST29.

[0057] In the second mode, the control unit (100) repeats these processes until an operation termination command is input to the control unit (100).

[0058] (6) Effects of the embodiment (6-1) The control unit (100) performs a first operation and a second operation. In the first operation, the control unit (100) determines a third time (t3) at which the electricity rate for the hot water supply system is lowest within a predetermined target period (ΔP) from a first time (t1) after the end of the water heating operation to a second time (t2) at which the next water heating operation is required. In the second operation, the control unit (100) executes the water heating operation during a period that includes the third time (t3). Strictly speaking, the control unit (100) starts the water heating operation at the third time (t3).

[0059] With this configuration, as shown in Figure 5, water heating operation can be performed at the timing when the electricity rate is lowest during the target period (ΔP), allowing water heating operation to be performed with reduced electricity rates. Specifically, in the first mode, water heating operation is performed at the second time (t2), and the electricity rate is the rate shown by A2 in Figure 5. In contrast, in the second mode, the next water heating operation is performed at the third time (t3), and the electricity rate is the rate shown by A3 in Figure 5.

[0060] The target period (ΔP) obtained by the first operation is a predetermined period from the first time (t1) after the water heating operation to the third time (t3) when the next water heating operation is required, so that the water heating operation can be performed at a timing when the electricity rate is low until the time when the water heating operation is actually required. In addition, in this embodiment, the timing of the water heating operation when the electricity rate will be low can be determined without using a large amount of data or performing complex calculations.

[0061] (6-2) In the first operation, the control unit (100) determines the estimated time when the temperature of the water in the tank (34) is estimated to reach the first reference temperature (Ts1) as the second time (t2), so that the heating operation can be performed before the temperature of the water in the tank (34) drops.

[0062] The control unit (100) executes the boiling operation after the first time (t1) when the temperature of the water in the tank (34) reaches the second reference temperature (Ts2). This makes it possible to suppress the execution of the boiling operation during a short period when the operating efficiency is low. The operating efficiency is particularly low until the refrigeration cycle reaches steady-state operation. Therefore, if the duration of the boiling operation can be extended, the proportion of the period during which the operating efficiency is low during the boiling operation can be reduced. As a result, the overall operating efficiency of the boiling operation can be improved.

[0063] The second reference temperature (Ts2) is higher than the first reference temperature (Ts1), which is the reference for determining when to start the next heating-up operation, and therefore, it is possible to reliably prevent the tank (34) from running short of hot water when there is a demand for hot water due to the timing of starting the next heating-up operation being too late.

[0064] (6-3) When the temperature of the water in the tank (34) reaches the third reference temperature (Ts3) during the boiling operation, the control unit (100) terminates the boiling operation. Therefore, the temperature of the water in the tank (34) can be reliably increased during the boiling operation, thereby meeting the demands of the user.

[0065] The second reference temperature (Ts2) is lower than the third reference temperature (Ts3), which is the criterion for determining whether to end the water boiling operation. Therefore, after the water boiling operation, the water temperature in the tank (34) can be lowered to a certain degree before the next water boiling operation can be performed. This further reduces the number of times the water boiling operation is performed within a short period of time.

[0066] (7) Variations The above-described embodiment may be modified as follows: In the following description, differences from the above-described embodiment will be mainly described.

[0067] (7-1) Variation 1 The control unit (100) of the first modification has a third mode. The third mode is an operation mode that takes into consideration a request for heating operation of the heating device (5). Here, in the heating operation, the control unit (100) causes the refrigerant circuit (11) to perform the first refrigeration cycle, operates the pump (33), and sets the three-way valve (43) to the second state. As a result, the hot water heated in the water heat exchanger (32) dissipates heat to the air surrounding the utilization-side heat exchanger (6) of the heating device (5), thereby heating the room.

[0068] The third mode will be described with reference to Figures 6 and 7. The third mode is a mode for responding to a request for heating operation by shifting the execution time of the water heating operation when a period when electricity rates are low overlaps with a period when heating operation is requested.

[0069] In the third mode of this embodiment, the control unit (100) determines whether to start or stop the boiling-up operation based on the temperature detected by the first temperature sensor (51), in other words, the temperature detected by one and the same temperature sensor. In the following description, the time when the boiling-up operation ends is used as the reference point.

[0070] After the boiling operation ends in step ST41, the control section (100) performs a decision in step ST42 and a first operation in step ST43. These processes are the same as steps ST22 to ST26 in the embodiment, and therefore will not be described again.

[0071] Next, in step ST44, the control unit (100) determines a first period (ΔP1) during which the heating operation is required. The control unit (100) estimates the first period (ΔP1), for example, based on the past operation history of the heating device (5). The user may set the first period (ΔP1) in advance as a schedule by operating the operation unit (121).

[0072] Next, in step ST45, the control unit (100) determines whether the third time (t3) determined in the first operation overlaps with the first period (ΔP1). If the third time (t3) does not overlap with the first period (ΔP1) in step ST45, the control unit (100) executes the heating operation at the third time (t3) in step ST46, as in the above-described embodiment. Next, if the first detected temperature (T1) becomes equal to or higher than the third reference temperature (Ts3) in step ST47, the control unit (100) ends the heating operation in step ST48. Thereafter, the control unit (100) executes the heating operation in step ST49 during the period during which the heating operation is requested. If the heating operation overlaps with the period during which the heating operation is requested, the control unit (100) executes the heating operation with priority, and executes the heating operation for the remaining period after the end of the heating operation.

[0073] If the third time (t3) overlaps with the first period (ΔP1) in step ST45, the control unit (100) determines a fourth time (t4) different from the third time (t3) in step ST50. As shown in FIG. 7, the fourth time (t4) is the time when the electricity rate is lowest in the second period (ΔP2) obtained by excluding the first period (ΔP1) in which heating operation is required from the target period (ΔP) determined in the first operation. In the example of FIG. 7, the electricity rate indicated by A3 is lowest in the target period (ΔP), but this time overlaps with the first period (ΔP1) in which heating operation is required. The electricity rate indicated by A4 is lowest in the second period (ΔP2) that does not overlap with the first period (ΔP1).

[0074] In step ST51, the control unit (100) executes the water-heating operation at the fourth time (t4), thereby preventing the water-heating operation and the heating operation from overlapping, and reducing the electricity charges for the water-heating operation.

[0075] Thereafter, when the first detected temperature (T1) becomes equal to or higher than the third reference temperature (Ts3) in step ST47, the control unit (100) ends the water heating operation in step ST48. Thereafter, the control unit (100) performs the heating operation in step ST49 during the period for which the heating operation is requested. As shown in the example of FIG. 7, when the water heating operation and the period for which the heating operation is requested overlap, the control unit (100) performs the water heating operation with priority, and performs the heating operation for the remaining period after the water heating operation is completed.

[0076] The hot water supply system (1) of the first modification is configured to perform a heating operation in which water heated by a heating section (internal heat exchanger (35)) is supplied to a heating device (5). The control section (100) determines a first period (ΔP1) during which the heating operation is required. If the third time (t3) determined in the first operation overlaps with the first period (ΔP1), the control section (100) determines a fourth time (t4) at which the electricity rate for the hot water supply system is lowest during a second period (ΔP2) of the target period (ΔP) excluding the first period (ΔP1). The control section (100) starts a water heating operation at the fourth time (t4).

[0077] In this configuration, the heating operation can be started at a timing other than the first period (ΔP1) when there is a request for heating operation, so the request for heating operation can be met. Since the fourth time (t4) is a timing when electricity rates are low, the electricity rate for the heating operation can be reduced.

[0078] (7-2) Variation 2 The second modification has a fourth mode. The fourth mode is an operation mode that takes into consideration a request for heating operation of the heating device (5). The fourth mode will be described with reference to FIG. 8. In the fourth mode, when a period when electricity rates are low overlaps with a period when heating operation is requested, one of the two operations, which consumes more power, is performed at the time when the electricity rate is low.

[0079] The fourth mode partially overlaps with the third mode. FIG. 8 shows the differences from the third mode. If the third time (t3) does not overlap with the first period (ΔP1) in step ST45, the process proceeds to step ST46, and steps ST47 to ST49 of the third mode are performed. If the third time (t3) overlaps with the first period (ΔP1) in step ST45, the control unit (100) calculates the power consumption required for the water heating operation in step ST61. Specifically, the control unit (100) calculates the power consumption required for the water heating operation (first power consumption (W1)) based on the thermal load of the hot water supply target, the efficiency of the refrigeration cycle during the water heating operation, the rated capacity and rotation speed of the compressor (12), etc. The first detected temperature (T1), the second detected temperature (T2), and the set temperature (target temperature) of the water are used to estimate the thermal load of the hot water supply target. In step ST62, the control unit (100) calculates the power consumption (second power consumption (W2)) required for the heating operation of the heating device (5). Specifically, the control unit (100) calculates the power consumption for the heating operation based on the heat load of the target space, the efficiency of the refrigeration cycle during the heating operation, the rated capacity and rotation speed of the compressor (12), etc. The air temperature and the set temperature (target temperature) of the target space are used to estimate the heat load of the target space. The order of steps ST61 and ST62 may be reversed.

[0080] Next, if the first power consumption (W1) is equal to or greater than the second power consumption (W2) in step ST63, the control unit (100) executes the heating operation in a period including the third time (t3) in step ST64. In step ST65, the control unit (100) executes the heating operation in a period during which the heating operation is requested. If the heating operation overlaps with the period during which the heating operation is requested, the control unit (100) executes the heating operation with priority, and executes the heating operation for the remaining period after the end of the heating operation.

[0081] If the second power consumption (W2) is greater than the first power consumption (W1) in step ST63, the control unit (100) executes the heating operation in a period including a third time (t3) in step ST66. In step ST67, the control unit (100) executes the water heating operation in a period that does not overlap with the period during which the heating operation is performed. In this case, the control unit (100) preferably executes the water heating operation in a period that includes the time when the electricity rate is lowest among the periods that do not overlap with the period during which the heating operation is performed.

[0082] The hot water supply system (1) of the second modification is configured to perform a heating operation in which water heated by a heating section (internal heat exchanger (35)) is supplied to a heating device (5). The control section (100) determines a first period (ΔP1) during which the heating operation is required. When a third time (t3) determined in the first operation overlaps with the first period (ΔP1), the control section (100) executes the boiling operation or the heating operation, whichever consumes more power, during the period including the third time (t3).

[0083] In this configuration, the operation with the higher power consumption is performed when electricity rates are low, thereby reducing the power consumption of the entire hot water supply system.

[0084] (8) Other embodiments The above-described embodiment and each of the modifications may have the following configuration.

[0085] The hot water supply system may be a system that supplies hot water only to the heating device 5. The heating unit does not have to be the internal heat exchanger 35 in the tank 34, but may be a heat exchanger disposed in the water circuit 31. The heating unit may also be a heater.

[0086] The control unit (100) may be provided in the hot water supply unit (30) or the heat source unit (10), or in a terminal device capable of communicating with these units. The terminal device may be a remote monitoring device, a smartphone, a tablet terminal, a personal computer, a server device, or the like.

[0087] The control unit (100) may make various determinations by comparing the second detected temperature (T2) with each reference temperature (Ts1, Ts2, Ts3). The control unit (100) may compare the first detected temperature (T1) with a certain reference temperature and the second detected temperature (T2) with another reference temperature. Since the temperature detected by the temperature sensor varies depending on its height position, the detected temperature may be corrected according to its height position before being compared with the reference temperature. The tank (34) may include one temperature sensor for detecting the water temperature, or three or more temperature sensors.

[0088] The target period (ΔP) does not have to be from the first time (t1) to the second time (t2), but may be a period within a predetermined range between the first time (t1) and the second time (t2).

[0089] The hot water supply system (1) may include an operation unit (121) for allowing a user to set at least one of the first time (t1) and the second time (t2) as a set time. In this configuration, a period desired by the user is set as a target period (ΔP), and a third time (t3) at which the electricity rate is low can be obtained.

[0090] The control unit (100) may determine as the third time (t3) the time at which the electricity rate becomes lower than a predetermined rate during the target period (ΔP). In this case, the control unit (100) may determine as the third time (t3), for example, the time at which the electricity rate is lower than the average electricity rate during the target period (ΔP). If there are multiple times at which the electricity rate is lower than the predetermined rate, it is preferable to determine as the third time (t3) the time closest to the second time (t2). This can prevent the operating time of the water heating operation from being shortened.

[0091] The control unit (100) may start the boiling operation a predetermined time before the third time (t3), as long as the boiling operation is being performed at the third time (t3).

[0092] The three-way valve (43) may be a mixing control valve that distributes water flowing into the first port (P1) to both the second port (P2) and the third port (P3) at a predetermined ratio.

[0093] (9) Other explanations The control methods according to the above-described embodiments, modifications, and other embodiments include any of the steps described above. The control unit (100) according to the above-described embodiments, modifications, and other embodiments includes a program for causing a computer to execute these steps, and a storage device or storage medium for storing the program.

[0094] Although the embodiments and modifications have been described above, it will be understood that various modifications in form and details are possible without departing from the spirit and scope of the claims. Furthermore, the above embodiments, modifications, and other embodiments may be combined or substituted as appropriate as long as the functionality of the subject matter of the present disclosure is not impaired.

[0095] The terms "first," "second," "third," etc. mentioned above are used to distinguish the terms to which these terms are attached, and do not limit the number or order of the terms. [Industrial Applicability]

[0096] As described above, the present disclosure is useful for hot water supply systems. [Explanation of symbols]

[0097] 1. Hot water system 5. Heating equipment 34 Tank 35 Internal heat exchanger (heating section) 100 control section 121 Operation section t1 1st time t2 2nd time t3 3rd time t4 4th time Ts1 1st reference temperature Ts2 2nd reference temperature Ts3 3rd reference temperature ΔP target period ΔP1 1st period ΔP2 Second period

Claims

1. a tank (34) for storing water to be supplied to the user; a heating section (35); a control unit (100) that performs a boiling operation to heat the water in the tank (34) by the heating unit (35), The control unit (100) a first operation of determining a third time (t3) at which the electricity rate for the hot water supply system is lowest or lower than a predetermined rate within a target period (ΔP) of a predetermined range from a first time (t1) after the end of the heating operation to a second time (t2) at which the next heating operation is required; and a second operation of performing the heating-up operation during a period including the third time (t3). Hot water system.

2. In the first operation, the control section (100) determines the estimated time when the temperature of the water in the tank (34) is estimated to reach a first reference temperature (Ts1) as the second time (t2). The hot water system according to claim 1 .

3. The control unit (100) performs the first operation at the first time (t1) when the temperature of the water in the tank (34) reaches a second reference temperature (Ts2) after the end of the boiling operation. The hot water supply system according to claim 2 .

4. When the temperature of the water in the tank (34) reaches a third reference temperature (Ts3) during the boiling operation, the control unit (100) terminates the boiling operation. The hot water supply system according to claim 3 .

5. The device further includes an operation unit (121) for a user to set at least one of the first time (t1) and the second time (t2) as a set time. The hot water supply system according to any one of claims 1 to 4.

6. The hot water supply system (1) is configured to perform a heating operation in which water heated in the heating section (35) is supplied to a heating device (5), The control unit (100) A first period (ΔP1) requiring the heating operation is calculated, If the third time (t3) calculated in the first operation overlaps with the first period (ΔP1), a fourth time (t4) is calculated at which the electricity rate for the hot water supply system becomes the lowest or becomes lower than a predetermined rate in a second period (ΔP2) of the target period (ΔP) excluding the first period (ΔP1); When the fourth time (t4) arrives, the boiling operation is executed. The hot water supply system according to any one of claims 1 to 4.

7. The hot water supply system (1) is configured to perform a heating operation in which water heated in the heating section (35) is supplied to a heating device (5), The control unit (100) A first period (ΔP1) requiring the heating operation is calculated, When the third time (t3) obtained in the first operation overlaps with the first period (ΔP1), the operation with the larger power consumption out of the boiling operation and the heating operation is executed during a period including the third time (t3). The hot water supply system according to any one of claims 1 to 4.

8. A method for controlling a hot water supply system having a tank (34) for storing water to be supplied to a user and a heating section (35), comprising the steps of: a first operation of determining a third time (t3) at which the electricity rate of the hot water supply system becomes the lowest or becomes lower than a predetermined rate within a target period (ΔP) of a predetermined range from a first time (t1) after the end of a water heating operation in which the water in the tank (34) is heated by the heating section (35) to a second time (t2) at which the next water heating operation is required; and a second operation of performing the heating-up operation during a period including the third time (t3). Control method.

9. A program for causing a computer to execute the control method according to claim 8.

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