Hot water supply system

Abstract

Provided is a hot water supply system with improved convenience for a user. A hot water supply system (100) comprises a tank (21) and a control unit (190). The control unit (190) controls the operation of a hot water supply device (1) that includes the tank (21). The control unit (190) receives a demand response request. The control unit (190) performs a boiling operation for reheating the hot water in the tank (21) if the amount of heat in the tank (21) is less than or equal to a first reference value during a second period, which is a period other than a first period in which the power consumption set on the basis of the demand response request is suppressed. During the first period, the control unit (190) determines whether or not to perform the boiling operation if the amount of heat in the tank (21) is less than or equal to the first reference value.

Description

Hot water system

[0001] Regarding hot water systems.

[0002] A mechanism for adjusting the balance between supply and demand of electricity has been known in the past, in which an electricity supplier (electric power company) requests a demand response (DR) from an electricity consumer regarding the consumption or reduction of electricity, and the electricity consumer adjusts the amount of electricity consumed.

[0003] When a DR request for power reduction (lower DR request) is received, the hot water storage type water heater performs planned heating operation during time periods other than the time periods based on the lower DR request, and stores the heated hot water in the hot water storage tank. In addition, the hot water storage type water heater performs heating operation when the amount of remaining hot water in the hot water storage tank falls below a certain reference value during time periods other than the time periods based on the lower DR request.

[0004] Patent Literature 1 (JP 2019-105984 A) discloses an equipment control device that changes the setting conditions of an air conditioner to setting conditions desired by a user while demand response control is being performed in response to a request for a lower DR. The user selects the desired setting conditions from one or more setting conditions displayed by the equipment control device.

[0005] A hot water storage type water heater performs planned heating operation to automatically maintain the amount of hot water remaining in the hot water storage tank above a certain reference value. Therefore, the device control device of Patent Document 1, which requires user selection, may reduce user convenience.

[0006] The present disclosure provides a hot water supply system that improves user convenience.

[0007] A hot water supply system according to a first aspect includes a tank and a control unit. The control unit controls the operation of a hot water supply device having the tank. The control unit receives a demand response request. If the amount of heat in the tank falls below a first reference value during a second period other than a first period for suppressing power consumption that is set based on the demand response request, the control unit performs a boil-up operation to heat hot water in the tank. If the amount of heat in the tank falls below the first reference value during the first period, the control unit determines whether to perform the boil-up operation.

[0008] Prohibiting the water heating operation during the first period reduces user convenience. With this configuration, user convenience is improved.

[0009] A hot water supply system according to a second aspect is the hot water supply system according to the first aspect, in which the amount of heat in the tank is the amount of hot water remaining in the tank, and the first reference value is a first amount of hot water that is a predetermined amount of hot water.

[0010] The hot water supply system of the third aspect is the hot water supply system of the second aspect, and when the control unit determines that boiling operation should be performed during the first period, the control unit performs boiling operation so that the amount of hot water remaining after the boiling operation is equal to or greater than the first amount.

[0011] This configuration can prevent hot water from running out, improving user convenience.

[0012] The hot water supply system of the fourth aspect is the hot water supply system of the second aspect, and when the control unit determines that heating operation should be performed during the first period, the control unit performs heating operation so that the amount of hot water remaining after the heating operation is equal to or greater than the second amount of hot water, which is the planned amount of hot water to be dispensed after the end of the first period.

[0013] By boiling the planned amount of hot water to be dispensed in advance, there is no need to perform the boiling operation again, improving the operating efficiency of the hot water heater. Also, by preparing the hot water dispense schedule in advance, user convenience is improved.

[0014] A hot water supply system of a fifth aspect is a hot water supply system of any of the first aspect to the fourth aspect, in which the control unit does not perform heating operation if the heat amount in the tank becomes less than a first reference value during a first period.

[0015] With this configuration, it is possible to respond to requests for lower DR.

[0016] A hot water supply system according to a sixth aspect is the hot water supply system according to the fifth aspect, wherein the control unit performs the heating operation after the first period has elapsed.

[0017] With this configuration, it is possible to respond to requests for lower DR.

[0018] A hot water supply system of a seventh aspect is a hot water supply system of a fifth or sixth aspect, in which, if hot water is scheduled to be dispensed after the first period has elapsed, the control unit performs boiling operation after the first period has elapsed until the scheduled hot water dispense time.

[0019] This configuration makes it possible to respond to requests for lowered DR. Also, by preparing for the hot water supply schedule in advance, user convenience is improved.

[0020] A hot water supply system according to an eighth aspect is the hot water supply system according to any one of the fifth aspect to the seventh aspect, wherein the control unit performs the boiling operation within a predetermined first time period after the first period has elapsed.

[0021] This configuration makes it possible to respond to requests for lowered DR. Also, by preparing for hot water supply in advance, user convenience is improved.

[0022] A hot water supply system of a ninth aspect is a hot water supply system of any one of the fifth aspect to the eighth aspect, in which the control unit does not dispense hot water based on a hot water dispensing instruction from the time it determines that heating operation will not be performed until the end time of the first period.

[0023] With this configuration, it is possible to respond to requests for lower DR.

[0024] A hot water supply system according to a tenth aspect is the hot water supply system according to the second aspect, wherein the control unit performs a boiling operation when the remaining amount of hot water is equal to or less than a third amount of hot water that is smaller than the first amount of hot water.

[0025] This configuration can prevent hot water from running out, improving user convenience.

[0026] A hot water supply system according to an eleventh aspect is the hot water supply system according to the tenth aspect, wherein the control unit suppresses the boiling operation when the remaining amount of hot water is greater than the third amount of hot water and equal to or less than the first amount of hot water.

[0027] This configuration reduces power consumption and prevents hot water shortages, making it possible to respond to requests for lowered DRs and improving user convenience.

[0028] A hot water supply system of a twelfth aspect is a hot water supply system of any one of the second, third, fourth, tenth, and eleventh aspects, in which the control unit determines whether to perform boiling operation based on a second time period from the time when the remaining hot water amount becomes equal to or less than the first hot water amount to the end time of the first period.

[0029] By determining whether or not to perform the heating operation depending on the time remaining until the end of the lowering DR period, convenience for the user is improved.

[0030] A hot water supply system according to a thirteenth aspect is the hot water supply system according to the twelfth aspect, wherein the control unit performs the boiling operation when the second time is equal to or longer than a predetermined third time.

[0031] Such a configuration improves user convenience.

[0032] A hot water supply system according to a fourteenth aspect is the hot water supply system according to the twelfth or thirteenth aspect, wherein the control unit does not perform the heating operation when the second time is less than a predetermined third time.

[0033] With this configuration, it is possible to respond to requests for lower DR.

[0034] A hot water supply system according to a fifteenth aspect is the hot water supply system according to the thirteenth or fourteenth aspect, wherein the third time period is set by a user.

[0035] Such a configuration improves user convenience.

[0036] A hot water supply system according to a sixteenth aspect is the hot water supply system according to any one of the first to fifteenth aspects, wherein the control unit controls the operation of two or more hot water supply devices. When one hot water supply device performs a boiling operation during the first period, the control unit restricts the operation of the other hot water supply devices.

[0037] With this configuration, it is possible to respond to requests for lower DR.

[0038] A hot water supply system of a 17th aspect is a hot water supply system of any one of the 1st aspect to the 16th aspect, in which the control unit sets the target value for power consumption reduction to a value equal to or greater than the power consumption reduction level value set based on a demand response request.

[0039] With this configuration, it is possible to respond to requests for lower DR.

[0040] A hot water supply system according to an eighteenth aspect is the hot water supply system according to any one of the first aspect to the seventeenth aspect, wherein the control unit limits the number of hot water supply devices that perform the heating operation during the first period.

[0041] With this configuration, it is possible to respond to requests for lower DR.

[0042] Fig. 1 is a schematic configuration diagram of a hot water supply system. Fig. 2 is a functional block diagram of a hot water supply system. Fig. 3 is a flowchart showing the process flow for determining whether to perform a boiling-up operation according to a first embodiment. Fig. 4 is a diagram for explaining a first hot water amount, a second hot water amount, and a third hot water amount. Fig. 5 is a flowchart showing the process flow for determining whether to perform a boiling-up operation according to a second embodiment. Fig. 6 is a flowchart showing the process flow for determining whether to perform a boiling-up operation according to a third embodiment. Fig. 7 is a functional block diagram of a hot water supply system according to a fourth embodiment.

[0043] First Embodiment (1) Overall Configuration A hot water supply system 100 according to a first embodiment will be described with reference to the drawings.

[0044] The hot water supply system 100 adjusts the power consumption of the commercial power grid in response to a demand response request (hereinafter, sometimes referred to as a DR request).

[0045] Demand response is when a user (consumer) receiving power from a commercial power system adjusts the power consumption of the commercial power system in response to a request from an aggregator 90 such as an electric power company that supplies power from the commercial power system. The aggregator 90 pays the user a remuneration as compensation for the demand response, depending on the amount of adjustment of the power consumption of the commercial power system.

[0046] Fig. 1 is a schematic diagram of a hot water supply system 100. As shown in Fig. 1, the hot water supply system 100 mainly includes a heat pump unit 110, a hot water storage unit 120, a remote controller 130, and a control unit 190. A hot water supply unit 140, a bathtub 150, and a stop valve 160 are connected to the hot water storage unit 120.

[0047] The heat pump unit 110 heats hot water supplied from the hot water storage unit 120 and supplies the heated hot water to the hot water storage unit 120. The hot water storage unit 120 stores the heated hot water supplied from the heat pump unit 110, mixes the stored hot water with water supplied from a stop valve 160, and supplies the water to the hot water supply unit 140 and the bathtub 150. The heat pump unit 110 and the hot water storage unit 120 constitute a hot water supply device 1 that boils hot water in a hot water storage tank (tank) 21 included in the hot water storage unit 120. The hot water supply unit 140 is, for example, a faucet and a shower. The stop valve 160 is connected to an external water supply source such as a water line. The stop valve 160 is operated to supply water to the hot water storage unit 120.

[0048] Here, "hot water" refers to at least one of hot water and cold water. Therefore, both water before being heated by the heat pump unit 110 and water after being heated by the heat pump unit 110 are referred to as hot water.

[0049] (2) Detailed Configuration (2-1) Heat Pump Unit The heat pump unit 110 mainly includes a compressor 11, a water heat exchanger 12, an expansion valve 13, and an air heat exchanger 14. The compressor 11, the water heat exchanger 12, the expansion valve 13, and the air heat exchanger 14 are connected in a ring shape by refrigerant piping to form a heat pump cycle. The discharge side of the compressor 11 is connected to the water heat exchanger 12, and the suction side of the compressor 11 is connected to the air heat exchanger 14. One end of the expansion valve 13 is connected to the water heat exchanger 12, and the other end of the expansion valve 13 is connected to the air heat exchanger 14. The heat pump unit 110 also includes a first control device 10.

[0050] The refrigerant circulating through the heat pump cycle has a critical temperature higher than the temperature of the heated water supplied from the heat pump unit 110 to the hot water storage unit 120. The critical temperature of the refrigerant is preferably 10°C or more higher than the temperature of the heated water. Examples of refrigerants include R32 (critical temperature 78.1°C), HFO-1234yf (critical temperature 95.0°C), and R410 (critical temperature 71.4°C).

[0051] The compressor 11 has a compression mechanism that compresses the refrigerant by driving a motor 11a. The refrigerant compressed by the compressor 11 is sent to a water heat exchanger 12. The heating capacity of the heat pump unit 110 can be adjusted by controlling the operating frequency of the motor 11a.

[0052] The water heat exchanger 12 exchanges heat between the high-temperature refrigerant compressed by the compressor 11 and the hot water supplied from the hot water storage unit 120, thereby heating the hot water. The water heat exchanger 12 is, for example, a double-pipe heat exchanger consisting of an outer pipe and an inner pipe inserted inside the outer pipe. The water heat exchanger 12 may also be a plate-type heat exchanger, etc. The heating capacity of the heat pump unit 110 is, for example, the amount of heat that the water heat exchanger 12 imparts to the hot water supplied from the hot water storage unit 120 per unit time.

[0053] The expansion valve 13 reduces the pressure of the refrigerant that has passed through the water heat exchanger 12 and exchanged heat. The expansion valve 13 is, for example, an electric expansion valve. The expansion valve 13 may be a capillary tube or the like.

[0054] The air heat exchanger 14 exchanges heat between the refrigerant, which has been decompressed after passing through the expansion valve 13, and outside air, thereby heating the refrigerant. Outside air is supplied to the air heat exchanger 14 by, for example, an outside air fan. The refrigerant that has passed through the air heat exchanger 14 and exchanged heat is sent to the compressor 11.

[0055] (2-2) Hot Water Storage Unit The hot water storage unit 120 mainly comprises a hot water storage tank 21, a first drain valve 22, a water inlet valve 23, a boiling pump 24, a bypass valve 25, a boiling valve 26, a first mixing valve 27, a second mixing valve 28, a pressure reducing valve 29, a first flow rate sensor 30, a hot water filling solenoid valve 31, a second drain valve 32, a second flow rate sensor 33, a reheating pump 34, and a reheating heat exchanger 35. These elements are connected by pipes L1 to L19 through which hot water flows. Temperature sensors T1 to T10 are provided in the hot water storage tank 21 and pipes L10, L13, L14, and L16. The hot water storage unit 120 also has a second control device 20.

[0056] The hot water storage tank 21 stores hot water. Six temperature sensors T1 to T6 are provided in the hot water storage tank 21. The six temperature sensors T1 to T6 are composed of a first hot water quantity temperature sensor T1, a second hot water quantity temperature sensor T2, a third hot water quantity temperature sensor T3, a fourth hot water quantity temperature sensor T4, a fifth hot water quantity temperature sensor T5, and an upper temperature sensor T6. The upper temperature sensor T6 is provided near the upper end surface of the hot water storage tank 21. The first to fifth hot water quantity temperature sensors T1 to T5 are provided on the side of the hot water storage tank 21 at intervals from the top to the bottom.

[0057] Because the density of water changes depending on the temperature, the hot water stored in hot water storage tank 21 forms layers with a higher temperature at the top and a lower temperature at the bottom. Therefore, by detecting the temperature distribution of the hot water in hot water storage tank 21 in the vertical direction based on the output signals of temperature sensors T1 to T6, the amount of hot water (remaining hot water) in hot water storage tank 21 can be obtained. The number of temperature sensors provided in hot water storage tank 21 to obtain the remaining hot water amount in hot water storage tank 21 may be any number other than six.

[0058] One end of the water inlet pipe L1 is connected to the bottom surface of the hot water storage tank 21, and the other end of the water inlet pipe L1 is connected to the inlet side of the water heat exchanger 12 of the heat pump unit 110. A water inlet valve 23, a boiling pump 24, and a bypass valve 25 are provided in the water inlet pipe L1 from the hot water storage tank 21 to the water heat exchanger 12. The water inlet valve 23 and the bypass valve 25 are electric three-way valves.

[0059] The first drain pipe L2 branches off from the water inlet pipe L1 between the hot water storage tank 21 and the water inlet valve 23. A first drain valve 22 is provided on the first drain pipe L2. The first drain pipe L2 is connected to a drain pipe outside the hot water storage unit 120. The first drain valve 22 is operated, for example, to discharge hot water from the hot water storage tank 21 to the outside.

[0060] One end of the hot water outlet pipe L3 is connected to the outlet side of the water heat exchanger 12 of the heat pump unit 110, and the other end of the hot water outlet pipe L3 is connected to the boiling valve 26. The boiling valve 26 is an electric three-way valve.

[0061] One end of the first return pipe L4 is connected to the boiling valve 26, and the other end of the first return pipe L4 is connected to the upper end surface of the hot water storage tank 21.

[0062] One end of the second return pipe L5 is connected to the boiling valve 26, and the other end of the second return pipe L5 is connected to the lower end surface of the hot water storage tank 21.

[0063] One end of the bypass pipe L6 is connected to the bypass valve 25, and the other end of the bypass pipe L6 is connected to the hot water outlet pipe L3.

[0064] One end of the first boiling pipe L7 is connected to the upper end surface of the hot water storage tank 21, and the other end of the first boiling pipe L7 is connected to the first mixing valve 27. The first mixing valve 27 is an electric three-way valve.

[0065] One end of the second boiling pipe L8 is connected to the upper end surface of the hot water storage tank 21, and the other end of the second boiling pipe L8 is connected to the second mixing valve 28. The second mixing valve 28 is an electric three-way valve.

[0066] One end of the tank water supply pipe L9 is connected to a stop valve 160 outside the hot water storage unit 120, and the other end of the tank water supply pipe L9 is connected to the lower end surface of the hot water storage tank 21. A pressure reducing valve 29 is provided in the tank water supply pipe L9. The pressure reducing valve 29 is operated to adjust the pressure (water supply pressure) of the water supplied to the hot water storage unit 120 via the stop valve 160.

[0067] The branch water supply pipe L10 branches off from the tank water supply pipe L9 between the pressure reducing valve 29 and the hot water storage tank 21. The branch water supply pipe L10 branches off into a first mixed water pipe L11 and a second mixed water pipe L12. The first mixed water pipe L11 is connected to the first mixing valve 27. The second mixed water pipe L12 is connected to the second mixing valve 28. A mixed water temperature sensor T7 is provided in the branch water supply pipe L10. The mixed water temperature sensor T7 detects the temperature of the hot water flowing through the branch water supply pipe L10.

[0068] One end of the first hot water supply pipe L13 is connected to the first mixing valve 27, and the other end of the first hot water supply pipe L13 is connected to the hot water supply unit 140. A first flow rate sensor 30 is provided in the first hot water supply pipe L13. The first flow rate sensor 30 detects the flow rate of hot water in the first hot water supply pipe L13. A first hot water supply temperature sensor T8 is provided in the first hot water supply pipe L13 between the first flow rate sensor 30 and the hot water supply unit 140. The first hot water supply temperature sensor T8 detects the temperature of the hot water flowing in the first hot water supply pipe L13.

[0069] One end of the second hot water supply pipe L14 is connected to the second mixing valve 28, and the other end of the second hot water supply pipe L14 is connected to the bathtub 150. The second hot water supply pipe L14 is provided with a water filling solenoid valve 31 and a second flow rate sensor 33 from the second mixing valve 28 toward the bathtub 150. The second flow rate sensor 33 detects the flow rate of hot water and water in the second hot water supply pipe L14.

[0070] The second drain pipe L15 branches off from the second hot water supply pipe L14 between the hot water filling solenoid valve 31 and the second flow rate sensor 33. A second drain valve 32 is provided in the second drain pipe L15. The second drain pipe L15 is connected to a drain pipe outside the hot water storage unit 120. The second drain valve 32 is operated to discharge a portion of the hot water flowing through the second hot water supply pipe L14 to the outside, for example, in order to adjust the amount of hot water flowing through the second hot water supply pipe L14.

[0071] One end of the first bathtub return pipe L16 is connected to the bathtub 150, and the other end of the first bathtub return pipe L16 is connected to the inlet side of the reheating heat exchanger 35. A reheating pump 34 is provided in the first bathtub return pipe L16. A bathtub return temperature sensor T10 is provided in the first bathtub return pipe L16 between the bathtub 150 and the reheating pump 34. The bathtub return temperature sensor T10 detects the temperature of the hot water flowing through the first bathtub return pipe L16.

[0072] One end of the second bathtub return pipe L17 is connected to the outlet side of the reheating heat exchanger 35, and the other end of the second bathtub return pipe L17 is connected to the second hot water supply pipe L14 between the second flow rate sensor 33 and the bathtub 150. A second hot water temperature sensor T9 is provided in the second hot water supply pipe L14 between the bathtub 150 and the connection point between the second bathtub return pipe L17 and the second hot water supply pipe L14. The second hot water temperature sensor T9 detects the temperature of the hot water flowing through the second hot water supply pipe L14.

[0073] The first reheating pipe L18 branches off from the second hot water supply pipe L14 between the second mixing valve 28 and the hot water filling solenoid valve 31. The first reheating pipe L18 is connected to the inlet side of the reheating heat exchanger 35.

[0074] One end of the second reheating pipe L19 is connected to the outlet side of the reheating heat exchanger 35, and the other end of the second reheating pipe L19 is connected to the water inlet valve 23.

[0075] (2-3) Remote Controller The remote controller 130 is a user interface for controlling the water heating apparatus 1. The remote controller 130 is installed, for example, in the kitchen and bathroom. As shown in FIG. 2 , the remote controller 130 is connected to the first control device 10 and the second control device 20 via wireless or wired communication to enable bidirectional data communication. Signals for instructing the operation of the water heating apparatus 1 are input from the remote controller 130 to the first control device 10 and the second control device 20 via wireless or wired communication. In addition to the remote controller 130, a mobile information terminal such as a smartphone may be used as the user interface for the water heating apparatus 1.

[0076] The remote controller 130 includes a display unit 130a and an operation unit 130b. The display unit 130a is, for example, a liquid crystal display or an organic EL display.

[0077] Display unit 130a displays information related to the state of water heater 1 and information related to the settings of water heater 1. Display unit 130a displays, for example, the set value of the temperature (hot water supply temperature) of hot water supplied to hot water supply unit 140 and bathtub 150, and the amount of hot water remaining in hot water storage tank 21.

[0078] Operation unit 130b includes buttons, dials, keys, etc. that are operated by a user of water heating apparatus 1. The user of water heating apparatus 1 operates operation unit 130b to input information such as the set value for the hot water temperature. Display unit 130a may be a touch screen that also has the functions of operation unit 130b.

[0079] The remote controller 130 may further include a speaker, a microphone, etc. In this case, the remote controller 130 may notify the user of information displayed on the display unit 130a using the speaker, and may acquire information input by the operation unit 130b via the microphone.

[0080] (2-4) Control Unit The control unit 190 is mainly composed of a first control device 10 of the heat pump unit 110 and a second control device 20 of the hot water storage unit 120. The first control device 10 and the second control device 20 are typically composed of a microcomputer equipped with a control and arithmetic device and a storage device, and an input / output circuit. The control and arithmetic device is a processor such as a CPU or a GPU. The control and arithmetic device reads a control program stored in the storage device and controls the operation of the hot water supply device 1 in accordance with the control program. The control and arithmetic device can write calculation results to the storage device and read information stored in the storage device in accordance with the control program.

[0081] However, the configuration of the control unit 190 is not limited to the above. For example, the first control device 10 and the second control device 20 may communicate with each other and operate cooperatively. Furthermore, instead of providing the first control device 10 and the second control device 20, a device having the functions of both the first control device 10 and the second control device 20 and provided in either the heat pump unit 110 or the hot water storage unit 120 may be provided. Such a device may be installed outside the hot water supply apparatus 1 and connected to the heat pump unit 110 and the hot water storage unit 120 via a network.

[0082] 2 is a functional block diagram of the hot water supply system 100. As shown in FIG. 2, the control unit 190 controls the compressor 11, the expansion valve 13, the water inlet valve 23, the boiling pump 24, the bypass valve 25, the boiling valve 26, the first mixing valve 27, the second mixing valve 28, the hot water filling solenoid valve 31, the reheating pump 34, and the like, based on signals from the temperature sensors T1 to T10, the first flow rate sensor 30, and the second flow rate sensor 33. The control unit 190 is also connected to the aggregator 90 via the network NW so as to be able to communicate with it.

[0083] The control unit 190 mainly performs a heating operation, a hot water supply operation, a bath filling operation, and a reheating operation. The control unit 190 also has a receiving unit 191 and a DR control unit 192 as functional blocks.

[0084] (2-4-1) Heating Operation Heating operation is an operation in which the heat pump unit 110 heats the hot water in the hot water storage tank 21. In heating operation, the boiling pump 24 is driven to guide the hot water in the hot water storage tank 21 to the water heat exchanger 12 via the water inlet pipe L1 and heat it. The hot water heated in the water heat exchanger 12 is returned to the hot water storage tank 21 via the hot water outlet pipe L3, the first return pipe L4, and the second return pipe L5. In this way, in heating operation, the hot water in the hot water storage tank 21 is heated in the water heat exchanger 12 while circulating via the water inlet pipe L1, the hot water outlet pipe L3, the first return pipe L4, and the second return pipe L5.

[0085] The control unit 190 performs boiling operation by controlling the compressor 11, expansion valve 13, water inlet valve 23, boiling pump 24, bypass valve 25, and boiling valve 26. The control unit 190 controls the operating frequency of the motor 11a of the compressor 11 and the opening degree of the expansion valve 13 to adjust the heating capacity of the heat pump unit 110 and the temperature of the hot water heated in the water heat exchanger 12 (outlet hot water temperature), etc. The control unit 190 controls the rotation speed of the boiling pump 24 to adjust the outlet hot water temperature, the amount of hot water remaining in the hot water storage tank 21, the flow rate of hot water supplied to the hot water storage tank 21 (storage flow rate), etc.

[0086] In normal heating operation in which hot water is circulated in the hot water storage tank 21, the control unit 190 controls the water inlet valve 23 so that the water inlet pipe L1 does not communicate with the second reheating pipe L19, and controls the bypass valve 25 so that the water inlet pipe L1 does not communicate with the bypass pipe L6. As will be described later, the control unit 190 controls the water inlet valve 23 when performing the reheating operation.

[0087] The control unit 190 controls the bypass valve 25 to switch between a state in which hot water flowing through the water inlet pipe L1 passes through the water heat exchanger 12 and is supplied to the hot water outlet pipe L3, and a state in which hot water flowing through the water inlet pipe L1 bypasses the water heat exchanger 12 and is supplied to the hot water outlet pipe L3. In the state in which the water heat exchanger 12 is bypassed, the water inlet pipe L1 communicates with the bypass pipe L6, and the hot water in the hot water storage tank 21 circulates without being heated in the water heat exchanger 12.

[0088] The control unit 190 can control the boiling valve 26 to switch between a state in which hot water is supplied from the water heat exchanger 12 to the hot water storage tank 21 via the first return pipe L4, and a state in which hot water is supplied from the water heat exchanger 12 to the hot water storage tank 21 via the second return pipe L5.

[0089] The control unit 190 may acquire the outlet hot water temperature, remaining hot water volume and storage flow rate based on the operating frequency of the motor 11a of the compressor 11, the opening degree of the expansion valve 13, the rotation speed of the boiling pump 24, the state of the bypass valve 25 and the boiling valve 26, and the output signals of the temperature sensors T1 to T6 of the hot water storage tank 21.

[0090] The control unit 190 may feedback control the operating frequency of the motor 11a of the compressor 11, the opening degree of the expansion valve 13, the rotation speed of the boiling pump 24, and the state of the bypass valve 25 and the boiling valve 26 so that the outlet hot water temperature, remaining hot water amount, and storage flow rate reach predetermined target values.

[0091] Control unit 190 executes the water heating operation using power from the commercial power grid. The time period during which the water heating operation is executed may be set by a user of water heating apparatus 1 operating remote controller 130.

[0092] The control unit 190 executes the heating operation when the amount of heat in the hot water storage tank 21 becomes equal to or less than a first reference value. In this embodiment, the amount of heat in the hot water storage tank 21 is the amount of hot water remaining in the hot water storage tank 21. The first reference value is a first hot water amount W1, which is a predetermined amount of hot water.

[0093] Here, the amount of hot water used by a faucet or shower when a user takes a bath is generally 50 liters per person. If the remaining hot water amount is less than 50 liters, there is a high possibility that the hot water will run out when the user takes a bath. Therefore, the predetermined first hot water amount W1 is, for example, 50 liters.

[0094] (2-4-2) Hot Water Supply Operation Hot water supply operation is an operation in which hot water in the hot water storage tank 21 is discharged from the hot water supply unit 140. In the hot water supply operation, if the hot water supply unit 140 is a faucet, by opening the faucet, water from outside is supplied into the hot water storage tank 21 from the bottom of the hot water storage tank 21 via the tank water supply pipe L9 due to the water supply pressure. As a result, high-temperature hot water stored in the hot water storage tank 21 is pushed out from the top of the hot water storage tank 21 via the first boiling pipe L7.

[0095] High-temperature hot water is supplied from the hot water storage tank 21 to the first mixing valve 27 via the first boiling pipe L7, and water from the outside is supplied to the first mixing valve 27 via the tank water supply pipe L9, the branch water supply pipe L10, and the first mixed water pipe L11. In the first mixing valve 27, the high-temperature hot water from the first boiling pipe L7 is mixed with the water from the first mixed water pipe L11. The mixed hot water is discharged from the hot water supply unit 140 via the first hot water supply pipe L13.

[0096] When the user opens the hot water supply unit 140 and the first flow rate sensor 30 detects an increase in the flow rate of hot water in the first hot water supply pipe L13, the control unit 190 starts the hot water supply operation. During the hot water supply operation, the control unit 190 controls the first mixing valve 27 in accordance with the temperature of the hot water supplied from the hot water supply unit 140. The control unit 190 may use the temperature detected by the first hot water supply temperature sensor T8 as the temperature of the hot water supplied from the hot water supply unit 140.

[0097] The control unit 190 may feedback control the mixing ratio of high-temperature hot water and water in the first mixing valve 27 based on the output signals of the mixed water temperature sensor T7 and the first hot water temperature sensor T8, etc., so that the temperature of the hot water discharged from the hot water supply unit 140 becomes a predetermined target value.

[0098] The time period when the hot water supply operation was performed and the amount of hot water used are stored in a storage device as hot water supply history information, for example.

[0099] (2-4-3) Filling operation Filling operation is an operation in which hot water in the hot water storage tank 21 is supplied into the bathtub 150. In filling operation, by opening the filling solenoid valve 31, water from outside is supplied into the hot water storage tank 21 from the bottom of the hot water storage tank 21 via the tank water supply pipe L9 due to the water supply pressure. As a result, high-temperature hot water stored in the hot water storage tank 21 is pushed out from the top of the hot water storage tank 21 via the second boiling pipe L8.

[0100] High-temperature hot water is supplied from the hot water storage tank 21 to the second mixing valve 28 via the second boiling pipe L8, and water from outside is supplied to the second mixing valve 28 via the tank water supply pipe L9, the branch water supply pipe L10, and the second mixed water pipe L12. In the second mixing valve 28, the high-temperature hot water from the second boiling pipe L8 is mixed with the water from the second mixed water pipe L12. The mixed hot water is supplied into the bathtub 150 via the second hot water supply pipe L14.

[0101] When the control unit 190 receives a signal to start the water filling operation via the user's operation of the remote controller 130, it opens the water filling solenoid valve 31, and when the second flow rate sensor 33 detects an increase in the flow rate of hot water in the second hot water supply pipe L14, the control unit 190 starts the water filling operation. During the water filling operation, the control unit 190 controls the second mixing valve 28 according to the temperature of the hot water supplied to the bathtub 150. The control unit 190 may use the temperature detected by the second hot water supply temperature sensor T9 as the temperature of the hot water supplied to the bathtub 150.

[0102] The control unit 190 may feedback control the mixing ratio of high-temperature hot water and cold water in the second mixing valve 28 based on the output signals of the mixed water temperature sensor T7 and the second hot water temperature sensor T9, etc., so that the temperature of the hot water supplied into the bathtub 150 becomes a predetermined target value.

[0103] In addition, while the water filling operation is in progress, the control unit 190 may close the water filling solenoid valve 31 and end the water filling operation when it receives a signal to end the water filling operation by the user operating the remote controller 130, or when the water level in the bathtub 150 detected by a water level sensor (not shown) installed in the bathtub 150 reaches a predetermined target value.

[0104] The time period during which the hot water filling operation is performed may be set by the user of the water heater 1 operating the remote controller 130. The time period during which the hot water filling operation is performed and the amount of hot water to be used are stored in the storage device as hot water discharge schedule information, for example.

[0105] (2-4-4) Reheating Operation Reheating operation is an operation in which the hot water in the bathtub 150 is heated in the reheating heat exchanger 35 and returned to the bathtub 150. In reheating operation, by driving the reheating pump 34, a portion of the hot water in the bathtub 150 is guided to the reheating heat exchanger 35 via the first bathtub return pipe L16 and heated. The hot water heated in the reheating heat exchanger 35 is returned to the bathtub 150 via the second bathtub return pipe L17 and the second hot water supply pipe L14. In this way, in reheating operation, the hot water in the bathtub 150 is heated in the reheating heat exchanger 35 while circulating via the first bathtub return pipe L16, the second bathtub return pipe L17, and the second hot water supply pipe L14.

[0106] The reheating heat exchanger 35 exchanges heat between high-temperature hot water supplied from the hot water storage tank 21 via the second hot water supply pipe L14 and the first reheating pipe L18 and low-temperature hot water supplied from inside the bathtub 150 via the first bathtub return pipe L16. In this way, the reheating heat exchanger 35 heats the hot water supplied from inside the bathtub 150 via the first bathtub return pipe L16. The high-temperature hot water supplied to the reheating heat exchanger 35 via the first reheating pipe L18 undergoes heat exchange and is then supplied to the water inlet pipe L1 via the second reheating pipe L19 and the water inlet valve 23. The reheating heat exchanger 35 may be, for example, a counterflow heat exchanger in which high-temperature hot water and low-temperature hot water flow in opposite directions to exchange heat.

[0107] When the control unit 190 receives a signal to start the reheating operation via the user's operation of the remote controller 130, it controls the water inlet valve 23 to connect the water inlet pipe L1 to the second reheating pipe L19, and drives the boiling pump 24 and the reheating pump 34 to start the reheating operation. During the reheating operation, the control unit 190 controls the rotation speed of the boiling pump 24 and the reheating pump 34 according to the temperature of the hot water in the bathtub 150 and the temperature of the hot water returned from the reheating heat exchanger 35 to the bathtub 150. The control unit 190 may use the temperature detected by the bathtub return temperature sensor T10 as the temperature of the hot water in the bathtub 150, and the temperature detected by the second hot water temperature sensor T9 as the temperature of the hot water returned from the reheating heat exchanger 35 to the bathtub 150.

[0108] The control unit 190 may feedback control the rotation speed of the boiling pump 24 and the reheating pump 34 based on the output signals of the second hot water temperature sensor T9 and the bathtub return temperature sensor T10, etc., so that the temperature of the hot water in the bathtub 150 becomes a predetermined target value.

[0109] In addition, while the reheating operation is being performed, the control unit 190 may receive a signal to end the reheating operation by the user operating the remote controller 130, or when the temperature of the hot water in the bathtub 150 reaches a predetermined target value, control the water inlet valve 23 so that the second reheating pipe L19 does not communicate with the water inlet pipe L1, stop the reheating pump 34, and end the reheating operation.

[0110] The time period when the reheating operation was performed and the amount of hot water used are stored in a storage device as hot water discharge history information, for example.

[0111] (2-4-5) Receiving Unit The receiving unit 191 receives a DR request from the aggregator 90 via the network NW. The DR request includes a decrease DR request and an increase DR request.

[0112] The request for a reduced DR is a request to reduce the power consumption of water heating apparatus 1 in a first period from a normal level. Aggregator 90 makes a request for a reduced DR to control unit 190 before the arrival of a first period in which the power supply in the commercial power grid is predicted to be tight.

[0113] The increased DR request is a request to increase the power consumption of water heating apparatus 1 in the second period from the normal level. Aggregator 90 makes an increased DR request to control unit 190 before the second period arrives, during which excess power is predicted to be in the commercial power grid.

[0114] The lowering DR request and the raising DR request may include a target value for power consumption.

[0115] (2-4-6) DR Control Unit The DR control unit 192 performs control so as not to perform the water heating operation during the first period. However, as will be described later, if the DR control unit 192 determines that the water heating operation should be performed, the water heating operation is performed.

[0116] The DR control unit 192 determines whether to perform the boiling operation when the remaining amount of hot water during the first period becomes equal to or less than a first hot water amount W1. The first hot water amount W1 is stored in advance in a storage device. The first hot water amount W1 may be set by the user operating the remote controller 130.

[0117] When the amount of remaining hot water becomes equal to or less than the first amount of hot water W1, the DR control unit 192 determines whether or not to perform the boiling operation depending on the amount of remaining hot water, as shown in the flowchart of FIG.

[0118] When the remaining hot water amount becomes equal to or less than the first hot water amount W1, the DR control unit 192 determines whether or not it is the first period (step S11). If it is not the first period (NO in step S11), the DR control unit 192 does not determine whether or not to perform the boiling operation. In this case, the control unit 190 performs the boiling operation as usual.

[0119] If it is the first period (YES in step S11), the DR control unit 192 determines whether the remaining hot water volume is equal to or less than a third hot water volume W3 (step S12). The third hot water volume W3 is an amount of hot water smaller than the first hot water volume W1, for example, 15 liters. If the remaining hot water volume is equal to or less than the third hot water volume W3, there is a high possibility that the hot water will run out.

[0120] Fig. 4 is a diagram for explaining the first hot water volume W1, the second hot water volume W2, and the third hot water volume W3. The hot water in the hot water storage tank 21 is boiled from the top of the hot water storage tank 21 toward the bottom of the hot water storage tank 21. As shown in Fig. 4, the first hot water volume W1 is the amount of hot water above the dashed line G1. The third hot water volume W3 is an amount of hot water smaller than the first hot water volume W1 and above the dashed line G3.

[0121] If the remaining amount of hot water is greater than the third amount of hot water W3 (NO in step S12), the DR control unit 192 determines not to perform the boiling operation (step S16).

[0122] On the other hand, if the amount of remaining hot water is equal to or less than the third hot water amount W3 (YES in step S12), the DR control unit 192 determines to perform the boiling operation (step S13).

[0123] The DR control unit 192 determines whether or not there is a hot water dispense schedule after the end of the first period based on the hot water dispense history information regarding the time period when the hot water supply operation was performed, the time period when the reheating operation was performed, and the amount of hot water used (step S14). The DR control unit 192 also determines whether or not there is a hot water dispense schedule after the end of the first period based on the time period when the hot water filling operation was performed and the hot water dispense schedule information regarding the amount of hot water used (step S14). Note that "after the end of the first period" refers to within a predetermined fourth hour from the end time of the first period.

[0124] If it is determined that hot water is scheduled to be dispensed after the end of the first period (YES in step S14), the DR control unit 192 determines to boil more than the second amount of hot water W2 during the boiling operation (step S15). The second amount of hot water W2 is the amount of hot water scheduled to be dispensed after the end of the first period (planned amount of hot water to be dispensed). The DR control unit 192 calculates the second amount of hot water W2 based on the hot water dispense history information and the hot water dispense plan information. As shown in FIG. 4, the second amount of hot water W2 is the amount of hot water above the dashed line G2. In other words, if the remaining amount of hot water is less than the third amount of hot water W3 and hot water is scheduled to be dispensed after the end of the first period, the DR control unit 192 determines to boil more than the planned amount of hot water to be dispensed during the boiling operation.

[0125] On the other hand, if it is determined that there is no plan to dispense hot water after the end of the first period (NO in step S14), the DR control unit 192 determines to boil the first amount of hot water W1 or more in the boiling operation (step S17). In other words, if the remaining amount of hot water is the third amount of hot water W3 or less and there is no plan to dispense hot water after the end of the first period, the DR control unit 192 determines to boil the first amount of hot water W1 or more in the boiling operation.

[0126] (3) Features (3-1) Conventionally, there has been known an equipment control device that changes the setting conditions of an air conditioner to setting conditions desired by a user while demand response control is being performed in response to a request for a lower DR. The user selects the desired setting conditions from one or more setting conditions displayed by the equipment control device.

[0127] However, since hot water storage type water heaters perform planned heating operations to automatically maintain the amount of hot water remaining in the hot water storage tank above a certain reference value, the device control device of Patent Document 1, which requires user selection, may reduce user convenience.

[0128] The hot water supply system 100 of this embodiment includes a hot water storage tank 21 and a control unit 190. The control unit 190 controls the operation of the hot water supply device 1 having the hot water storage tank 21. The control unit 190 receives a demand response request. If the amount of heat in the hot water storage tank 21 falls below a first reference value during a second period, which is a period other than the first period for suppressing power consumption that is set based on the demand response request, the control unit 190 performs a boiling operation to heat the hot water in the hot water storage tank 21. If the amount of heat in the hot water storage tank 21 falls below the first reference value during the first period, the control unit 190 determines whether to perform a boiling operation.

[0129] Prohibiting the water heating operation during the first period reduces user convenience. With this configuration, user convenience is improved.

[0130] (3-2) In the hot water supply system 100 of this embodiment, the amount of heat in the hot water storage tank 21 is the amount of hot water remaining in the hot water storage tank 21. The first reference value is a first hot water amount W1, which is a predetermined amount of hot water.

[0131] (3-3) In the hot water supply system 100 of this embodiment, when the control unit 190 determines that a boiling operation should be performed in the first period, the control unit 190 performs the boiling operation so that the amount of hot water remaining after the boiling operation is equal to or greater than the first hot water amount W1.

[0132] This configuration can prevent hot water from running out, improving user convenience.

[0133] (3-4) In the hot water supply system 100 of this embodiment, when the control unit 190 determines that boiling operation should be performed during the first period, the control unit 190 performs boiling operation so that the amount of hot water remaining after the boiling operation is equal to or greater than the second hot water amount W2, which is the planned amount of hot water to be dispensed after the end of the first period.

[0134] By boiling the planned amount of hot water to be dispensed in advance, there is no need to perform the boiling operation again, improving the operating efficiency of the hot water supply apparatus 1. Furthermore, by preparing the hot water dispense schedule in advance, convenience for the user is improved.

[0135] (3-5) In the hot water supply system 100 of this embodiment, the control unit 190 performs the boiling operation when the remaining amount of hot water is equal to or less than the third hot water amount W3, which is smaller than the first hot water amount W1.

[0136] This configuration can prevent hot water from running out, improving user convenience.

[0137] (4) Modifications (4-1) Modification 1A In this embodiment, the DR control unit 192 determines not to perform the boiling operation when the remaining amount of hot water is greater than the third hot water amount W3 and equal to or less than the first hot water amount W1. However, the DR control unit 192 may also determine to suppress the boiling operation when the remaining amount of hot water is greater than the third hot water amount W3 and equal to or less than the first hot water amount W1. Specifically, the DR control unit 192 may determine to perform the boiling operation at a heating capacity lower than the standard heating capacity. Note that the standard heating capacity refers to the heating capacity during normal boiling operation, and refers to the heating capacity based on the rated power using commercial power (the maximum power that can be used in continuous operation at a specified ambient temperature).

[0138] This configuration reduces power consumption and prevents hot water shortages, making it possible to respond to requests for lowered DRs and improving user convenience.

[0139] (4-2) Modification 1B In this embodiment, when the amount of remaining hot water is equal to or less than the third hot water amount W3, the DR control unit 192 determines to perform the boiling operation. However, the DR control unit 192 may also determine to perform the boiling operation when the amount of remaining hot water is equal to or less than the first hot water amount W1.

[0140] This configuration can prevent hot water from running out, improving user convenience.

[0141] (4-3) Variation 1C In this embodiment, the amount of heat in the hot water storage tank 21 is the amount of hot water remaining in the hot water storage tank 21. The first reference value is a first hot water amount W1, which is a predetermined amount of hot water. However, the amount of heat in the hot water storage tank 21 may also be the temperature of the hot water at a predetermined temperature sensor among the temperature sensors T1 to T6 provided in the hot water storage tank 21. The first reference value may also be a predetermined temperature.

[0142] Second Embodiment A hot water supply system 200 according to a second embodiment will be described with reference to the drawings. The basic configuration and operation of the hot water supply system 200 are the same as those of the hot water supply system 100 according to the first embodiment. The following description of the hot water supply system 200 according to the second embodiment will focus on the differences from the hot water supply system 100 according to the first embodiment.

[0143] The control unit 290 mainly performs the heating operation, the hot water supply operation, the hot water filling operation, and the reheating operation. The control unit 290 also has, as functional blocks, a receiving unit 291 and a DR control unit 292. The receiving unit 291 is the same as the receiving unit 191, and therefore a description thereof will be omitted.

[0144] (1) DR Control Unit The DR control unit 292 determines not to perform boiling operation when the amount of remaining hot water during the first period is equal to or less than a first hot water amount W1. The first hot water amount W1 is stored in advance in a storage device. The first hot water amount W1 may be set by the user operating the remote controller 130.

[0145] When the remaining amount of hot water becomes equal to or less than the first amount of hot water, the DR control unit 292 determines the schedule for the boiling operation after the first period according to the hot water discharge schedule, as shown in the flowchart of FIG.

[0146] When the remaining hot water amount becomes equal to or less than the first hot water amount W1, the DR control unit 292 determines whether or not it is the first period (step S21). If it is not the first period (NO in step S21), the DR control unit 292 does not determine whether or not to perform the boiling operation. In this case, the control unit 290 performs the boiling operation as usual.

[0147] If it is in the first period (YES in step S21), the DR control unit 292 determines not to perform the heating operation (step S22).

[0148] The DR control unit 292 determines whether or not there is a hot water dispense schedule after the end of the first period based on the hot water dispense history information (Step S23). The DR control unit 292 also determines whether or not there is a hot water dispense schedule after the end of the first period based on the hot water dispense schedule information (Step S23).

[0149] If it is determined that hot water is scheduled to be dispensed after the end of the first period (YES in step S23), the DR control unit 292 determines that the water heater operation will be performed from the time the first period has elapsed until the scheduled hot water dispense time (step S24). The DR control unit 292 may store the time period during which the water heater operation will be performed in the storage device. Note that "after the end of the first period" refers to a predetermined fourth hour period from the end of the first period.

[0150] On the other hand, if it is determined that there is no plan to dispense hot water after the end of the first period (NO in step S23), the DR control unit 292 determines that the boiling operation will be performed within a predetermined first time after the first period has elapsed (step S25). The DR control unit 292 may store the time period during which the boiling operation will be performed in the storage device. The first time is, for example, 30 minutes. In this case, the DR control unit 292 determines that the boiling operation will be performed within 30 minutes after the first period has elapsed.

[0151] (2) Features (2-1) In the hot water supply system 200 of this embodiment, the control unit 290 does not perform the heating operation when the amount of heat in the hot water storage tank 21 becomes equal to or less than the first reference value during the first period.

[0152] With this configuration, it is possible to suppress the power consumption by water heater 1 in the first period, and to respond to the request for lower DR.

[0153] (2-2) In the hot water supply system 200 of this embodiment, the control unit 290 performs the boiling operation after the first period has elapsed.

[0154] With this configuration, it is possible to suppress the power consumption by water heater 1 in the first period, and to respond to the request for lower DR.

[0155] (2-3) In the hot water supply system 200 of this embodiment, if hot water is scheduled to be dispensed after the first period has elapsed, the control unit 290 performs boiling operation from the first period has elapsed until the scheduled hot water dispense time.

[0156] With this configuration, it is possible to reduce the power consumption by water heater 1 in the first period and respond to the request for lower DR. Furthermore, by preparing for the hot water dispense schedule in advance, convenience for the user is improved.

[0157] (2-4) In the hot water supply system 200 of this embodiment, the control unit 290 performs the boiling operation within a predetermined first time period after the first period has elapsed.

[0158] With this configuration, it is possible to reduce the power consumption by water heater 1 in the first period and respond to the request for lower DR. Furthermore, by preparing for hot water supply in advance, convenience for the user is improved.

[0159] (3) Modifications (3-1) Modification 2A The DR control unit 292 may control the DR control unit 292 not to dispense hot water based on a hot water dispensing instruction during the period from when it is determined that heating operation will not be performed until the end time of the first period.

[0160] With this configuration, it is possible to suppress the power consumption by water heater 1 in the first period, and to respond to the request for lower DR.

[0161] Third Embodiment A hot water supply system 300 according to a third embodiment will be described with reference to the drawings. The basic configuration and operation of the hot water supply system 300 are the same as those of the hot water supply system 100 according to the first embodiment. The following description of the hot water supply system 300 according to the third embodiment will focus on the differences from the hot water supply system 100 according to the first embodiment.

[0162] The control unit 390 mainly performs the heating operation, hot water supply operation, water filling operation, and reheating operation. The control unit 390 also has, as functional blocks, a receiving unit 391 and a DR control unit 392. The receiving unit 391 is the same as the receiving unit 191, and therefore a description thereof will be omitted.

[0163] (1) DR Control Unit The DR control unit 392 performs control so as not to perform the water heating operation during the first period. However, as will be described later, if the DR control unit 392 determines that the water heating operation should be performed, the water heating operation is performed.

[0164] The DR control unit 392 determines whether to perform the boiling operation when the remaining amount of hot water during the first period becomes equal to or less than a first hot water amount W1. The first hot water amount W1 is stored in advance in a storage device. The first hot water amount W1 may be set by the user operating the remote controller 130.

[0165] When the amount of remaining hot water becomes equal to or less than the first hot water amount W1, the DR control unit 392 determines whether or not to perform the boiling operation depending on the second time period, as shown in the flowchart of FIG.

[0166] When the remaining hot water amount becomes equal to or less than the first hot water amount W1, the DR control unit 392 determines whether or not it is the first period (step S31). If it is not the first period (NO in step S31), the DR control unit 392 does not determine whether or not to perform the boiling operation. In this case, the control unit 390 performs the boiling operation as usual.

[0167] If it is the first period (YES in step S31), the DR control unit 392 calculates the second time from the time when the remaining hot water volume becomes equal to or less than the first hot water volume to the end time of the first period (step S32). The time when the remaining hot water volume becomes equal to or less than the first hot water volume may be the current time. The end time of the first period may be included in the request for a lower DR.

[0168] If the second time is less than the predetermined third time (NO in step S33), the DR control unit 392 determines that the water heating operation will not be performed (step S35). The third time is a time set by the user and is the time during which the water heating operation can be waited. The user can input the third time by operating the remote controller 130.

[0169] On the other hand, if the second time is equal to or greater than the third time (YES in step S33), the DR control unit 392 determines to perform the boiling operation (step S34).

[0170] (2) Features (2-1) In the hot water supply system 300 of this embodiment, the control unit 390 determines whether to perform boiling operation based on the second time period from the time when the remaining hot water amount becomes equal to or less than the first hot water amount to the end time of the first period.

[0171] By determining whether or not to perform the heating operation depending on the time remaining until the end of the lowering DR period, convenience for the user is improved.

[0172] (2-2) In the hot water supply system 300 of this embodiment, the control unit 390 performs the boiling operation when the second time is equal to or greater than the predetermined third time.

[0173] If the second time is equal to or longer than the third time, which is the time that the user can wait for the boiling operation, the boiling operation is performed, thereby improving user convenience.

[0174] (2-3) In the hot water supply system 300 of this embodiment, the control unit 390 does not perform the boiling operation if the second time is less than the predetermined third time.

[0175] If the second time is less than a third time, which is the time the user can wait for the water heater to start the water heater operation, the water heater operation is not performed. With this configuration, it is possible to reduce the power consumption due to the water heater operation and respond to a request for a lower DR.

[0176] (2-4) In the hot water supply system 300 of this embodiment, the third time period is set by the user.

[0177] This configuration allows the user to set the desired time, improving user convenience.

[0178] (3) Modifications (3-1) Modification 3A In this embodiment, the DR control unit 392 determines whether to perform the boiling operation based on the second time. However, the DR control unit 392 may also determine whether to perform the boiling operation based on a combination of the second time and the amount of remaining hot water. The DR control unit 392 may also determine whether to perform the boiling operation based on a combination of the second time, the amount of remaining hot water, and the hot water delivery schedule.

[0179] For example, the DR control unit 392 may determine to perform boiling operation if the remaining amount of hot water is less than the third hot water amount W3 even if the second time is less than the third time.

[0180] Furthermore, for example, the DR control unit 392 may determine to perform boiling operation if hot water is scheduled to be dispensed after the first period has elapsed, even if the second time is less than the third time.

[0181] Furthermore, for example, the DR control unit 392 may determine not to perform boiling operation if there is no plan to dispense hot water after the first period has elapsed, even if the second time is equal to or longer than the third time.

[0182] This configuration further improves user convenience.

[0183] Fourth Embodiment A hot water supply system 400 according to a fourth embodiment will be described with reference to the drawings.

[0184] 7 , a hot water supply system 400 according to the fourth embodiment includes two or more hot water supply devices 4. The basic configuration and operation of each hot water supply device 4 are the same as those of the hot water supply device 1 according to the first embodiment. The following describes the hot water supply system 400 according to the fourth embodiment, focusing on the differences from the hot water supply system 100 according to the first embodiment.

[0185] Control unit 490 mainly performs the heating operation, hot water supply operation, water filling operation, and reheating operation of each hot water heater 4. Control unit 490 also has, as functional blocks, a receiving unit 491 and a DR control unit 492. Since receiving unit 491 is the same as receiving unit 191, a description thereof will be omitted.

[0186] (1) DR Control Unit When one hot water heating apparatus 4 performs the heating operation during the first period, DR control unit 492 restricts the operation of the other hot water heating apparatuses 4.

[0187] Specifically, the DR control unit 492 limits the number of water heating devices 4 performing water heating operation during the first period. The DR control unit 492 sets the power consumption reduction target value to a value equal to or greater than the power consumption target value (reduction level value) included in the down-DR request. The DR control unit 492 calculates the limit number of water heating devices 4 based on the reduction target value. Information associating the reduction target value with the limit number may be stored in advance in a storage device as reference information. The DR control unit 492 may determine the limit number based on the reference information.

[0188] DR control unit 492 stores in the storage device the number of water heating devices 4 that performed water heating operation during the first period. When the limited number of water heating devices 4a have already started water heating operation and an instruction to perform water heating operation on water heating device 4b is received, DR control unit 492 determines that water heating operation on water heating device 4b will not be performed.

[0189] (2) Features (2-1) In hot water supply system 400 of the present embodiment, control unit 490 controls the operation of two or more hot water supply devices 4. When one hot water supply device 4 performs a heating operation during a first period, control unit 490 restricts the operation of the other hot water supply devices 4.

[0190] With this configuration, it is possible to limit the power consumption of all of the plurality of water heaters 4. As a result, it is possible to respond to requests for lower DR.

[0191] (2-2) In the hot water supply system 400 of this embodiment, the control unit 490 sets the power consumption reduction target value to a value equal to or greater than the power consumption reduction level value set based on a demand response request.

[0192] With this configuration, even when one or more water heaters 4 are operating in a boiling operation, it is possible to limit the power usage across all of the plurality of water heaters 4. As a result, it is possible to respond to requests for lower DR.

[0193] (2-3) In hot water supply system 400 of the present embodiment, control unit 490 limits the number of hot water supply devices 4 that perform the heating operation during the first period.

[0194] With this configuration, it is possible to limit the power consumption of all of the plurality of water heaters 4. As a result, it is possible to respond to requests for lower DR.

[0195] (3) Modifications (3-1) Modification 4A In this embodiment, DR control unit 492 limits the number of water heating devices 4 that perform water heating operation in the first period. However, when performing water heating operation with one water heating device 4, DR control unit 492 may determine that the other water heating devices 4 perform water heating operation at a heating capacity that is smaller than the standard heating capacity. Note that the standard heating capacity refers to the heating capacity during normal water heating operation, and refers to the heating capacity based on the rated power using commercial power (the maximum power that can be used in continuous operation at a specified ambient temperature).

[0196] With this configuration, it is possible to limit the power consumption of all of the plurality of water heaters 4. As a result, it is possible to respond to requests for lower DR.

[0197] Although the embodiments of the present disclosure have been described above, it will be understood that various changes in form and details can be made without departing from the spirit and scope of the present disclosure as defined in the claims.

[0198] REFERENCE SIGNS LIST 1 Hot water supply device 4 Hot water supply device 21 Hot water storage tank, tank 100 Hot water supply system 190 Control unit 200 Hot water supply system 290 Control unit 300 Hot water supply system 390 Control unit 400 Hot water supply system 490 Control unit

[0199] JP 2019-105984 A

Claims

1. A hot water supply system (100, 200, 300, 400) comprising: a tank (21); and a control unit (190, 290, 390, 490) that controls the operation of a hot water supply device (1, 4) having the tank, wherein the control unit receives a demand response request; and if the amount of heat in the tank falls below a first reference value during a second period that is a period other than a first period for suppressing power consumption that is set based on the demand response request, performs a boiling operation to heat the hot water in the tank; and if the amount of heat in the tank falls below the first reference value during the first period, determines whether to perform the boiling operation.

2. A hot water supply system as described in claim 1, wherein the heat quantity in the tank is the amount of hot water remaining in the tank, and the first reference value is a first hot water quantity, which is a predetermined hot water quantity.

3. The hot water supply system of claim 2, wherein when the control unit determines that the heating operation should be performed during the first period, the control unit performs the heating operation so that the remaining hot water amount after the heating operation is equal to or greater than the first hot water amount.

4. The hot water supply system of claim 2, wherein when the control unit determines to perform the heating operation during the first period, the control unit performs the heating operation so that the amount of remaining hot water after the heating operation is equal to or greater than a second amount of hot water, which is the planned amount of hot water to be dispensed after the end of the first period.

5. A hot water supply system as described in any one of claims 1 to 4, wherein the control unit does not perform the heating operation if the heat quantity in the tank becomes equal to or less than the first reference value during the first period.

6. The hot water supply system according to claim 5, wherein the control unit performs the heating operation after the first period has elapsed.

7. The hot water supply system of claim 5 or 6, wherein, if hot water is scheduled to be dispensed after the first period has elapsed, the control unit performs the heating operation after the first period has elapsed and until the scheduled hot water dispense time.

8. The hot water supply system according to any one of claims 5 to 7, wherein the control unit performs the heating operation within a predetermined first time period after the first period has elapsed.

9. A hot water supply system as described in any one of claims 5 to 8, wherein the control unit does not dispense hot water based on a hot water dispensing instruction during the period from after determining that the heating operation will not be performed until the end time of the first period.

10. The hot water supply system according to claim 2, wherein the control unit performs the boiling operation when the remaining amount of hot water is equal to or less than a third amount of hot water that is smaller than the first amount of hot water.

11. The hot water supply system according to claim 10, wherein the control unit suppresses the boiling operation when the remaining amount of hot water is greater than the third amount of hot water and equal to or less than the first amount of hot water.

12. A hot water supply system as described in any one of claims 2, 3, 4, 10 and 11, wherein the control unit determines whether or not to perform the boiling operation depending on a second time period from the time when the remaining hot water amount becomes less than the first hot water amount to the end time of the first period.

13. The hot water supply system according to claim 12, wherein the control unit performs the boiling operation when the second time is equal to or greater than a predetermined third time.

14. The hot water supply system according to claim 12, wherein the control unit does not perform the heating operation when the second time is less than a predetermined third time.

15. The hot water supply system according to claim 13 or 14, wherein the third time period is set by a user.

16. A hot water supply system as described in any one of claims 1 to 15, wherein the control unit controls the operation of two or more of the hot water supply devices, and when one of the hot water supply devices performs the boiling operation during the first period, the control unit restricts the operation of the other hot water supply devices.

17. A hot water supply system as described in any one of claims 1 to 16, wherein the control unit sets the target value for power consumption reduction to a value equal to or greater than the power consumption reduction level value set based on the demand response request.

18. The hot water supply system according to any one of claims 1 to 17, wherein the control unit limits the number of the hot water supply devices that perform the heating operation during the first period.

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