System and method for hot water supply

Abstract

To enhance efficiency through hot water storage and low temperature heat storage in a hot water storage tank and enhance convenience of general hot water supply, bath hot water delivery, bath water reheating and the like.SOLUTION: A hot water supply system includes: a heat source machine (HP unit 6) for heating supply water (W) to first hot water (HW 1) or heating the supply water to second hot water (HW 2) of which temperature is higher than that of the first hot water; and a hot water storage tank (hot water storage tank unit 4) that stores the first hot water or stores the second hot water on the upper side of the first hot water. At normal time, the first hot water is stored in the hot water storage tank, and before bath reheating, the second hot water is introduced to the hot water storage tank to store the second hot water on the upper side of the first hot water. During the bath reheating, heat exchange is performed between the second hot water taken out from the hot water storage tank and bath water to heat the bath water.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a hot water supply system and method, for example, including a heat pump in a heat source unit, storing hot water obtained by the heat source unit in a hot water storage tank to store heat, and using the hot water for heat exchange with water supply, general hot water supply, bath water supply, bath reheating, etc. [Background technology]

[0002] For example, it is already known to store hot water obtained by heating a gas water heater in multiple hot water storage tanks and selectively supply hot water from the hot water storage tanks, or to generate hot water using a heat pump type heating source and store this hot water in the hot water storage tanks.

[0003] It is known that in a hot water storage system having a plurality of hot water storage tanks, hot water in each hot water storage tank is selectively circulated to a heating means for heating (for example, Patent Document 1).

[0004] In a system equipped with multiple hot water storage tanks and a heat pump type heating source, it is known that low-temperature water discharged from the hot water storage tank is heated by a heat exchanger of the heat pump type heating source, and this high-temperature water is stored in the hot water storage tank (for example, Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2001-65982 A [Patent Document 2] JP 2007-298226 A Summary of the Invention [Problem to be solved by the invention]

[0006] Hot water storage systems using multiple hot water storage tanks have issues such as high equipment costs, and there are also issues such as the deterioration of the heat storage efficiency of the hot water when hot water is moved between the heat source unit and multiple hot water storage tanks.

[0007] Conventionally, hot water supply systems equipped with a heat pump as the main heat source and a gas water heater as the auxiliary heat source store hot water heated by the heat pump in a hot water storage tank, and supplement the heat deficiency during hot water supply with the gas water heater. This type of hybrid hot water supply is affected by the operating costs of the main heat source unit, such as nighttime operation, and has issues such as the inability to maintain permanent low costs.

[0008] Therefore, an object of the present disclosure is to improve the efficiency of hot water storage in a hot water storage tank and low-temperature heat storage, as well as to increase the convenience of general hot water supply, bath water supply, bath water reheating, etc. [Means for solving the problem]

[0009] In order to achieve the above-mentioned objectives, according to one aspect of the hot water supply system disclosed herein, the system includes a heat source unit that heats supply water to first hot water or to second hot water at a higher temperature than the first hot water, and a hot water storage tank that stores the first hot water or stores the second hot water above the first hot water, and under normal conditions, the first hot water is stored in the hot water storage tank, and before bath reheating, the second hot water is introduced into the hot water storage tank and stored above the first hot water, and during bath reheating, the bath water is heated by heat exchange between the second hot water taken out of the hot water storage tank and bath water.

[0010] In this hot water supply system, a temperature difference between the first hot water and the second hot water may be 10° C. or more.

[0011] This hot water supply system may include a temperature sensor installed at a storage position of the second hot water in the hot water storage tank, and a control unit that acquires temperature information from the temperature sensor when the second hot water is being introduced into the hot water storage tank, and stops the introduction of the second hot water when this temperature information transitions from the first hot water to temperature information representing the second hot water.

[0012] This hot water supply system may include a hot water supply path that supplies third hot water obtained by mixing the first hot water or the second hot water discharged from the hot water storage tank with the supply water, a distribution valve that distributes the supply water between the hot water storage tank and the hot water supply path, a regulating valve that regulates the amount of the third hot water flowing through the hot water supply path, a temperature sensor that detects the temperature of the third hot water, and a control unit that acquires detected temperature information from the temperature sensor and adjusts the opening of the distribution valve and / or the regulating valve to control the temperature of the third hot water to a hot water supply set temperature.

[0013] This hot water supply system may include a heat exchanger that exchanges heat between the bath water and the second hot water drawn from the hot water storage tank, and when reheating the bath, the second hot water after heat exchange with the bath water may be heated by the heat source unit and then returned to the hot water storage tank.

[0014] This hot water supply system may include a hot water inlet section that introduces the first hot water or the second hot water into the hot water storage tank, and a buffer section that buffers the hot water flow in the hot water storage tank when hot water is introduced from the hot water inlet section.

[0015] In order to achieve the above-mentioned objectives, according to one aspect of the hot water supply method disclosed herein, the method includes a step of a heat source unit heating supply water to first hot water, or to second hot water having a higher temperature than the first hot water, a step of storing the first hot water in a hot water storage tank, or storing the second hot water above the first hot water, a step of storing the first hot water in the hot water storage tank under normal conditions, and before bath re-heating, introducing the second hot water into the hot water storage tank to store the second hot water above the first hot water, and a step of heating the bath water by heat exchange between the second hot water taken out of the hot water storage tank and the bath water during bath re-heating.

[0016] In this hot water supply method, the temperature difference between the first hot water and the second hot water may be set to 10° C. or more.

[0017] This hot water supply method may include a step of acquiring temperature information from a temperature sensor installed at a storage position of the second hot water in the hot water storage tank when the second hot water is being introduced into the hot water storage tank, and a step of stopping the introduction of the second hot water when the temperature information transitions from the first hot water to temperature information representing the second hot water.

[0018] This hot water supply method may include a step of supplying third hot water obtained by mixing the first hot water or the second hot water discharged from the hot water storage tank with the supply water to a hot water supply path, a step of distributing the supply water to the hot water storage tank and the hot water supply path using a distribution valve, a step of regulating the amount of the third hot water flowing through the hot water supply path using a regulating valve, a step of detecting the temperature of the third hot water using a temperature sensor, and a step of acquiring detected temperature information from the temperature sensor and adjusting the opening of the distribution valve and / or the regulating valve to control the third hot water to a hot water supply set temperature.

[0019] This hot water supply method may include a step of returning the second hot water after heat exchange with the bath water to the hot water storage tank after heating the second hot water by the heat source device during bath reheating. Effect of the Invention

[0020] As described above, according to the present disclosure, any of the following effects can be obtained. (1) It is possible to provide a hot water supply system that is highly efficient through hot water storage in a hot water storage tank and low-temperature thermal storage, and that has improved convenience through hot water heat exchange, general hot water supply, bath water supply, and bath reheating.

[0021] (2) The heat storage temperature can be changed according to the purpose, such as general hot water supply, bath hot water supply, bath heat retention, and bath reheating, thereby improving the efficiency of heat storage and hot water supply.

[0022] (3) A heat pump can be used in the heat source unit to generate hot water and store it in the hot water storage tank, simplifying the hot water supply system.

[0023] (4) When the first hot water is poured from the hot water storage tank into the bath, the second hot water of a higher temperature than the first hot water is stored in the hot water storage tank in preparation for bath reheating and hot water supply. This makes it possible to quickly reheat the bath and provide general hot water without a shortage of heat, and improves the convenience of heat exchange between the second hot water and bath water and hot water supply. [Brief description of the drawings]

[0024] [Figure 1] FIG. 1 is a diagram showing a hot water supply system according to a first embodiment. [Diagram 2] FIG. 2 is a diagram illustrating an example of a heat pump unit. [Diagram 3] FIG. 3 is a diagram showing a control system for the hot water supply system. [Figure 4] FIG. 4 is a diagram showing an operation pattern of the hot water supply system according to the second embodiment. [Diagram 5] FIG. 5A is a diagram showing the state of waiting before automatic pouring of hot water into the bath, and FIG. 5B is a flow chart showing the process of waiting before automatic pouring of hot water into the bath. [Figure 6] FIG. 6A is a diagram showing the operation of the automatic bath water pouring, and FIG. 6B is a flow chart showing the processing of the automatic bath water pouring. [Figure 7] FIG. 7 shows the state after automatic bath water pouring has ended. [Figure 8] FIG. 8A is a diagram showing the operation during bath temperature maintenance, and FIG. 8B is a flow chart showing the processing during bath temperature maintenance. [Figure 9] FIG. 9A is a diagram showing the operation during bath warming and reheating, and FIG. 9B is a flow chart showing the processing during bath warming and reheating. [Figure 10] FIG. 10A is a diagram showing the operation during bath warming and reheating, and FIG. 10B is a flow chart showing the processing during bath warming and reheating. [Figure 11] FIG. 11A is a diagram showing the operation during bath warming and heat storage start, and FIG. 11B is a flow chart showing the process during bath warming and heat storage start. [Figure 12]FIG. 12A is a diagram showing the operation of bath temperature keeping, hot water supply use, and heat storage start, and FIG. 12B is a flow chart showing the processing of bath temperature keeping, hot water supply use, and heat storage start. [Figure 13] FIG. 13A is a diagram showing the operation during bath warming and heat storage start, and FIG. 13B is a flow chart showing the process during bath warming and heat storage start. [Figure 14] FIG. 14A is a diagram showing the operation of the heat storage for hot water supply after automatic bath water pouring has been completed in the third embodiment, and FIG. 14B is a diagram showing the operation after the amount of heat for hot water supply has been secured. [Figure 15] FIG. 15A is a perspective view showing a hot water inlet / outlet structure of a hot water storage tank unit according to a fourth embodiment, and FIG. 15B is a cross-sectional view showing the hot water inlet / outlet structure of the hot water storage tank unit. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0025] First Embodiment Fig. 1 shows a hot water supply system 2 according to a first embodiment. The configuration shown in Fig. 1 is an example, and the present disclosure is not limited to such a configuration.

[0026] The hot water supply system 2 includes a hot water storage tank unit 4 (hereinafter simply referred to as "tank unit 4"), a heat pump unit 6 (hereinafter referred to as "HP unit 6"), a hot water supply control unit 8, and a remote control device 10 (hereinafter referred to as "remote control 10").

[0027] Tank unit 4 is an example of a hot water storage tank of the present disclosure, and has a hot water storage capacity of, for example, about 380 liters. A water supply passage 12 is connected to the lower side of tank unit 4, and a hot water outlet passage 14 is connected to the upper side. When hot water is to be discharged, hot water HW1 or hot water HW2 can be discharged from tank unit 4 to hot water outlet passage 14 by supplying water W from water supply passage 12.

[0028] The tank unit 4 stores first hot water HW1 (hereinafter referred to as "hot water HW1") as low-temperature heat storage, temporarily stores second hot water HW2 (hereinafter referred to as "hot water HW2"), and also temporarily stores water W. As an example of a hot water storage form, the tank unit 4 normally stores hot water HW1, and before bath reheating, stores hot water HW2 above the hot water HW1. The hot water HW1 is hot water heated to a first set temperature Tc1 (for example, hot water of 40°C to 45°C), and the hot water HW2 is hot water heated to a second set temperature Tc2 (for example, hot water of 60°C to 65°C). Although the temperatures of hot water HW1 and hot water HW2 are shown as examples, the temperature difference between hot water HW1 and hot water HW2 may be 10°C or more, and more preferably 20°C or more, and is not limited to the exemplified temperatures as long as the temperature is suitable for low-temperature heat storage.

[0029] Therefore, low-temperature feed water W is supplied to the tank unit 4 in relation to the hot water HW1 and hot water HW2, and this feed water W is placed in the bottom layer with hot water HW1 stored above it and hot water HW2 stored above the hot water HW1. This type of hot water storage is in a state where hot water HW1 is stored below hot water HW2 and hot water HW2 is stored above hot water HW1 due to the relationship between specific gravity and gravity, which depends on the temperatures of hot water HW1 and hot water HW2. This type of hot water storage does not require a strict temperature division, and is a layered hot water storage state due to the temperature difference between hot water HW1 and hot water HW2.

[0030] A distribution valve 16 is installed in the water supply passage 12, and a flow rate regulation valve 18 is installed in the hot water supply passage 22. A bypass passage 20 that bypasses the tank unit 4 is connected between the distribution valve 16 and the flow rate regulation valve 18. The distribution valve 16 and the flow rate regulation valve 18 are, for example, configured as a single valve unit. The distribution ratio of the distribution valve 16 is controlled by the hot water supply control unit 8. This distribution valve 16 distributes a predetermined amount of supply water W to the tank unit 4 and the bypass passage 20 according to the distribution ratio set by the hot water supply control unit 8. The flow rate regulation valve 18 regulates the supply amount of the third hot water HW3 (hereinafter referred to as "hot water HW3") obtained by mixing the supply water W on the bypass passage 20 side and the hot water HW1 or hot water HW2 on the hot water outlet passage 14 side. In this case, the hot water HW3 is regulated to a desired hot water supply amount and adjusted to a preset water supply setting temperature. This hot water HW3 is used for general hot water supply as well as for filling the bath 38.

[0031] <HPユニット6> The HP unit 6 is an example of a heat source machine for heating the feed water W to hot water HW1, or to hot water HW2 that is hotter than the hot water HW1. The HP unit 6 includes a pump 24 and an HP (heat pump) control unit 26. When the HP unit 6 is driven, the pump 24 is operated under the control of the HP control unit 26 to circulate and heat the feed water W, etc. Therefore, the HP unit 6 can heat the feed water W, etc. to hot water HW1 or hot water HW2, and store either of them in the tank unit 4 at an appropriate time.

[0032] <1st circulation path 28-1 to 4th circulation path 28-4, additional heating circulation path 30> The HP unit 6 and the tank unit 4 are provided with a first circulation path 28-1, a second circulation path 28-2, a third circulation path 28-3, and a fourth circulation path 28-4, and a reheating circulation path 30 is provided in addition to the fourth circulation path 28-4.

[0033] First circulation path 28-1: A flow path from the lower layer side of the tank unit 4 to the inlet side of the HP unit 6, and is equipped with a three-way valve 32. This three-way valve 32 is used to select whether the circulating water flowing through the first circulation path 28-1 is the supply water W from the tank unit 4 or the hot water HW2 after heat exchange from the fourth circulation path 28-4. This selection is controlled by the hot water supply control unit 8.

[0034] Second circulation path 28-2: A flow path from the outlet side of the HP unit 6 to the upper layer side of the tank unit 4, and is equipped with a switching valve 34. This switching valve 34 is used to select whether the destination of the circulating water from the HP unit 6 is the upper layer or the lower layer of the tank unit 4.

[0035] Third circulation path -3: A flow path from the switching valve to the lower layer side of the tank unit 4. That is, the second circulation path -2 or the third circulation path -3 on the outlet side of the HP unit 6 is selectively switched by the switching valve .

[0036] Fourth circulation path 28-4: A flow path extending from the upper side of the tank unit 4 to the three-way valve 32 located on the lower side of the tank unit 4.

[0037] Reheating circulation path 30: A flow path that circulates bath water BW during bath reheating operation.

[0038] A heat exchanger 36 is installed in the fourth circulation path 28-4, and a reheating circulation path 30 is connected to this heat exchanger 36. A circulation port 40 of a bath 38 is connected to this reheating circulation path 30, and a pump 42 is installed. During bath reheating operation, the pump 42 is driven to circulate bath water BW through the reheating circulation path 30 to the heat exchanger 36.

[0039] <Temperature sensors 44-1 to 44-13> The hot water supply system 2 includes temperature detection objects, which are provided with temperature sensors 44-1, 44-2, 44-3, 44-4, 44-5, 44-6, 44-7, 44-8, 44-9, 44-10, 44-11, 44-12, and 44-13.

[0040] Temperature sensors 44-1, 44-2, 44-3, 44-4, 44-5: Installed, for example, at equal intervals from the top to the bottom of the tank unit 4, with the temperature sensor 44-1 detecting the temperature T1 of the top layer, the temperature sensor 44-5 detecting the temperature T5 of the bottom layer, and the temperature sensors 44-2, 44-3, 44-4 detecting the temperatures T2, T3, T4 of the intermediate layers extending from the top to the bottom. The hot water supply control unit 8 obtains temperature information from the temperature sensors 44-1, 44-2, 44-3, 44-4, 44-5, and uses the installation positions of the temperature sensors 44-1, 44-2, 44-3, 44-4, 44-5 to detect or determine the amount of hot water HW2 stored in the tank unit 4, the amount of hot water HW1 stored, the amount of water W supplied, and the like. Therefore, the temperature sensor 44-1 is disposed at a hot water storage position for setting the amount of hot water HW2 to be stored in the tank unit 4.

[0041] Temperature sensor 44-6: Installed on first circulation path 28-1, detects temperature T6 on the inlet side of HP unit 6.

[0042] Temperature sensor 44-7: Installed on second circulation path 28-2, and detects temperature T7 on the outlet side of HP unit 6.

[0043] Temperature sensor 44-8: Installed in hot water outlet passage 14, detects temperature T8 of hot water HW1 or hot water HW2 discharged from tank unit 4.

[0044] Temperature sensor 44-9: Installed in the fourth circulation path 28-4, and detects the temperature T9 of the hot water after heat exchange in the heat exchanger 36.

[0045] Temperature sensors 44-10, 44-11: The temperature sensors 44-10, 44-11 are installed in the reheating circuit 30. The temperature sensor 44-10 detects a temperature T10 on the inlet side of the heat exchanger 36, and the temperature sensor 44-11 detects a temperature T11 on the outlet side of the heat exchanger 36.

[0046] Temperature sensor 44-12: Installed in the water supply passage 12 to detect the temperature T12 of the water supply W entering the distribution valve 16.

[0047] Temperature sensor 44-13: Installed in hot water supply passage 22, detects temperature T13 on the outlet side of flow rate regulating valve 18.

[0048] Hot water supply control unit 8 acquires input information such as operation information from remote control 10, temperature information from temperature sensors 44-1 to 44-13, and flow rate information from a flow rate sensor, and controls functional units such as distribution valve 16, flow rate regulating valve 18, three-way valve 32, switching valve 34, and pump 42 to execute operation modes such as hot water storage, hot water supply, and bath reheating. The control of this hot water supply control unit 8 includes information such as information presented by remote control 10, and cooperative control with HP control unit 26 for hot water storage, etc.

[0049] Remote control 10 is used to set a first set temperature Tc1 for generating hot water HW1, a second set temperature Tc2 for generating hot water HW2, instruct hot water supply, and display the hot water supply state. Remote control 10 is used for linkage control with hot water supply control unit 8 and HP control unit 26. Linkage relationships between hot water supply control unit 8 and HP control unit 26 can be assumed in various ways, such as wireless connection or wired connection, and are not limited to the wired connection shown in the figure.

[0050] The HP control unit 26 realizes cooperative control with the remote control 10 or the hot water supply control unit 8, and controls the heat pump to generate either the hot water HW1 or the hot water HW2.

[0051] <HPユニット6> 2 shows an example of the HP unit 6. This HP unit 6 includes a refrigerant circuit 46, a heat exchanger 48-1, a heat exchanger 48-2, an expansion valve 50, an air heat exchanger 52, a compressor 54, and a part of the first circuit 28-1 described above.

[0052] A refrigerant 56 circulates through the refrigerant circulation path 46. As the refrigerant 56, a propane refrigerant (for example, R290) or the like that is suitable for low-temperature heat storage in the tank unit 4 is used.

[0053] The heat exchanger 48-1 exchanges heat between the refrigerant 56 flowing in the refrigerant circulation path 46 and the feed water W flowing in the first circulation path 28-1 or the hot water HW2 whose temperature has been lowered after heat exchange, to generate hot water HW1 or hot water HW2.

[0054] The temperature sensor 44-14 detects the inlet temperature of the heat exchanger 48-1, and the temperature sensor 44-15 detects the outlet temperature of the heat exchanger 48-1. The temperature sensor 44-16 detects the temperature of the air heat exchanger 52, the temperature sensor 44-17 detects the temperature of the refrigerant 56 exiting the air heat exchanger 52, and the temperature sensor 44-18 detects the temperature of the refrigerant 56 after compression by the compressor 54. These detected temperature information are provided to the HP control unit 26 and are used for controlling the temperature of the refrigerant 56, etc.

[0055] The heat exchanger 48-2 exchanges heat between the refrigerant 56, whose temperature has been lowered by heat exchange with the water supply W, and the refrigerant 56 after heat exchange with air. The expansion valve 50 reduces the pressure of the refrigerant 56 to expand it. After the pressure reduction, the refrigerant 56 is guided to the air heat exchanger 52, where it absorbs heat from the air by heat exchange with the air. The compressor 54 compresses the refrigerant 56 to increase its temperature. In the heat exchanger 48-1, the heat of the refrigerant 56 is exchanged with the water supply W or the like. In this heat exchange, if the target temperature set in the HP control unit 26 is the first set temperature Tc1, hot water HW1 is obtained, and if the target temperature set in the HP control unit 26 is the second set temperature Tc2, hot water HW2 is obtained.

[0056] <Control System 58> 3 shows a control system 58 in the hot water supply system 2. This control system 58 is an example of the control unit of the present disclosure.

[0057] This control system 58 is equipped with a hot water supply control unit 8, a remote control 10, and an HP control unit 26. The hot water supply control unit 8 is composed of a computer with a communication function, and includes a processor 60, a memory unit 62, an input / output unit (I / O) 64, a communication unit 66, etc. The processor 60 executes an OS (Operating System) and a control program in the memory unit, and performs calculation processing, learning processing, and control of various functional units. The memory unit 62 stores the OS, control programs, etc., and this control program includes a database used for calculation and control. The I / O 64 acquires control information such as temperatures T1 to T13, and inputs control signals and drive signals output by the processor to the functional units.

[0058] The remote control 10 uses a computer with communication capabilities and is installed in the kitchen or bathroom, etc., and is used for coordinating operations of the hot water supply control unit 8 or the HP control unit 26, and for presenting control information provided by the hot water supply control unit 8 or the HP control unit 26.

[0059] A computer equipped with a communication function is used for the HP control unit 26, which performs cooperative control with the hot water supply control unit 8 and control based on operation input from the remote control 10. It receives settings such as the first set temperature Tc1 and the second set temperature Tc2 as the above-mentioned target temperatures, and performs heat exchange to generate hot water HW1 and HW2.

[0060] In this control system 58, under normal circumstances, hot water HW1 is introduced into tank unit 4. Then, before bath reheating, hot water HW2 is introduced into tank unit 4 and this hot water HW2 is stored above hot water HW1. Then, during bath reheating, hot water supply control unit 8 obtains temperature information from temperature sensor 44-1, and when this temperature information transitions from hot water HW1 to temperature information representing hot water HW2, performs control such as canceling the introduction of hot water HW2 into tank unit 4.

[0061] <Advantages of the First Embodiment> According to the first embodiment, any one of the following effects can be obtained. (1) Depending on the purpose of the hot water HW1, HW2, such as general hot water supply, bath hot water supply, bath heat retention, bath reheating, etc., the hot water HW1, HW2 in the tank unit 4 is stored with a temperature difference of, for example, 10°C or more, thereby improving the heat storage efficiency and hot water supply efficiency.

[0062] (2) Hot water HW1 and HW2 can be generated using the HP unit 6, and no other auxiliary heat source is required, so the system can be simplified.

[0063] (3) The hot water HW3 can be used for general hot water supply and for supplying hot water to the bath 38. Even if the hot water HW3 is supplied to the bath 38, if the hot water HW2 is stored in the tank unit 4, there is no heat shortage in the hot water supply from the tank unit 4, and hot water heat exchange, supplying hot water to the bath, reheating the bath, general hot water supply, etc. can be performed quickly, thereby improving convenience.

[0064] (4) Under normal circumstances, hot water HW1 is stored in tank unit 4, and before the bath is heated, hot water HW2 is stored above the hot water HW1. During the bath heating, hot water HW2 is extracted from tank unit 4, and bath water BW is heated by hot water HW2 through heat exchange between this hot water HW2 and bath water BW.

[0065] Second Embodiment 4 shows an example of an operation pattern of the hot water supply system 2 according to the second embodiment. Each operation pattern is an example of a hot water supply method of the present disclosure. This hot water supply method includes a method of supplying water W and a method of discharging hot water HW1 or hot water HW2.

[0066] The operating patterns of this hot water supply system 2 include a state of waiting before automatically pouring hot water into the bath (this state includes a stopped or standby state of the pump 24, or an operating state), processing (S100: A and B in Figure 5), operation of automatically pouring hot water into the bath (S200: A and B in Figure 6), state when automatic bath pouring has ended (S300: Figure 7), operation while keeping the bath warm (S400: A and B in Figure 8), operation while keeping the bath warm and reheating (initial heating) (S500: A and B in Figure 9), operation while keeping the bath warm and reheating (combined with heating by the HP unit 6) (S600: A and B in Figure 10), operation while keeping the bath warm and starting to store heat (S700: A and B in Figure 11), operation while keeping the bath warm and using hot water and starting to store heat (S800: A and B in Figure 12), operation while keeping the bath warm and starting to store heat (S900: A and B in Figure 13), etc.

[0067] Waiting state before automatic bath water pouring (S100): Hot water HW1 heated to a first set temperature Tc1 is stored in the tank unit 4. The hot water supply control unit 8 obtains temperature information from temperature sensors 44-1, . . . , 44-5, etc., and the hot water HW1 is maintained by the heating operation of the HP unit 6.

[0068] Operation of automatic bath water pouring (S200): During automatic bath water pouring, hot water HW1 from tank unit 4 is used, and hot water HW3 is poured from hot water supply path 22 into bath 38.

[0069] Bath automatic hot water pouring end state (S300): When the pouring of a predetermined amount of hot water HW1 into the bath 38 is completed, the bath automatic hot water pouring is ended.

[0070] Operation while keeping bath warm (S400): While keeping the bath warm, hot water HW1 is consumed to fill the bath, the water supply W supplied to the tank unit 4 is heated by the HP unit 6, and hot water HW2 is stored in the tank unit 4 in preparation for reheating the bath.

[0071] Operation during bath warming and reheating (initial heating) (S500): When bath reheating occurs during bath warming, the bath water BW is heated to the bath set temperature using hot water HW2 stored in tank unit 4.

[0072] Operation during bath warming and reheating (combined with heating by HP unit 6) (S600): When hot water HW2 is consumed from tank unit 4 during bath reheating, there is a risk that the hot water HW2 in tank unit 4 will run out. Therefore, after heat exchange with bath water BW, the hot water HW2 is heated by HP unit 6 and circulated to heat exchanger 36, raising the temperature of bath water BW to the bath set temperature.

[0073] Bath warming and heat storage start operation (S700): While the bath is warmed, the water supply W in the tank unit 4 is heated by the HP unit 6, and hot water HW2 is stored in the tank unit 4.

[0074] Bath warming, hot water supply, and heat storage start operation (S800): When hot water is required while the bath is being kept warm, hot water HW2 is discharged from tank unit 4, and this hot water HW2 is mixed with supply water W to obtain hot water HW3 adjusted to the set temperature, and hot water supply begins.

[0075] Bath warming / heat storage start operation (S900): When hot water supply is completed, the system transitions to heat storage operation, water W is guided from tank unit 4 to HP unit 6 where it is heated, and hot water HW2 is stored in tank unit 4.

[0076] <Bathroom automatic pouring standby state> A in Fig. 5 shows the state of standby before automatic bath water pouring. During this standby state, hot water HW1 is stored in the tank unit 4, and the heat storage state of the hot water HW1 is maintained in the tank unit 4. This maintenance includes heating control by the HP unit 6. In other words, hot water HW1 is stored in the tank unit 4 under normal circumstances.

[0077] 5B shows the processing procedure during standby before automatic bath water pouring. The hot water supply control unit 8 acquires temperature information of the tank unit 4 from the temperature sensors 44-1, 44-2, 44-3, 44-4, and 44-5 (S101), and determines whether each detected temperature Tn (where n=1, 2, 3, 4, and 5) is equal to or higher than the first set temperature Tc1 (S102).

[0078] If Tn < Tc1 (NO in S102), the hot water supply control unit 8 operates the pump 24 from the time when Tn < Tc1 is reached (S103), performs the heating operation by the HP unit 6, and returns to S101. As a result, the hot water HW1 heated to the first set temperature Tc1 is stored in the tank unit 4, and the heat storage state is maintained.

[0079] If Tn ≥ Tc1 (YES in S102), the pump 24 is stopped and the heating operation by the HP unit 6 is stopped (S104). After the pump 24 is stopped, it is determined whether to shift to automatic bath water filling (S105). If not shifting to automatic bath water filling (NO in S105), the standby before automatic bath water filling is continued, and if it is automatic bath water filling (YES in S105), it shifts to during automatic bath water filling (S200). This control is an example, and the control during the standby before automatic bath water filling is not limited to the above.

[0080] <Operation during automatic bath water filling> A in FIG. 6 shows the operation of automatic bath water filling. The thick line represents the supply state of the water supply W and the hot water discharge state of the hot water HW1. During automatic bath water filling, the hot water HW1 is discharged from the tank unit 4 to the hot water discharge path 14, and at this time, the water supply W flows through the water supply path 12 and the bypass path 20. For this bath water filling, the hot water HW3, which is the mixed water of the hot water HW1 and the water supply W, is used, and this hot water HW3 is poured into the bathtub 38 through the hot water supply path 22.

[0081] B in FIG. 6 shows the processing procedure of automatic bath water filling. The hot water supply control unit 8 starts pouring the hot water HW3 into the bathtub 38 (S201), acquires the temperature information (temperatures T8, T12, T13, etc.) of the water supply W, the hot water HW1, or the hot water HW3 (S202), and controls the opening ratio of the distribution valve 16 in order to achieve the set temperature for pouring water into the bathtub 38 (S203). The flow rate regulating valve 18 mixes the hot water HW1 and the water supply W, and the hot water HW3 adjusted to the set temperature for pouring water is obtained. This hot water HW3 is poured into the bathtub 38 from the hot water supply path 22.

[0082] For example, hot water supply control unit 8 acquires flow rate information of hot water HW3 from a flow rate sensor (not shown), monitors the amount of hot water being poured into bath 38 (S204), and when the amount of hot water HW3 reaches a reference value (YES in S204), ends the pouring (S205). After the end of pouring, the process proceeds to the process of keeping the bath warm (S400).

[0083] <Bath automatic pouring completed> Figure 7 shows the end of the automatic bath water pouring. At the end of this automatic bath water pouring, the amount of water W supplied by the tank unit 4 has increased compared to the standby state before the automatic bath water pouring shown in Figure 5A.

[0084] Hot water HW3 is used to pour hot water into the bath 38, and this hot water HW3 is a mixture of hot water HW1 and supply water W. When hot water HW1 is used to pour hot water, the supply water W equivalent to the consumption of hot water HW1 enters the tank unit 4. In this example, the supply water W has reached the installation level of the temperature sensor 44-3. From this reached level, the amount of hot water HW1 used to pour hot water can be predicted or calculated.

[0085] <Bath warming operation> A in Fig. 8 shows the operation during bath warming. During bath warming, a predetermined amount of hot water HW2, for example 20 liters of hot water HW2, is supplied to and stored in the upper layer of tank unit 4 in preparation for bath reheating. During this bath warming, tank unit 4 stores supply water W in the lower layer, hot water HW1 in the middle layer, and hot water HW2 in the upper layer. In other words, before bath reheating, hot water HW2 is introduced from HP unit 6 to tank unit 4, and hot water HW2 is stored in tank unit 4 above hot water HW1.

[0086] B in Fig. 8 shows the processing procedure during bath temperature keeping. When the system switches to bath temperature keeping, the hot water supply control unit 8 switches the three-way valve 32 (S401), switches the selector valve 34 (S402), and drives the pump 24 of the HP unit 6 (S403), circulating the water supply W from the tank unit 4 to the HP unit 6. The water supply W is heated to hot water HW2 by the HP unit 6, and the hot water HW2 is stored in the tank unit 4. In this case, when 20 liters of hot water HW2 are stored in the tank unit 4, 20 liters of water supply W will have been heated to hot water HW2.

[0087] The hot water supply control unit 8 acquires the temperature information (Tn) and compares it with the second set temperature Tc2 (S404), and determines whether the amount of hot water HW2 stored in the tank unit 4 has reached a reference value (S405). When the temperature information acquired from the temperature sensor 44-1 transitions from temperature HW1 to temperature information representing hot water HW2, the hot water supply control unit 8 stops the introduction of hot water HW2 to the tank unit 4. In other words, when the amount of hot water HW2 stored in the tank unit 4 has reached the reference value, the process proceeds to bath warming reheating (initial heating) processing (S500).

[0088] <Bathroom warming reheating (initial heating) operation> A in Fig. 9 shows the operation during bath warming and reheating (initial heating). Bath warming and reheating involves heat exchange between the hot water HW2 in the upper layer of the tank unit 4 and the bath water BW, and the bath water BW is heated to the reheating set temperature using the heat of the hot water HW2.

[0089] In this case, the three-way valve 32 is switched to connect the fourth circulation path 28-4 and the first circulation path 28-1, and the changeover valve 34 is switched to connect the first circulation path 28-1 and the third circulation path 28-3. At this time, when the pump 24 on the HP unit 6 side is operated, the hot water HW2 is circulated from the tank unit 4 to the heat exchanger 36, and the hot water HW2 after heat exchange passes through the HP unit 6 and is introduced into the lower layer of the tank unit 4. The reason why the hot water HW2 after heat exchange is passed through the HP unit 6 is to reuse the heat remaining in the hot water HW2 after heat exchange with the bath water BW, and to use this residual heat for warming up the HP unit 6.

[0090] At this time, by operating the pump 42 of the reheating circulation path 30, the bath water BW can be forcibly circulated through the heat exchanger 36 via the reheating circulation path 30, and after heat exchange with the hot water HW2, the bath water BW can be heated to the reheating set temperature.

[0091] 9B shows the processing procedure during bath warming and reheating (initial heating). When the hot water supply control unit 8 shifts to bath warming and reheating, it switches the three-way valve 32 (S501), switches the selector valve 34 (S502), and drives the pump 24 of the HP unit 6 and the pump 42 of the reheating circulation path 30 (S503). This causes the hot water HW2 and bath water BW to circulate through the heat exchanger 36, and the bath water BW can be heated by the hot water HW2 through heat exchange between the two. In other words, this initial heating heats the bath water BW using the hot water HW2 stored in the tank unit 4.

[0092] The hot water supply control unit 8 judges whether the initial heating has ended since the start of the bath warming and reheating (S504). This initial heating is continued, for example, until the initial heating time ends or until the amount of hot water HW2 stored, for example, 20 liters, is consumed (NO in S504). If the initial heating is ended (YES in S504), the process proceeds to the bath warming and reheating process (heating by the HP unit 6) (S600).

[0093] <Bathroom heating operation (HP unit 6 heating)> A in Fig. 10 shows the operation during bath warming and reheating (heating by HP unit 6). In this bath warming and reheating (heating by HP unit 6), heat exchange occurs between the hot water HW2 in the upper part of the tank unit 4 and the bath water BW, the bath water BW is heated to the reheating set temperature using the heat of the hot water HW2 (initial heating), and then the hot water HW2 after heat exchange with the bath water BW is heated by the HP unit 6. The heated hot water HW2 is used for heat exchange with the bath water BW. In other words, the hot water HW2 repeatedly exchanges heat with the bath water BW and is heated by heating in the HP unit 6.

[0094] In this case, the three-way valve 32 is switched to connect the fourth circulation path 28-4 and the first circulation path 28-1, and the switching valve 34 is switched to connect the first circulation path 28-1 and the second circulation path 28-2. At this time, the pump 24 on the HP unit 6 side is operated, so that the hot water HW2 heated by heating the tank unit 4 can be circulated to the heat exchanger 36.

[0095] At this time, the pump 42 of the reheating circulation path 30 continues to operate, so that the bath water BW circulates through the reheating circulation path 30 to the heat exchanger 36, and after heat exchange with the hot water HW2, the temperature can be raised to the reheating set temperature.

[0096] Fig. 10B shows the processing procedure during bath warming and reheating (combined heating of HP unit 6). Even after the initial heating of bath warming and reheating is completed, the hot water supply control unit 8 maintains the switched state of the three-way valve 32 as in the initial heating, switches the switching valve 34 (S601), and keeps the pump 24 of the HP unit 6 and the pump 42 of the reheating circulation path 30 in operation (S602). Then, the heating capacity of the HP unit 6 is increased (S603), and the hot water HW2, which has been cooled after heat exchange with the bath water BW, is heated by the heating of the HP unit 6, and then heat exchange with the bath water BW is performed, and processing proceeds to the bath warming and heat storage start processing (S700).

[0097] <Bathroom heating and heat storage start operation> A in FIG. 11 shows the operation during bath warming and heat storage start. During bath warming, if bath reheating is performed, hot water HW2 is consumed to heat the bath water BW, so the hot water HW2 in the tank unit 4 is depleted. In order to prepare for bath warming reheating or hot water supply, hot water HW2 storage in the tank unit 4 is started. The hot water supply control unit 8 detects the depletion of hot water HW2 using temperature information obtained from the temperature sensor 44-1 and the like. In response to this, the hot water supply control unit 8 switches the three-way valve 32, connects the lower layer of the tank unit 4 to the first circulation path 28-1, drives the HP unit 6 to guide the water supply W from the tank unit 4 to the HP unit 6 and heats it to the second set temperature Tc2, and guides the hot water HW2 obtained in the HP unit 6 through the second circulation path 28-2 to the tank unit 4 for storage.

[0098] In addition, if it is determined that there will be a shortage of hot water HW1 in the tank unit 4 due to the start of hot water supply use, the HP unit 6 heats the water supply W and stores the hot water HW1 in the tank unit 4 to replenish the hot water, and further, the HP unit 6 may heat the water supply W and store the hot water HW2 in the tank unit 4.

[0099] B in Fig. 11 shows the processing procedure for bath warming / heat storage start. Hot water supply control unit 8 monitors the end of bath reheating (S701), and when bath reheating is finished (YES in S701), switches three-way valve 32 (S702) and connects the lower part of tank unit 4 to first circulation path 28-1. The heating operation of HP unit 6 is maintained (S703), and supply water W is heated to second set temperature Tc2. Hot water HW2 obtained by this heating is stored in tank unit 4 (S704), and the operation proceeds to bath warming / hot water supply use / heat storage start (S800).

[0100] <Bath warming, hot water supply in use, heat storage start operation> A in Fig. 12 shows the operation of keeping the bath warm, using hot water supply, and starting heat storage. When supplying hot water during the bath warming and heat storage operations, hot water HW2 stored in the tank unit 4 is discharged and used for hot water supply. To adjust the hot water supply temperature, part of the water supply W supplied to the tank unit 4 is used and mixed with the hot water HW2, and hot water supply is started with hot water HW3 adjusted to the hot water supply setting temperature. In this case, the heat storage operation is performed in parallel, so the hot water HW2 obtained by the heat storage operation can be used for hot water supply.

[0101] 12B shows the processing procedure for bath temperature keeping, hot water supply use, and heat storage start. In this processing procedure, the hot water supply operation and the heat storage operation during bath temperature keeping are performed in parallel.

[0102] In the processing of the hot water supply operation, it is determined whether a demand for hot water has arisen (S801), and if a demand for hot water has arisen (YES in S801), hot water HW2 is discharged from the tank unit 4 to the hot water outlet passage 14 in response to the demand for hot water supply, and water supply W enters the tank unit 4 from the water supply passage 12 in response to this discharge (S802). The hot water supply control unit 8 acquires temperature information from the temperature sensors 44-8, 44-12, 44-13, etc., and controls the opening of the distribution valve 16 to adjust the hot water HW3 to the hot water supply set temperature (S803), and supplies hot water by regulating the amount of hot water HW3 adjusted to the hot water supply set temperature with the flow rate regulation valve 18 (S804). In this case, the amount of hot water supply may be adjusted by adjusting the opening of the flow rate regulation valve 18 under the control of the hot water supply control unit 8. Then, the hot water supply control unit 8 monitors the hot water supply (S805), and when the hot water supply is completed (YES in S805), the process returns to S801.

[0103] In the heat storage operation during bath warming, which is performed in parallel with this hot water supply operation, the previously described bath warming / heat storage start operation (FIG. 11) is continued, and similarly, three-way valve 32 is switched (S811), and the lower part of tank unit 4 is connected to first circulation path 28-1 and maintained. The heating operation of HP unit 6 is maintained (S812), and supply water W is heated to second set temperature Tc2. Hot water HW2 obtained by this heating is stored in tank unit 4 (S813), and the process proceeds to bath warming / heat storage start (S900).

[0104] <Bath warming / heat storage start operation> A in Fig. 13 shows the operation when the bath is being kept warm and heat storage starts. When hot water supply during the bath is being kept warm and heat storage operation is finished, the operation proceeds to the same operation as the bath is being kept warm and heat storage start operation (Fig. 11) described above. In other words, the supply of water W to the tank unit 4 is stopped, and the water W in the tank unit 4 is heated by the HP unit 6 to hot water HW2, which is then stored in the tank unit 4.

[0105] B in Fig. 13 shows the processing procedure for bath warming and heat storage start. This processing procedure includes stopping the supply of water W to the tank unit 4 (S901), maintaining the heating operation of the HP unit 6 (S902), storing hot water HW2 in the tank unit 4 (S903), and returning to the operation of waiting before automatic bath hot water pouring (S100).

[0106] <Advantages of the second embodiment> According to the second embodiment, any one of the following effects can be obtained. (1) In standby mode before automatic bath water pouring, hot water HW1 is stored in tank unit 4, and the heat stored in the hot water HW1 can be used to supply hot water and pour hot water into the bath.

[0107] (2) In the automatic bath water pouring system, hot water HW1 from the tank unit 4 can be used to pour hot water into the bath.

[0108] (3) When the automatic bath water pouring is completed, the amount of water W supplied in the tank unit 4 or the amount of hot water HW1 stored can be known by obtaining temperature information from the temperature sensors 44-1, 44-2, ..., 44-5, and the amount of hot water HW1 or hot water HW2 that is insufficient for the desired heat storage amount can be known.

[0109] (4) During bath warming, the water W supplied to the tank unit 4 for bath hot water supply is circulated through the HP unit 6 and heated to hot water HW1 or hot water HW2, so that a predetermined amount of hot water HW1 or hot water HW2 can be stored in the tank unit 4.

[0110] (5) During bath warming and reheating, the bath water BW can be initially heated using hot water HW2 from tank unit 4, thereby increasing the rate at which the bath water BW rises in temperature during bath reheating.

[0111] (6) When the bath is kept warm, by using the HP unit 6 for heating as well, the bath water BW can be heated without consuming the heat stored in the tank unit 4 due to the heat exchange between the bath water BW and the hot water HW2.

[0112] (7) During bath warming and while the bath water BW is being reheated or after that time has elapsed, the water W in the tank unit 4 is guided to the HP unit 6 and heated in preparation for hot water supply, so that the tank unit 4 can be replenished with hot water HW2.

[0113] (8) During the bath temperature maintenance, hot water HW2 is discharged from tank unit 4, and supply water W is led from water supply passage 12 to tank unit 4 and the bypass passage, so that hot water HW3 at a predetermined temperature, which is a mixture of hot water HW2 and supply water W, can be supplied. At this time, supply water W from tank unit 4 is led to HP unit 6 and heated, and hot water HW2 is replenished to tank unit 4 and heat is stored.

[0114] (9) During bath temperature maintenance, even after hot water supply is stopped, water W is introduced from tank unit 4 to HP unit 6 and heated, and hot water HW2 is replenished to tank unit 4 and stored as heat, enabling efficient heat storage using hot water HW2.

[0115] (10) In this hot water supply system 2, a propane refrigerant (R290), which has good thermal efficiency at low temperatures (below 60°C), is used as refrigerant 56. The system is primarily based on low-temperature heat storage. Therefore, the thermal efficiency (COP) of HP unit 6 is COP: 6.0 for heat storage using hot water HW1 (=45°C) and COP: 4.7 for heat storage using hot water HW2 (=60°C), achieving high thermal efficiency.

[0116] (11) This hot water supply system 2 or hot water supply method can realize a highly efficient operation without controlling the start and stop of the heat storage operation based on the electricity fee. As mentioned above, heat is stored in hot water HW1 (for example, 40°C) except when the bath is being kept warm, and after automatic bath water pouring is completed (=warming), a certain amount (about 20 liters) of hot water HW2 (for example, 60°C) is stored in the upper layer of the tank unit 4, and when bath reheating is started, heat is exchanged between the hot water HW2 and the bath water BW until the heat output of the HP unit 6 stabilizes (for example, about 3 minutes), and the bath water BW can be heated to the reheating set temperature.

[0117] In this case, if hot water is required for the shower or faucet before the bath is reheated, hot water HW2 is dispensed, and if the amount of hot water HW2 in the tank unit 4 decreases, the hot water HW2 can be replenished to the tank unit 4 by heating it in the HP unit 6.

[0118] (12) As described above, according to this hot water supply system 2 or hot water supply method, the heating capacity of the HP unit 6 and the hot water storage capacity of the tank unit 4 are combined to change the heat storage temperature according to the purpose, such as general hot water supply, bath hot water supply, or bath reheating, thereby improving the heat storage efficiency and hot water supply efficiency.

[0119] Third embodiment 14A and 14B show operation patterns of hot water supply system 2 according to the third embodiment. In 14A and 14B, the same parts as in FIG. 1 are denoted by the same reference numerals.

[0120] It is expected that the amount of heat stored for hot water supply will be insufficient as a result of using hot water HW1 for automatic bath water pouring. Therefore, in the third embodiment, when the amount of heat stored for hot water supply in tank unit 4 is insufficient after automatic bath water pouring is completed, the amount of heat for hot water supply is secured by hot water HW1, and the amount of heat for bath reheating is secured by hot water HW2, thereby improving the convenience of hot water supply and bath reheating.

[0121] FIG. 14A shows a heat storage operation for hot water supply using hot water HW1 when the heat storage amount of the tank unit 4 is insufficient for hot water supply.

[0122] The hot water supply control unit 8 obtains temperature information from the temperature sensors 44-1, ..., 44-5 and determines the amount of heat stored in the tank unit 4. In this case, since the temperature sensor 44-4 detects the temperature of the supply water W, the amount of hot water stored in the tank unit 4 represents the amount of hot water HW1 stored in the tank unit 4 excluding the supply water W up to the level of the temperature sensor 44-4. In this case, the supply water W is taken out of the tank unit 4 and circulated to the HP unit 6, and the hot water HW1 heated to the first set temperature Tc1 is stored in the tank unit 4, and the amount of heat stored necessary for hot water supply is ensured by the amount of hot water HW1 stored.

[0123] If a request for bath reheating occurs during this operation, the hot water supply control unit 8 executes a process to raise the heating temperature of the HP unit 6 to the second set temperature Tc2, raising the temperature to hot water HW2 and discharging the hot water. In this case, since the HP unit 6 is already in a warm-up state, it is possible to quickly raise the temperature to hot water HW2. The process thereafter is the same as the operation or process described in FIG.

[0124] FIG. 14B shows an operation for increasing the amount of heat for hot water supply or for securing the amount of heat for reheating after the amount of heat for hot water supply has been secured.

[0125] After the heat quantity for hot water supply is secured in the tank unit 4 by the hot water HW1, the hot water supply control unit 8 uses this as an opportunity to raise the set temperature from the first set temperature Tc1 to the second set temperature Tc2, that is, to increase the heating capacity of the HP unit 6. Then, the water W is circulated from the tank unit 4 to the HP unit 6, and the hot water HW2 at the second set temperature Tc2 is stored in the tank unit 4, thereby increasing the heat quantity for hot water supply or securing the heat quantity for reheating.

[0126] <Advantages of the Third Embodiment> According to the third embodiment, any one of the following effects can be obtained. (1) In the third embodiment, the same effects as in the first or second embodiment can be obtained.

[0127] (2) It is possible to store heat and supply hot water as desired according to the amount of hot water stored in the tank unit 4, thereby realizing an efficient hot water supply system or method.

[0128] [Fourth embodiment] Fig. 15A shows a hot water inlet / outlet structure of a hot water storage tank unit according to a fourth embodiment, and Fig. 15B shows a hot water inlet / outlet structure of a hot water storage tank unit. In Fig. 15A and B, the same parts as in Fig. 1 are given the same symbols.

[0129] 15A and 15B, the hot water inlet / outlet section 68 includes a hot water inlet pipe 70 and a hot water outlet pipe 72, which are adjacent to each other and inserted into the tank unit 4 from the top. The hot water inlet pipe 70 is a pipe used to introduce the hot water HW1 or HW2 into the tank unit 4. The hot water outlet pipe 72 is a pipe used to take out the hot water HW1 or HW2 from the tank unit 4.

[0130] A buffer section 74 is provided on the hot water inlet pipe 70 side to buffer the discharge pressure of the hot water HW1 or hot water HW2 discharged from the hot water inlet pipe 70. A buffer panel 76 is provided on this buffer section 74, opening at the opening of the hot water inlet pipe 70, and a pair of standing walls 78, 79 are provided between this buffer panel 76 and the ceiling section 80 of the tank unit 4. The standing walls 78, 79 and the buffer panel 76 form a groove that opens in the front-to-rear direction on the paper surface, as shown in B of Fig. 15.

[0131] With this configuration, the buffer section 74 reduces the discharge pressure of the hot water HW1 or hot water HW2 introduced into the tank unit 4 from the hot water inlet pipe 70, thereby preventing the collapse of the stratified state of the hot water HW1 or hot water HW2 in the tank unit 4. Here, the collapse of stratification refers to a state in which the hot water HW1 enters the area of ​​the hot water HW2.

[0132] The hot water extraction pipe 72 protrudes from the ceiling 80 of the tank unit 4 by a shorter length than the hot water introduction pipe 70, and the ceiling 80 of the tank unit 4 is curved outward. Therefore, the hot water HW1 or HW2 is guided to the hot water extraction pipe 72 along the curved surface of the ceiling 80 of the tank unit 4, and the hot water HW1 or HW2 in the tank unit 4 can be gently taken out of the tank unit 4 without disturbing the stratified state.

[0133] <Advantages of the Fourth Embodiment> According to the fourth embodiment, any one of the following effects can be obtained. (1) In the hot water supply system 2, the stratified state of the hot water HW1 and the hot water HW2 in the tank unit 4 is not disturbed, and the regularity of the heat storage form can be maintained.

[0134] (2) Since the stratified state of the hot water HW1 and the hot water HW2 can be maintained, the hot water HW1 or the hot water HW2 can be selectively discharged from the tank unit 4, thereby improving the hot water supply functions such as hot water supply, heat exchange, bath water supply, and bath reheating using the hot water HW1 or the hot water HW2, thereby achieving a highly reliable hot water supply function.

[0135] Other Embodiments The present disclosure includes the following other embodiments. (1) In the above embodiment, a propane refrigerant (R290), which has good thermal efficiency at low temperatures (below 60° C.), is used as refrigerant 56 (FIG. 2), and low-temperature heat storage is the main focus. However, the hot water supply method and system disclosed herein are not limited to propane refrigerant, and other refrigerants may be used.

[0136] (2) In the first embodiment, a single tank unit 4 and HP unit 6 are provided, but a plurality of these may be provided.

[0137] (3) Although a flow rate sensor is not shown in FIG. 1, a flow rate sensor may be provided to detect the inflow rate of the water W and the supply rate of the hot water HW3.

[0138] (4) In the above embodiment, two types of hot water HW1, HW2 with different temperatures are generated from the supply water W and stored in the tank unit 4. However, three or more types of hot water with different temperatures may be generated and stored in the tank unit 4. The hot water stored in the tank unit 4 is not limited to HW1, HW2.

[0139] As described above, the most preferred embodiment of the present disclosure has been described. The present disclosure is not limited to the above description. Various modifications and changes are possible for those skilled in the art based on the gist of the claims or the disclosure of the embodiments of the invention. It goes without saying that such modifications and changes are included in the scope of the present disclosure. [Industrial Applicability]

[0140] According to the hot water supply system and hot water supply method disclosed herein, under normal circumstances, a first hot water is stored in the hot water storage tank, and before bath reheating, a second hot water is introduced into the hot water storage tank and stored above the first hot water, and during bath reheating, the second hot water is extracted from the hot water storage tank for heat exchange with the bath water and hot water supply, etc., and by using a heat pump as the heat source unit, in combination with heat storage in the hot water storage tank, highly convenient hot water supply including bath water supply and bath reheating can be realized. [Explanation of symbols]

[0141] W Water Supply HW1 1st hot water HW2 Second hot water HW3 Third hot water Tc1 1st set temperature Tc2 2nd set temperature 2. Hot water system 4 Hot water tank unit 6 Heat pump unit 8 Hot water supply control unit 10 Remote control device 12 Water supply channel 14 Hot water outlet 16 Distribution valve 18 Flow control valve 20 Bypass Road 22 Hot water supply 24 Pump 26 HP control unit 28-1 1st circulation route 28-2 Second circulation route 28-3 Third circulation route 28-4 4th circulation route 30 Reheating circulation route 32 Three-way valve 34 Switching valve 36 Heat exchanger 38 Bath 40 Circulation port 42 Pump 44-1, 44-2, 44-3, 44-4, 44-5, 44-6, 44-7, 44-8, 44-9, 44-10, 44-11, 44-12, 44-13 Temperature Sensors 46 Refrigerant circuit 48-1, 48-2 heat exchanger 50 Expansion valve 52 Air heat exchanger 54 Compressor 56 Refrigerants 58 Control Systems 60 processors 62 Memory section 64 Input / output section (I / O) 66 Communications Department 68 Hot water inlet / outlet 70 Hot water introduction pipe 72 Hot water outlet pipe 74 Buffer 76 Buffer Panel 78, 79 Standing Wall 80 Ceiling

Claims

1. A heat source machine that heats the supply water to a first hot water or to a second hot water having a higher temperature than the first hot water; A hot water storage tank that stores the first hot water or stores the second hot water above the first hot water; The hot water supply system includes: under normal circumstances, the first hot water is stored in the hot water storage tank; before bath reheating, the second hot water is introduced into the hot water storage tank and stored above the first hot water; and during bath reheating, the bath water is heated by heat exchange between the second hot water taken out of the hot water storage tank and the bath water.

2. The hot water supply system according to claim 1 , wherein a temperature difference between the first hot water and the second hot water is 10° C. or more.

3. A temperature sensor installed at a hot water storage position of the second hot water storage tank; a control unit that acquires temperature information from the temperature sensor while the second hot water is being introduced into the hot water storage tank, and when the temperature information changes from the first hot water to temperature information representing the second hot water, stops the introduction of the second hot water; The hot water system of claim 1 .

4. a hot water supply passage for supplying third hot water obtained by mixing the first hot water or the second hot water discharged from the hot water storage tank with the supply water; A distribution valve that distributes the supply water to the hot water storage tank and the hot water supply path; a regulating valve that regulates an amount of the third hot water flowing through the hot water supply passage; A temperature sensor for detecting a temperature of the third hot water; a control unit that acquires detected temperature information from the temperature sensor and adjusts the opening degree of the distribution valve and / or the regulating valve to control the temperature of the third hot water to a hot water supply setting temperature; The hot water system of claim 1 .

5. A heat exchanger is provided for exchanging heat between the bath water and the second hot water discharged from the hot water storage tank. The hot water supply system according to any one of claims 1 to 4, wherein, during bath reheating, the second hot water after heat exchange with the bath water is heated by the heat source unit and then returned to the hot water storage tank.

6. A hot water introduction section that introduces the first hot water or the second hot water into the hot water storage tank; a buffer section that buffers the hot water flow in the hot water storage tank when hot water is introduced from the hot water introduction section; The hot water supply system according to any one of claims 1 to 4, comprising:

7. A step in which a heat source unit heats the supply water to first hot water or to second hot water having a higher temperature than the first hot water; Storing the first hot water in a hot water storage tank or storing the second hot water above the first hot water; A step of storing the first hot water in the hot water storage tank under normal conditions, and introducing the second hot water into the hot water storage tank before a bath reheating operation, and storing the second hot water above the first hot water; During bath reheating, the bath water is heated by heat exchange between the second hot water taken out of the hot water storage tank and the bath water; A hot water supply method comprising:

8. The hot water supply method according to claim 7 , wherein a temperature difference between the first hot water and the second hot water is set to 10° C. or more.

9. acquiring temperature information from a temperature sensor installed at a storage position of the second hot water in the hot water storage tank while the second hot water is being introduced into the hot water storage tank; When the temperature information changes from the first hot water to temperature information representing the second hot water, stopping the introduction of the second hot water; The hot water supply method according to claim 7, comprising:

10. supplying third hot water obtained by mixing the first hot water or the second hot water discharged from the hot water storage tank with the supply water to a hot water supply path; distributing the water supply to the hot water storage tank and the hot water supply path by a distribution valve; regulating an amount of the third hot water flowing through the hot water supply passage with a regulating valve; Detecting the temperature of the third hot water with a temperature sensor; A step of acquiring detected temperature information from the temperature sensor and adjusting the opening degree of the distribution valve and / or the regulating valve to control the third hot water to a hot water supply setting temperature; The hot water supply method according to claim 7, comprising:

11. The hot water supply method according to claim 7, further comprising a step of heating the second hot water after heat exchange with the bath water by the heat source device and then returning the second hot water to the hot water storage tank during bath reheating.

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