Hot water system

Abstract

To obtain a hot water system which contributes to suppression of power consumption in a power amount limiting time zone and can store hot water even in the power amount limiting time zone.SOLUTION: A hot water system 100 includes an operation limitation part 80 for controlling an operation control part 60 so as to perform heating operation and circulation operation by limiting power to be consumed by heating operation to be performed by a heating unit 200 and by circulation operation to be performed by a circulation part 500 to a limit value shown by power amount limitation information or less in the case of receiving the power amount limitation information, and a hot water supply control part for stopping discharging hot water from a hot water supply end 46 in the case that a hot water storage tank temperature sensor 32 detects that an outside air temperature detected by an outside temperature sensor 21 is a prescribed outside air temperature or less and that a temperature of hot water stored in a hot water storage tank 31 is a prescribed temperature of hot water or less within a power amount limitation time zone.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a hot water supply system. [Background technology]

[0002] There is a storage-type hot water supply device that stores hot water heated by a heating means such as a heat pump device in a hot water storage tank and supplies the hot water stored in the hot water storage tank to a user. In a time period when the demand for electricity is high, an electricity supplier may request an electricity consumer to limit the amount of power consumption to be less than the power amount limit value. For example, Patent Document 1 discloses a storage-type hot water supply device having a normal mode and a peak cut operation mode as a hot water supply device that can respond to such a request to limit the amount of power consumption. In this storage-type hot water supply device, the normal mode is a mode in which the heating means can heat and store hot water even in a time period when the power consumption limit request is received (hereinafter referred to as a power amount limit time period), and the peak cut operation mode is a mode in which hot water is heated and stored in a time period other than the power amount limit time period and the heating means is prohibited from heating hot water during the power amount limit time period, thereby performing an operation that contributes to limiting the amount of power consumption in a time period when the demand for electricity is high.

[0003] A hot water storage type hot water supply apparatus may be partially installed outdoors, and if the ambient temperature of the installation location, such as outdoors, drops to near the freezing temperature of water, freezing of water pipes, valves, joints, etc., or the water circuit through which hot water and water flow can cause the hot water storage type hot water supply apparatus to break down. In order to prevent this freezing of the water circuit, when the conditions for freezing of the water circuit are met, a freeze prevention operation may be performed to keep the water circuit warm by circulating hot water from the hot water storage tank through the water circuit and prevent freezing. During this freeze prevention operation, the temperature of the hot water in the hot water storage tank decreases, so if the temperature of the hot water in the hot water storage tank drops below the temperature required for the freeze prevention operation, a heating operation using a heating means must be performed to keep the temperature of the hot water in the hot water storage tank at or above the temperature required for the freeze prevention operation. For example, if such a function for performing anti-freeze operation is applied to the storage type hot water supply device of Patent Document 1, when the temperature of the hot water in the storage tank drops below the temperature required for anti-freeze operation during a power restriction period, in normal mode, a heating operation will be performed and therefore will not contribute to limiting the amount of power consumed during the power restriction period, and in peak cut operation mode, heating operation is prohibited and therefore the hot water temperature required to prevent freezing cannot be maintained, and freezing cannot be prevented. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2013-221720 A Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, in the storage type water heater disclosed in Patent Document 1, in normal mode, which does not limit power consumption even during power limit time periods, it is unable to contribute to the restriction request to reduce power consumption below the power limit value, and in peak cut operation mode, in which heating operation is prohibited, it is unable to store hot water at the required temperature in the hot water tank, such as hot water at the temperature used for the above-mentioned anti-freeze operation.

[0006] The present disclosure has been made to solve the problems described above, and aims to provide a hot water supply system that contributes to reducing power consumption during power restriction times, and can store hot water at the required temperature even during power restriction times. [Means for solving the problem]

[0007] The hot water supply system according to the present disclosure includes a heating unit that performs a heating operation to heat water to generate hot water, a water circuit through which water heated by the heating unit and the hot water generated by the heating unit circulate, a hot water storage tank that stores the hot water generated by the heating unit and supplies the stored hot water, a circulation unit that performs a circulation operation to circulate water or hot water through the water circuit, an operation control unit that controls the heating operation by the heating unit and the circulation operation by the circulation unit when storing hot water in the hot water storage tank, and when power amount limit information indicating a limit value for power consumption is received, instructs the operation control unit to control the amount of power consumed in the heating operation and the circulation operation. The system is equipped with an operation limiting unit that controls the heating and circulation operations by limiting the amount of electric power consumed to below a limit value indicated in the electric power limit information, an outside air temperature sensor that detects the outside air temperature, a hot water storage tank temperature sensor that detects the temperature of hot water stored in the hot water storage tank, a hot water supply end that dispenses hot water stored in the hot water storage tank, and a hot water supply control unit that stops the supply of hot water from the hot water supply end when, during a power limit time period indicated in the electric power limit information, the outside air temperature detected by the outside air temperature sensor is below a predetermined outside air temperature and the hot water temperature detected by the hot water storage tank temperature sensor is below the predetermined hot water temperature. Effect of the Invention

[0008] The hot water supply system of the present disclosure, when it receives power amount limit information indicating a limit value for power consumption, is equipped with an operation limiting unit that controls the operation control unit, which controls the heating operation by the heating unit and the circulation operation by the circulation unit, to limit the power consumed in the heating operation and circulation operation to below the limit value indicated in the power amount limit information, thereby controlling the heating operation and circulation operation.Since the heating operation and circulation operation when the power consumption is limited are performed below the limit value indicated in the power amount limit information, this contributes to reducing the amount of power consumption during power amount limit time periods, and has the effect of ensuring hot water at the required temperature even during power amount limit time periods by carrying out the heating operation and circulation operation. [Brief description of the drawings]

[0009] [Figure 1]1 is a configuration diagram showing a schematic configuration of a hot water supply system according to a first embodiment. [Diagram 2] FIG. 2 is a functional configuration diagram showing the functional configuration of each unit of the hot water supply system according to the first embodiment. [Diagram 3] FIG. 2 is a schematic diagram showing a flow of water during a heating operation of the hot water supply system according to the first embodiment of the present invention. [Figure 4] FIG. 2 is a schematic diagram showing a water flow during an anti-freeze operation of the hot water supply system according to the first embodiment of the present invention. [Diagram 5] FIG. 2 is a schematic diagram showing a water flow during hot water supply operation of the hot water supply system according to the first embodiment of the present invention. [Figure 6] 4 is a graph showing an example of a change in heating capacity of a heating unit of the hot water supply system according to the first embodiment of the present invention. [Figure 7] 4 is a graph showing an example of a change in heating capacity of a heating unit of the hot water supply system according to the first embodiment of the present invention. [Figure 8] 4 is a graph showing an example of a change in heating capacity of a heating unit of the hot water supply system according to the first embodiment of the present invention. [Figure 9] 4 is a flowchart showing an outline of the operation of the hot water supply system according to the first embodiment of the present invention. [Figure 10] 4 is a flowchart showing an anti-freeze operation of the hot water supply system according to the first embodiment of the present invention. [Figure 11] 4 is a flowchart showing the hot water supply operation of the hot water supply system according to the first embodiment of the present invention. [Figure 12] 5 is a flowchart showing a heating operation of the hot water supply system according to the first embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments will be described with reference to the drawings. In each drawing, the same reference numerals are used to denote common or corresponding elements, and the description is simplified or omitted. The configurations shown in the following embodiments are examples of the technical ideas of the present disclosure, and may be combined with other known technologies, or multiple technical ideas described in the present disclosure may be combined. A part of the configuration may be omitted or modified without departing from the gist of the present disclosure.

[0011] Embodiment 1 FIG. 1 is a configuration diagram that shows a schematic configuration of a hot water supply system 100 according to the first embodiment, and FIG. 2 is a functional configuration diagram that shows the functional configuration of each part of the hot water supply system 100 according to the first embodiment.

[0012] The hot water supply system 100 of the first embodiment contributes to suppressing the amount of power consumption during power limit time periods and is capable of storing hot water at a required temperature even during power limit time periods, and for this purpose is provided with an operation limiting unit that, when power limit information indicating a limit value for the amount of power consumption (hereinafter referred to as the power limit value) is received, controls the heating operation to heat water and the circulation operation to circulation to limit the power consumed to less than the power limit value, thereby controlling the heating operation and the circulation operation. The detailed configuration will be described below.

[0013] As shown in FIG. 1, the hot water supply system 100 of this embodiment includes a heating unit 200 that performs a heating operation of heating water to produce hot water, a hot water storage unit 300 that is connected to the heating unit 200 by a heating unit hot water inlet piping 40a and a heating unit hot water outlet piping 40b and has a hot water storage tank 31 that stores the hot water produced by the heating unit 200 and supplies the stored hot water, an operation control unit 60 that controls the overall operation of the hot water supply system 100, such as the heating operation by the heating unit 200 when storing hot water in the hot water storage tank 31, and a remote controller (hereinafter referred to as a remote control) 70 that performs two-way communication with the operation control unit 60 via wired or wireless communication, and allows the user to set operation information for the hot water supply system 100 and displays the operation information for the hot water supply system 100.

[0014] The heating unit 200 has an outdoor air temperature sensor 21 that detects the outdoor air temperature, a heating temperature sensor 22 that detects the temperature of hot water generated by the heating unit 200, and a heat pump circuit (not shown) that performs a heating operation of heating water to generate hot water. The heat pump circuit has a general configuration including a compressor, an outdoor heat exchanger, an expansion valve, an outdoor fan, a water-refrigerant heat exchanger, and a refrigerant pipe, and the compressor, the outdoor heat exchanger, the expansion valve, and the water-refrigerant heat exchanger are connected in a ring shape by the refrigerant pipe. The water flowing in from the hot water storage unit 300 through the heating unit hot water inlet pipe 40a is heated by the water-refrigerant heat exchanger, and the hot water generated by this heating operation is supplied to the hot water storage unit 300 through the heating unit hot water outlet pipe 40b. As the heat pump circuit, a supercritical heat pump circuit in which the pressure of the refrigerant in the compressor is equal to or higher than the critical pressure may be used, or a heat pump circuit in which the pressure of the refrigerant in the compressor is equal to or lower than the critical pressure may be used. In the case of a heat pump circuit that operates when the pressure of the refrigerant in the compressor is equal to or lower than the critical pressure, the refrigerant may be fluorocarbon gas, ammonia, etc. In addition, refrigerants capable of producing hot water at high temperatures, such as carbon dioxide, R410A, propane, and propylene, may be used as the refrigerant for the heat pump circuit. However, the refrigerants used in the heat pump circuit are not limited to the above examples. In this embodiment, the heating unit 200 is described as being configured with a heat pump circuit as described above, but the configuration of the heating unit 200 is not limited to this, and it may be configured to perform a heating operation of heating water to generate hot water.

[0015] As shown in FIG. 1, the hot water storage unit 300 is composed of a hot water storage tank 31 that stores hot water generated by the heating unit 200 and supplies the stored hot water, a four-way valve 41, three-way valves 42a-44, an on-off valve 45, a hot water supply end 46, a water supply end 47, a tank-side pump 51, and various pipes 40a-40r that connect these. Four-way valve 41, three-way valves 42a-44, on-off valve 45, hot water supply end 46, cold water supply end 47, tank-side pump 51, and pipes 40a-40r connecting these constitute a water circuit 400 through which water before being heated by heating unit 200, hot water generated by heating unit 200, and hot water supplied from hot water storage tank 31 circulate. In addition, a circulating section 500 is constituted which performs a circulating operation to circulate water or hot water through water circuit 400 by driving tank-side pump 51.

[0016] In such a hot water storage unit 300, the opening and closing directions of the four-way valve 41 and the three-way valves 42a-44, and the opening and closing of the on-off valve 45, the hot water supply end 46, and the water supply end 47 are controlled by the operation control unit 60, so that the water circuit 400 is formed into the desired flow paths, such as a flow path for storing hot water in the hot water storage tank 31 and a flow path for supplying the hot water stored in the hot water storage tank 31 to a bathtub, and in each case, the operation control unit 60 controls the driving and stopping of the tank side pump 51, which is the circulating unit 500 that performs the circulating operation of circulating water or hot water through the water circuit 400, and the desired operation is performed. The operation control unit 60 also controls the heating operation by the heating unit 200 when hot water is stored in the hot water storage tank 31. That is, the operation control unit 60 controls the heating operation by the heating unit 200 and the circulating operation by the circulating unit 500.

[0017] Furthermore, the hot water supply system 100 is equipped with an operation limiting unit 80 that, when power amount limiting information indicating a limit value for power consumption is received, controls the operation control unit 60 to limit the power consumed in the heating operation by the heating unit 200 and the circulation operation by the circulation unit 500 to below the limit value indicated in the power amount limiting information, thereby controlling the heating operation and the circulation operation.

[0018] The hot water supply system 100 of this embodiment is shown as being applied to a home, and a bathtub (not shown) to which the hot water supply system 100 supplies hot water is connected via a bathtub supply pipe 40r and a bathtub return pipe 40q. This hot water supply system 100 supplies hot water in a hot water storage tank 31 to the connected bathtub, or heats the water in the bathtub circulating via the bathtub supply pipe 40r and the bathtub return pipe 40q using a water heat exchanger 33. This embodiment shows such a hot water supply system 100 for a home, but the application of the hot water supply system 100 is not limited to this.

[0019] Each device constituting the hot water storage unit 300 will be described below.

[0020] Hot water storage tank 31 is hollow, and stores hot water generated by heating unit 200 in the internal space. The temperature of the hot water stored in hot water storage tank 31 can be low, medium, and high, in that order. Within hot water storage tank 31, a temperature layer is formed in which the upper part of hot water storage tank 31 is hotter and the lower part is colder due to differences in water density caused by differences in temperature. Hot water generated by heating unit 200 is stored in the upper part of hot water storage tank 31, and water before being heated by heating unit 200 is stored in the lower part of hot water storage tank 31.

[0021] Connected to the top of the hot water storage tank 31 are a hot water supply pipe 40d that communicates with a hot water inlet pipe 40f and a second hot water pipe 40n via a three-way valve 42b, and a hot water supply pipe 40c that communicates with a hot water supply mixing valve 43 and a bathtub hot water supply mixing valve 44. Connected to the bottom of the hot water storage tank 31 are a hot water storage tank water supply pipe 40h, a first hot water pipe 40m, and a hot water supply pipe 40p.

[0022] Hot water storage tank temperature sensors 32a, 32b, 32c, and 32d are installed in this order at intervals in the vertical direction from the top to the bottom of hot water storage tank 31, and the vertical temperature distribution inside hot water storage tank 31 can be grasped from the temperatures detected by these hot water storage tank temperature sensors 32a, 32b, 32c, and 32d, thereby determining the amount of hot water stored in hot water storage tank 31 (hereinafter referred to as the hot water storage amount). Because the hot water storage tank temperature sensors 32a, 32b, 32c, and 32d have the same basic configuration, they will be referred to as hot water storage tank temperature sensor 32 when there is no need to particularly distinguish between them.

[0023] The water heat exchanger 33 heats the hot water in the bathtub. The water heat exchanger 33 is connected to the top of the hot water storage tank 31 by hot water inlet pipe 40f, and is connected to the bottom of the hot water storage tank 31 by hot water outlet pipe 40g through a three-way valve 42a. The water heat exchanger 33 is also connected to a bathtub circulation circuit consisting of the bathtub, bathtub return pipe 40q, and bathtub forward pipe 40r, and the hot water in the bathtub passes through it. In other words, the water heat exchanger 33 heats the hot water in the bathtub by exchanging heat between the hot water circulating in the bathtub circulation circuit and the hot water in the hot water storage tank 31 introduced from the hot water inlet pipe 40f.

[0024] The four-way valve 41 is a flow path switching means having ports A, B, C, and D. The four-way valve 41 is configured to be able to switch between four paths: AC, AD, BC, and BD. The A port of the four-way valve 41 is connected to a water pipe 40k, the B port is connected to a heating unit hot water outlet pipe 40b, the C port is connected to a first hot water pipe 40m, and the D port is connected to a second hot water pipe 40n.

[0025] The three-way valve 42a is a flow path switching means having an A port, a B port, and a C port. The three-way valve 42a is configured to be able to switch the flow path among three paths, AB, AC, and BC. The A port of the three-way valve 42a is connected to the hot water storage tank 31 via the hot water supply pipe 40p, the B port is connected to the hot water outlet pipe 40g, and the C port is connected to the tank-side pump 51. The three-way valve 42b is a flow path switching means having an A port, a B port, and a C port. The three-way valve 42b is configured to be able to switch between two paths, AB and BC. The A port of the three-way valve 42b is connected to the second hot water / cold water pipe 40n, the B port is connected to the heating unit hot water outlet pipe 40b, and the C port is connected to the water heat exchanger 33 via the hot water inlet pipe 40f. The three-way valve 42a and the three-way valve 42b have the same basic configuration, and therefore will be referred to as the three-way valve 42 when there is no need to distinguish between them.

[0026] The hot water mixing valve 43 is a flow path switching means having an A port, a B port, and a C port. The hot water mixing valve 43 is configured to be able to switch between three paths, ABC, AC, and BC. The hot water control unit 60c adjusts the mixture ratio of the hot water from the hot water supply pipe 40c and the tap water from the water supply end 47 by changing the opening degree of the A port and the B port of the hot water mixing valve 43, and adjusts the temperature so that the hot water has a temperature set by the user. The temperature-adjusted hot water is discharged from the hot water supply end 46 via the hot water supply pipe 40j.

[0027] The bathtub hot water supply mixing valve 44 is a flow path switching means having ports A, B, and C. The bathtub hot water supply mixing valve 44 is configured to be able to switch between three paths: ABC, AC, and BC. The hot water supply control unit 60c adjusts the mixture ratio of the hot water from the hot water supply pipe 40c and the tap water from the water supply end 47 by changing the opening degree of ports A and B of the bathtub hot water supply mixing valve 44, thereby adjusting the temperature of the hot water supplied to the bathtub.

[0028] The on-off valve 45 is connected to the bathtub hot water supply mixing valve 44 via the hot water filling pipe 40i. When the on-off valve 45 is opened by the hot water supply control unit 60c, hot water in the hot water storage tank 31 is supplied to the bathtub via the bathtub supply pipe 40r.

[0029] The inlet of the tank-side pump 51, which is the circulating section 500, is connected to the three-way valve 42a, and the outlet of the tank-side pump 51 is connected to the heating unit 200 via the heating unit hot water inlet pipe 40a. The tank-side pump 51 is controlled by the operation control section 60, and performs a circulating operation to circulate the hot water stored in the hot water storage tank 31 through the water circuit 400.

[0030] Next, the functional configuration of each unit of hot water supply system 100 will be described with reference to Fig. 2. Operation control unit 60, remote control 70, and operation limiting unit 80 each include a microcomputer having a memory and a processor.

[0031] The operation control unit 60 is configured to be capable of two-way communication via wired or wireless communication between the remote control 70, the operation limiting unit 80, the heating unit 200, and the hot water storage unit 300, and acquires operation information of the hot water supply system 100 input from the remote control 70, temperature information of the hot water in the hot water storage tank 31 detected by the hot water storage tank temperature sensor 32, outside air temperature information detected by the outside air temperature sensor 21, and power consumption limit information transmitted from the operation limiting unit 80, and controls the operation of the heating unit 200 and the hot water storage unit 300.

[0032] The operation control unit 60 includes a heating control unit 60a, an anti-freeze control unit 60b, and a hot water supply control unit 60c. When the hot water supply system 100 performs a heating operation, the heating control unit 60a controls the heating operation by the heat pump circuit in the heating unit 200, and controls the pump rotation speed of the tank side pump 51 and the switching between opening and closing of the four-way valve 41 and the three-way valve 42. The anti-freeze control unit 60b controls switching of the pump rotation speed of the tank-side pump 51 and opening / closing of the four-way valve 41 and the three-way valve 42 when the hot water supply system 100 performs an anti-freeze operation. The hot water supply control unit 60c controls the switching between opening and closing of the hot water supply mixing valve 43, the bathtub hot water supply mixing valve 44, the on-off valve 45, the hot water supply end 46, and the water supply end 47 when the hot water supply system 100 performs hot water supply operation. The operation control unit 60 also includes a timer unit (not shown) and acquires current time information. The operation control unit 60 also includes a calendar unit (not shown) and acquires current date information. The operation control unit 60 may acquire time information or date information from the remote control 70 or an external device. In the first embodiment, the current day is from 0:00 to 23:59. The timer unit divides the current day into a late night time zone, a morning time zone, a daytime time zone, and a night time zone. The late night time zone is, for example, a time zone from 0:00 to 7:00. The morning time zone is, for example, a time zone from 7:00 to 10:00. The daytime time zone is, for example, a time zone from 10:00 to 17:00. The night time zone is, for example, a time zone from 17:00 to 23:59. A year is from January 1 to December 31. The calendar unit divides a year into a summer period and a winter period. The summer period, for example, refers to the dates from July 1 to September 30. The winter period, for example, refers to the dates from December 1 to March 31. However, the late night time zone, morning time zone, daytime time zone, night time zone, summer time zone, and winter time zone are not limited to the above examples, and may change depending on the contract with the power company or the power amount adjustment intermediary, etc.

[0033] Here, with reference to Figures 3 to 5, we will explain the heating circuit 301 that is formed when a heating operation is performed by the heating control unit 60a, the anti-freeze circuit 302 that is formed when an anti-freeze operation is performed by the anti-freeze control unit 60b, and the hot water supply circuit 303 that is formed when a hot water supply operation is performed by the hot water supply control unit 60c.

[0034] 3 is a schematic diagram showing the flow of water during the heating operation of the hot water supply system 100. The heating control unit 60a opens the four-way valve 41 in the BD direction, the three-way valve 42a in the AC direction, and the three-way valve 42b in the AB direction, forming a heating circuit 301 shown by a thick line in FIG. 3 in part of the water circuit 400. The heating circuit 301 is a circuit that communicates from the lower part of the hot water storage tank 31 to the heating unit 200 via the hot water supply pipe 40p and the heating unit hot water supply pipe 40a, and is connected to the upper part of the hot water storage tank 31 via the heating unit hot water outlet pipe 40b, the second hot water pipe 40n, and the hot water supply pipe 40d. Water and hot and cold water in the heating circuit 301 flow in the direction of the arrows.

[0035] FIG. 4 is a schematic diagram showing the flow of water during the freeze prevention operation of the hot water supply system 100. The freeze prevention control unit 60b opens the four-way valve 41 in the BC direction, the three-way valve 42a in the BC direction, and the three-way valve 42b in the BC direction, forming a freeze prevention circuit 302 shown by a thick line in FIG. 4 in a part of the water circuit 400. The freeze prevention circuit 302 is a circuit that communicates with the water heat exchanger 33 from the upper part of the hot water storage tank 31 via the hot water supply pipe 40d and the hot water introduction pipe 40f, passes through the heating unit 200 via the hot water discharge pipe 40g and the heating unit hot water inlet pipe 40a, and then connects to the lower part of the hot water storage tank 31 via the heating unit hot water outlet pipe 40b and the first hot water pipe 40m. Water and hot and cold water in the freeze prevention circuit 302 flow in the direction of the arrow.

[0036] In both the heating operation and the anti-freeze operation described above, the tank side pump 51 serving as the circulating section 500 is driven to perform a circulating operation in which water or hot and cold water is circulated through the heating circuit 301 and the anti-freeze circuit 302 serving as part of the water circuit 400.

[0037] Fig. 5 is a schematic diagram showing the flow of water during hot water supply operation of hot water supply system 100. Hot water supply control unit 60c adjusts the opening of ports A and B of hot water mixing valve 43 to form hot water supply circuit 303 shown by the thick line in Fig. 5. Water and hot water in hot water supply circuit 303 flow in the direction of the arrows, and by changing the opening of ports A and B, the mixture ratio of hot water from hot water supply pipe 40c and tap water from water supply end 47 is adjusted, and hot water adjusted to the temperature set by the user is discharged from hot water supply end 46 via hot water supply pipe 40j.

[0038] Next, a description will be given of the water filling circuit (not shown) that is formed when the water filling operation is performed by the operation control unit 60, and the reheating circuit (not shown) that is formed when the reheating operation is performed.

[0039] The filling circuit is formed by adjusting the opening of ports A and B of bathtub hot water mixing valve 44 and opening on-off valve 45 by operation control unit 60. In this filling circuit, the mixing ratio of hot water from hot water supply pipe 40c and tap water from water supply end 47 is adjusted by changing the opening of ports A and B of bathtub hot water mixing valve 44, and hot water whose temperature has been adjusted to the temperature set by the user is supplied to the bathtub via filling pipe 40i, on-off valve 45, and bathtub supply pipe 40r, and filling the bathtub is performed.

[0040] The reheating circuit is formed by opening three-way valve 42a in the AB direction and three-way valve 42b in the BC direction by operation control unit 60. The reheating circuit is a circuit that communicates from the top of hot water storage tank 31 to water heat exchanger 33 via hot water supply pipe 40d and hot water inlet pipe 40f, and is connected to the bottom of hot water storage tank 31 via hot water outlet pipe 40g and hot water supply pipe 40p, and heats the hot water in the bathtub by exchanging heat in water heat exchanger 33 between the hot water introduced from hot water inlet pipe 40f and the hot water circulating in the bathtub circulation circuit.

[0041] Remote control 70 is configured to be capable of two-way communication with operation control unit 60 via wired or wireless communication, and a user can input operation information of hot water supply system 100 by operating remote control 70. Operation information of hot water supply system 100 includes, for example, the temperature of hot water dispensed from hot water supply end 46, the temperature and amount of hot water dispensed into the bathtub, the temperature when the hot water in the bathtub is reheated, and the like. Remote control 70 may also include a display unit such as a liquid crystal panel or an alarm unit such as a voice guidance device, and may be configured to notify the user of current operation information of hot water supply system 100 via the display unit or alarm unit. The remote control 70 may be installed on a wall of, for example, a kitchen, a living room, or a bathroom. A plurality of remote controls 70 may be capable of communicating with the operation control unit 60. In addition to or instead of the remote control 70, a mobile terminal such as a smartphone, a smart speaker, a television, or other device may be configured to be used as a user interface. The operation control unit 60, the remote control 70, and other user interfaces may be capable of communicating with each other via the Internet or a local area network. In the following description, an operation using the remote control 70 may be substituted with an operation using a user interface other than the remote control 70.

[0042] The operation limiting unit 80 receives power amount limit information from a power company or a power amount adjustment intermediary. The power amount limit information is a limit request from a power company or a power amount adjustment intermediary to a power consumer to reduce the amount of power consumed below the power amount limit value, and is information including a power amount limit day, a power amount limit time period, and a power amount limit value. For example, during daytime hours in summer and daytime hours in winter, the amount of power consumed by consumers increases compared to other days or time periods, and the power supply may not be able to keep up, so a power company or a power amount adjustment intermediary requests a power consumer to reduce the amount of power consumed. The power amount limit value specifies the maximum amount of power that the hot water supply system 100 can use for each 30-minute segment. Even if the amount of power consumed by the hot water supply system 100 reaches the power amount limit value, it becomes possible to use power if 30 minutes have passed and the system moves to the next segment. Furthermore, the operation limiting unit 80 externally acquires weather information for the next day in the area where the hot water supply system 100 is installed. The weather information is, for example, the predicted weather for the next day or the predicted outside air temperature for the next day. The operation limiting unit 80 of this embodiment acquires weather information for the next day, but may also acquire weather information for, for example, one week.

[0043] In the present embodiment 1, the operation limiting unit 80 receives the power amount limit information and the weather information from the power company or the power amount adjustment intermediary by 23:00 of the previous day. The time for receiving the power amount limit information and the weather information is not limited to the above example, and may vary depending on the contract with the power company or the power amount adjustment intermediary.

[0044] The operation limiting unit 80 is configured to communicate bidirectionally with the operation control unit 60 via wired or wireless communication, and transmits power amount limit information received from the power company or the power amount adjustment intermediary to the operation control unit 60. In addition, the operation limiting unit 80 transmits the operation information of the hot water supply system 100 received from the operation control unit 60 to the power company or the power amount adjustment intermediary.

[0045] Next, a description will be given of the operation of the hot water supply system 100 configured as above. First, the heating operation, anti-freezing operation, and hot water supply operation of the hot water supply system 100 will be described.

[0046] The heating operation is an operating operation in which the heat pump circuit in the heating unit 200 heats low-temperature water in the hot water storage tank 31 to medium-temperature water or high-temperature water, or heats medium-temperature water in the hot water storage tank 31 to high-temperature water. By driving the tank-side pump 51 as the circulating section 500, a circulating operation is performed in the heating circuit 301, in which the water flowing out from the lower part of the hot water storage tank 31 flows into the heating unit 200 via the hot water supply pipe 40p and the heating unit hot water supply pipe 40a. Then, a heating operation is performed in which the water circulating in the heating unit 200 is heated to a target temperature by the heat pump circuit in the heating unit 200, and hot water is generated. This generated hot water flows into the hot water storage tank 31 via the heating unit hot water outlet pipe 40b, the second hot water pipe 40n, and the hot water supply pipe 40d by the circulating operation. When such a circulating operation and heating operation are performed, hot water is stored while maintaining a temperature distribution state in which the upper part of the hot water storage tank 31 becomes high-temperature hot water and the lower part of the hot water storage tank 31 becomes low-temperature water.

[0047] The following describes the hot water temperature control executed by the heating control unit 60a during the heating operation. The temperature control is a feedback control of the rotation speed of the tank-side pump 51 by the heating control unit 60a so that the temperature of the hot water detected by the heating temperature sensor 22 is equal to the target temperature of the hot water to be generated by the heating operation (hereinafter referred to as the target hot water temperature). The feedback control is executed periodically at a certain time interval, for example. In the heating operation, hot water storage is executed in a state where the target hot water temperature is set to the target temperature of the hot water to be stored in the hot water storage tank 31 (hereinafter referred to as the target hot water storage temperature). That is, the target hot water temperature is equal to the target hot water storage temperature. For example, the heating control unit 60a sets the target hot water storage temperature, i.e., the target hot water temperature, in relation to the capacity of the hot water storage tank 31 so that the target hot water storage amount can be stored in the hot water storage tank 31. The target hot water storage amount corresponds to the target value of the heat storage amount of the hot water storage tank 31. A method of calculating the heat storage amount will be described later. The heating control unit 60a may set the target hot water storage amount based on the operation information set by the user via the remote control 70, for example, or a calculation unit (not shown) included in the operation control unit 60 may learn the total amount of heat (hereinafter referred to as consumed heat information) of hot water consumed in one day within a specified period in the past, and the heating control unit 60a may calculate the target hot water storage amount based on the learning results. Also, the heating control unit 60a sets the target hot water storage temperature, i.e., the target hot water temperature, to be within a predetermined range (for example, 40°C to 90°C).

[0048] Next, the heating capacity control of the heat pump circuit executed by the heating control unit 60a during the heating operation will be described. In the above-mentioned temperature control, the tank-side pump 51 only controls the flow rate of hot water circulating in the heating circuit 301, so the maximum value of the hot water temperature realized by the temperature control depends on the heating capacity of the heat pump circuit. Therefore, even if the target hot water temperature is set to the maximum value (for example, 90°C) within the range of hot water temperatures that can be generated by the heating operation, the heat pump circuit is required to have a heating capacity that can realize this. For this reason, in the heating capacity control by the heating control unit 60a, the heating control unit 60a sets a target value of the heating capacity (hereinafter referred to as the target heating capacity) that can generate the target hot water temperature based on, for example, the amount of hot water stored in the hot water storage tank 31, the outside air temperature, the temperature of water flowing into the heat pump circuit, and the like. The heating control unit 60a controls the frequency of the compressor so that the actual heating capacity of the heat pump circuit is equal to the target heating capacity. By controlling the heating capacity of the heat pump circuit in this way, it is possible to stably ensure the hot water temperature required by the user even when the target hot water temperature setting and external conditions such as the outside air temperature change. The heating capacity control is executed periodically at regular time intervals. The lower the temperature of the water flowing into the heat pump circuit, the higher the operating efficiency of the heating operation of the heat pump circuit, and hot water can be generated with less power consumption.

[0049] The heating control unit 60a of this embodiment performs a normal heating operation when the current time is outside the power amount limit time zone, and performs a power amount limit heating operation when the current time is within the power amount limit time zone. In the normal heating operation that is performed when the current time is outside the power amount limit time zone, the target hot and cold water temperature (for example, 60°C) is set based on the operation information set by the user via the remote control 70. On the other hand, in the power amount limit heating operation that is performed when the current time is within the power amount limit time zone, the target hot and cold water temperature is set lower than the target hot and cold water temperature during the normal heating operation, and the power amount limit heating operation is performed (for example, 30°C). The target hot and cold water temperature during the power amount limit heating operation is calculated and set by the calculation unit based on the power amount limit value indicated in the power amount limit information received by the operation limit unit 80. The power amount limit value used at this time may be the value included in the most recently received power amount limit information, or the calculation unit may learn the power amount limit value received within a specified period in the past, and the target hot and cold water temperature may be set based on the learning result before the power amount limit value is received. Since the normal heating operation and the power-limited heating operation are basically similar in operation, they will be referred to as heating operation unless otherwise distinguished.

[0050] In this way, in power-amount-limited heating operation in which the target hot and cold water temperature is set based on the power amount limit information, the amount of power consumed by heating unit 200 during power-amount-limited heating operation can be reduced compared to normal heating operation by setting the target hot and cold water temperature lower than the target hot and cold water temperature during normal heating operation. In other words, in power-amount-limited heating operation, the amount of power consumed in the operation of hot water supply system 100, including the circulation operation and the heating operation, can be limited to less than the power amount limit value.

[0051] The anti-freeze operation is an operation to prevent damage to the water circuit 400, etc. due to freezing, by keeping the anti-freeze circuit 302, which is part of the water circuit 400, warm using the heat contained in the hot water in the hot water storage tank 31 when the outside air temperature T (hereinafter referred to as T) detected by the outside air temperature sensor 21 is below a temperature To (hereinafter referred to as To, To is, for example, 5°C) at which water may begin to freeze. The anti-freeze control unit 60b starts the anti-freeze operation when T becomes equal to or lower than To, and ends the anti-freeze operation when T becomes equal to or higher than a predetermined temperature (for example, 7°C or higher). In the anti-freeze operation, the tank-side pump 51 serving as the circulating section 500 is driven, and in the anti-freeze circuit 302, the hot water flowing out from the top of the hot water storage tank 31 passes through the water heat exchanger 33 via the hot water inlet pipe 40f, and flows through the hot water outlet pipe 40g, the heating unit hot water inlet pipe 40a, the heating unit 200, the heating unit hot water outlet pipe 40b, and the first hot water pipe 40m in this order, before flowing into the bottom of the hot water storage tank 31. In this way, the hot water in the hot water storage tank 31 flows through the anti-freeze circuit 302 serving as part of the water circuit 400, and the heat contained in the hot water can be used to keep the anti-freeze circuit 302 and the surrounding water circuit 400 warm, thereby preventing freezing.

[0052] Here, the antifreeze control unit 60b of this embodiment performs two types of antifreeze operations. When the current time is outside the power-amount-restricted time zone, the antifreeze control unit 60b performs a normal antifreeze operation, and when the current time is within the power-amount-restricted time zone, the antifreeze control unit 60b performs a power-amount-restricted antifreeze operation. Both of these antifreeze operations are basically the operations described above, but in the normal antifreeze operation performed outside the power-amount-restricted time zone, the antifreeze operation is performed with the pump speed of the tank-side pump 51 set to a preset speed based on an experiment or simulation, whereas in the power-amount-restricted antifreeze operation performed within the power-amount-restricted time zone, the antifreeze operation is performed with the pump speed of the tank-side pump 51 lowered than the pump speed of the tank-side pump 51 during the normal antifreeze operation. Since the power-amount limiting anti-freezing operation and the normal anti-freezing operation are basically similar in operation, they will be referred to as anti-freezing operations unless otherwise distinguished.

[0053] In this way, in the power-limited anti-freeze operation which controls the rotation speed of the tank-side pump 51, by setting the rotation speed of the tank-side pump 51 lower than the rotation speed of the tank-side pump 51 during normal heating operation, the flow rate of hot water circulating through the anti-freeze circuit 302 and the surrounding water circuit 400 is reduced compared to normal times, and the amount of heat radiated from piping, etc. within the hot water supply system 100 is also reduced.Therefore, when the temperature of the hot water in the hot water storage tank 31 drops within the power-limited time, the number of times heating operations are performed to generate hot water containing the heat required for the anti-freeze operation can be reduced compared to normal heating operation, and control can be performed to limit the amount of power consumed in the operation of the hot water supply system 100, including the circulation operation and the anti-freeze operation, to below the power limit value.

[0054] The hot water supply operation involves mixing the hot water in the hot water storage tank 31 with tap water supplied from the water supply terminal 47, adjusting the temperature of the hot water to the set temperature set by the user via the remote control 70, and supplying hot water at the set temperature to the user based on the user's operation. By the hot water supply operation, tap water supplied from the water supply end 47 is automatically supplied to the hot water storage tank 31 from the bottom of the hot water storage tank 31 via the hot water storage tank water supply pipe 40h in accordance with the reduction in the amount of hot water flowing out of the hot water storage tank 31. The hot water supply operation can be performed in parallel with the heating operation or the anti-freeze operation.

[0055] Next, the hot water filling operation and the reheating operation of the hot water supply system 100 will be described.

[0056] The filling operation involves mixing the hot water in the hot water storage tank 31 with tap water supplied from the water supply end 47, adjusting the temperature of the hot water to the set temperature set by the user via the remote control 70, and supplying hot water at the set temperature to the bathtub, which is the target of the hot water supply system 100. The filling operation is stopped when the water level in the bathtub reaches the level set by the user via remote control 70. The water level in the bathtub is detected by a water level sensor (not shown) installed in the filling circuit. In addition, tap water supplied from water supply end 47 is automatically supplied to hot water storage tank 31 from the bottom via hot water storage tank water supply piping 40h in accordance with the decrease in the amount of hot water flowing out of hot water storage tank 31.

[0057] The reheating operation is an operation in which heat is exchanged in the water heat exchanger 33 between the medium-temperature or high-temperature water in the hot water storage tank 31 and the low-temperature or medium-temperature water in the bathtub, thereby heating the water in the bathtub to high temperature water and supplying water at the set temperature set by the user via the remote control 70. The reheating operation continues until the hot water in the bathtub reaches the temperature set by the user via remote control 70, and stops when the hot water in the bathtub reaches the temperature set by the user. The temperature of the hot water in the bathtub is detected by a temperature sensor (not shown) installed in the reheating circuit.

[0058] When the hot water supply system 100 executes the above-mentioned heating operation, anti-freeze operation, hot water supply operation, hot water filling operation, and reheating operation, it is necessary to calculate the amount of heat stored in the hot water storage tank 31. This amount of heat is calculated by the operation control unit 60. The method by which the operation control unit 60 calculates the amount of heat stored in the hot water storage tank 31 will be described below.

[0059] The calculation unit calculates the amount of heat stored in the hot water tank 31 Q [kWh] (hereinafter referred to as Q). 3 ] and the amount of hot water stored in the hot water tank 31 [m 3 ], the temperature [°C] of the hot water in the hot water storage tank 31, and the temperature [°C] of the tap water supplied from the water supply end 47, according to the following formula (1). The operation control unit 60 acquires the calculated Q as heat storage amount information of the hot water storage tank 31.

[0060] Q [kWh] = water specific heat [kJ / kgK] × water density [kg / m 3 ] × amount of hot water stored in hot water tank 31 [m3 ] × (temperature of hot water in hot water storage tank 31 [°C] - temperature of tap water supplied from water supply end 47 [°C]) Equation (1)

[0061] Since the temperature [°C] of the hot water in the hot water tank 31 varies in the vertical direction of the hot water tank 31, the stored heat amounts Qa [kWh], Qb [kWh], Qc [kWh], and Qd [kWh] (hereinafter referred to as Qa, Qb, Qc, and Qd) (hereinafter referred to as Qa, Qb, Qc, and Qd) are calculated according to formula (1) using the temperatures Ta [°C], Tb [°C], Tc [°C], and Td [°C] (hereinafter referred to as Ta, Tb, Tc, and Td) in the hot water tank 31 detected by the hot water tank temperature sensors 32a, 32b, 32c, and 32d, respectively. Then, Q held by the hot water tank 31 is calculated according to the following formula (2).

[0062] Q = Qa + Qb + Qc + Qd Equation (2)

[0063] Next, with reference to Figs. 6 to 8, an example of an operation schedule for controlling adjustment of the amount of hot water stored in hot water storage tank 31 in hot water supply system 100 on a day when there is a power amount restriction time zone will be described.

[0064] 6 is a graph showing the heating capacity P of the heating unit 200 when operating according to a basic operation schedule as an example of a first operation schedule. The heating capacity P is the amount of power consumption per unit time required for the heating unit 200 to generate the amount V of hot water. At 23:00 on the previous day, the operation limiting unit 80 receives the power amount limit information for the day from the power company or the power amount adjustment intermediary, and weather information from the outside. Based on the power amount limit information, weather information, and heat consumption information received by the operation limiting unit 80, the calculation unit calculates the amount of hot water V0 (hereinafter referred to as V0) expected to be used for the day, and the amount of hot water V1 (hereinafter referred to as V1) that is greater than V0. Furthermore, the calculation unit calculates the amount of hot water that needs to be generated within the late-night hours based on the amount of hot water remaining in the hot water storage tank 31, and calculates the heating capacity P1 (hereinafter referred to as P1) per unit time required to generate this amount of hot water. The amount of hot water generated (hereinafter referred to as the amount of hot water generated) is determined by the heating capacity and the time for which the heating operation is performed, and each of these may be appropriately determined according to the amount of hot water that needs to be generated. The heating control unit 60a controls the heating unit 200 so that the heating capacity becomes P1, and causes the heating unit 200 to perform normal heating operation during the heating operation time in the late night hours. As a result, hot water is generated during the late night hours, and hot water V1 is stored in the hot water storage tank 31. At 23:00 on the current day, the operation limiting unit 80 receives power amount limit information and weather information for the next day from the power company or power amount adjustment intermediary, and these are used for the heating operation to store hot water for the next day. By performing normal heating operations during the middle of the night and storing hot water V1, which is greater than V0, in the hot water storage tank 31 in advance, it is possible to prevent a shortage of hot water used by users or hot water needed for anti-freeze operations.This reduces the number of times that power-limited heating operations are performed to generate additional hot water during power-limited timeslots, and allows power-limited anti-freeze operations to be performed continuously.

[0065] In the example of the operation schedule shown in Fig. 6, a normal heating operation is performed in the middle of the night, and before the power consumption limit time period starts, the amount of hot water expected to be used on that day is generated and stored in hot water storage tank 31, but the operation schedule is not limited to the example of Fig. 6. Fig. 7 is a graph showing the heating capacity P of heating unit 200 as a second example of the operation schedule when a normal heating operation is performed twice from the middle of the night to the morning before the power consumption limit time period starts. Based on the power amount limit information, weather information, and heat consumption information received by the operation limit unit 80 at 23:00 the previous day, the calculation unit calculates the amount of hot water V2 (hereinafter referred to as V2) expected to be used before the start of the power amount limit time period on that day. Furthermore, the calculation unit calculates the amount of hot water that needs to be produced within the late-night time period based on the amount of hot water remaining in the hot water storage tank 31, and calculates the heating capacity P2 (hereinafter referred to as P2) per unit time required to produce this amount of hot water. The heating control unit 60a controls the heating unit 200 so that the heating capacity becomes P2, and causes the heating unit 200 to perform normal heating operation during the heating operation time in the late-night hours. As a result, hot water is generated during the late-night hours, and V2 hot water is stored in the hot water storage tank 31. <V1とする。

[0066] The calculation unit then obtains information on the amount of hot water used during the morning hours of the day, and based on that information, calculates the amount of hot water V21 (hereinafter referred to as V21) expected to be used after the power restriction time period begins. Furthermore, based on the amount of hot water remaining in the hot water storage tank 31, the calculation unit calculates the amount of hot water that needs to be produced during the morning hours before the power restriction time period begins, and calculates the heating capacity P21 (hereinafter referred to as P21) per unit time required to produce this amount of hot water. The heating control unit 60a controls the heating unit 200 so that the heating capacity becomes P21, and causes the heating unit 200 to perform additional normal heating operation during the morning hours until the start of the power consumption restriction time period, thereby storing further hot water of V21 in the hot water storage tank 31. At 23:00 on the current day, the operation limiting unit 80 receives the power amount limit information and weather information for the next day from the power company or the power amount adjustment intermediary, and these are used for the heating operation for storing hot water for the next day.

[0067] The amount of hot water produced according to an operation schedule such as that shown in FIG. 7 is determined by the heating capacity and the time for which the heating operation is performed, and each of these may be determined appropriately depending on the amount of hot water that needs to be produced. In addition, an operation schedule such as that shown in Figure 7 performs additional heating operations based on information about the amount of hot and cold water used during the morning of that day, so the sum of V2 and V21 can sometimes be reduced below V1, resulting in the effect of reducing daily power consumption more than the operation schedule shown in Figure 6.

[0068] FIG. 8 is a graph showing the heating capacity P of the heating unit 200 when the heating operation is performed in two time periods, a late night time period and a night time period, as a third example of an operation schedule. Based on the power amount limit information, weather information, and heat consumption information received by the operation limit unit 80 at 23:00 the previous day, the calculation unit calculates the amount of hot water V3 (hereinafter referred to as V3) expected to be used until the end of the power amount limit time period on that day. Furthermore, based on the amount of hot water remaining in the hot water storage tank 31, the calculation unit calculates the amount of hot water that needs to be produced within the late-night time period, and calculates the heating capacity P3 (hereinafter referred to as P3) per unit time required to produce this amount of hot water. The heating control unit 60a controls the heating unit 200 so that the heating capacity becomes P3, and causes the heating unit 200 to perform normal heating operation during the heating operation time in the late-night hours. As a result, hot water is generated during the late-night hours, and V3 of hot water is stored in the hot water storage tank 31. <V1とする。

[0069] The calculation unit then calculates the amount of hot water V31 (hereinafter referred to as V31) expected to be used after the end of the power restriction time period based on information on the amount of hot water used until the end of the power restriction time period on that day, the power restriction information, the weather information, and the heat consumption information. Furthermore, the calculation unit calculates the amount of hot water that needs to be produced during the night time period based on the amount of hot water remaining in the hot water storage tank 31, and calculates the heating capacity P31 (hereinafter referred to as P31) per unit time required to produce this amount of hot water. The heating control unit 60a controls the heating capacity to be P31, and causes the heating unit 200 to perform an additional normal heating operation during the nighttime hours, thereby storing additional hot water of V31 in the hot water storage tank 31. At 23:00 on the current day, the operation limiting unit 80 receives the power amount limit information and weather information for the next day from the power company or the power amount adjustment intermediary, and these are used for the heating operation for storing hot water for the next day.

[0070] The amount of hot water produced according to an operation schedule such as that shown in FIG. 8 is determined by the heating capacity and the time for which the heating operation is performed, and each of these may be appropriately determined according to the amount of hot water that needs to be produced. An operation schedule such as that of Figure 8 performs additional heating operations based on information on the amount of hot and cold water used during past nighttime hours, so the sum of V3 and V31 may be reduced more than in the operation schedules of Figures 6 and 7, and the amount of power consumed in one day can be reduced more than in the operation schedules of Figures 6 and 7. Furthermore, if a user uses unlimited amounts of hot and cold water during the power limit time period, the user is notified via the remote control 70 or the like that additional heating operations may be performed after the power limit time ends, so the user is expected to refrain from using hot and cold water, which has the effect of reducing the amount of hot and cold water used in one day more than in the case of the operation schedules of Figures 6 and 7.

[0071] The operation of the hot water supply system 100, including the heating operation, the freeze prevention operation, and the hot water supply operation, will be described below. First, when the operation of the hot water supply system 100 is started, in step S1, the outdoor air temperature sensor 21 detects T. The operation control unit 60 acquires T and compares T with To. If the result of this comparison is T≦To, the process proceeds to step S2, and if T≦To is not true, step S1 is repeated. Note that To may be appropriately determined by experiment, simulation, or the like to be a temperature at which it is better to start anti-freeze operation.

[0072] When it is determined in step S1 that T≦To, in step S2, the anti-freeze control unit 60b starts an anti-freeze operation for the hot water supply system 100. The details of this anti-freeze operation will be described later.

[0073] Next, in step S3, hot water supply control unit 60c performs a hot water supply operation of hot water supply system 100. This hot water supply operation is an operation for supplying hot water to a user based on an operation by the user, and the details of the hot water supply operation will be described later.

[0074] Next, in step S4, the heating control unit 60a performs a heating operation of the hot water supply system 100. This heating operation is an operation for heating the hot water when the amount of heat held by the hot water in the hot water storage tank 31 becomes equal to or less than a predetermined value, and the details of the heating operation will be described later.

[0075] After the heating operation is performed in step S4, in step S5, the outside air temperature sensor 21 detects T, and the operation control unit 60 acquires T and compares it with To. If the result of this comparison is that T>To is not true, the process returns to step S2, and the heating operation, anti-freezing operation, etc. are repeated. If T>To is true in step S5, the process ends this routine and returns to the start, and the operation of the hot water supply system 100 as described above is repeated.

[0076] Next, the freeze prevention operation, hot water supply operation, and heating operation of hot water supply system 100 carried out in steps S2 to S4 will be described.

[0077] Fig. 10 is a flowchart showing the freeze prevention operation of the hot water supply system 100 performed in step S2 of Fig. 9. When it is determined in step S1 that T≦To, in step S201, the operation control unit 60 compares the power amount limit time acquired from the operation limiting unit 80 with the current time information acquired from the timer unit. If the result of this comparison shows that the current time is within the power amount limit time zone, the process proceeds to step S202, and if the current time is outside the power amount limit time zone, the process proceeds to step S203.

[0078] If it is determined in step S201 that the current time is within the power amount limit time zone, then in step S202, the anti-freeze control unit 60b starts a power amount limiting anti-freeze operation for the hot water supply system 100. After starting the power amount limiting anti-freeze operation, the process proceeds to step S3. In this way, when the current time is within the power amount limit time zone, the anti-freeze control unit 60b starts a power amount limiting anti-freeze operation, thereby suppressing the amount of power consumption to below the power amount limit value.

[0079] If it is determined in step S201 that the current time is outside the power amount restriction time period, then in step S203, the anti-freeze control unit 60b starts a normal anti-freeze operation of the hot water supply system 100. After starting the normal anti-freeze operation, the process proceeds to step S3. In this way, when the current time is outside the power amount restriction time period, the anti-freeze control unit 60b starts a normal anti-freeze operation that does not suppress the amount of power consumption, thereby enabling anti-freeze operation with sufficient heat retention capacity. In this manner, the freeze prevention operation of hot water supply system 100, which is carried out in step S2, is performed.

[0080] Next, a description will be given of the hot water supply operation of hot water supply system 100 carried out in step S3 of Fig. 9. Fig. 11 is a flowchart showing the hot water supply operation of hot water supply system 100.

[0081] During the implementation of the freeze prevention operation by the hot water supply system 100, if the user uses the hot water in the hot water storage tank 31 without restriction, the amount of hot water stored in the hot water storage tank 31 that holds the heat required for the freeze prevention operation may decrease, and the freeze prevention operation may not be able to continue. This is because the hot water supply system 100 cannot perform the heating operation in parallel with the freeze prevention operation. In order to store hot water that holds the heat required for the freeze prevention operation in the hot water storage tank 31, the operation control unit 60 may end the hot water supply operation and restrict the user from using the hot water in the hot water storage tank 31. Steps S301 to S313 are performed to determine whether to restrict the user from using the hot water in the hot water storage tank 31.

[0082] In step S301, the arithmetic unit compares Ta detected by the hot water storage tank temperature sensor 32a with the temperature Tw of the hot water (hereinafter referred to as Tw. Tw is, for example, 42°C) that is the criterion for stopping the supply of the hot water in the hot water storage tank 31 to the user. As a result of this comparison, if Ta < Tw, the process proceeds to step S302, and if Ta ≥ Tw, the process proceeds to step S313. In the present embodiment, when detecting the temperature of the hot water stored in the hot water storage tank 31, among the plurality of hot water storage tank temperature sensors 32 installed in the hot water storage tank 31, the hot water storage tank temperature sensor 32a installed at the highest position is used. When the freeze prevention operation is executed, a temperature distribution state is formed in which the upper part of the hot water storage tank 31 becomes hot water at a high temperature and the lower part of the hot water storage tank 31 becomes cold water. Therefore, when Ta < Tw, it can be determined that hot water with a temperature lower than Tw is stored in the hot water storage tank 31 below the height of the hot water storage tank temperature sensor 32a. In other words, since the hot water with a temperature of Tw or higher in the hot water stored in the hot water storage tank 31 is flowing through the freeze prevention circuit 302 and the surrounding water circuit 400, it is possible to prevent the water circuit 400 from being damaged by freezing.

[0083] In step S301, the temperature Ta of the hot water detected by the hot water storage tank temperature sensor 32a installed at the highest position among the plurality of hot water storage tank temperature sensors 32 installed in the hot water storage tank 31 is used, but it is not limited to this. For example, the temperature of the hot water detected by any one or a predetermined number of the hot water storage tank temperature sensors 32 among the hot water storage tank temperature sensors 32a, 32b, 32c, and 32d may be used. In addition, Tw can be appropriately determined by experiments, simulations, etc. as the temperature of the hot water at which the supply of the hot water in the hot water storage tank 31 to the user is stopped.

[0084] When it is determined in step S301 that Ta < Tw, in step S302, the operation control unit 60 acquires the current time information from the timer unit. The operation control unit 60 compares the power consumption limit time among the power consumption limit information acquired from the operation restriction unit 80 with the current time information. As a result of this comparison, if the current time is within the power consumption limit time zone, the process proceeds to step S303, and if the current time is outside the power consumption limit time zone, the process proceeds to step S306.

[0085] When it is determined in step S302 that the current time is within the power consumption limit time zone, in S303, in order to prompt the user to stop using the hot water in the hot water storage tank 31, the operation control unit 60 displays on the remote controller 70 in characters that the hot water cannot be used, such as "The supply of hot water has been stopped to ensure hot water for freeze prevention operation." In this embodiment, the user is notified of using the hot water in the hot water storage tank 31 through the characters displayed on the remote controller 70, but it may also be displayed through pictures or a combination of characters and pictures. Also, in this embodiment, the user is notified of the stop of use through the remote controller 70, but it may also be notified through an external device.

[0086] In step S303, even after notifying the user to stop using the hot water in the hot water storage tank 31, in order to determine whether the hot water in the hot water storage tank 31 is still coming out of the hot water supply end 46 so that the user can use the hot water in the hot water storage tank 31, the hot water supply control unit 60c determines in step S304 whether the A port of the hot water supply mixing valve 43 is open. If the hot water supply control unit 60c determines that the A port of the hot water supply mixing valve 43 is open, it proceeds to step S305, and if it determines that the A port of the hot water supply mixing valve 43 is closed, it proceeds to step S4.

[0087] If it is determined in step S304 that the hot water in the hot water storage tank 31 is being used, then in step S305, the hot water supply control unit 60c closes port A of the hot water supply mixing valve 43 to stop the supply of hot water in the hot water storage tank 31. As a result, tap water supplied from the water supply end 47 is supplied to the user from the hot water supply end 46. The hot water supply control unit 60c also closes port A of the bathtub hot water supply mixing valve 44 to stop the supply of hot water in the hot water storage tank 31 to the bathtub. After a certain period of time has elapsed in step S305, the process proceeds to step S4. The certain period of time required to proceed from step S305 to step S4 is determined as appropriate by experiment, simulation, or the like.

[0088] Next, the operation of the hot water supply system 100 when it is determined in step S302 that the current time is outside the power amount restriction period will be described. If it is determined in step S302 that the current time is outside the power amount limited time period, in step S306, the operation control unit 60 stops the power amount limited anti-freezing operation or the normal anti-freezing operation started in step S2, and then starts a normal heating operation. By carrying out this normal heating operation, hot water having the amount of heat required for the anti-freeze operation can be generated and stored in the hot water storage tank 31.

[0089] In order to encourage the user to stop using the hot water in the hot water storage tank 31 while the normal heating operation is being performed in step S306, in step S307, the operation control unit 60 displays in text on the remote control 70 a message indicating that the hot water cannot be used, such as "The supply of hot water has been stopped to secure hot water for the anti-freeze operation." In this embodiment, the user is notified that hot water in hot water storage tank 31 cannot be used via text displayed on remote control 70, but this may also be displayed via a picture or a combination of text and a picture. Also, in this embodiment, the user is notified of the suspension of use via remote control 70, but this may also be displayed via an external device.

[0090] In step S307, even after notifying the user to stop using the hot water in the hot water storage tank 31, in order to determine whether the hot water in the hot water storage tank 31 is still coming out of the hot water supply end 46 so that the user can use the hot water in the hot water storage tank 31, the hot water supply control unit 60c determines in step S308 whether the A port of the hot water supply mixing valve 43 is open. If the hot water supply control unit 60c determines that the A port of the hot water supply mixing valve 43 is open, it proceeds to step S309, and if it determines that the A port of the hot water supply mixing valve 43 is closed, it proceeds to step S310.

[0091] If it is determined in step S308 that the A port of the hot water mixing valve 43 is open, that is, that the hot water in the hot water storage tank 31 is being used by the user, then in step S309 the hot water supply control unit 60c closes the A port of the hot water mixing valve 43 to stop the supply of hot water in the hot water storage tank 31. As a result, tap water supplied from the water supply end 47 is supplied to the user from the hot water supply end 46. The hot water supply control unit 60c also closes the A port of the bathtub hot water mixing valve 44 to stop the supply of hot water in the hot water storage tank 31 to the bathtub. After a certain period of time has elapsed in step S309, the process proceeds to step S310. The certain period of time required to proceed from step S309 to step S310 is appropriately determined by experiment, simulation, or the like.

[0092] After a certain period of time has elapsed since step S309, in step S310, the arithmetic unit compares Ta and Tw. As a result of this comparison, if Ta ≥ Tw, the process proceeds to step S311, and if Ta < Tw, the process proceeds to step S310. The time at which the arithmetic unit starts comparing Ta and Tw is appropriately determined by experiments, simulations, or the like.

[0093] If it is determined in step S310 that Ta ≥ Tw, in step S311, the operation control unit 60 ends the normal heating operation started in step S306 and starts the power consumption limit freezing prevention operation or the normal freezing prevention operation stopped in step S306.

[0094] When the normal heating operation ends in step S311, in step S312, the hot water supply control unit 60c opens the A port of the hot water mixing valve 43 closed in step S309 and starts supplying the hot water in the hot water storage tank 31. The hot water supply control unit 60c mixes with the tap water from the water supply end 47, controls it to reach the set temperature, and then discharges the hot water from the hot water outlet 46 through the hot water supply pipe 40j. Also, the hot water supply control unit 60c opens the A port of the bathtub hot water mixing valve 44 and starts supplying the hot water in the hot water storage tank 31 to the bathtub. The hot water supply control unit 60c mixes with the tap water from the water supply end 47, controls it to reach the set temperature, and then discharges the hot water to the bathtub through the water filling pipe 40i and the bathtub inlet pipe 40r. In step S312, after a certain period of time has elapsed, the process proceeds to step S4. The certain period of time from step S312 until the process proceeds to step S4 is appropriately determined by experiments, simulations, or the like.

[0095] Next, the operation of the hot water supply system 100 when it is determined in step S301 that Ta < Tw will be described. If it is determined in step S301 that Ta < Tw, in step S313, the operation control unit 60 continues to supply the hot water in the hot water storage tank 31 and performs the hot water supply operation. In step S313, after a certain period of time has elapsed, the process proceeds to step S4. The time from step S313 until the process proceeds to step S4 is appropriately determined by experiments, simulations, or the like. In the manner described above, the hot water supply operation of hot water supply system 100 is carried out in step S3.

[0096] Next, a description will be given of the heating operation of hot water supply system 100 carried out in step S4 of Fig. 9. Fig. 12 is a flowchart showing the heating operation of hot water supply system 100.

[0097] The hot water supply system 100 performs a freeze prevention operation to prevent damage to the water circuit 400 due to freezing. However, the hot water flowing out from the upper part of the hot water storage tank 31 drops from high temperature to medium temperature water or low temperature water while passing through the freeze prevention circuit 302, and the medium temperature water or low temperature water flows into the lower part of the hot water storage tank 31, so the temperature of the hot water in the hot water storage tank 31 drops compared to when the freeze prevention operation started, and the water circuit 400 cannot be kept warm, and damage due to freezing may occur. Therefore, when the temperature of the hot water in the hot water storage tank 31 drops due to the freeze prevention operation and the amount of heat held by the hot water in the hot water storage tank 31 also decreases, a heating operation is performed to generate hot water that has the amount of heat required for the freeze prevention operation, and the hot water is stored in the hot water storage tank 31. Steps S401 to S411 are performed to determine whether or not to perform a heating operation to generate hot water that has the amount of heat required for the freeze prevention operation.

[0098] In step S401, the operation control unit 60 acquires current time information from the timer unit. The operation control unit 60 compares the power amount limit time in the power amount limit information acquired from the operation limiting unit 80 with the current time information. If the result of this comparison shows that the current time is within the power amount limit time zone, the process proceeds to step S402, and if the current time is outside the power amount limit time zone, the process proceeds to step S407.

[0099] If it is determined in step S401 that the current time is within the power amount limit time zone, in step S402, the calculation unit compares the Q calculated by the calculation unit with the reference heat storage amount Qs_lim (hereinafter referred to as Qs_lim) for starting the power amount limit heating operation. If the result of this comparison is Q≦Qs_lim, proceed to step S403, and if not, proceed to step S5. The value of Qs_lim and the time when the calculation unit starts comparing Q with Qs_lim are appropriately determined by experiments, simulations, or the like.

[0100] If it is determined in step S402 that Q≦Qs_lim, then in step S403, the operation control unit 60 ends the power-amount-limited anti-freezing operation or the normal anti-freezing operation started in step S2. Then, in step S404, the operation control unit 60 starts the power-amount-limited heating operation of the hot water supply system 100.

[0101] In step S404, the power-amount-limited heating operation is started, and after a certain time has elapsed, in step S405, the calculation unit compares the Q calculated by the calculation unit with the reference heat storage amount Qe_lim (hereinafter referred to as Qe_lim) for ending the power-amount-limited heating operation. If the result of this comparison is Q>Qe_lim, the process proceeds to step S406, and if Q>Qe_lim is not true, the process proceeds to step S404. The value of Qe_lim and the time when the calculation unit starts comparing Q with Qe_lim are appropriately determined by experiments, simulations, or the like.

[0102] If it is determined in step S405 that Q>Qe_lim, then in step S406, the operation control unit 60 ends the power amount limited heating operation started in step S404, and proceeds to step S5.

[0103] Next, the operation of the hot water supply system 100 when it is determined in step S401 that the current time is outside the power amount restriction period will be described. When it is determined in step S401 that the current time is outside the power limit time zone, in step S407, the calculation unit compares Q calculated by the calculation unit with the reference heat storage amount Qs_nor (hereinafter referred to as Qs_nor) at which the normal heating operation starts. As a result of this comparison, if Q≤Qs_nor, the process proceeds to step S408, and if Q>Qs_nor, the process proceeds to step S5. The value of Qs_nor and the time when the calculation unit starts comparing Q with Qs_nor are appropriately determined by experiments, simulations, etc.

[0104] When it is determined in step S407 that Q≤Qs_nor, in step S408, the operation control unit 60 ends the power limit freeze prevention operation or the normal freeze prevention operation started in step S2.

[0105] In step S409, the operation control unit 60 starts the normal heating operation of the hot water supply system 100. After starting the normal heating operation in step S409 and after a certain period of time has elapsed, in step S410, the calculation unit compares Q calculated by the calculation unit with the reference heat storage amount Qe_nor (hereinafter referred to as Qe_nor) at which the normal heating operation ends. As a result of this comparison, if Q>Qe_nor, the process proceeds to step S406, and if Q≤Qe_nor, the process proceeds to step S409. Qe_nor and the time when the calculation unit starts comparing Q with Qe_nor are appropriately determined by experiments, simulations, etc.

[0106] When it is determined in step S410 that Q>Qe_nor, in step S411, the normal heating operation started in step S409 is ended, and the process proceeds to step S5.

[0107] Here, Qs_lim is set so that Qs_lim<Qs_nor. By setting it in this way, the number of heating operations in the power limit time zone is reduced compared to the number of heating operations outside the power limit time zone, so that the effect of suppressing power consumption is achieved. Similarly, Qe_lim is set so that Qe_lim<Qe_nor.

[0108] As described above, the power-amount-limited anti-freezing operation performed when T≦To during the power-amount-limited time period reduces the pump speed of the tank-side pump 51 during the power-amount-limited anti-freezing operation compared to the pump speed of the tank-side pump 51 during the normal anti-freezing operation, thereby providing the effect of limiting the amount of power consumed in the circulation operation to the power amount limit value or less. In addition, the power-amount-limited anti-freezing operation reduces the flow rate of hot water circulating in the anti-freezing circuit 302 and the water circuit 400 therearound compared to the normal anti-freezing operation, and also reduces the amount of heat radiated from the piping and the like in the hot water supply system 100. Therefore, when the temperature of hot water in the hot water storage tank 31 drops during the power amount-limited time period, the number of times that the heating operation is performed to generate hot water having the amount of heat required for the anti-freezing operation can be reduced compared to the normal heating operation. In other words, the number of times that the power-amount-limited anti-freezing operation is stopped can be reduced, providing the effect of limiting the amount of power consumed in the operation of the hot water supply system 100, including the anti-freezing operation and the heating operation, to the power amount limit value or less.

[0109] In addition, the power-limited heating operation performed when Q≦Qs_lim during the power-limited heating time period lowers the temperature of the hot water generated by the heating unit 200 during the power-limited heating operation below the temperature of the hot water generated by the heating unit 200 during normal heating operation, and further sets the temperature of the hot water generated by the heating unit 200 during the power-limited heating operation to Tw, thereby making it possible to supply hot water at the temperature desired by the user even during the power-limited heating time period, and achieving the effect of generating hot water containing the heat amount required to perform anti-freeze operation while keeping the power consumption of the hot water supply system 100 below the power limit value.

[0110] As shown in step S305 of FIG. 11, when T≤To and Ta<Tw in the power consumption limit time zone, by stopping the supply of the hot water in the hot water storage tank 31 to the user, hot water holding the amount of heat required for the freezing prevention operation can be ensured in the hot water storage tank 31. Therefore, the number of times of performing the additional heating operation for generating hot water holding the amount of heat required for the freezing prevention operation is reduced, and the power consumption of the hot water supply system 100 can be suppressed below the power consumption limit value, which has the effect of suppressing the power consumption of the hot water supply system 100 below the power consumption limit value.

[0111] Hereinafter, various aspects of the present disclosure will be collectively described as appendices.

[0112] (Appendix 1) A heating unit that performs a heating operation of heating water to generate hot water, A water circuit through which the water heated by the heating unit and the hot water generated by the heating unit flow, A hot water storage tank that stores the hot water generated by the heating unit and supplies the stored hot water, A flow section that performs a flow operation of causing the water or the hot water to flow through the water circuit, An operation control unit that controls the heating operation by the heating unit and the flow operation by the flow section when storing hot water in the hot water storage tank, When receiving power consumption limit information indicating a limit value of power consumption, a driving restriction unit that performs control to restrict the power consumed in the heating operation and the flow operation to be below the limit value indicated by the power consumption limit information and cause the heating operation and the flow operation to be performed on the operation control unit, An outside air temperature sensor that detects the outside air temperature, A hot water storage tank temperature sensor that detects the temperature of the hot water stored in the hot water storage tank, A hot water supply end that discharges the hot water stored in the hot water storage tank, a hot water supply control unit that stops hot water supply from the hot water supply end when the outdoor air temperature detected by the outdoor air temperature sensor is equal to or lower than a predetermined outdoor air temperature and the hot water temperature detected by the hot water storage tank temperature sensor is equal to or lower than a predetermined hot water temperature during the power amount limit time period indicated by the power amount limit information; A hot water system comprising: (Appendix 2) The hot water storage tank temperature sensors are installed at regular intervals in the vertical direction of the hot water storage tank, and the hot water supply control unit stops hot water from being discharged from the hot water supply end when a predetermined number of the hot water storage tank temperature sensors among the multiple hot water storage tank temperature sensors detect that the temperature of the hot water is below the predetermined hot water temperature.The hot water supply system described in Appendix 1. (Appendix 3) A hot water supply system as described in any one of Appendix 1 to Appendix 2, wherein the hot water supply control unit stops hot water from being dispensed from the hot water supply end when, during the power amount restriction time period, the outside air temperature detected by the outside air temperature sensor is below the specified outside air temperature and the temperature of the hot water detected by the hot water storage tank temperature sensor is below 42 degrees. (Appendix 4) A hot water supply system as described in any one of Appendix 1 to Appendix 3, comprising a remote controller that notifies a user that hot water supply from the hot water supply end will be stopped if, during the power consumption limit time period, the outside air temperature detected by the outside air temperature sensor is below the specified outside air temperature and the hot water temperature detected by the hot water storage tank temperature sensor is below the specified hot water temperature. (Appendix 5) The hot water supply system of any one of Appendix 1 to Appendix 4, wherein the operation control unit stores the amount of hot water in the hot water storage tank before the power consumption limit time period begins in a larger amount than the amount of hot water that would be stored in the hot water storage tank if the power consumption limit information had not been received, and performs the heating operation and the circulation operation. (Appendix 6) The hot water supply system of any one of Appendix 1 to Appendix 5, wherein the operation control unit performs the heating operation and the circulation operation by lowering the temperature of the hot water stored in the hot water storage tank by the heating operation when the power amount limit information is received, lower than the temperature of the hot water stored in the hot water storage tank by the heating operation when the power amount limit information is not received. (Appendix 7) a freeze prevention control unit that performs a freeze prevention operation to keep the water circuit warm using the hot water stored in the hot water storage tank when the outside air temperature detected by the outside air temperature sensor is equal to or lower than the predetermined outside air temperature; The hot water supply system described in Appendix 6, wherein the operation control unit performs the heating operation and the circulation operation when the hot water does not contain the amount of heat required for the anti-freeze operation performed by the anti-freeze control unit during the power amount limit time period. (Appendix 8) The hot water supply system described in Appendix 7, wherein the anti-freeze control unit controls the amount of hot water circulated through the water circuit by the circulation operation when the anti-freeze operation is performed during the power amount restriction time period to be less than the amount of hot water circulated through the water circuit by the circulation operation when the anti-freeze operation is performed outside the power amount restriction time period. (Appendix 9) The hot water supply system of any one of Appendix 1 to Appendix 8, wherein the operation control unit uses heat consumption information indicating the total amount of heat consumed by the hot water per day within a specified period to perform the heating operation multiple times before the power restriction time period begins, and controls the amount of the hot water stored in the hot water storage tank. (Appendix 10) A hot water supply system as described in any one of Appendix 1 to Appendix 9, wherein the operation control unit uses the heat consumption information to control the amount of hot water stored in the hot water storage tank by the heating operation performed until the end of the power restriction time period. [Explanation of symbols]

[0113] 100 hot water supply system, 200 heating unit, 21 outdoor air temperature sensor, 22 heating temperature sensor, 300 hot water storage unit, 301 heating circuit, 302 anti-freeze circuit, 303 hot water supply circuit, 31 hot water storage tank, 32, 32a, 32b, 32c, 32d hot water storage tank temperature sensor, 33 water heat exchanger, 400 water circuit, 40a heating unit hot water inlet pipe, 40b heating unit hot water outlet pipe, 40c hot water supply pipe, 40d hot water supply pipe, 40e water supply pipe, 40f hot water introduction pipe, 40g hot water discharge pipe, 40h hot water storage tank water supply pipe, 40i hot water filling pipe, 40j hot water supply pipe, 40k water pipe, 40m first hot water pipe, 40n second hot water pipe, 40p hot water supply piping, 40q bathtub return piping, 40r bathtub forward piping, 41 four-way valve, 42a three-way valve, 42b three-way valve, 43 hot water supply mixing valve, 44 bathtub hot water supply mixing valve, 45 on-off valve, 46 hot water supply end, 47 water supply end, 500 circulation section, 51 tank side pump, 60 operation control section, 60a heating control section, 60b anti-freeze control section, 60c hot water supply control section, 70 remote control, 80 operation limit section

Claims

1. A heating unit that performs a heating operation of heating water to generate hot water; a water circuit through which the water heated by the heating unit and the hot and cold water generated by the heating unit flow; a hot water storage tank that stores the hot water generated by the heating unit and supplies the stored hot water; A circulating unit that performs a circulating operation of circulating the water or the hot and cold water through the water circuit; an operation control unit that controls the heating operation by the heating unit and the circulating operation by the circulating unit when storing hot water in the hot water storage tank; an operation limiting unit that, when receiving power amount limiting information indicating a limit value of power consumption, controls the operation control unit to limit the power consumed in the heating operation and the circulation operation to the limit value indicated by the power amount limiting information or less, and causes the heating operation and the circulation operation to be performed; an outside air temperature sensor for detecting an outside air temperature; A hot water storage tank temperature sensor that detects the temperature of the hot water stored in the hot water storage tank; A hot water supply terminal that supplies the hot water stored in the hot water storage tank; a hot water supply control unit that stops hot water supply from the hot water supply end when the outdoor air temperature detected by the outdoor air temperature sensor is equal to or lower than a predetermined outdoor air temperature and the hot water temperature detected by the hot water storage tank temperature sensor is equal to or lower than a predetermined hot water temperature during the power amount limit time period indicated by the power amount limit information; A hot water system comprising:

2. The hot water storage tank temperature sensors are installed at regular intervals in the vertical direction of the hot water storage tank, and the hot water supply control unit stops hot water from being discharged from the hot water supply end when a predetermined number of the hot water storage tank temperature sensors among the multiple hot water storage tank temperature sensors detect that the temperature of the hot water is below the predetermined hot water temperature.The hot water supply system described in claim 1.

3. The hot water supply system of claim 1 or claim 2, wherein the hot water supply control unit stops hot water from being dispensed from the hot water supply end when, during the power consumption limit time period, the outside air temperature detected by the outside air temperature sensor is below the specified outside air temperature and the temperature of the hot water detected by the hot water storage tank temperature sensor is below 42 degrees.

4. The hot water supply system of claim 1 or claim 2, further comprising a remote controller that notifies a user that hot water supply from the hot water supply end will be stopped if, during the power consumption limit time period, the outside air temperature detected by the outside air temperature sensor is below the specified outside air temperature and the hot water temperature detected by the hot water storage tank temperature sensor is below the specified hot water temperature.

5. The hot water supply system of claim 1 or claim 2, wherein the operation control unit performs the heating operation and the circulation operation by storing a larger amount of hot water in the hot water storage tank before the power consumption limit time period begins than the amount of hot water that would be stored in the hot water storage tank if the power consumption limit information had not been received.

6. The hot water supply system of claim 1 or claim 2, wherein the operation control unit performs the heating operation and the circulation operation by lowering the temperature of the hot water stored in the hot water storage tank by the heating operation when the power amount limit information is received, lower than the temperature of the hot water stored in the hot water storage tank by the heating operation when the power amount limit information is not received.

7. a freeze prevention control unit that performs a freeze prevention operation to keep the water circuit warm using the hot water stored in the hot water storage tank when the outside air temperature detected by the outside air temperature sensor is equal to or lower than the predetermined outside air temperature; The hot water supply system of claim 6, wherein the operation control unit performs the heating operation and the circulation operation when the hot water does not contain the amount of heat required for the anti-freeze operation performed by the anti-freeze control unit during the power consumption limit time period.

8. The hot water supply system of claim 7, wherein the anti-freeze control unit controls the amount of hot water circulated through the water circuit by the circulation operation when the anti-freeze operation is performed during the power consumption limit time period to be less than the amount of hot water circulated through the water circuit by the circulation operation when the anti-freeze operation is performed outside the power consumption limit time period.

9. The hot water supply system of claim 1 or claim 2, wherein the operation control unit uses heat consumption information indicating the total amount of heat consumed by the hot water in one day within a specified period to perform the heating operation multiple times before the power restriction time period begins, and controls the amount of the hot water stored in the hot water storage tank.

10. The hot water supply system of claim 1 or claim 2, wherein the operation control unit uses the heat consumption information to control the amount of hot water stored in the hot water storage tank by the heating operation performed until the end of the power restriction time period.

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