Hot water production system

Abstract

To provide a hot water production system which can maintain appropriate heat supply to a load system while allowing effective execution of a reverse cycle defrost operation of an air heat source heat pump.SOLUTION: A hot water production system includes: a heating device 1 which is capable of executing a heating operation for heating service water Wa using an air heat source heat pump 10 and a reverse-cycle defrost operation for performing a defrost operation on a refrigerant evaporator 14; a specific service water passage having at least one of a first service water passage WR1 through which service water Wa sent from a first service water tank 21 to a second service water tank 22 flows through the heating device 1, and a second service water passage WR2 through which service water Wa in the second service water tank 22 is circulated so as to pass through the heating device 1; and a third service water passage WR3 through which service water Wa in the first service water tank 21 is circulated so as to pass through the heating device 1, wherein service water Wa is caused to flow through the third service water passage WR3 during execution of the reverse-cycle defrost operation.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hot water production system for heating water. [Background technology]

[0002] Conventionally, systems that heat water for use in load facilities within a business facility have used air-source heat pumps to heat water. Air-source heat pumps have a refrigerant evaporator that enables heating using the heat of the air, and are known as an excellent heating method that is highly energy efficient and can reduce carbon dioxide emissions.

[0003] However, when the air in an air-source heat pump's evaporator absorbs heat and cools below the dew point, the water vapor in the air condenses, causing condensation on the evaporator's heat transfer surface. When the outside air temperature is low and the condensed water cools below 0°C, the water freezes on the evaporator's heat transfer surface, causing frosting. The frost layer that grows on the evaporator's heat transfer surface increases thermal resistance and ventilation resistance, causing a decrease in the evaporator's heat transfer performance. For this reason, defrosting is required to remove the frost layer that forms on the evaporator, especially in winter when the outside air temperature is low.

[0004] Patent Document 1 mentions that a defrosting operation is performed in a hot water production system equipped with an air-source heat pump. Known defrosting operation types include the reverse cycle defrosting operation disclosed in Patent Document 2 and the hot gas bypass operation disclosed in Patent Document 3, as well as electric heater and hot water spray types. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2024-014372 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-152174 [Patent Document 3] Japanese Patent Application Laid-Open No. 2012-107836 Summary of the Invention [Problem to be solved by the invention]

[0006] In an air-source heat pump that performs reverse cycle defrosting, when the amount of frost is relatively small, it is possible to defrost the evaporator using only the heat of compression generated by the compressor. On the other hand, when the amount of frost is large, it is advantageous to use the heat absorbed from the condenser in addition to the heat of compression. For example, in a system that stores heated water in a hot water storage tank and supplies the high-temperature hot water in the hot water storage tank to a load facility, performing defrosting while circulating the high-temperature hot water in the hot water storage tank through the condenser as a heat source fluid can significantly reduce the time it takes to complete defrosting of the evaporator.

[0007] However, if such high-temperature hot water is used for defrosting, the stored heat temperature in the hot water tank will drop, making it difficult to maintain an appropriate heat supply to meet the temperature requirements of the load equipment.In view of the above problems, the present invention aims to provide a hot water production system that can effectively perform reverse cycle defrosting operation of an air-source heat pump while maintaining an appropriate heat supply to the load equipment. [Means for solving the problem]

[0008] The hot water production system of the present invention is a hot water production system that heats water used in load equipment within a business premises, and is equipped with a heating device that has an air-source heat pump with a refrigerant evaporator and is capable of performing a heating operation that heats water using the air-source heat pump and a reverse cycle defrost operation that defrosts the refrigerant evaporator, a first water tank that primarily stores water from a water supply source, a second water tank that secondary stores water from the first water tank, a specific water path that has at least one of a first water path that allows water sent from the first water tank to the second water tank to flow through the heating device and a second water path that circulates the water in the second water tank through the heating device, a third water path that circulates the water in the first water tank through the heating device, and a control means, wherein the control means is configured to circulate water through the third water path when the reverse cycle defrost operation is performed. According to this configuration, it is possible to effectively perform reverse cycle defrosting operation of the air-source heat pump while maintaining an appropriate heat supply to the load equipment.

[0009] More specifically, the above configuration includes a first heat accumulation correlation value detection means for detecting a first heat accumulation correlation value that correlates with the amount of heat accumulated in the water stored in the first water tank, and a second heat accumulation correlation value detection means for detecting a second heat accumulation correlation value that correlates with the amount of heat accumulated in the water stored in the second water tank, and the control means includes a first heating operation control section that causes water to flow through the specific water path and causes the heating device to perform the heating operation based on the second heat accumulation correlation value, and a control section that controls the heating device to perform the heating operation when the first heating operation is not being performed. The system may also include a second heating operation control unit that, based on the first heat storage correlation value, causes water to flow through the third water path and causes the heating device to perform a second heating operation in which the heating device performs the heating operation in this state; a defrost necessity determination unit that determines whether or not a defrosting operation is necessary while the first heating operation or the second heating operation is being performed; and a defrost operation control unit that, when it is determined by the defrost necessity determination unit that the defrosting operation is necessary, causes water to flow through the third water path and performs the reverse cycle defrosting operation.

[0010] More specifically, as the above configuration, if the second heating operation is being performed when the defrost necessity determination unit determines that the defrosting operation is necessary, the defrost operation control unit may be configured to circulate water through the third water path and perform the reverse cycle defrost operation after the second heating operation is completed.

[0011] More specifically, the above configuration may include an air temperature detection means for detecting the temperature of the heat source air before heat exchange in the refrigerant evaporator, and a refrigerant temperature detection means for detecting the temperature of the refrigerant after heat exchange in the refrigerant evaporator, and the defrost necessity determination unit may be configured to determine whether or not a defrosting operation is necessary based on the detected temperatures of the air temperature detection means and the refrigerant temperature detection means, respectively.

[0012] More specifically, the above configuration may be such that the first heat storage correlation value is at least one of the values ​​of the temperature, water level, and remaining hot water amount of the water in the first water tank, and the second heat storage correlation value is at least one of the values ​​of the temperature, water level, and remaining hot water amount of the water in the second water tank.

[0013] More specifically, the above configuration may be such that the specific water path has the first water path and the second water path, the air-source heat pump is configured by connecting a compressor, a four-way valve, a first heat dissipation heat exchanger, a second heat dissipation heat exchanger, an expansion valve, and the refrigerant evaporator in a ring, the first water path is arranged to cause water sent from the first water tank to the second water tank to flow through the second heat dissipation heat exchanger, the second water path is arranged to circulate the water in the second water tank to the first heat dissipation heat exchanger, and the third water path is arranged to circulate the water in the first water tank to the second heat dissipation heat exchanger.

[0014] More specifically, the specific water path has the first water path and the second water path, and the heating device includes the air-source heat pump that functions as a low-stage heat pump circuit configured by connecting a first compressor, a first four-way valve, a cascade heat exchanger, a first heat-radiating heat exchanger, a first expansion valve, and the refrigerant evaporator in a ring shape, and a second compressor, a second four-way valve, a second heat-radiating heat exchanger, a third heat-radiating heat exchanger, a second expansion valve, and the cascade heat exchanger in a ring shape. and a high-stage heat pump circuit configured as follows: the first water path is arranged to cause the water sent from the first water tank to the second water tank to flow through the first heat dissipation heat exchanger and the third heat dissipation heat exchanger; the second water path is arranged to circulate the water in the second water tank to the second heat dissipation heat exchanger; and the third water path is arranged to circulate the water in the first water tank to the first heat dissipation heat exchanger. [Effects of the Invention]

[0015] According to the hot water producing system of the present invention, it is possible to effectively perform reverse cycle defrosting operation of the air-source heat pump while maintaining an appropriate heat supply to the load equipment. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic configuration diagram of a hot water producing system according to a first embodiment. [Figure 2] FIG. 1 is a schematic diagram of an air-source heat pump. [Figure 3] FIG. 10 is a schematic configuration diagram of a hot water producing system according to a second embodiment. [Figure 4] FIG. 10 is a schematic configuration diagram of a hot water producing system according to a third embodiment. [Figure 5] FIG. 10 is a schematic configuration diagram of a hot water producing system according to a fourth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] Each embodiment of the present invention will be described below with reference to the drawings.

[0018] 1. First embodiment Fig. 1 is a schematic diagram of a hot water production system 100 according to a first embodiment. As shown in the figure, the hot water production system 100 includes a heating device 1 having an air-source heat pump 10, a first water tank 21, a second water tank 22, a first pump 31, a second pump 32, a first valve 41, a second valve 42, a temperature sensor 51, a water level sensor 52, and a control unit 9. The hot water production system 100 serves to heat water Wa to be used in load equipment X within a business premises. The load equipment X directly consumes the heated water Wa as cleaning water, etc.

[0019] In this context, establishments refer to individual locations where the production of goods or the provision of services is carried out as a business, such as factories, commercial facilities, medical institutions, welfare facilities, accommodation facilities, research facilities, etc. Water refers to water used in connection with the production of goods or the provision of services.

[0020] If the business establishment is a factory, the load equipment would be production equipment (equipment directly involved in the production of goods) such as food and beverage manufacturing plants, automobile, metal product, and machinery and equipment manufacturing plants. An example of load equipment other than factory production equipment is a steam boiler unit (heat source equipment involved in the operation of production equipment), in which case part of the heated water is used as boiler feed water.

[0021] As shown in Figure 1, the hot water production system 100 includes lines (paths for the water Wa): a first line L1 that circulates the water Wa from the water supply source Y to the first water tank 21; a second line L2 that circulates the water Wa from the second water tank 22 to the load equipment X; a third line L3 that circulates the water Wa from the first water tank 21 to the heating device 1; a fourth line L4 that circulates the water Wa from the heating device 1 to a predetermined position P1; a fifth line L5 that circulates the water Wa from the predetermined position P1 to the first water tank 21; and a sixth line L6 that circulates the water Wa from the predetermined position P1 to the second water tank 22.

[0022] The first pump 31 is disposed on the second line L2, and the second pump 32 is disposed on the third line L3. The first valve 41 is disposed on the sixth line L6, and the second valve 42 is disposed on the fifth line L5. The arrangement of the pumps and valves in the hot water production system 100 may be changed as appropriate without departing from the spirit of the present invention.

[0023] The first water tank 21 serves to temporarily store the water Wa from the water supply source Y. The first water tank 21 is provided with a temperature sensor 51 that continuously detects the temperature T1 of the water Wa in the first water tank 21 (the temperature of the stored water).

[0024] Note that the higher the temperature T1, the higher the amount of heat stored in the water Wa stored in the first water tank 21 (hereinafter, sometimes simply referred to as the "first heat storage amount HS1"). Therefore, the value of the temperature T1 can be seen as a type of first heat storage correlation value Z1 that correlates with the first heat storage amount HS1, and the temperature sensor 51 can be seen as a form of first heat storage correlation value detection means that detects the first heat storage correlation value Z1. Note that the first heat storage correlation value Z1 is not limited to the value of the temperature T1, and other examples of the first heat storage correlation value Z1 will be described later.

[0025] The first water tank 21 is provided with a water level sensor (not shown), and the first line L1 is provided with a make-up water valve (not shown). The make-up water valve opens when the water level sensor detects that the first water tank 21 is low in water, and closes when the first water tank 21 is detected to be full.

[0026] The second water tank 22 serves to secondarily store the water Wa from the first water tank 21. The second water tank 22 is provided with a water level sensor 52 that continuously detects the water level H2 (amount of stored hot water) of the water Wa in the second water tank 21.

[0027] Note that the higher the water level H2, the higher the amount of heat stored in the water Wa stored in the second water tank 22 (hereinafter, sometimes simply referred to as the "second heat storage amount HS2"). Therefore, the value of the water level H2 can be seen as a type of second heat storage correlation value Z2 that correlates with the second heat storage amount HS2, and the water level sensor 52 can be seen as a form of second heat storage correlation value detection means that detects the second heat storage correlation value Z2. Note that the second heat storage correlation value Z2 is not limited to the value of the water level H2, and other examples of the second heat storage correlation value Z2 will be described later. Information on the temperature T1 and water level H2 detected by each sensor 51, 52 is sent to the control unit 9.

[0028] The control unit 9 controls each part of the hot water production system 100 so that the system 100 operates appropriately. For example, the control unit 9 can drive the pumps 31 and 32 to circulate the water Wa in the direction shown by the colored arrows in Fig. 1. The control unit 9 can also switch the valves 41 and 42 between a conductive state (a state in which the water Wa is conducted) and a non-conductive state (a state in which the water Wa is not conducted).

[0029] The series of lines consisting of the third line L3, the fourth line L4, and the sixth line L6 can be seen as a first water path WR1 (a form of a specific water path, a path for heating the water Wa in one pass) that allows the water Wa sent from the first water tank 21 to the second water tank 22 to flow through the heating device 1. The specific water path is a path for the water Wa that is used mainly to increase the heat storage capacity (amount of stored hot water) of the water Wa in the second water tank 22. The series of lines consisting of the third line L3, the fourth line L4, and the fifth line L5 can be seen as a third water path WR3 that circulates the water Wa in the first water tank 21 through the heating device 1. The third water path WR3 is a path for the water Wa that is used mainly to increase the heat storage capacity (temperature of the stored water) of the water Wa in the first water tank 21.

[0030] Figure 2 is a schematic diagram of an air-source heat pump 10. As shown in the figure, the air-source heat pump 10 includes a compressor 11, a condenser 12, an expansion valve 13, an evaporator 14 (refrigerant evaporator), and a four-way valve 15, which are connected by a refrigerant circulation line Lc. A refrigerant R can be circulated through the refrigerant circulation line Lc.

[0031] The compressor 11 has a motor as a drive source, and compresses the refrigerant R received from the upstream side to produce high-temperature, high-pressure refrigerant R, which is then sent downstream. The rotation speed of the compressor 11 can be controlled by the control unit 9.

[0032] The condenser 12 functions as a heat dissipation heat exchanger, and exchanges heat between the water Wa sent through the water input line (third line L3 in the example shown in FIG. 1) of the heating device 1 and the refrigerant R sent from the compressor 11, thereby condensing the refrigerant R. The water Wa (heated water Wa) that has undergone heat exchange in the condenser 12 is sent out through the water output line (fourth line L4 in the example shown in FIG. 1) of the heating device 1.

[0033] The expansion valve 13 passes the refrigerant R sent from the condenser 12, thereby reducing the pressure and temperature of the refrigerant R. The evaporator 14 functions as an endothermic heat exchanger, exchanging heat between the heat source air Ar (outside air) and the refrigerant R sent from the expansion valve 13, and evaporating the refrigerant R by absorbing heat from the heat source air Ar.

[0034] The evaporator 14 in this embodiment is, for example, a fin-tube heat exchanger, and is configured to use a blower fan 14a to continuously send heat-source air Ar to a number of fins provided on the surface of a heat transfer tube (part of the refrigerant circulation line Lc) through which the refrigerant R passes. In addition, a refrigerant temperature sensor 14x (a form of refrigerant temperature detection means) that detects the temperature of the refrigerant R after heat exchange in the evaporator 14 is provided near the outlet of the heat transfer tube in the evaporator 14 through which the refrigerant R passes, and an air temperature sensor 14y (a form of air temperature detection means) that detects the temperature of the heat-source air Ar before heat exchange in the evaporator 14 is provided near the upstream side of the fin.

[0035] 2, four-way valve 15 has connection points a to d to which ends of refrigerant circulation line Lc are connected. Refrigerant circulation line Lc extending from connection point b is connected to connection point d via condenser 12, expansion valve 13, and evaporator 14 in this order. On the other hand, refrigerant circulation line Lc extending from connection point c is connected to connection point a via compressor 11.

[0036] Four-way valve 15 is configured to be switchable between a first state in which connection point a is connected to connection point b and connection point c is connected to connection point d, and a second state in which connection point a is connected to connection point d and connection point b is connected to connection point c. Switching of four-way valve 15 between the first state and the second state is controlled by control unit 9.

[0037] The heating device 1 may have multiple air-source heat pumps 10, or may further have heating means other than the air-source heat pumps 10. The heating device 1 may also be configured to heat the water Wa using a separately provided intermediate heat exchanger, instead of using the condenser 12 to heat the water Wa. In this case, for example, the condenser 12 and the intermediate heat exchanger may be connected by a circulation line for an intermediate medium (water), and heat may be exchanged between the water Wa and the intermediate medium while circulating the intermediate medium.

[0038] The heating device 1 is capable of performing a heating operation in which the service water Wa is heated using the air-source heat pump 10, and a defrosting operation (reverse cycle defrosting operation) in which the evaporator 14 is defrosted. The heating operation can be performed with the four-way valve 15 in a first state, and the defrosting operation can be performed with the four-way valve 15 in a second state.

[0039] That is, when the four-way valve 15 is in the first state, the refrigerant R circulates in the direction shown by the solid arrow in Fig. 2. At this time, the refrigerant R absorbs heat from the heat-source air Ar in the evaporator 14 and vaporizes, while the refrigerant R releases heat to the water Wa and condenses in the condenser 12. This achieves a heating operation in which the water Wa is heated using the air-source heat pump 10.

[0040] On the other hand, when the four-way valve 15 is in the second state, the refrigerant R circulates in the direction indicated by the dotted arrow in Fig. 2. As a result, the refrigerant R flows in the reverse direction, and the frost adhering to the evaporator 14 is melted by the heat generated by the refrigerant R, thereby realizing a reverse cycle defrosting operation.

[0041] The control unit 9 includes a first heating operation control unit 91 a, a second heating operation control unit 91 b, a defrost necessity determination unit 92, and a defrost operation control unit 93.

[0042] The first heating operation control unit 91a executes the first heating operation (an operation in which the water Wa is circulated through the first water path WR1, which is a specific water path, and the heating device 1 performs a heating operation) based on the second heat accumulation correlation value Z2. In this embodiment, the first heating operation control unit 91a starts the first heating operation when the second heat accumulation correlation value Z2 falls to a predetermined lower threshold PL2. Note that, to start the first heating operation, the heating device 1 may perform the heating operation, and the second pump 32 may be driven with the first valve 41 in a conductive state and the second valve 42 in a non-conductive state, for example, to circulate the water Wa through the first water path WR1.

[0043] On the other hand, the first heating operation control unit 91a terminates the first heating operation when the second heat accumulation correlation value Z2 reaches a predetermined upper threshold value PH2 (>lower threshold value PL2). The first heating operation can be terminated by at least one of stopping the heating operation and stopping the flow of the water Wa through the first water path WR1. This allows the heating operation to be performed so that the second heat accumulation correlation value Z basically falls within the range from the lower threshold value PL2 to the upper threshold value PH2, and the second amount of stored heat HS2 is appropriately maintained.

[0044] The second heating operation control unit 91b executes the second heating operation (an operation in which the water Wa is circulated through the third water path WR3 and the heating device 1 performs a heating operation) based on the first heat accumulation correlation value Z1 while the first heating operation is not being performed. In this embodiment, the second heating operation control unit 91b starts the second heating operation when the first heat accumulation correlation value Z1 falls to a predetermined lower threshold value PL1. Note that, to start the second heating operation, the heating device 1 may be caused to perform the heating operation, and the second pump 32 may be driven with the first valve 41 in a non-conductive state and the second valve 42 in a conductive state, for example, to circulate the water Wa through the third water path WR3.

[0045] On the other hand, the second heating operation control unit 91b terminates the second heating operation when the first heat accumulation correlation value Z1 reaches a predetermined upper threshold value PH1 (>lower threshold value PL1). The second heating operation can be terminated by performing at least one of the following: stopping the heating operation and stopping the flow of the water Wa through the third water path WR3. This allows the heating operation to be performed so that the first heat accumulation correlation value Z1 basically falls within the range from the lower threshold value PL1 to the upper threshold value PH1, thereby appropriately maintaining the first amount of heat accumulation HS1. As described above, in this embodiment, the first heating operation and the second heating operation are performed, making it possible to appropriately maintain both the first amount of heat accumulation HS1 and the second amount of heat accumulation HS2.

[0046] The defrost necessity determination unit 92 determines whether a defrosting operation is required for the evaporator 14 during the heating operation. In this embodiment, the defrost necessity determination unit 92 determines whether a defrosting operation is required based on the detected temperatures of the air temperature sensor 14y (air temperature detection means) and the refrigerant temperature sensor 14x (refrigerant temperature detection means). More specifically, the defrost necessity determination unit 22 determines that a defrosting operation is required when the difference ΔT between the detected temperatures of the air temperature sensor 14y and the refrigerant temperature sensor 14x exceeds a specified value Ts.

[0047] As the frost layer grows on the heat transfer surface of the evaporator 14, thermal resistance and ventilation resistance increase, and the difference ΔT between the temperature detected by the air temperature sensor 14y and the temperature detected by the refrigerant temperature sensor 14x becomes larger. Therefore, when the difference ΔT exceeds the specified value Ts, it is possible to determine that a defrosting operation for the evaporator 14 is necessary. The specific value of the specified value Ts may be set appropriately in advance so that the need for a defrosting operation can be appropriately determined. For example, when it is desired to determine whether a defrosting operation is necessary when frost on the heat transfer surface is in the early stages of growth, the specified value Ts is set to a relatively small value, and when it is desired to determine whether a defrosting operation is necessary when frost is in the advanced growth stage, the specified value Ts is set to a relatively large value.

[0048] In this embodiment, as described above, the necessity of a defrosting operation is determined based on the temperatures detected by the air temperature sensor 14y and the refrigerant temperature sensor 14x, and therefore, it is possible to very accurately determine whether a defrosting operation is required. However, the method for determining whether a defrosting operation is required is not limited to the method described above, and various methods, including well-known methods, may be used, for example, a method for determining whether a defrosting operation is required based on the temperature detected by only one of the air temperature sensor 14y and the refrigerant temperature sensor 14x.

[0049] When the defrost necessity determination unit 92 determines that a defrosting operation is necessary, the defrost operation control unit 93 causes the water Wa to flow through the third water path WR3 and executes the defrost operation (reverse cycle defrost operation) described above. The control of the pumps and valves when causing the water Wa to flow through the third water path WR3 may be the same as in the case of the second heating operation, for example.

[0050] This allows high-temperature water Wa (water Wa in the first water tank 21 where an appropriate amount of heat has been stored by the second heating operation) to flow through the condenser 12 when performing reverse cycle defrosting operation, and the heat of this water Wa can be used to effectively perform reverse cycle defrosting operation, thereby also shortening the time required to complete defrosting.

[0051] Furthermore, since the second heat storage capacity HS2 is basically unaffected at this time, an appropriate heat supply is maintained by supplying the service water Wa from the second service water tank 22 to the load equipment X. If the second heating operation is being performed when the defrost necessity determination unit 92 determines that a defrosting operation is necessary, the defrost operation control unit 93 causes the service water Wa to flow through the third service water path WR3 and performs a defrost operation after the second heating operation is completed. This makes it possible to perform the defrost operation with a sufficient first heat storage capacity HS1.

[0052] In the hot water production system 100, in summer and intermediate seasons when defrosting is not required, the first water tank 21 can be used as a spare heat storage tank to increase the heat storage capacity of the entire system. Therefore, even if the heat demand in the load equipment X suddenly increases, the heat supply can quickly follow up.

[0053] Furthermore, although the value of the temperature T1 described above is used as the first heat storage correlation value Z1 in this embodiment, it is also possible to use another value correlated with the first heat storage quantity HS1 as the first heat storage correlation value Z1. For example, if a sealed tank is used as the first water tank 21, the greater the remaining hot water quantity associated with the temperature stratification of the water Wa formed in the first water tank 21, the higher the first heat storage quantity HS1 becomes. Therefore, the value of this remaining hot water quantity may be used as the first heat storage correlation value Z1. In this case, a group of temperature sensors may be provided to detect the remaining hot water quantity WV associated with the temperature stratification of the water Wa formed in the first water tank 21 (sealed tank), and the detection information of the remaining hot water quantity WV detected by the group of temperature sensors may be continuously sent to the control unit 9. The group of temperature sensors may be a plurality of temperature sensors arranged in a vertical direction (the direction in which temperature stratification is formed) in the first water tank 21. The group of temperature sensors can be seen as one form of first heat accumulation correlation value detection means for detecting the first heat accumulation correlation value Z1.

[0054] As described above, the first heat accumulation correlation value Z1 can be either the temperature of the water Wa or the amount of remaining hot water in the first water tank 21. Furthermore, if the first water tank 21 is an open tank, the amount of heat calculated using the temperature and water level (amount of stored water) of the water Wa may be used as the first heat accumulation correlation value Z1, and the second heating operation may be performed based on this first heat accumulation correlation value Z1 (for example, based on the average value of these first heat accumulation correlation values ​​Z1).

[0055] Furthermore, although the above-described value of temperature T2 is used as the second heat storage correlation value Z2 in this embodiment, another value correlated with the second heat storage quantity HS2 may also be used as the second heat storage correlation value Z2. For example, if a sealed tank is used as the second water tank 22, the larger the remaining hot water quantity associated with the temperature stratification of the water Wa formed in the second water tank 22, the higher the second heat storage quantity HS2. Therefore, the value of this remaining hot water quantity may be used as the second heat storage correlation value Z2. In this case, a group of temperature sensors may be provided to detect the remaining hot water quantity WV associated with the temperature stratification of the water Wa formed in the second water tank 22 (sealed tank), and the detection information of the remaining hot water quantity WV by the group of temperature sensors may be continuously sent to the control unit 9. The group of temperature sensors may be a plurality of temperature sensors arranged in a vertical direction (the direction in which temperature stratification is formed) in the second water tank 22. The group of temperature sensors can be seen as one form of second heat accumulation correlation value detection means for detecting the second heat accumulation correlation value Z2.

[0056] As described above, the second heat accumulation correlation value Z2 can be either the water level or the remaining amount of hot water in the second water tank 22. Furthermore, if the second water tank 22 is an open tank, the amount of heat calculated using the temperature and water level (amount of stored water) of the water Wa may be used as the second heat accumulation correlation value Z2, and the first heating operation may be performed based on this second heat accumulation correlation value Z2 (for example, based on the average value of these second heat accumulation correlation values ​​Z2).

[0057] 2. Second embodiment Next, a second embodiment will be described. In the following description, emphasis will be placed on the differences from the first embodiment, and descriptions of the commonalities with the first embodiment may be omitted.

[0058] 3 is a schematic configuration diagram of a hot water producing system 100 according to the second embodiment. As shown in the figure, the hot water producing system 100 of the second embodiment includes third to fifth pumps 33-35, third to sixth valves 43-46, and eleventh to seventeenth lines L11-L17, instead of the second pump 32, first valve 41, second valve 42, and third to sixth lines L3-L6 of the first embodiment. In addition, the second water tank 22 is provided with a water level sensor 52 and a temperature sensor 53 that continuously detects the temperature T2 of the water Wa in the second water tank 22 (the temperature of the stored water).

[0059] The eleventh line L11 is a line that distributes the water Wa from the first water tank 21 to the predetermined position P2 via the third pump 33 and the third valve 43. The twelfth line L12 is a line that distributes the water Wa from the second water tank 22 to the predetermined position P2 via the fourth pump 34 and the fourth valve 44. The thirteenth line L13 is a line that distributes the water Wa from the predetermined position P2 to the heating device 1. The fourteenth line L14 is a line that distributes the water Wa from the heating device 1 to the predetermined position P3.

[0060] The fifteenth line L15 is a line that distributes the water Wa from the predetermined position P3 to the first water tank 21 via the fifth valve 45. The sixteenth line L16 is a line that distributes the water Wa from the predetermined position P3 to the second water tank 22 via the sixth valve 46. The seventeenth line L17 is a line that distributes the water Wa from the first water tank 21 to the second water tank 22 via the fifth pump 35. The fifth pump 35 is driven when the water level sensor 52 detects a decrease in the water level in the second water tank 22, and is stopped when the second water tank 22 is detected to be full.

[0061] The control unit 9 controls each part of the hot water production system 100 so that the system 100 operates appropriately. For example, the control unit 9 can drive each of the pumps 33-35 to circulate the water Wa in the direction indicated by the colored arrows in Fig. 3. The control unit 9 can also switch each of the valves 43-46 between a conductive state and a non-conductive state.

[0062] A series of lines consisting of the twelfth line L12, the thirteenth line L13, the fourteenth line L14, and the sixteenth line L16 can be seen as a second water route WR2 (one form of a specific water route, a route for circulating and heating the water Wa) that circulates the water Wa in the second water tank 22 through the heating device 1. In addition, a series of lines consisting of the eleventh line L11, the thirteenth line L13, the fourteenth line L14, and the fifteenth line L15 can be seen as a third water route WR3 that circulates the water Wa in the first water tank 21 through the heating device 1.

[0063] As described above, in the second embodiment, the second water path WR2 is formed as the specific water path instead of the first water path WR1. Furthermore, the first heating operation in the second embodiment is an operation in which the water Wa is circulated through the second water path WR2, which is the specific water path, and the heating device 1 performs heating operation.

[0064] The first heating operation control unit 91a executes the first heating operation based on the second heat accumulation correlation value Z2, as in the first embodiment. However, the second heat accumulation correlation value Z2 in the second embodiment is set to the temperature T2 instead of the water level H2. To start the first heating operation, the heating device 1 is caused to perform a heating operation, and, for example, the fourth and sixth valves 44, 46 are set to a conductive state and the third and fifth valves 43, 45 are set to a non-conductive state, the fourth pump 34 is driven, and the water Wa is circulated through the second water path WR2. To end the first heating operation, at least one of stopping the heating operation and stopping the flow of the water Wa through the second water path WR2 is performed.

[0065] The second heating operation control unit 91b executes the second heating operation (an operation in which the heating device 1 performs a heating operation while circulating the water Wa through the third water path WR3) based on the first heat accumulation correlation value Z1, as in the first embodiment, while the first heating operation is not being performed. To start the second heating operation, the heating device 1 performs the heating operation, and, for example, the fourth and sixth valves 44, 46 are set to a non-conductive state and the third and fifth valves 43, 45 are set to a conductive state, thereby driving the third pump 33 and circulating the water Wa through the third water path WR3. To end the second heating operation, at least one of stopping the heating operation and stopping the flow of the water Wa through the third water path WR3 is performed.

[0066] Also in the second embodiment, when the defrost necessity determination unit 92 determines that a defrosting operation is necessary, the defrost operation control unit 93 causes the water Wa to flow through the third water path WR3 and executes the reverse cycle defrost operation. The control of the pumps and valves when causing the water Wa to flow through the third water path WR3 may be the same as in the case of the second heating operation, for example.

[0067] When the second water tank 22 is an open tank, the amount of heat calculated using the temperature T2 and water level H1 (storage amount) of the water Wa may be used as the second heat accumulation correlation value Z2.

[0068] 3. Third embodiment Next, a third embodiment will be described. In the following description, the emphasis will be placed on the differences from the first embodiment, and the description of the commonalities with the first embodiment may be omitted.

[0069] 4 is a schematic configuration diagram of a hot water producing system 100 according to a third embodiment. As shown in the figure, the hot water producing system 100 of the third embodiment includes sixth and seventh pumps 36 and 37, a seventh valve 47, a first three-way valve 61, and 21st to 24th lines L21 to L24, instead of the second pump 32, first valve 41, second valve 42, and third to sixth lines L3 to L6 of the first embodiment. In addition, the second water tank 22 is provided with a water level sensor 52 and a temperature sensor 53 that continuously detects the temperature T2 of the water Wa in the second water tank 22 (the temperature of the stored water).

[0070] The air-source heat pump 10 of the third embodiment includes a first heat radiation heat exchanger 12a and a second heat radiation heat exchanger 12b instead of the condenser 12 of the first embodiment. The air-source heat pump 10 is configured by connecting a compressor 11, a four-way valve 15, the first heat radiation heat exchanger 12a, the second heat radiation heat exchanger 12b, an expansion valve 13, and an evaporator 14 in a ring shape.

[0071] The 21st line L21 is a line that distributes the water Wa from the first water tank 21 to the first three-way valve 61, successively via the sixth pump 36, the seventh valve 47, and the second heat dissipation heat exchanger 12b. The 22nd line L22 is a line that distributes the water Wa from the first three-way valve 61 to the first water tank 21. The 23rd line L23 is a line that distributes the water Wa from the first three-way valve 61 to the second water tank 22. The 24th line L24 is a line that distributes the water Wa from the second water tank 22 to the second water tank 22, successively via the seventh pump 36 and the first heat dissipation heat exchanger 12a.

[0072] The control unit 9 controls each part of the hot water production system 100 so that the system 100 operates appropriately. For example, the control unit 9 can drive the pumps 36, 37 to circulate the water Wa in the direction indicated by the colored arrows in Fig. 4. The control unit 9 can also switch the seventh valve 47 between a conductive state and a non-conductive state, and can switch the conductive state of the water Wa in the first three-way valve 61 (such as the direction in which the water Wa is conducted).

[0073] The series of lines consisting of the 21st line L21 and the 23rd line L23 can be seen as a first water path WR1 (one form of a specific water path) that causes the water Wa sent from the first water tank 21 to the second water tank 22 to flow through the heating device 1. The 24th line L24 can be seen as a second water path WR2 (one form of a specific water path) that circulates the water Wa in the second water tank 22 so that it passes through the heating device 1. In addition, the series of lines consisting of the 21st line L21 and the 22nd line L22 can be seen as a third water path WR3 that circulates the water Wa in the first water tank 21 so that it passes through the heating device 1.

[0074] As described above, in the third embodiment, the first water path WR1 and the second water path WR2 are formed as specific water paths. In addition, the first heating operation in the third embodiment is an operation in which the water Wa is circulated through both the first water path WR1 and the second water path WR2 and the heating device 1 performs heating operation.

[0075] The first heating operation control unit 91a executes the first heating operation based on the second heat storage correlation value Z2, as in the first embodiment. The first heating operation via the first water path WR1 (second heat dissipation heat exchanger 12b) uses the water level H2 as the second heat storage correlation value Z2. To start this first heating operation, the heating device 1 performs a heating operation, and, for example, the seventh valve 47 is placed in a conducting state, and the first three-way valve 61 is controlled to conduct the water Wa from the 21st line L21 to the 23rd line L23, thereby driving the sixth pump 36 and circulating the water Wa through the first water path WR1. The first heating operation via the second water path WR2 (first heat dissipation heat exchanger 12a) uses the temperature T2 as the second heat storage correlation value Z2. To start the first heating operation, the heating device 1 is caused to perform a heating operation, and the seventh pump 37 is driven, for example, to circulate the water Wa through the second water path WR2. To end the first heating operation, at least one of the following controls is performed: stopping the heating operation and stopping the flow of the water Wa through the first water path WR1 and the second water path WR2.

[0076] In the first heating operation, the second heat dissipation heat exchanger 12b heats the water Wa being replenished to the second water tank 22, while the first heat dissipation heat exchanger 12a heats the water Wa stored in the second water tank 22. This two-stage heat dissipation increases the degree of subcooling of the refrigerant R, thereby increasing the amount of heat absorbed from the heat source air Ar and improving the COP.

[0077] The second heating operation control unit 91b executes the second heating operation (an operation in which the heating device 1 performs a heating operation while circulating the water Wa through the third water path WR3) based on the first heat accumulation correlation value Z1, as in the first embodiment, while the first heating operation is not being performed. To start the second heating operation, the heating device 1 performs the heating operation, and, for example, the seventh valve 47 is placed in a conducting state, and the first three-way valve 61 is controlled to conduct the water Wa from the 21st line L21 to the 22nd line L22, thereby driving the sixth pump 36 and circulating the water Wa through the third water path WR3. To end the second heating operation, at least one of stopping the heating operation and stopping the flow of the water Wa through the third water path WR3 is performed.

[0078] In the second heating operation, the second heat dissipation heat exchanger 12b heats the water Wa stored in the first water tank 21. Even when the heat demand is low, heat is stored in the first water tank 21, so the operating time of the air-source heat pump 10 can be extended, thereby shortening the depreciation period of the equipment.

[0079] Also in the third embodiment, when the defrost necessity determination unit 92 determines that a defrosting operation is necessary, the defrost operation control unit 93 causes the water Wa to flow through the third water path WR3 and executes the reverse cycle defrost operation. The control of the pump, valves, and three-way valve when causing the water Wa to flow through the third water path WR3 may be the same as in the case of the second heating operation, for example.

[0080] In the defrosting operation, the second heat dissipation heat exchanger 12b absorbs heat from the high-temperature water Wa in the first water tank 21, while the refrigerant evaporator 14 (heat absorption heat exchanger) dissipates heat to melt the frost layer. This increases the temperature of the refrigerant R (hot gas), shortens the defrosting time, and allows the heat supply to be resumed promptly.

[0081] 4. Fourth embodiment Next, a fourth embodiment will be described. In the following description, the emphasis will be placed on the differences from the first embodiment, and the description of the commonalities with the first embodiment may be omitted.

[0082] 5 is a schematic configuration diagram of a hot water producing system 100 according to a fourth embodiment. As shown in the figure, the hot water producing system 100 of the fourth embodiment includes eighth and ninth pumps 38, 39, an eighth valve 48, a second three-way valve 62, and 31st to 34th lines L31-L34, instead of the second pump 32, first valve 41, second valve 42, and 3rd to 6th lines L3-L6 of the first embodiment. In addition to the water level sensor 52, the second water tank 22 is provided with a temperature sensor 53 that continuously detects the temperature T2 of the water Wa in the second water tank 22 (the temperature of the stored water).

[0083] The air-source heat pump 10 (low-stage heat pump circuit) of the fourth embodiment includes a cascade heat exchanger 12x and a first heat-dissipation heat exchanger 12a instead of the condenser 12 in the first embodiment. The air-source heat pump 10 is configured by connecting a compressor 11, a four-way valve 15, the cascade heat exchanger 12x, the first heat-dissipation heat exchanger 12a, an expansion valve 13, and an evaporator 14 in a ring shape.

[0084] Furthermore, the heating device 1 includes a high-stage heat pump circuit 10x in addition to the air-source heat pump 10. The high-stage heat pump circuit 10x is basically the same configuration as the air-source heat pump 10 in the first embodiment, except that a cascade heat exchanger 12x is provided instead of the evaporator 14, and that a second heat radiation heat exchanger 12b and a third heat radiation heat exchanger 12c are provided instead of the condenser 12. As described above, the heating device 1 of the fourth embodiment forms a dual heat pump cycle consisting of a low-stage heat pump circuit and a high-stage heat pump circuit.

[0085] The high-stage heat pump circuit 10x is provided with a second compressor 11x, a second expansion valve 13x, and a second four-way valve 15x, which correspond to the compressor 11 (first compressor), expansion valve 13 (first expansion valve), and four-way valve 15 (first four-way valve) of the air-source heat pump 10. The high-stage heat pump circuit 10x is configured by connecting the second compressor 11x, the second four-way valve 15x, the second heat-dissipation heat exchanger 12b, the third heat-dissipation heat exchanger 12c, the second expansion valve 13x, and the cascade heat exchanger 12x in a ring shape. The cascade heat exchanger 12x serves to transfer heat from the refrigerant R on the air-source heat pump 10 (low-stage heat pump circuit) side to the refrigerant R on the high-stage heat pump circuit 10x side.

[0086] The 31st line L31 is a line that distributes the water Wa from the first water tank 21 to the second three-way valve 62, successively via the eighth pump 38, the eighth valve 48, and the first heat dissipation heat exchanger 12a. The 32nd line L32 is a line that distributes the water Wa from the second three-way valve 62 to the first water tank 21. The 33rd line L33 is a line that distributes the water Wa from the second three-way valve 62 to the second water tank 22, successively via the third heat dissipation heat exchanger 12c. The 34th line L34 is a line that distributes the water Wa from the second water tank 22 to the second water tank 22, successively via the ninth pump 39 and the second heat dissipation heat exchanger 12b.

[0087] The control unit 9 controls each unit of the hot water production system 100 so that the system 100 operates appropriately. For example, the control unit 9 can drive the pumps 38, 39 to circulate the water Wa in the direction indicated by the colored arrows in Fig. 5. The control unit 9 can also switch the eighth valve 48 between a conductive state and a non-conductive state, and can switch the conductive state of the water Wa in the second three-way valve 62 (e.g., the direction in which the water Wa is conducted).

[0088] A series of lines consisting of the 31st line L31 and the 33rd line L33 can be seen as a first water path WR1 (one form of a specific water path) that causes the water Wa sent from the first water tank 21 to the second water tank 22 to flow through the heating device 1. The 34th line L34 can be seen as a second water path WR2 (one form of a specific water path) that circulates the water Wa in the second water tank 22 so that it passes through the heating device 1. In addition, a series of lines consisting of the 31st line L31 and the 32nd line L32 can be seen as a third water path WR3 that circulates the water Wa in the first water tank 21 so that it passes through the heating device 1.

[0089] As described above, in the fourth embodiment, the first water path WR1 and the second water path WR2 are formed as specific water paths. In addition, the first heating operation in the fourth embodiment is an operation in which the water Wa is circulated through both the first water path WR1 and the second water path WR2 and the heating device 1 performs heating operation.

[0090] The first heating operation control unit 91a executes the first heating operation based on the second heat storage correlation value Z2, as in the first embodiment. The first heating operation via the first water path WR1 (the first heat dissipation heat exchanger 12a and the third heat dissipation heat exchanger 12c) uses the water level H2 as the second heat storage correlation value Z2. To start this first heating operation, the heating device 1 performs a heating operation, and, for example, the eighth valve 48 is placed in a conducting state, and the second three-way valve 62 is controlled to conduct the water Wa from the 31st line L31 to the 33rd line L33, thereby driving the eighth pump 38 and circulating the water Wa through the first water path WR1. The first heating operation via the second water path WR2 (the second heat dissipation heat exchanger 12b) uses the temperature T2 as the second heat storage correlation value Z2. To start the first heating operation, the heating device 1 is caused to perform a heating operation, and the ninth pump 39 is driven, for example, to circulate the water Wa through the second water path WR2. To end the first heating operation, at least one of the following controls may be performed: stopping the heating operation and stopping the flow of the water Wa through the first water path WR1 and the second water path WR2.

[0091] In the first heating operation, the first heat dissipation heat exchanger 12a and the third heat dissipation heat exchanger 12c heat the water Wa being replenished to the second water tank 22, while the second heat dissipation heat exchanger 12b heats the water Wa stored in the second water tank 22. This two-stage heat dissipation by the low-stage heat pump circuit 10 and the high-stage heat pump circuit 10x increases the degree of subcooling of the refrigerant R, thereby increasing the amount of heat absorbed from the heat source air Ar and improving the COP.

[0092] The second heating operation control unit 91b executes the second heating operation (an operation in which the heating device 1 performs a heating operation while circulating the water Wa through the third water path WR3) based on the first heat accumulation correlation value Z1, as in the first embodiment, when the first heating operation is not being performed. To start the second heating operation, the heating device 1 performs the heating operation, and, for example, the eighth valve 47 is placed in a conducting state, and the second three-way valve 62 is controlled to conduct the water Wa from the 31st line L31 to the 32nd line L32, thereby driving the eighth pump 36 and circulating the water Wa through the third water path WR3. During the second heating operation, the second compressor 11x of the high-stage heat pump circuit 10x is stopped. To end the second heating operation, at least one of stopping the heating operation and stopping the flow of the water Wa through the third water path WR3 is performed.

[0093] In the second heating operation, the first heat dissipation heat exchanger 12a heats the water Wa stored in the first water tank 21. Even when the heat demand is low, heat is stored in the first water tank 21, so that the operating time of the heating device 1 can be extended and the depreciation period of the equipment can be shortened.

[0094] Also in the fourth embodiment, when the defrost necessity determination unit 92 determines that a defrosting operation is necessary, the defrost operation control unit 93 circulates the service water Wa through the third service water path WR3 and executes the reverse cycle defrost operation. The control of the pump, valves, and three-way valve when circulating the service water Wa through the third service water path WR3 may be the same as in the second heating operation, for example. When the defrost operation is executed, the second compressor 11x of the high-stage heat pump circuit 10x is stopped.

[0095] In the defrosting operation, the first heat dissipation heat exchanger 12a absorbs heat from the high-temperature water Wa in the first water tank 21, while the evaporator 14 (heat absorption heat exchanger) dissipates heat to melt the frost layer. This increases the temperature of the refrigerant R (hot gas), shortens the defrosting time, and allows the heat supply to be resumed promptly.

[0096] 5. Summary Although the embodiments of the present invention have been described above, the above embodiments are illustrative in all respects and should not be considered limiting. The technical scope of the present invention is defined by the claims, not by the description of the above embodiments, and should be understood to include all modifications that fall within the meaning and scope of the claims.

[0097] <Contribution to the United Nations-led Sustainable Development Goals (SDGs)> The hot water production system disclosed herein uses an air-source heat pump that heats water using electricity and does not use fossil fuels. Therefore, by promoting the reduction of carbon dioxide emissions, it can contribute to the achievement of Goal 13 of the Sustainable Development Goals (SDGs), "Take urgent action to combat climate change." [Industrial Applicability]

[0098] The present invention can be used in a hot water production system for heating water. [Explanation of symbols]

[0099] 1 Heating device 10. Air Source Heat Pump 10x high-stage heat pump circuit 11 Compressor 11x Second compressor 12 Condenser 12a 1st heat radiation heat exchanger 12b 2nd heat exchanger for heat radiation 12c 3rd heat exchanger for heat radiation 12x cascade heat exchangers 13 Expansion valve 13x Second Expansion Valve 14 Evaporator (refrigerant evaporator) 14x refrigerant temperature sensors 14y Air Temperature Sensor 15 Four-way valve 15x 2nd 4-way valve 21 First Water Tank 22 Second Water Tank 31~39 Pumps 1~9 41~48 1st to 8th valves 51 First temperature sensor 52 Second temperature sensor 61 First three-way valve 62 Second three-way valve 9 Control Unit 91a First heating operation control section 91b Second heating operation control section 92 Defrosting necessity judgment unit 93 Defrost operation control unit 93 100 Hot water production system L1~L34 1st~34th lines Lc refrigerant circulation line R refrigerant Wa water WR1 First Irrigation Route WR2 Second Irrigation Route WR3 Third Irrigation Route X load equipment Y Water source

Claims

1. A hot water production system that heats water used in load equipment within a business establishment, a heating device having an air-source heat pump with a refrigerant evaporator, and capable of performing a heating operation for heating water using the air-source heat pump and a reverse cycle defrost operation for defrosting the refrigerant evaporator; a first water tank for temporarily storing water from the water supply source; a second water tank for secondary storage of water from the first water tank; a specific water path having at least one of a first water path that causes the water sent from the first water tank to the second water tank to flow through the heating device and a second water path that circulates the water in the second water tank so that it passes through the heating device; a third water passage for circulating the water in the first water tank through the heating device; a control means; The control means controls the hot water production system to circulate water through the third water path when the reverse cycle defrosting operation is performed.

2. a first heat accumulation correlation value detection means for detecting a first heat accumulation correlation value that correlates with the amount of heat accumulated in the water stored in the first water tank; a second heat accumulation correlation value detection means for detecting a second heat accumulation correlation value that correlates with the amount of heat accumulated in the water stored in the second water tank, The control means a first heating operation control unit that causes the heating device to perform the heating operation while circulating water through the specific water path based on the second heat accumulation correlation value; and a second heating operation control unit that, when the first heating operation is not being performed, causes water to flow through the third water path and causes the heating device to perform the heating operation based on the first heat accumulation correlation value; and a defrost necessity determination unit that determines whether the defrosting operation is necessary during execution of the first heating operation or the second heating operation; 2. The hot water production system according to claim 1, further comprising: a defrost operation control unit that, when the defrost necessity determination unit determines that the defrosting operation is necessary, causes water to flow through the third water path and executes the reverse cycle defrost operation.

3. The defrost operation control unit is A hot water production system as described in claim 2, wherein if the second heating operation is being performed when the defrosting necessity determination unit determines that the defrosting operation is necessary, after the second heating operation is completed, water is circulated through the third water path and the reverse cycle defrost operation is performed.

4. an air temperature detection means for detecting the temperature of the heat source air before heat exchange in the refrigerant evaporator; a refrigerant temperature detection means for detecting the temperature of the refrigerant after heat exchange in the refrigerant evaporator; The defrosting necessity determination unit 2. The hot water producing system according to claim 1, wherein the necessity of the defrosting operation is determined based on the temperatures detected by the air temperature detecting means and the refrigerant temperature detecting means.

5. the first heat accumulation correlation value is at least one value of the temperature, the water level, and the remaining amount of hot water in the first water tank; 5. The hot water producing system according to claim 1, wherein the second heat storage correlation value is at least one of the temperature, water level, and remaining amount of hot water in the second water tank.

6. the specific water route includes the first water route and the second water route, The air-source heat pump is configured by connecting a compressor, a four-way valve, a first heat radiation heat exchanger, a second heat radiation heat exchanger, an expansion valve, and the refrigerant evaporator in a ring shape, the first water path is arranged so that the water sent from the first water tank to the second water tank flows through the second heat-dissipating heat exchanger; the second water path is arranged to circulate the water in the second water tank to the first heat-dissipating heat exchanger, 5. The hot water producing system according to claim 1, wherein the third water path is arranged to circulate the water in the first water tank to the second heat-dissipating heat exchanger.

7. the specific water route includes the first water route and the second water route, The heating device is the air-source heat pump functioning as a low-stage heat pump circuit configured by connecting a first compressor, a first four-way valve, a cascade heat exchanger, a first heat-dissipating heat exchanger, a first expansion valve, and the refrigerant evaporator in a ring shape; a high-stage heat pump circuit configured by connecting a second compressor, a second four-way valve, a second heat dissipation heat exchanger, a third heat dissipation heat exchanger, a second expansion valve, and the cascade heat exchanger in a ring shape, the first water path is arranged so that the water sent from the first water tank to the second water tank flows through the first heat dissipation heat exchanger and the third heat dissipation heat exchanger; the second water path is arranged to circulate the water in the second water tank to the second heat-dissipating heat exchanger, 5. The hot water producing system according to claim 1, wherein the third water path is arranged to circulate the water in the first water tank to the first heat-dissipating heat exchanger.

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