JP7586288B2 - Hot water storage device and hot water supply system using hot water storage - Google Patents

Description

The present disclosure relates to a hot water storage device and a hot water storage type hot water supply system including the hot water storage device.

Conventionally, as shown in Patent Document 1, for example, a storage-type hot water supply system has been disclosed that includes a hot water storage tank, a heating source, a high-temperature hot water outlet pipe connected to the upper part of the hot water storage tank, a medium-temperature hot water outlet pipe connected to the middle part of the hot water storage tank, and a boiling changeover valve, and in a high-temperature water boiling mode in which high-temperature water (the high-temperature water in Patent Document 1) is boiled, the boiling changeover valve switches the flow path to supply water heated by the heating source to the hot water storage tank via the high-temperature hot water outlet pipe, and in a medium-temperature water boiling mode in which medium-temperature water (the medium-temperature water in Patent Document 1) is boiled, water heated by the heating source is supplied to the hot water storage tank via the medium-temperature hot water outlet pipe. Patent Document 1 also discloses that the storage-type hot water supply system shown in Patent Document 1 transitions from the medium-temperature water boiling mode to the high-temperature water boiling mode.

JP 2009-204252 A

In Patent Document 1, the conditions for changing the direction of the boiling switching valve are disclosed based on the temperature of the hot water coming out of the heating source, but the conditions for switching from medium temperature boiling mode to high temperature boiling mode are not disclosed. Therefore, there is a risk that the mode will switch from medium temperature boiling mode to high temperature boiling mode before the water in the hot water storage tank has reached the desired temperature, and a sufficient amount of medium temperature water will not be stored in the hot water storage tank.

The present disclosure aims to provide a hot water storage device capable of storing a sufficient amount of medium-temperature water in a hot water storage tank and then supplying high-temperature water to the hot water storage tank, and a storage-type hot water supply system including the hot water storage device.

A hot water storage device and a hot water storage type hot water supply system according to one embodiment of the present disclosure includes a hot water storage tank for storing tank water therein, a heating source for heating the tank water, a lower pipe for supplying the tank water stored in a lower part of the hot water storage tank to the heating source, a middle pipe for supplying the tank water heated by the heating source to a middle part of the hot water storage tank located vertically above the lower part of the hot water storage tank, an upper pipe for supplying the tank water heated by the heating source to an upper part of the hot water storage tank located vertically above the lower and middle parts of the hot water storage tank, a flow path switching device for switching between a middle inflow tank water circulation circuit in which the tank water heated by the heat source passes through the middle pipe and flows into the middle part of the hot water storage tank, and an upper inflow tank water circulation circuit in which the tank water heated by the heat source passes through the upper pipe and flows into the upper part of the hot water storage tank, and and a tank temperature sensor that detects the temperature of tank water stored at a position a predetermined sensor height away.In hot water storage operation in which tank water heated by a heating source is stored in a hot water storage tank, when the temperature detected by the tank temperature sensor becomes lower than a predetermined temperature, the hot water storage operation is started, and when the flow path switching device is in a state in which a middle inflow tank water circulation circuit is formed and the temperature of the tank water before being heated by the heating source is equal to or higher than a predetermined desired medium-temperature water temperature, the flow path switching device switches from the middle inflow tank water circulation circuit to the upper inflow tank water circulation circuit, and the flow rate per unit time of the tank water supplied to the heat source when the flow path switching device has formed the middle inflow tank water circulation circuit is greater than the flow rate per unit time of the tank water supplied to the heat source when the flow path switching device has formed the upper inflow tank water circulation circuit .

The hot water storage device and hot water supply system of one embodiment of the present disclosure switches from the middle inflow tank water circulation circuit to the upper inflow tank water circulation circuit if the temperature of the tank water before being heated by the heating source is equal to or higher than the desired medium-temperature water temperature, so that a sufficient amount of medium-temperature water can be stored in the hot water storage tank before high-temperature water is supplied to the hot water storage tank.

1 is a schematic diagram of a storage type hot water supply system according to an embodiment. A hardware configuration diagram of a control device for a hot water storage type hot water supply system according to an embodiment. A functional block diagram of a hot water storage device of a hot water storage type hot water supply system according to an embodiment. A schematic diagram of a storage-type hot water supply system according to an embodiment in which a first usage terminal uses the tank water as is. A schematic diagram of a storage-type hot water supply system according to an embodiment in which a second usage terminal mixes tank water with water from a water source for use. 4 is a flowchart of the hot water storage operation of the hot water storage type hot water supply system according to the embodiment. 1 is a schematic diagram of the storage type hot water supply system according to the embodiment at the point when processing of step S101 of the hot water storage operation is completed. 13 is a schematic diagram of the storage type hot water supply system according to the embodiment at the point when processing of step S105 of the hot water storage operation is completed. FIG. This is a first diagram showing the temperature distribution of tank water inside the hot water storage tank during hot water storage operation in a hot water storage type hot water supply system of the embodiment. A second diagram showing the temperature distribution of tank water inside the hot water storage tank during hot water storage operation in the hot water storage type hot water supply system of the embodiment. A third diagram showing the temperature distribution of tank water inside the hot water storage tank during hot water storage operation in the hot water storage type hot water supply system of the embodiment. A fourth diagram showing the temperature distribution of tank water inside the hot water storage tank during hot water storage operation in the hot water storage type hot water supply system of the embodiment. A schematic diagram of a storage type hot water supply system relating to a modified example of an embodiment.

The hot water storage device and hot water supply system according to the embodiments of the present disclosure will be described with reference to the drawings. Note that the present disclosure is not limited to the following embodiments, and modifications or omissions may be made without departing from the spirit of the present disclosure. Furthermore, it is also possible to appropriately combine the configurations of the hot water storage device and hot water supply system according to each embodiment and modification, as well as additional configurations. Additionally, common elements in each figure are given the same symbols, and duplicate explanations will be omitted.

Embodiment
1 is a schematic diagram of a storage type hot water supply system according to an embodiment. The storage type hot water supply system 1000 includes a hot water storage device 1, a first user terminal 1100, a second user terminal 1200, a supply pipe 1300, and an extraction pipe 1400.

The hot water storage device 1 has a heating unit 2, a hot water storage unit 3, an inter-unit forward piping 4, and an inter-unit return piping 5. In addition, the hot water storage device 1 has a heat medium circulation circuit 100 in which the heat medium circulates, formed by connecting the heating unit 2, the hot water storage unit 3, the inter-unit forward piping 4, and the inter-unit return piping 5 so that the heat medium flows. Note that a fluid is used as the heat medium, and for example, water or a mixture of additives and water is used as the heat medium.

The heating unit 2 heats the heat medium. Examples of the means by which the heating unit 2 heats the heat medium include a means for heating the heat medium with a vapor compression heat pump that circulates a refrigerant to transfer heat from the atmosphere or water to the heat medium, a means for burning a fuel such as gas or kerosene and heating the heat medium with the heat of combustion, a means for heating the heat medium with an electric heater that generates heat when power is supplied, or a means for collecting heat from the sun to heat the heat medium. In particular, the means for heating the heat medium with a vapor compression heat pump is highly energy efficient, and it is desirable to use this means. In addition, in the means for heating the heat medium using a vapor compression heat pump, it is desirable for the heating unit 2 to have a refrigerant circuit in which the refrigerant circulates, and for the refrigerant to use a natural refrigerant such as R744 or R290. Natural refrigerants have a smaller global warming potential than HFC (hydrofluorocarbon) refrigerants such as R410A or R32, and can suppress the impact on the global environment.

The hot water storage unit 3 stores water that has been heated using a heat medium. Here, the water stored in the hot water storage unit 3 is referred to as tank water. In addition, in the embodiment, the tank water may be referred to as low-temperature water, medium-temperature water, or high-temperature water depending on the temperature of the tank water. Low-temperature water refers to tank water that is at a lower temperature than the medium-temperature water and high-temperature water. Furthermore, medium-temperature water refers to tank water that is at a higher temperature than the low-temperature water and lower than the high-temperature water. Furthermore, high-temperature water refers to tank water that is at a higher temperature than the low-temperature water and medium-temperature water.

The hot water storage unit 3 includes a hot water storage tank 10, a heat exchanger 11, a heat medium circulation pump 12, a tank water circulation pump 13, a flow path switching device 14, a supply pipe 20 in the hot water storage unit, an extraction pipe 21 in the hot water storage unit, a lower pipe 22, a post-heating pipe 23, a middle pipe 24, an upper pipe 25, a supply pipe connection part 26, an extraction pipe connection part 27, a tank temperature sensor 30, a pre-heating tank water temperature sensor 31, a post-heating tank water temperature sensor 32, and a control device 40. The hot water storage unit 3 also includes a tank water circulation circuit 200 through which the tank water circulates. The tank water circulation circuit 200 according to the embodiment includes two types: a middle inflow tank water circulation circuit 201 and an upper inflow tank water circulation circuit 202. The difference between the middle inflow tank water circulation circuit 201 and the upper inflow tank water circulation circuit 202 will be described later.

The hot water tank 10 is hollow and stores tank water in the internal space. The hot water tank 10 is preferably made of a highly corrosion-resistant material such as stainless steel. The shape of the hot water tank 10 is preferably cylindrical, having a top surface portion located at the topmost position in the vertical direction, a bottom surface portion located at the bottommost position in the vertical direction, and a body portion connecting the top surface portion and the bottom surface portion. Furthermore, the ends of the supply pipe 20 in the hot water storage unit, the extraction pipe 21 in the hot water storage unit, the lower pipe 22, the middle pipe 24, and the upper pipe 25 are located in the internal space of the hot water storage tank 10. The supply pipe 20 in the hot water storage unit, the extraction pipe 21 in the hot water storage unit, the lower pipe 22, the middle pipe 24, and the upper pipe 25 are exposed to the outside of the hot water storage tank 10 from the body of the hot water storage tank 10.

The heat exchanger 11 is formed with a first flow path 11a and a second flow path 11b, and performs heat exchange between the fluid flowing through the first flow path 11a and the fluid flowing through the second flow path 11b. In the embodiment, tank water flows through the first flow path 11a, and a heat medium flows through the second flow path 11b, and the tank water is heated by heat exchange between the tank water and the heat medium. Since the tank water is heated by the heating unit 2 and the heat exchanger 11, the heating unit 2 and the heat exchanger 11 correspond to a heat source that heats the tank water.

The heat medium circulation pump 12 pressurizes the heat medium and circulates it through the heat medium circulation circuit 100. The heat medium circulation pump 12 is provided midway through the inter-unit return pipe 5 and inside the hot water storage unit 3.

The tank water circulation pump 13 pressurizes the tank water and circulates it through the tank water circulation circuit 200. The tank water circulation pump 13 is provided midway through the post-heating piping 23. The tank water circulation pump 13 has an electric motor, and the flow rate of the tank water circulating through the tank water circulation circuit 200 can be changed by changing the rotation speed of the electric motor. Hereinafter, the rotation speed of the electric motor will be referred to as the rotation speed N. The relationship between the rotation speed N and the flow rate of the tank water circulating through the tank water circulation circuit 200 is such that the larger the value of the rotation speed N, the greater the flow rate of the tank water circulating through the tank water circulation circuit 200 per unit time.

The flow path switching device 14 switches the flow path of the tank water circulation circuit 200. As described later, the tank water circulation circuit 200 is divided into two types, a middle inflow tank water circulation circuit 201 and an upper inflow tank water circulation circuit 202, and the flow path switching device 14 switches to either the middle inflow tank water circulation circuit 201 or the upper inflow tank water circulation circuit 202. In the embodiment, the flow path switching device 14 has an A port 14a, a B port 14b, and a C port 14c, and is a three-way valve that switches between a flow path that connects the A port 14a and the B port 14b and a flow path that connects the A port 14a and the C port 14c. Note that, as described later, when the flow path switching device 14 connects the A port 14a and the B port 14b, the upper inflow tank water circulation circuit 202 is formed, and when the A port 14a and the C port 14c are connected, the middle inflow tank water circulation circuit 201 is formed.

The supply piping 20 in the hot water storage unit is a pipe having one end located in the space below the hot water storage tank 10 and the other end connected to the supply piping connection part 26.

The extraction pipe 21 in the hot water storage unit is a pipe having one end located in the space above the hot water storage tank 10 and the other end connected to the extraction pipe connection part 27.

The lower piping 22 is a piping having one end located in the lower space of the hot water storage tank 10 and the other end connected to one end of the first flow path 11a of the heat exchanger 11.

The post-heating piping 23 is a piping having one end connected to the other end of the first flow path 11a of the heat exchanger 11 and the other end connected to port A 14a of the flow path switching device 14.

The middle pipe 24 is a pipe having one end connected to the C port 14c of the flow path switching device 14 and the other end located in the central space of the hot water storage tank 10. The other end of the middle pipe 24 is located vertically above one end of the lower pipe 22 located in the lower space of the hot water storage tank 10.

The upper pipe 25 is a pipe having one end connected to the B port 14b of the flow path switching device 14 and the other end located in the upper space of the hot water storage tank 10. The other end of the upper pipe 25 is located vertically higher than one end of the lower pipe 22 located in the lower space of the hot water storage tank 10 and one end of the middle pipe 24 located in the middle space of the hot water storage tank 10.

The supply pipe connection part 26 is a part that connects the supply pipe 1300 to the hot water storage unit 3. By connecting an end of the supply pipe 1300 (corresponding to an end of the first supply pipe 1301 described later) to the supply pipe connection part 26, the supply pipe 1300 and the supply pipe 20 in the hot water storage unit are connected to each other.

The extraction pipe connection part 27 is a part that connects the extraction pipe 1400 to the hot water storage unit 3. By connecting an end of the extraction pipe 1400 (corresponding to the end of the first extraction pipe 1401 described later) to the extraction pipe connection part 27, the extraction pipe 1400 and the extraction pipe 21 in the hot water storage unit are connected to each other.

The tank temperature sensor 30 detects the temperature of the tank water located at the sensor height H of the hot water storage tank 10. Hereinafter, the temperature of the tank water located at the sensor height H of the hot water storage tank 10 is referred to as the tank temperature Tt. In the embodiment, the tank temperature sensor 30 is provided on the wall surface of the hot water storage tank 10 at a position vertically away from the bottom surface of the hot water storage tank 10 by the sensor height H. The sensor height H is a height determined in advance by a designer so that the volume of the tank water stored at a position above the sensor height H of the hot water storage tank 10 is the amount of high-temperature water stored in the hot water storage device 1. The amount of high-temperature water stored in the hot water storage device 1 is determined in advance by a designer based on the amount of water used by the first user terminal 1100, which is determined in advance. For example, when 50 liters of water are used in the first user terminal 1100, the hot water storage device 1 is designed to store at least 50 liters of high-temperature water, and the sensor height H is determined in advance so that the volume of the tank water stored at a position above the sensor height H of the hot water storage tank 10 is 50 liters or more.

The pre-heating tank water temperature sensor 31 detects the temperature of the tank water before it is heated through heat exchange with the heat medium in the heat exchanger 11. Hereinafter, the temperature of the tank water before it is heated through heat exchange with the heat medium is referred to as the pre-heating tank water temperature Thb. In the embodiment, the pre-heating tank water temperature sensor 31 is disposed midway through the lower piping 22, and detects the temperature of the tank water flowing through the lower piping 22 as the pre-heating tank water temperature Thb.

The post-heating tank water temperature sensor 32 detects the temperature of the tank water after it has been heated through heat exchange with the heat medium in the heat exchanger 11. Hereinafter, the temperature of the tank water after it has been heated through heat exchange with the heat medium is referred to as the post-heating tank water temperature Tha. In the embodiment, the post-heating tank water temperature sensor 32 is disposed midway through the post-heating piping 23, and detects the temperature of the tank water flowing through the post-heating piping 23 as the post-heating tank water temperature Tha.

Figure 2 is a hardware configuration diagram of a control device for a hot water storage type hot water supply system according to an embodiment. The control device 40 will be described using Figure 2. The control device 40 controls the components of the hot water storage device 1, such as the tank water circulation pump 13 and the flow path switching device 14. The control device 40 has a processor 41, a memory 42, and a hardware interface 43. The processor 41, the memory 42, and the hardware interface 43 are connected to each other so that information can be exchanged.

The processor 41 is a device that controls or processes data of the components of the hot water storage device 1 by executing a program stored in the memory 42. The processor 41 may be, for example, a CPU (Central Processing Unit).

The memory 42 stores the programs executed by the processor 41 and data necessary for executing the programs. The memory 42 is also used as a working area for the processor 41. The memory 42 may be a non-volatile or volatile semiconductor memory such as a random access memory (RAM), a read only memory (ROM), or a flash memory.

The hardware interface 43 transmits or receives signals to or from the components of the hot water storage device 1. The components that transmit or receive signals to or from the hardware interface 43 are connected to the hardware interface 43 so that signals can be transmitted or received by wire or wirelessly. The hardware interface 43 may be, for example, a terminal block to which a signal line is connected, a GPIO (General Purpose Input/Output), or a transceiver that transmits or receives radio waves for wireless communication.

Figure 3 is a functional block diagram of a hot water storage device of a hot water supply system of a storage type according to an embodiment. Next, the functional block diagram of the hot water storage device 1 will be explained using Figure 3.

The control device 40 includes a receiving unit 50, a transmitting unit 51, a storage unit 52, a control unit 53, and a judgment unit 54. The receiving unit 50 and the transmitting unit 51 are realized by the hardware interface 43. The storage unit 52 is realized by storing various information in the memory 42. The control unit 53 and the judgment unit 54 are realized by the processor 41 performing processing according to the program stored in the memory 42.

The receiving unit 50 receives a signal transmitted to the control device 40. The receiving unit 50 is connected to the tank temperature sensor 30, the pre-heating tank water temperature sensor 31, and the post-heating tank water temperature sensor 32, and the receiving unit 50 receives a signal including information regarding the temperature detected by each sensor.

The transmitter 51 transmits a control signal generated by the controller 53 to components external to the control device 40, as described below. The transmitter 51 is connected to the heating unit 2, the heat medium circulation pump 12, the tank water circulation pump 13, and the flow path switching device 14, and each component operates in response to the control signal transmitted from the transmitter 51.

The memory unit 52 stores information necessary for the control unit 53 to generate a control signal and information necessary for the judgment unit 54 to make a judgment. Details of the information stored in the memory unit 52 will be described later.

The control unit 53 generates a control signal based on information included in the signal received by the receiving unit 50 and information stored in the memory unit 52. The control unit 53 generates a control signal for the heating unit 2, a control signal for the heat medium circulation pump 12, a control signal for the tank water circulation pump 13, and a control signal for the flow path switching device 14. In other words, the control unit 53 controls the heating unit 2, the heat medium circulation pump 12, the tank water circulation pump 13, and the flow path switching device 14.

The determination unit 54 makes a determination based on the information contained in the signal received by the receiving unit 50 and the information stored in the memory unit 52. The determination made by the determination unit 54 will be described in detail later.

Next, the inter-unit supply piping 4 and the inter-unit return piping 5 will be explained using Figure 1. The inter-unit supply piping 4 is a pipe having one end connected to the heating unit 2 and the other end connected to one end of the second flow path 11b of the heat exchanger 11. The inter-unit return piping 5 is a pipe having one end connected to the other end of the second flow path 11b of the heat exchanger 11 and the other end connected to the heating unit 2.

Next, the components of the hot water supply system 1000, excluding the hot water storage device 1, will be described with reference to FIG. 1. The first user terminal 1100 and the second user terminal 1200 each take out and use the tank water stored in the hot water storage device 1. The first user terminal 1100 and the second user terminal 1200 each have a set temperature of water to be used, and the temperature of the water used by the first user terminal 1100 is higher than the temperature of the water used by the second user terminal 1200. An example of the first user terminal 1100 is a dishwasher. An example of the second user terminal 1200 is a shower or a washbasin. In addition, the first user terminal 1100 and the second user terminal 1200 have a stopper (not shown) that can open and close the flow path connected to the extraction pipe 1400, and when the tank water is to be used, the stopper is operated to open the flow path.

The supply pipe 1300 has a first supply pipe 1301 and a second supply pipe 1302. The first supply pipe 1301 is a pipe having one end connected to a water source and the other end connected to the supply pipe connection portion 26 of the hot water storage device 1. The second supply pipe 1302 is a pipe having one end connected to a flow path in the middle of the first supply pipe 1301 and the other end connected to a flow path in the middle of the second extraction pipe 1402 described later.

The extraction pipe 1400 has a first extraction pipe 1401 and a second extraction pipe 1402. The first extraction pipe 1401 is a pipe having one end connected to the extraction pipe connection part 27 of the hot water storage device 1 described later and the other end connected to the first usage terminal 1100. The second extraction pipe 1402 is a pipe having one end connected to a flow path in the middle of the first extraction pipe 1401 and the other end connected to the second usage terminal 1200.

Figure 4 is a schematic diagram of a storage-type hot water supply system according to an embodiment, in which the first user terminal uses the tank water as is. In Figure 4, the flow path through which the water passes is shown in bold. Next, the flow of water when the first user terminal 1100 uses the tank water as is will be explained using Figure 4. When the first user terminal 1100 uses the tank water as is, the plug of the first user terminal 1100 opens the flow path connected to the extraction pipe 1400.

The tank water stored at the top of the hot water storage tank 10 flows out into the extraction piping 21 in the hot water storage unit. The tank water that flows out from the hot water storage tank 10 to the extraction piping 21 in the hot water storage unit passes through the extraction piping 21 in the hot water storage unit, the extraction piping connection part 27, and the first extraction piping 1401, and flows into the first user terminal 1100. The tank water that flows into the first user terminal 1100 is used by the first user terminal 1100.

In addition, water from the water source passes through the first supply pipe 1301, the supply pipe connection part 26, and the supply pipe 20 in the hot water storage unit and flows into the hot water storage tank 10. The water from the water source that flows into the hot water storage tank 10 is used as tank water.

Figure 5 is a schematic diagram of a storage-type hot water supply system according to an embodiment in which the second user terminal mixes tank water with water from the water source for use. In Figure 5, the flow path through which the water passes is indicated by a thick line. Next, the flow of water when the second user terminal 1200 mixes tank water with water from the water source for use will be explained using Figure 5. When tank water is used by the second user terminal 1200, the plug of the second user terminal 1200 opens the flow path connected to the extraction pipe 1400.

The tank water stored at the top of the hot water storage tank 10 flows out into the extraction pipe 21 in the hot water storage unit. The tank water that flows out from the hot water storage tank 10 to the extraction pipe 21 in the hot water storage unit passes through the extraction pipe 21 in the hot water storage unit, the extraction pipe connection part 27, the first extraction pipe 1401, and the second extraction pipe 1402, and flows into the second user terminal 1200. As the tank water flows through the second extraction pipe 1402, it is mixed with water from the water source that has passed through the first supply pipe 1301 and the second supply pipe 1302. The mixture of the tank water and water from the water source that flows into the second user terminal 1200 is used by the second user terminal 1200.

In addition, water from the water source passes through the first supply pipe 1301, the supply pipe connection part 26, and the supply pipe 20 in the hot water storage unit and flows into the hot water storage tank 10. The water from the water source that flows into the hot water storage tank 10 is used as tank water.

Figure 6 is a flowchart of the hot water storage operation of the hot water storage type hot water supply system according to the embodiment. Next, the hot water storage operation in which high temperature water and medium temperature water are stored inside the hot water storage tank 10 will be described with reference to Figure 6. The state of the hot water storage type hot water supply system 1000 before the hot water storage operation is started is a state in which the heating unit 2, the heat medium circulation pump 12, and the tank water circulation pump 13 are stopped. In addition, the conditions for starting the hot water storage operation include, for example, when a signal including a command to boil the tank water is received from a remote control (not shown) connected to the control device 40 so as to be able to transmit and receive signals, when a predetermined boiling start time is stored in the memory unit 52 and the time becomes the boiling start time, or when a boiling start temperature is stored in the memory unit 52 and the temperature detected by the tank temperature sensor 30 becomes lower than the boiling start temperature and the judgment unit 54 judges that the heat amount of the tank water stored in the hot water storage tank 10 is insufficient.

In addition, in hot water storage operation, the desired high-temperature water temperature Th and the desired medium-temperature water temperature Tm are stored in the memory unit 52. Furthermore, in hot water storage operation, the rotation speed of the motor of the tank water circulation pump 13 is changed by the control unit 53 to the rotation speed Nh when boiling high-temperature water or the rotation speed Nm when boiling medium-temperature water.

The desired high temperature water temperature Th and the desired medium temperature water temperature Tm are each values that are determined in advance before the start of hot water storage operation, and the desired high temperature water temperature Th is a value greater than the desired medium temperature water temperature Tm. In addition, in the embodiment, the desired high temperature water temperature Th is equal to or greater than the temperature of the water used by the first user terminal 1100, and the desired medium temperature water temperature Tm is equal to or greater than the temperature of the water used by the second user terminal 1200. The desired high temperature water temperature Th and the desired medium temperature water temperature Tm may each be determined by the designer or installer at the time of shipment or installation of the hot water storage device 1.

The rotation speed Nh during high-temperature water boiling is the rotation speed of the motor of the tank water circulation pump 13 that can obtain tank water heated to the desired high-temperature water temperature Th. The rotation speed Nm during medium-temperature water boiling is the rotation speed of the motor of the tank water circulation pump 13 that is greater than the rotation speed Nh during high-temperature water boiling. As a method for changing the rotation speed of the motor of the tank water circulation pump 13 to the rotation speed Nh during high-temperature water boiling, for example, the control unit 53 acquires the heated tank water temperature Tha, and if the acquired heated tank water temperature Tha is lower than the desired high-temperature water temperature Th, the control unit 53 decreases the rotation speed of the motor of the tank water circulation pump 13, and if the acquired heated tank water temperature Tha is higher than the desired high-temperature water temperature Th, the control unit 53 increases the rotation speed of the motor of the tank water circulation pump 13. Another method is to derive the high-temperature water boiling rotation speed Nh by experiment or simulation, store the derived high-temperature water boiling rotation speed Nh in advance in memory unit 52, and have control unit 53 set the rotation speed of the motor of tank water circulation pump 13 to the derived high-temperature water boiling rotation speed Nh when heating the tank water to the desired high-temperature water temperature Th. The medium-temperature water boiling rotation speed Nm only needs to be greater than the high-temperature water boiling rotation speed Nh, and is, for example, the maximum rotation speed Nmax at which the motor of tank water circulation pump 13 can operate, or a value obtained by adding a constant to the high-temperature water boiling rotation speed Nh stored in memory unit 52.

After the hot water storage operation starts, the process proceeds to step S100. In step S100, the control unit 53 switches the flow path switching device 14 to a state in which port A 14a and port C 14c are connected to each other.

After completing step S100, the process proceeds to step S101. In step S101, the control unit 53 starts the operation of the heating unit 2, the heat medium circulation pump 12, and the tank water circulation pump 13.

Figure 7 is a schematic diagram of the hot water storage type hot water supply system according to the embodiment at the time when the processing of step S101 of the hot water storage operation is completed. Note that in Figure 7, the flow paths through which the water and heat medium pass are indicated by thick lines. The flow of tank water and heat medium at the time when the processing of step S101 of the hot water storage operation is completed will be explained using Figure 7.

In step S101, the heating unit 2 is operated, and the heat medium is heated in the heating unit 2. In addition, in step S101, the heat medium circulation pump 12 is operated, and the heat medium circulates through the heat medium circulation circuit 100. Specifically, the heat medium heated in the heating unit 2 passes through the inter-unit supply piping 4, the second flow path 11b of the heat exchanger 11, and the inter-unit return piping 5, and flows back into the heating unit 2.

In step S100, the flow path switching device 14 is brought into a state in which port A 14a and port C 14c are connected, so that the hot water storage tank 10, the lower piping 22, the first flow path 11a of the heat exchanger 11, the post-heating piping 23, the flow path switching device 14, and the middle piping 24 are connected so that tank water can flow, and a middle inflow tank water circulation circuit 201 is formed.

In step S101, when the middle inflow tank water circulation circuit 201 is formed, the tank water circulation pump 13 operates, and the tank water circulates through the middle inflow tank water circulation circuit 201. Specifically, the tank water flows as described below. The tank water stored in the lower part of the hot water storage tank 10 flows out to the lower pipe 22. The tank water that flows out from the hot water storage tank 10 to the lower pipe 22 is supplied to the heat exchanger 11 and passes through the first flow path 11a of the heat exchanger 11. The heat medium passing through the second flow path 11b is heated by the heating unit 2, and therefore has a higher temperature than the tank water passing through the first flow path 11a. For this reason, the tank water passing through the first flow path 11a is heated by the heat medium passing through the second flow path 11b, and the temperature rises. After passing through the first flow path 11a, the tank water passes through the post-heating pipe 23, the flow path switching device 14, and the middle pipe 24, and is supplied to the middle part of the hot water storage tank 10.

Using Figure 6, we will explain the hot water storage operation after the processing of step S101 is completed. After the processing of step S101 is completed, proceed to step S102. In step S102, the control unit 53 changes the rotation speed N of the motor of the tank water circulation pump 13 to the rotation speed Nm when boiling medium temperature water. In other words, the control unit 53 controls the tank water circulation pump 13 so that N = Nm.

After completing the processing of step S102, proceed to step S103. In step S103, the receiving unit 50 acquires the pre-heating tank water temperature Thb detected by the pre-heating tank water temperature sensor 31.

After the process of step S103 is completed, the process proceeds to step S104. In step S104, the judgment unit 54 judges whether the pre-heating tank water temperature Thb acquired by the receiving unit 50 in step S103 is equal to or higher than the desired medium-temperature water temperature Tm. In other words, in step S104, the judgment unit 54 judges whether the condition Thb ≧ Tm is satisfied.

In the processing of step S104, if the judgment unit 54 determines that the pre-heating tank water temperature Thb is lower than the desired medium-temperature water temperature Tm (step S104, No), the processing returns to step S103 and the receiving unit 50 again acquires the pre-heating tank water temperature Thb.

In the process of step S104, if the judgment unit 54 judges that the pre-heating tank water temperature Thb is equal to or higher than the desired medium-temperature water temperature Tm (step S104, Yes), the process proceeds to step S105. In step S105, the control unit 53 switches the flow path switching device 14 to a state in which the A port 14a and the B port 14b are connected to each other.

Figure 8 is a schematic diagram of the hot water storage type hot water supply system according to the embodiment at the time when the processing of step S105 of the hot water storage operation is completed. In Figure 8, the flow paths through which the water and heat medium pass are indicated by thick lines. The flow of tank water at the time when the processing of step S105 of the hot water storage operation is completed will be explained using Figure 8. Note that the flow of the heat medium at the time when the processing of step S105 of the hot water storage operation is completed is the same as the flow of the heat medium at the time when the processing of step S101 of the hot water storage operation described using Figure 7 is completed, so the explanation will be omitted.

In step S105, the flow path switching device 14 is brought into a state in which port A 14a and port B 14b are connected, so that the hot water storage tank 10, the lower piping 22, the first flow path 11a of the heat exchanger 11, the post-heating piping 23, the flow path switching device 14, and the upper piping 25 are connected so that tank water can flow, and an upper inflow tank water circulation circuit 202 is formed.

When the upper inflow tank water circulation circuit 202 is formed, the tank water circulates through the upper inflow tank water circulation circuit 202 by operating the tank water circulation pump 13. Specifically, the tank water flows as described below. The tank water stored in the lower part of the hot water storage tank 10 flows out to the lower pipe 22. The tank water that flows out from the hot water storage tank 10 to the lower pipe 22 is supplied to the heat exchanger 11 and passes through the first flow path 11a of the heat exchanger 11. As described in the middle inflow tank water circulation circuit 201, the tank water passing through the first flow path 11a is heated by the heat medium passing through the second flow path 11b, and the temperature increases. After passing through the first flow path 11a, the tank water passes through the post-heating pipe 23, the flow path switching device 14, and the upper pipe 25, and is supplied to the upper part of the hot water storage tank 10.

Using Figure 6, the hot water storage operation after the processing of step S105 is completed will be described. After the processing of step S105 is completed, proceed to step S106. In step S106, the control unit 53 changes the rotation speed N of the motor of the tank water circulation pump 13 to the rotation speed Nh during high-temperature water heating. In other words, the control unit 53 controls the rotation speed N of the motor of the tank water circulation pump 13 so as to obtain tank water heated to the desired high-temperature water temperature Th.

After completing step S106, the process proceeds to step S107. In step S107, the receiving unit 50 acquires the tank internal temperature Tt detected by the tank temperature sensor 30.

After the process of step S107 is completed, the process proceeds to step S108. In step S108, the judgment unit 54 judges whether the tank temperature Tt acquired by the receiving unit 50 in step S107 is equal to or higher than the desired high-temperature water temperature Th. In other words, in step S108, the judgment unit 54 judges whether the condition Tt ≧ Th is satisfied.

In the processing of step S108, if the judgment unit 54 determines that the tank temperature Tt is lower than the desired high-temperature water temperature Th (step S108, No), the processing returns to step S107 and the receiving unit 50 again acquires the tank temperature Tt.

In the process of step S108, if the judgment unit 54 judges that the tank internal temperature Tt is equal to or higher than the desired high-temperature water temperature Th (step S108, Yes), the process proceeds to step S109. In step S109, the control unit 53 stops the operation of the heating unit 2, the heat medium circulation pump 12, and the tank water circulation pump 13.

After processing of step S109 is completed, the hot water storage type hot water supply system 1000 terminates hot water storage operation.

Figures 9 to 12 are first to fourth diagrams showing the temperature distribution of the tank water inside the hot water storage tank during hot water storage operation in a hot water storage type hot water supply system according to an embodiment of the present invention. Next, using Figures 9 to 12, the change in the temperature distribution of the tank water inside the hot water storage tank 10 during hot water storage operation will be explained. In this explanation, the desired medium temperature water temperature Tm is set to 40°C and the desired high temperature temperature Th is set to 60°C.

The temperature distribution of the tank water inside the hot water storage tank 10 immediately before the start of hot water storage operation is as shown in Figure 9. Specifically, inside the hot water storage tank 10, a temperature boundary is formed at a boundary height Hh away from the bottom of the hot water storage tank 10. In addition, tank water at 40°C is stored in the part of the hot water storage tank 10 above the temperature boundary, and tank water at 10°C is stored in the part of the hot water storage tank 10 below the temperature boundary.

When the hot water storage operation is started with the temperature distribution of the tank water inside the hot water storage tank 10 as shown in FIG. 9, the tank water flows out from the bottom of the hot water storage tank 10 from the point when step S101 is completed, and the outflowing tank water is heated by the heat exchanger 11 and flows back into the hot water storage tank 10 from the middle of the hot water storage tank 10. The tank water that flows into the hot water storage tank 10 mixes with the tank water in the middle and lower parts, and the temperature of the tank water below the temperature boundary rises. Here, generally, the higher the temperature of water, the lower the density, and the lower the temperature, the higher the density. When the temperature of the tank water below the temperature boundary is lower than 40°C, the tank water below the temperature boundary does not move above the temperature boundary because it has a higher density than water at 40°C, and does not mix with the tank water above the temperature boundary. Therefore, when heated tank water flows in from the center of the hot water storage tank 10, the tank water below the temperature boundary mixes with the heated tank water and the temperature rises, while the tank water above the temperature boundary maintains its temperature. As a result, the temperature distribution of the tank water inside the hot water storage tank 10 shifts from the state shown in Figure 9 to the state shown in Figure 10.

In the state where the temperature distribution of the tank water inside the hot water storage tank 10 is shown in FIG. 10, the temperature flowing out from the hot water storage tank 10 is 20°C, so the pre-heating temperature Thb is also 20°C, which is lower than the desired medium-temperature water temperature Tm of 40°C. Therefore, the condition of step S104 of the hot water storage operation is not met, and the tank water heated by the heat exchanger 11 flows into the hot water storage tank 10 from the middle part of the hot water storage tank 10. In addition, when the temperature of the tank water below the temperature boundary rises, the temperature of the tank water flowing out from the hot water storage tank 10 also rises, and the temperature of the tank water heated by the heat exchanger 11 and flowing into the hot water storage tank 10 also rises. For this reason, if the hot water storage operation is continued in the state shown in FIG. 10, the temperature of the tank water flowing into the hot water storage tank 10 will be 40°C or higher, the temperature boundary will disappear, and the temperature inside the hot water storage tank 10 will become uniform. As a result, the temperature distribution of the tank water inside the hot water storage tank 10 will transition from the state shown in FIG. 10 to the state shown in FIG. 11.

In the state where the temperature distribution of the tank water inside the hot water storage tank 10 is shown in FIG. 11, the temperature flowing out from the hot water storage tank 10 is 40°C, so the pre-heating temperature Thb is also 40°C, which is the same as the desired medium-temperature water temperature Tm of 40°C. Therefore, the condition of step S104 of the hot water storage operation is met, and the processing of steps S105 and S106 of the hot water storage operation is performed. By performing the processing of steps S105 and S106, the outflowing tank water is heated to the high-temperature desired temperature Th of 60°C in the heat exchanger 11, and the heated tank water flows into the hot water storage tank 10 from the top of the hot water storage tank 10. The temperature of the tank water flowing in from the top of the hot water storage tank 10 is 60°C, which is higher than the temperature of the tank water already stored in the hot water storage tank 10, which is 40°C. For this reason, the tank water flowing in from the top of the hot water storage tank 10 does not mix with the tank water already stored in the hot water storage tank 10, and a temperature boundary is formed again. That is, inside the hot water storage tank, tank water at 60°C is stored above the temperature boundary, and tank water at 40°C is stored below the temperature boundary. Furthermore, if more time passes after the processing of steps S105 and S106 of the hot water storage operation has been performed, the amount of tank water at 60°C stored in the hot water storage tank 10 will increase, and the amount of tank water at 40°C stored in the hot water storage tank 10 will decrease. Therefore, the temperature boundary moves downward over time, and the boundary height Hh becomes lower. As a result, the temperature distribution of the tank water inside the hot water storage tank 10 transitions from the state shown in FIG. 11 to the state shown in FIG. 12.

In the state shown in FIG. 12, where the temperature distribution of the tank water inside the hot water storage tank 10 is the same as the sensor height Hh. In the state shown in FIG. 12, the tank water temperature Tt detected by the tank temperature sensor 30 is 60°C, which is the same as the high temperature desired temperature Th of 60°C. Therefore, after the conditions of step S108 of the hot water storage operation are met and the processing of step S109 is performed, the hot water storage type hot water supply system 1000 ends the hot water storage operation. Also, as described above, the sensor height H is determined so that the volume of the tank water stored above the sensor height H of the hot water storage tank 10 is the amount of high-temperature water stored in the hot water storage device 1. Therefore, in the state shown in FIG. 12, where the boundary height Hh is the same as the sensor height H, the hot water storage tank 10 is in a state where the amount of high-temperature water predetermined by the designer is stored.

As described above, the hot water storage device 1 and the hot water supply system 1000 according to the embodiment include a hot water storage tank 10 that stores tank water therein, a heating source (corresponding to the heating unit 2 and the heat exchanger 11) that heats the tank water, a lower pipe 22 that supplies the tank water stored in the lower part of the hot water storage tank 10 to the heating source, a middle pipe 24 that supplies the tank water heated by the heating source to a middle part of the hot water storage tank 10 that is located vertically above the lower part of the hot water storage tank 10, an upper pipe 25 that supplies the tank water heated by the heating source to an upper part of the hot water storage tank 10 that is located vertically above the lower and middle parts of the hot water storage tank 10, and the tank water heated by the heating source passes through the middle pipe 24 and reaches the middle of the hot water storage tank 10. and a flow path switching device 14 that switches between a middle inflow tank water circulation circuit 201 through which tank water heated by a heating source passes through the upper piping 25 and flows into the upper part of the hot water storage tank 10. During hot water storage operation in which tank water heated by a heating source is stored in the hot water storage tank 10, when the flow path switching device 14 is in a state in which the middle inflow tank water circulation circuit 201 is formed and the temperature of the tank water before being heated by the heating source (which corresponds to the pre-heating tank water temperature Thb) is higher than or equal to a predetermined medium-temperature water desired temperature Tm (step S104, YES corresponds), the flow path switching device 14 is configured to switch from the middle inflow tank water circulation circuit 201 to the upper inflow tank water circulation circuit 202. In this configuration, when the temperature of the tank water before being heated by the heating source is equal to or higher than a predetermined desired medium-temperature water temperature Tm, the flow path switching device 14 is configured to switch from the middle inflow tank water circulation circuit 201 to the upper inflow tank water circulation circuit 202, thereby achieving the effect that the hot water storage device 1 and the storage-type hot water supply system 1000 according to the embodiment can store a sufficient amount of medium-temperature water in the hot water storage tank 10 and then supply high-temperature water to the hot water storage tank 10. Note that, in the hot water storage device 1 and the storage-type hot water supply system 1000 according to the embodiment, a sufficient amount of medium-temperature water refers to a state in which medium-temperature water is stored up to the bottom of the hot water storage tank 10 where the end of the lower piping 22 is located.

In addition, the hot water storage device 1 and the hot water supply system 1000 according to the embodiment have an additional configuration in which the flow rate per unit time of the tank water supplied to the heating source when the flow path switching device 14 forms the middle inflow tank water circulation circuit 201 is greater than the flow rate per unit time of the tank water supplied to the heating source when the flow path switching device 14 forms the upper inflow tank water circulation circuit 202. By being provided with this additional configuration, the hot water storage device 1 and the hot water supply system 1000 according to the embodiment have a greater flow rate when boiling medium-temperature water than when boiling high-temperature water, improving energy efficiency during boiling.

In addition, the hot water storage device 1 and the hot water supply system 1000 according to the embodiment include, as an additional configuration, a tank water circulation pump 13 that has an electric motor and can change the flow rate of the circulating tank water per unit time by circulating the tank water to the middle inflow tank water circulation circuit 201 or the upper inflow tank water circulation circuit 202 and changing the rotation speed of the electric motor, and the rotation speed of the motor of the tank water circulation pump 13 when the flow path switching device 14 forms the middle inflow tank water circulation circuit 201 is higher than the rotation speed of the motor of the tank water circulation pump 13 when the flow path switching device 14 forms the upper inflow tank water circulation circuit 202. By including this additional configuration, the hot water storage device 1 and the hot water supply system 1000 according to the embodiment can control the rotation speed of the tank water circulation pump 13 to boil medium-temperature water at a higher flow rate than when boiling high-temperature water, improving energy efficiency during boiling.

In addition, the hot water storage device 1 and the hot water supply system 1000 according to the embodiment have an additional configuration in which the rotation speed of the motor of the tank water circulation pump 13 when the flow path switching device 14 forms the middle inflow tank water circulation circuit 201 is the maximum rotation speed at which the motor can operate. In general, when the heat source heats the running water, the amount of heat of the running water is proportional to the flow rate of the running water. In other words, in the hot water storage device 1 and the hot water supply system 1000 according to the embodiment, the higher the rotation speed of the motor of the tank water circulation pump 13, the greater the amount of heat of the tank water flowing through the heat exchanger 11, which is the heating source, and the more energy efficient it is. By having this additional configuration, the hot water storage device 1 and the hot water supply system 1000 according to the embodiment operate at the maximum flow rate that the tank water circulation pump 13 can achieve when the middle inflow tank water circulation circuit 201 is formed, so that the tank water can be boiled with excellent energy efficiency.

In addition, the hot water storage device 1 and the hot water supply system 1000 according to the embodiment have an additional configuration in which the temperature of the tank water after being heated by the heating source when the flow path switching device 14 forms the middle inflow tank water circulation circuit 201 is lower than the temperature of the tank water after being heated by the heating source when the flow path switching device 14 forms the upper inflow tank water circulation circuit 202. By being provided with this additional configuration, the hot water storage device 1 and the hot water supply system 1000 according to the embodiment have the effect of being able to store water of two temperatures, high temperature water and medium temperature water, in the hot water storage tank 10.

In addition, the hot water storage device 1 and the hot water supply system 1000 according to the embodiment include, as an additional configuration, a tank water circulation pump 13 that has an electric motor and can circulate the tank water to the middle inflow tank water circulation circuit 201 or the upper inflow tank water circulation circuit 202 and change the flow rate of the circulating tank water per unit time by changing the rotation speed of the electric motor, and the rotation speed of the motor of the tank water circulation pump when the flow path switching device 14 forms the upper inflow tank water circulation circuit 202 is a rotation speed at which the temperature of the tank water after being heated by the heating source becomes a predetermined high-temperature water desired temperature Th, which is a temperature higher than the medium-temperature water desired temperature Tm. By including this additional configuration, the hot water storage device 1 and the hot water supply system 1000 according to the embodiment have the effect of being able to store water of two temperatures, high temperature water and medium temperature water, in the hot water storage tank 10.

In addition, the hot water storage device 1 and the hot water supply system 1000 according to the embodiment include, as an additional configuration, a pre-heating tank water temperature sensor 31 that detects the temperature of the tank water stored in the lower part of the hot water storage tank 10 or the temperature of the tank water flowing through the lower piping 22, and the temperature of the tank water detected by the pre-heating tank water temperature sensor 31 is the temperature of the tank water before it is heated by the heat source. By including this additional configuration, the hot water storage device 1 and the hot water supply system 1000 according to the embodiment achieve the effect of being able to accurately detect the temperature of the tank water before it is heated by the heat source by the pre-heating tank water temperature sensor 31.

In addition, the hot water storage device 1 and the hot water supply system 1000 according to the embodiment have an additional configuration in which the lower pipe 22, the middle pipe 24, and the upper pipe 25 are each exposed from the body of the hot water storage tank 10 to the outside of the hot water storage tank 10. By being provided with this additional configuration, the hot water storage device 1 and the hot water supply system 1000 according to the embodiment have the effect of being able to reduce the vertical height of the hot water storage device 1.

In addition, the hot water storage device 1 and the hot water supply system 1000 according to the embodiment have, as an additional configuration, a configuration in which the heat source has a heating unit 2 that heats a heat medium and a heat exchanger 11 that performs heat exchange between the heat medium heated by the heating unit 2 and the tank water. By being provided with this additional configuration, the hot water storage device 1 and the hot water supply system 1000 according to the embodiment can reduce the risk of the refrigerant or fuel in the heating unit 2 mixing with the tank water, compared to a means in which the heating unit 2 directly heats the tank water.

In addition, the hot water storage device 1 and the hot water supply system 1000 according to the embodiment have an additional configuration in which the heating unit 2 is a vapor compression heat pump. By being provided with this additional configuration, the hot water storage device 1 and the hot water supply system 1000 according to the embodiment have the effect of being more energy efficient than a means of burning fuel and heating a heat medium with the combustion heat.

In addition, the hot water storage device 1 and the hot water supply system 1000 according to the embodiment have an additional configuration in which a refrigerant circuit is formed in the heating unit through which a refrigerant circulates, and the refrigerant is a natural refrigerant. By being provided with this additional configuration, the hot water storage device 1 and the hot water supply system 1000 according to the embodiment have the effect of reducing the impact on the global environment compared to when an HFC refrigerant is used as the refrigerant.

The hot water storage type hot water supply system 1000 according to the embodiment further comprises, as an additional configuration, a first user terminal 1100 and a second user terminal 1200 that extract and use the tank water stored in the hot water storage device 1 and the hot water storage tank 10, and the temperature of the water used by the first user terminal 1100 and the second user terminal 1200 is predetermined, the temperature of the water used by the first user terminal 1100 is higher than the temperature of the water used by the second user terminal 1200, and the desired medium-temperature water temperature Tm is equal to or higher than the temperature of the water used by the second user terminal 1200. By having this additional configuration, the hot water storage type hot water supply system 1000 according to the embodiment can use the second user terminal 1200 by supplying medium-temperature water to the second user terminal 1200.

Furthermore, the storage type hot water supply system 1000 according to the embodiment has, as an additional configuration, a configuration in which the temperature of the water after being heated by the heating source in a state in which the flow path switching device 14 forms the upper inflow tank water circulation circuit 202 is equal to or higher than the temperature of the water used by the first user terminal 1100. By having this additional configuration, the storage type hot water supply system 1000 according to the embodiment has the effect of being able to use the first user terminal 1100 by supplying high-temperature water to the first user terminal 1100.

In addition, the hot water storage type hot water supply system 1000 according to the embodiment is further provided with, as an additional configuration, a tank temperature sensor 30 that detects the temperature of the tank water stored in the hot water storage tank 10 at a predetermined sensor height H away from the lowest part of the hot water storage tank 10 in the vertical direction (corresponding to the bottom surface), the amount of water used by the first user terminal 1100 is predetermined, the volume of the tank water stored in the hot water storage tank 10 located above the sensor height H in the vertical direction is equal to or greater than the amount of water used by the first user terminal 1100, and the hot water storage operation is terminated when the flow path switching device 14 forms the upper inflow tank water circulation circuit 202 during hot water storage operation and the temperature of the tank water detected by the tank temperature sensor 30 is equal to or greater than the temperature of the water used by the first user terminal 1100. By having this additional configuration, the storage type hot water supply system 1000 of this embodiment has the effect of being able to store in the hot water storage tank 10 an amount of high-temperature water to be used by the first user terminal 1100 during hot water storage operation.

Figure 13 is a schematic diagram of a storage type hot water supply system according to a modified embodiment. Next, a modified embodiment will be described. A storage type hot water supply system 1001 according to a first modified embodiment differs from the storage type hot water supply system 1000 according to the embodiment in the positions at which the supply piping 20 in the storage unit, the extraction piping 21 in the storage unit, the lower piping 22, the middle piping 24, and the upper piping 25 are exposed from the hot water storage tank 10, and the position of the pre-heating tank water temperature sensor 31. Note that the storage type hot water supply system 1001 according to the first modified embodiment is similar to the storage type hot water supply system 1000 according to the embodiment except for the above-mentioned differences, and therefore a description of the similar parts will be omitted.

In the hot water storage type hot water supply system 1001, the supply pipe 20 and the lower pipe 22 in the hot water storage unit are exposed from the bottom surface of the hot water storage tank 10. In addition, the extraction pipe 21, the middle pipe 24, and the upper pipe 25 in the hot water storage unit are exposed from the top surface of the hot water storage tank 10.

In addition, in the hot water storage type hot water supply system 1001, the pre-heating tank water temperature sensor 31 is located at the bottom of the hot water storage tank 10. Because the tank water flows out to the heat exchanger 11 through the lower piping 22 exposed from the bottom, even if the pre-heating tank water temperature sensor 31 is located at the bottom of the hot water storage tank 10, the pre-heating tank water temperature sensor 31 can acquire the pre-heating tank water temperature Thb.

As described above, the hot water storage device 1 and the hot water supply system 1001 according to the modified embodiment are similar to the hot water storage device 1 and the hot water supply system 1001 according to the modified embodiment, and include a hot water storage tank 10 that stores tank water therein, a heating source that heats the tank water (the heating unit 2 and the heat exchanger 11), a lower pipe 22 that supplies the tank water stored in the lower part of the hot water storage tank 10 to the heating source, a middle pipe 24 that supplies the tank water heated by the heating source to a middle part of the hot water storage tank located vertically above the lower part of the hot water storage tank 10, an upper pipe 25 that supplies the tank water heated by the heating source to the lower and upper parts of the hot water storage tank located vertically above the middle part, and a tank water heated by the heating source is supplied to the middle pipe 2 4 and flows into the middle of the hot water storage tank 10, and an upper inflow tank water circulation circuit 202 in which the tank water heated by the heating source flows into the upper part of the hot water storage tank 10 through the upper piping 25. In a hot water storage operation in which the tank water heated by the heating source is stored in the hot water storage tank 10, when the flow path switching device 14 forms the middle inflow tank water circulation circuit 201 and the temperature of the tank water before being heated by the heating source (the tank water temperature before heating Thb) is equal to or higher than a predetermined desired medium-temperature water temperature Tm (YES in step S104), the flow path switching device 14 is configured to switch from the middle inflow tank water circulation circuit 201 to the upper inflow tank water circulation circuit 202. Therefore, the hot water storage device 1 and the hot water storage type hot water supply system 1001 according to the embodiment also have the same effects as those described in the embodiment.

In addition, the hot water storage device 1 and the hot water supply system 1001 according to the modified embodiment have an additional configuration in which at least one of the lower pipe 22, the middle pipe 24, and the upper pipe 25 is exposed to the outside of the hot water storage tank from the top or bottom of the hot water storage tank 10. By being provided with this additional configuration, the hot water storage device 1 and the hot water supply system 1001 according to the modified embodiment can reduce the horizontal area of the hot water storage device 1 and the installation area of the hot water storage device 1 compared to the hot water storage device 1 and the hot water supply system 1000 according to the modified embodiment in which the lower pipe 22, the middle pipe 24, and the upper pipe 25 are exposed from the body.

In the hot water storage device 1 and the hot water supply system 1001 according to the modified embodiment, the supply pipe 20 and the lower pipe 22 in the hot water storage unit are exposed from the bottom surface of the hot water storage tank 10, and the extraction pipe 21, the middle pipe 24, and the upper pipe 25 in the hot water storage unit are exposed from the top surface of the hot water storage tank 10, but this is not limited to the above. For example, the supply pipe 20 and the lower pipe 22 in the hot water storage unit may be exposed from the top surface of the hot water storage tank 10, and the extraction pipe 21, the middle pipe 24, and the upper pipe 25 in the hot water storage unit may be exposed from the bottom surface of the hot water storage tank 10.

In addition, in the hot water storage device 1 and the hot water supply system 1000 according to the embodiment, the heating unit 2 and the hot water storage unit 3 are in separate housings, but this is not limited thereto, and the heating unit 2 and the hot water storage unit 3 may be in a single housing.

In addition, in the hot water storage device 1 and the hot water supply system 1000 according to the embodiment, the heat medium circulation pump 12 is located inside the hot water storage unit 3, but this is not limited thereto and it may be located inside the heating unit 2. In addition, the heat medium circulation pump 12 may be provided midway in the inter-unit supply piping 4.

In addition, in the hot water storage device 1 and the hot water storage type hot water supply system 1000 according to the embodiment, the tank water circulation pump 13 is provided midway through the post-heating piping 23, but this is not limited thereto and it may also be provided midway through the lower piping 22.

In addition, in the hot water storage device 1 and the hot water supply system 1000 according to the embodiment, in step S102 of the hot water storage operation, the control unit 53 changes the rotation speed N of the motor of the tank water circulation pump 13 to the rotation speed Nm when boiling medium-temperature water, but this is not limited to this, and the control unit 53 may set the rotation speed N of the motor of the tank water circulation pump 13 to the rotation speed Nm when boiling medium-temperature water and start operation at the stage of step S101. In this case, the process of step S102 is not performed, and the process of step S103 is performed after the process of step S101 is completed.

In addition, in the hot water storage device 1 and hot water storage type hot water supply system 1000 according to the embodiment, the tank water is heated by exchanging heat between the heat medium heated by the heating unit 2 and the tank water using the heating unit 2 and the heat exchanger 11, but this is not limited to the above. For example, a means for directly heating the tank water by burning fuel such as gas or kerosene, a means for directly heating the tank water with an electric heater, or a means for directly heating the tank water by collecting heat from the sun may be used. In this case, the device for directly heating the tank water corresponds to the heat source.

In addition, in the hot water storage device 1 and the hot water supply system 1000 according to the embodiment, the desired high-temperature water temperature Th and the desired medium-temperature water temperature Tm are set by the designer or installer when the hot water storage device 1 is shipped or installed, but this is not limited to the above. The desired high-temperature water temperature Th and the desired medium-temperature water temperature only need to be set before the start of the hot water storage operation, and may be set to the values desired by the user by operating a remote control (not shown).

1 hot water storage device, 2 heating unit, 3 hot water storage unit, 4 inter-unit forward piping, 5 inter-unit return piping, 10 hot water storage tank, 11 heat exchanger, 11a first flow path, 11b second flow path, 12 heat medium circulation pump, 13 tank water circulation pump, 14 flow path switching device, 14a A port, 14b B port, 14c C port, 20 supply piping in hot water storage unit, 21 extraction piping in hot water storage unit, 22 lower piping, 23 post-heating piping, 24 middle piping, 25 upper piping, 26 supply piping connection part, 27 extraction piping connection part, 30 tank temperature sensor, 31 pre-heating tank water temperature sensor, 32 post-heating tank water temperature sensor, 40 control device, 41 processor, 42 memory, 43 hardware interface, 50 receiving unit, 51 transmitting unit, 52 storage unit, 53 control unit, 54 Judgment unit, 100 heat medium circulation circuit, 200 tank water circulation circuit, 201 middle inflow tank water circulation circuit, 202 upper inflow tank water circulation circuit, 1000 storage type hot water supply system, 1001 storage type hot water supply system, 1100 first user terminal, 1200 second user terminal, 1300 supply piping, 1301 first supply piping, 1302 second supply piping, 1400 extraction piping, 1401 first extraction piping, 1402 second extraction piping.

Claims (14)

A hot water storage tank for storing tank water therein;
A heating source for heating the tank water;
A lower pipe that supplies the tank water stored in a lower portion of the hot water storage tank to the heating source;
a middle pipe that supplies the tank water heated by the heating source to a middle part of the hot water storage tank that is located vertically above the lower part of the hot water storage tank;
an upper pipe that supplies the tank water heated by the heating source to an upper portion of the hot water storage tank that is located vertically above the lower portion and the middle portion of the hot water storage tank;
a flow path switching device that switches between a middle inflow tank water circulation circuit in which the tank water heated by the heating source passes through the middle piping and flows into the middle of the hot water storage tank, and an upper inflow tank water circulation circuit in which the tank water heated by the heating source passes through the upper piping and flows into the upper part of the hot water storage tank;
a tank temperature sensor that detects the temperature of the tank water stored at a position that is a predetermined sensor height away from the lowermost portion of the hot water storage tank in the vertical direction;
In a hot water storage operation in which the tank water heated by the heating source is stored in the hot water storage tank, when the temperature detected by the tank temperature sensor becomes lower than a predetermined temperature, the hot water storage operation is started,
When the flow path switching device is in a state where the middle inflow tank water circulation circuit is formed and the temperature of the tank water before being heated by the heating source is equal to or higher than a predetermined desired medium-temperature water temperature, the flow path switching device switches from the middle inflow tank water circulation circuit to the upper inflow tank water circulation circuit.
A hot water storage device in which the flow rate per unit time of the tank water supplied to the heating source when the flow path switching device forms the middle inflow tank water circulation circuit is greater than the flow rate per unit time of the tank water supplied to the heating source when the flow path switching device forms the upper inflow tank water circulation circuit. a tank water circulation pump having an electric motor, circulating the tank water in the middle inflow tank water circulation circuit or the upper inflow tank water circulation circuit, and capable of changing the flow rate of the circulating tank water per unit time by changing the rotation speed of the electric motor;
A hot water storage device as described in claim 1, wherein the rotation speed of the motor of the tank water circulation pump when the flow path switching device forms the middle inflow tank water circulation circuit is faster than the rotation speed of the motor of the tank water circulation pump when the flow path switching device forms the upper inflow tank water circulation circuit. The hot water storage device according to claim 2, wherein the rotational speed of the motor of the tank water circulation pump when the flow path switching device forms the middle inflow tank water circulation circuit is the maximum rotational speed at which the motor can operate. The hot water storage device according to any one of claims 1 to 3, wherein the temperature of the tank water after being heated by the heating source when the flow path switching device forms the middle inflow tank water circulation circuit is lower than the temperature of the tank water after being heated by the heating source when the flow path switching device forms the upper inflow tank water circulation circuit. a tank water circulation pump having an electric motor, circulating the tank water in the middle inflow tank water circulation circuit or the upper inflow tank water circulation circuit, and capable of changing the flow rate of the circulating tank water per unit time by changing the rotation speed of the electric motor;
A hot water storage device as described in claim 1, wherein the rotation speed of the motor of the tank water circulation pump when the flow path switching device forms the upper inflow tank water circulation circuit is a rotation speed at which the temperature of the tank water after being heated by the heating source becomes a predetermined desired high temperature water temperature, which is higher than the desired medium temperature water temperature. a pre-heating tank water temperature sensor for detecting the temperature of the tank water stored in the lower portion of the hot water storage tank or the temperature of the tank water flowing through the lower piping;
The hot water storage device according to claim 1 , wherein the temperature of the tank water detected by the pre-heating tank water temperature sensor is the temperature of the tank water before it is heated by the heat source. The hot water storage device according to any one of claims 1 to 6, wherein the lower pipe, the middle pipe, and the upper pipe are each exposed to the outside of the hot water storage tank from the body of the hot water storage tank. The hot water storage device according to any one of claims 1 to 6, wherein at least one of the lower pipe, the middle pipe, and the upper pipe is exposed to the outside of the hot water storage tank from the top or bottom of the hot water storage tank. The hot water storage device according to any one of claims 1 to 6, wherein the heat source has a heating unit that heats a heat medium, and a heat exchanger that exchanges heat between the heat medium heated by the heating unit and the tank water. The hot water storage device according to claim 9, wherein the heating unit is a vapor compression heat pump. The hot water storage device according to claim 10, wherein the heating unit is formed with a refrigerant circuit through which a refrigerant circulates, and the refrigerant is a natural refrigerant. The hot water storage device according to any one of claims 1 to 11 ,
a first usage terminal and a second usage terminal for extracting and using the tank water stored in the hot water storage tank;
A storage-type hot water supply system in which the temperature of water used by the first user terminal and the second user terminal are each predetermined, the temperature of water used by the first user terminal is higher than the temperature of water used by the second user terminal, and the desired medium-temperature water temperature is higher than or equal to the temperature of water used by the second user terminal. The hot water storage device according to any one of claims 1 to 11,
a first usage terminal and a second usage terminal for extracting and using the tank water stored in the hot water storage tank;
a temperature of water to be used is preset for each of the first user terminal and the second user terminal, the temperature of water to be used at the first user terminal is higher than the temperature of water to be used at the second user terminal, and the desired medium-temperature water temperature is equal to or higher than the temperature of water to be used at the second user terminal;
The amount of water used by the first utilization terminal is predetermined,
The volume of the tank water stored in the hot water storage tank that is located above the sensor height in the vertical direction is equal to or greater than the amount of water used by the first user terminal,
A storage-type hot water supply system that terminates the hot water storage operation when the flow path switching device forms the upper inflow tank water circulation circuit during the hot water storage operation and the temperature of the tank water detected by the tank temperature sensor is higher than the temperature of the water used by the first usage terminal. A storage-type hot water supply system as described in claim 12 or 13, wherein the temperature of the tank water after being heated by the heating source when the flow path switching device forms the upper inflow tank water circulation circuit is higher than the temperature of the water used by the first usage terminal.

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