JP2020190347A - Hot water storage type hot water supply device - Google Patents

Abstract

To provide a hot water storage type hot water supply device advantageous for improving energy efficiency and preventing freezing of pipes.SOLUTION: Circuit switching means of a hot water storage type hot water supply device 35 can switch among a tank utilization heating circuit that is a circuit leading to an intermediate part of a hot water storage tank 8 by passing through a primary side flow passage 60a of a bath heat exchanger 60 without passing through an HP unit 7 from an upper part of the hot water storage tank 8, a first heat recovery circuit that is a circuit leading to the intermediate part of the hot water storage tank 8 by passing through the primary side flow passage 60a without passing through the HP unit 7 from a lower part of the hot water storage tank 8, and a second heat recovery circuit that is a circuit leading to the intermediate part of the hot water storage tank 8 by passing through the HP unit 7 and the primary side flow passage 60a from the lower part of the hot water storage tank 8. When executing heat recovery operation, a control device 36 executes first heat recovery operation for causing water to flow through the first heat recovery circuit if there is no possibility that water pipes connected to the HP unit 7 will freeze, and executes second heat recovery operation for causing water to flow through the second heat recovery circuit if there is a possibility of freezing.SELECTED DRAWING: Figure 4

Description

The present invention relates to a hot water storage type hot water supply device.

In the hot water storage type hot water supply device disclosed in Patent Document 1 below, energy efficiency can be improved by performing a bath heat recovery operation for recovering the waste heat of the remaining hot water in the bathtub after bathing in the hot water storage tank.

JP-A-2018-091504

Further improvement in energy efficiency is required for hot water storage type water heaters. Further, in winter, it is required to prevent freezing of pipes exposed to the outside air.

An object of the present invention is to provide a hot water storage type hot water supply device which is advantageous in improving energy efficiency and preventing freezing of pipes.

The hot water storage type hot water supply device according to the present invention can store hot water heated by a heating means for heating water and hot water heated by the heating means, and has a hot water storage having an upper portion, a lower portion, and an intermediate portion between the upper portion and the lower portion. A heat exchanger having a tank, a primary side flow path and a secondary side flow path, and exchanging heat between a primary fluid flowing through the primary side flow path and a secondary fluid flowing through the secondary side flow path, and hot water. Circuit switching means that can switch the circuit of the above, and a control means that can execute a heating operation in which the secondary fluid is heated by the primary fluid in the heat exchanger and a heat recovery operation after the heating operation are provided. The means are a tank-utilizing heating circuit that reaches the middle part of the hot water storage tank from the upper part of the hot water storage tank through the primary side flow path without passing through the heating means, and the primary from the lower part of the hot water storage tank without passing through the heating means. A first heat recovery circuit that reaches the middle part of the hot water storage tank through the side flow path, and a second heat recovery circuit that reaches the middle part of the hot water storage tank from the lower part of the hot water storage tank through the heating means and the primary side flow path. ,, And the control means, when performing the heat recovery operation, causes water to flow to the first heat recovery circuit when there is no possibility that the water pipe connected to the heating means freezes. The heat recovery operation is executed, and if there is a possibility, the second heat recovery operation in which water flows through the second heat recovery circuit is executed.

According to the present invention, it is possible to provide a hot water storage type hot water supply device which is advantageous in improving energy efficiency and preventing freezing of pipes.

It is a figure which shows the hot water storage type hot water supply apparatus by Embodiment 1. FIG. It is a figure which shows the circuit which circulates hot water at the time of a chasing operation. It is a figure which shows the flow of hot water of a 1st heat recovery circuit. It is a figure which shows the flow of hot water of a 2nd heat recovery circuit.

Hereinafter, embodiments will be described with reference to the drawings. Common or corresponding elements in the drawings are designated by the same reference numerals to simplify or omit duplicate description.

Embodiment 1.
FIG. 1 is a diagram showing a hot water storage type hot water supply device 35 according to the first embodiment. As shown in FIG. 1, the hot water storage type hot water supply device 35 of the first embodiment includes a tank unit 33, an HP (heat pump) unit 7, and a remote control device 44. The HP unit 7 and the tank unit 33 are connected to each other via an HP going pipe 14, an HP returning pipe 15, and an electric wiring (not shown). The control device 36 is built in the tank unit 33. The operation of various valves, pumps, etc. included in the tank unit 33 and the HP unit 7 is controlled by a control device 36 electrically connected to these. The control device 36 includes, for example, a microcomputer having at least one memory and at least one processor. The control device 36 corresponds to a control means for controlling the operation of the hot water storage type hot water supply device 35. The control device 36 has a timer function for managing the date and time.

The remote control device 44 has a function of accepting a user's operation regarding a driving operation command and a change of a set value. The remote control device 44 is an example of a user interface. The control device 36 and the remote control device 44 are connected by wire or wireless so that data communication is possible in both directions. Although not shown, the remote controller 44 is equipped with a display unit that displays information such as the state of the hot water storage type hot water supply device 35, an operation unit such as a switch operated by the user, a speaker, a microphone, and the like. The display unit of the remote controller device 44 has a function as a notification means for notifying the user of information. The remote control device 44 in the present embodiment includes a display unit as a notification means, but as a modification, other notification means such as a voice guidance device may be provided.

In the present embodiment, the remote control device 44 may be installed on a wall such as a kitchen, a living room, or a bathroom. A plurality of remote control devices 44 may be able to communicate with the control device 36. Further, a mobile terminal such as a smartphone may be configured to be usable as the remote control device 44. The mobile terminal and the control device 36 may communicate with each other via a network.

The HP unit 7 is an example of a heating means for heating water. The HP unit 7 includes a refrigerant circuit in which a compressor 1, a water refrigerant heat exchanger 3, an expansion valve 4, and an air heat exchanger 6 are cyclically connected by a refrigerant pipe 5. The HP unit 7 operates the heat pump cycle by this refrigerant circuit. In the water refrigerant heat exchanger 3, water is heated by exchanging heat between the refrigerant compressed by the compressor 1 and the water guided from the tank unit 33.

The HP unit 7 is attached to a hot water temperature sensor 39 provided in a hot water outlet of the water refrigerant heat exchanger 3 or a pipe communicating with the hot water outlet, and a pipe communicating with the water inlet of the water refrigerant heat exchanger 3 or the water inlet. It is provided with a water entry temperature sensor 40 provided. The hot water temperature sensor 39 detects the temperature of the hot water flowing out from the water refrigerant heat exchanger 3. The water entry temperature sensor 40 detects the temperature of the water flowing into the water refrigerant heat exchanger 3.

The tank unit 33 contains the following various parts and pipes. The hot water storage tank 8 stores hot water. Inside the hot water storage tank 8, a temperature stratification can be formed in which the upper side is high temperature and the lower side is low temperature due to the difference in water density depending on the temperature.

As shown in FIG. 1, the hot water storage tank 8 includes an upper part, an intermediate part, and a lower part. The middle portion of the hot water storage tank 8 is a height portion between the upper portion of the hot water storage tank 8 and the lower portion of the hot water storage tank 8. The hot water storage tank 8 is not limited to a single tank as shown in the figure, and may include a plurality of tanks connected in series. In the present disclosure, regarding the description of the position of the hot water storage tank 8 in the height direction, that is, in the vertical direction, when the hot water storage tank 8 includes a plurality of tanks connected in series, the highest tank to the lowest tank 8 are provided. The vertical position shall be specified in the entire hierarchy up to the tank.

A water inlet 8a, a water outlet 8b, and a water inlet 8c are provided below the hot water storage tank 8. A hot water introduction outlet 8d and a hot water introduction outlet 8e are provided above the hot water storage tank 8. A medium-temperature water introduction port 8g and a medium-temperature water introduction port 8f are provided in the middle portion of the hot water storage tank 8. In the present embodiment, the medium temperature water introduction port 8g is located higher than the medium temperature water introduction port 8f.

A third water supply pipe 9c is connected to the water inlet 8a. The water supplied from a water source such as a water supply through the first water supply pipe 9a is adjusted to a predetermined pressure by the pressure reducing valve 31 and then flows into the hot water storage tank 8 through the third water supply pipe 9c. A plurality of hot water storage temperature sensors 41, 42, and 43 are attached to the surface of the hot water storage tank 8 at positions at different heights from each other. The hot water storage temperature sensor 41 detects the water temperature in the middle portion of the hot water storage tank 8. In the illustrated example, the hot water storage temperature sensor 41 detects the water temperature at the same height as the medium hot water introduction outlet 8f or at a height close to the medium hot water introduction outlet 8f. The hot water storage temperature sensor 42 detects the water temperature at the upper part of the hot water storage tank 8. The hot water storage temperature sensor 43 detects the water temperature at the bottom of the hot water storage tank 8. The control device 36 can detect the amount of remaining hot water and the amount of heat stored in the hot water storage tank 8 by detecting the temperature distribution of the hot water in the hot water storage tank 8 with these hot water storage temperature sensors 41, 42, 43. Not limited to the illustrated example, four or more hot water storage temperature sensors may be provided in the hot water storage tank 8.

The tank unit 33 contains a bath heat exchanger 60 and a bath circulation pump 29. The bath heat exchanger 60 has a primary side flow path 60a and a secondary side flow path 60b. The bath heat exchanger 60 corresponds to a heat exchanger that exchanges heat between the primary fluid flowing through the primary side flow path 60a and the secondary fluid flowing through the secondary side flow path 60b. In the present embodiment, an example in which the bath water circulating from the bath tub 30 flows through the secondary side flow path 60b as the secondary fluid will be described. Instead of this example, the secondary fluid in the present disclosure may be a fluid other than bath water. For example, the secondary fluid may be a heat medium for heating or water supplied from a water source.

The bath going pipe 27 connects the outlet of the secondary side flow path 60b and the bathtub 30. A bath going temperature sensor 37 for detecting the temperature of the bath water flowing out of the bath heat exchanger 60 is installed in the middle of the bath going pipe 27. The bath return pipe 28 connects the inlet of the secondary side flow path 60b and the bathtub 30. In the middle of the bath return pipe 28, a bath circulation pump 29 for circulating bath water in the secondary side flow path 60b, a bath return temperature sensor 38 for detecting the temperature of the bath water discharged from the bathtub 30, and a bath return temperature sensor 38. A water level sensor 46 for detecting the water level in the bathtub 30 and a flow switch 47 for detecting the presence or absence of circulation of bath water are provided. The bath circulation pump 29 corresponds to a secondary fluid pump that allows a secondary fluid to flow through the secondary side flow path 60b.

The tank unit 33 further includes a three-way valve 11, a circulation pump 12, a four-way valve 16, and a four-way valve 18. Each of the three-way valve 11, the four-way valve 16, and the four-way valve 18 corresponds to a flow path switching means capable of switching the flow path of hot water. The hot water storage type hot water supply device 35 includes a piping device including these flow path switching means, an HP going pipe 14, an HP returning pipe 15, and pipes described later. The circulation pump 12 is a pump for circulating hot water in this piping device.

The three-way valve 11 has an a port and a b port as an inlet and a c port as an outlet. The three-way valve 11 is configured so that the flow path can be switched between the two paths ac and bc. The four-way valve 16 has an inlet port a and a port b, and an outlet c port and d port. The four-way valve 16 is configured so that the flow path can be switched between the four paths of ac, ad, bc, and bd. The four-way valve 18 has an inlet a port and an outlet b port, c port, and d port. The four-way valve 18 is configured so that the flow path can be switched between the three paths of ab, ac, and ad.

The tank unit 33 has a low temperature pipe 10, a first water supply pipe 13a, a first hot water pipe 17a, a second hot water pipe 17b, a third hot water pipe 19a, a fourth hot water pipe 19b, and a fifth hot water pipe 19c. .. The low temperature pipe 10 connects the water outlet 8b and the a port of the three-way valve 11. The first water supply pipe 13a connects the c port of the three-way valve 11 and the inlet of the circulation pump 12. The HP going pipe 14 connects the outlet of the circulation pump 12 and the water inlet of the water refrigerant heat exchanger 3. The HP return pipe 15 connects the hot water outlet of the water refrigerant heat exchanger 3 and the b port of the four-way valve 16. The first hot water pipe 17a connects the d port of the four-way valve 16 and the a port of the four-way valve 18. The second hot water pipe 17b connects the c port of the four-way valve 16 and the water introduction port 8c. The third hot water pipe 19a connects the b port of the four-way valve 18 and the hot water introduction outlet 8e. The fourth hot water pipe 19b connects the d port of the four-way valve 18 and the hot water introduction outlet 8d. The fifth hot water pipe 19c connects the c port of the four-way valve 18 and the medium hot water introduction port 8g.

The pipe 20a connects the hot water introduction outlet 8e and the inlet of the primary side flow path 60a. The pipe 20c connects the outlet of the primary side flow path 60a and the b port of the three-way valve 11. The second water supply pipe 13b branches from the branch portion 51 formed in the middle of the HP going pipe 14 and is connected to the a port of the four-way valve 16.

The tank unit 33 includes a medium temperature pipe 79, a first water supply pipe 9a, a second water supply pipe 9b, a third water supply pipe 9c, a fourth water supply pipe 9d, a hot water supply mixing valve 22, a bath mixing valve 23, and a medium temperature water switching valve 78. It has a hot water supply pipe 24, a bath pipe 25, a pipe 20b, and a check valve 50.

The medium-temperature water switching valve 78 is a flow path switching means having an inlet a port and a b port and an outlet c port. The medium-temperature water switching valve 78 is configured so that the flow path can be switched between the two paths ac and bc.

The hot water supply mixing valve 22 is a mixing means including a first inlet, a second inlet, and an outlet. The bath mixing valve 23 is a mixing means including a first inlet, a second inlet, and an outlet.

One end of the first water supply pipe 9a is connected to a water source such as water supply. The second water supply pipe 9b and the third water supply pipe 9c are connected to the other end of the first water supply pipe 9a via the pressure reducing valve 31. The second water supply pipe 9b is connected to the a port of the medium temperature water switching valve 78. The medium temperature pipe 79 connects the medium temperature water introduction outlet 8f and the b port of the medium temperature water switching valve 78. One end of the pipe 20b is connected to a branch portion 52 formed in the middle of the pipe 20c. The other end of the pipe 20b is connected to a branch portion 53 formed in the middle of the medium temperature pipe 79. The check valve 50 is installed in the middle of the pipe 20b. The check valve 50 prevents water in the middle portion of the hot water storage tank 8 from flowing to the lower part of the hot water storage tank 8 through the pipe 20b. One end of the fourth water supply pipe 9d is connected to the c port of the medium / hot water switching valve 78. The other end of the fourth water supply pipe 9d is connected to the first inlet of each of the hot water supply mixing valve 22 and the bath mixing valve 23. One end of the high temperature pipe 21 communicates with the hot water introduction outlet 8d. The other end of the high temperature pipe 21 is connected to the second inlet of each of the hot water supply mixing valve 22 and the bath mixing valve 23.

The medium temperature water switching valve 78 has two flows, a first flow path state in which the second water supply pipe 9b and the fourth water supply pipe 9d communicate with each other, and a second flow path state in which the medium temperature pipe 79 and the fourth water supply pipe 9d communicate with each other. Use by switching the road condition. When the medium-temperature water switching valve 78 is set to the first flow path state, the low-temperature water supplied from the water source is supplied to the hot water supply mixing valve 22 and the bath mixing valve 23 through the second water supply pipe 9b and the fourth water supply pipe 9d. It will be in a state of being done. When the medium-temperature water switching valve 78 is placed in the second flow path state, the medium-temperature water supplied from the hot water storage tank 8 through the medium-temperature water introduction outlet 8f and the medium-temperature pipe 79 passes through the fourth water supply pipe 9d and is a hot water supply mixing valve. It is in a state of being supplied to 22 and the bath mixing valve 23.

The hot water supply mixing valve 22 is used by adjusting the flow rate ratio of the high temperature water supplied from the hot water storage tank 8 through the high temperature pipe 21 to the low temperature water or medium hot water supplied from the fourth water supply pipe 9d. Generates hot water at a set temperature set by the remote control device 44 and flows it into the hot water supply pipe 24. The hot water whose temperature has been adjusted by the hot water supply mixing valve 22 is supplied from the hot water supply pipe 24 to a faucet (not shown) such as a shower or a curan via a hot water tap 34.

The bath mixing valve 23 is used by adjusting the flow rate ratio of the high temperature water supplied from the hot water storage tank 8 through the high temperature pipe 21 to the low temperature water or medium hot water supplied from the fourth water supply pipe 9d. Generates hot water at a set temperature set by the remote control device 44 and flows it into the bath pipe 25. The hot water adjusted to the set temperature by the bath mixing valve 23 flows into the bathtub 30 through the bath flow sensor 45, the bath electromagnetic valve 26, the bath going pipe 27, and the bath returning pipe 28.

The control device 36 determines the completion of the hot water filling of the bathtub 30 based on the information detected by the bath flow sensor 45 and the water level sensor 46, thereby determining the amount of bath water in the bathtub 30 at the completion of the hot water filling. The amount of hot water filled can be controlled to be equal to the amount of hot water set by the user on the remote controller 44. The hot water storage type hot water supply device 35 of the present embodiment may be capable of executing automatic bath operation. When the automatic bath operation is set by the remote control device 44, the control device 36 maintains the temperature and amount of the bath water in the bathtub 30 at the temperature and amount set by the remote control device 44 after the completion of hot water filling. As needed, the bath water is heated, cooled, hot water, and squeezed water are added.

The hot water storage type hot water supply device 35 can execute the hot water storage operation. The hot water storage operation is an operation in which a hot water storage circuit is formed from the lower part of the hot water storage tank 8 to the upper part of the hot water storage tank 8 through the HP unit 7, and hot water, that is, high temperature water heated by the HP unit 7 is stored in the hot water storage tank 8. .. The control device 36 controls the start and stop of the hot water storage operation according to the amount of remaining hot water or the amount of heat stored in the hot water storage tank 8. In the hot water storage operation, the HP unit 7 and the circulation pump 12 are operated and are as follows. The low-temperature water at the bottom of the hot water storage tank 8 passes through the water outlet 8b, the low-temperature pipe 10, the three-way valve 11, the first water supply pipe 13a, the circulation pump 12, and the HP going pipe 14 to the water refrigerant heat exchanger 3. Inflow. The high-temperature water generated by heating this low-temperature water in the water refrigerant heat exchanger 3 passes through the HP return pipe 15, the four-way valve 16, the first hot water pipe 17a, the four-way valve 18, and the fourth hot water pipe 19b. Then, it flows into the hot water storage tank 8 from the hot water introduction outlet 8d. A circuit in which hot water circulates in this way corresponds to a hot water storage circuit. When the hot water storage operation is executed, hot water is stored from the upper part to the lower part of the hot water storage tank 8, and the layer of the high temperature water gradually becomes thicker. When the amount of hot water stored or the amount of heat stored in the hot water storage tank 8 detected by the hot water storage temperature sensors 41, 42, 43 exceeds a predetermined amount, the control device 36 ends the hot water storage operation.

The control device 36 can execute a repelling operation in which the bath water circulating from the bathtub 30 is heated by the bath heat exchanger 60. FIG. 2 is a diagram showing a circuit in which hot water circulates during a chasing operation. The control device 36 may perform a chasing operation to maintain the temperature of the bath water stored in the bathtub 30, or perform a chasing operation to raise the temperature of the bath water stored in the bathtub 30. May be good. The repelling operation in the present embodiment corresponds to a heating operation in which the secondary fluid is heated by the primary fluid in the bath heat exchanger 60.

At the time of repelling operation, the control device 36 controls as follows. In the three-way valve 11, the b port and the c port communicate with each other, and the a port is closed. In the four-way valve 16, the a port and the d port communicate with each other, and the b port and the c port are closed. In the four-way valve 18, the a port and the c port communicate with each other, and the b port and the d port are closed. The circulation pump 12 and the bath circulation pump 29 are operated. The hot water flowing out from the upper part of the hot water storage tank 8 through the hot water introduction outlet 8e is supplied as the primary fluid to the primary side flow path 60a through the pipe 20a. The primary fluid that has passed through the primary side flow path 60a is the pipe 20c, the three-way valve 11, the first water supply pipe 13a, the circulation pump 12, the branch 51, the second water supply pipe 13b, the four-way valve 16, the first hot water pipe 17a, and the four sides. It flows in the order of the valve 18 and the fifth hot water pipe 19c, and flows into the intermediate portion of the hot water storage tank 8 from the medium hot water introduction port 8g. The circuit in which hot water circulates in this way corresponds to a tank-utilizing heating circuit that reaches the intermediate portion of the hot water storage tank 8 from the upper part of the hot water storage tank 8 through the primary side flow path 60a without passing through the HP unit 7. The bath water that has flowed from the bathtub 30 through the bath return pipe 28 into the secondary side flow path 60b is heated by receiving the heat of the hot water flowing through the primary side flow path 60a. The heated bath water returns to the bathtub 30 through the bath going pipe 27.

In the following description, among the hot water remaining in the pipe, the hot water having a temperature higher than the low temperature water supplied from the water source is referred to as "residual hot water". Since the residual hot water has a higher temperature than the low temperature water, it can be said that it has an effective amount of heat. If the residual hot water in the pipe is left as it is, the residual hot water dissipates heat to the surroundings and the temperature drops. As a result, the heat possessed by the residual hot water is wasted. On the other hand, if the residual hot water in the pipe can be recovered in the hot water storage tank 8, the amount of heat required to be generated by the HP unit 7 in the hot water storage operation in the midnight time zone can be reduced, so that the energy efficiency can be improved.

The control device 36 can continue the heat recovery operation after the end of the repelling operation. After the chasing operation is completed, there is residual hot water in the piping of the tank utilization heating circuit. In the present embodiment, the residual hot water in at least a part of the piping of the tank utilization heating circuit can flow into the intermediate portion of the hot water storage tank 8 by performing the heat recovery operation after the end of the repelling operation. As a result, the heat of the residual hot water can be recovered in the intermediate portion of the hot water storage tank 8, so that energy efficiency can be improved.

In the present embodiment, a first heat recovery circuit and a second heat recovery circuit can be formed as a circuit through which hot water flows during the heat recovery operation. The first heat recovery circuit and the second heat recovery circuit can be switched by the four-way valve 16 and the four-way valve 18. The first heat recovery circuit is a circuit that reaches the intermediate portion of the hot water storage tank 8 from the lower part of the hot water storage tank 8 through the primary side flow path 60a without passing through the HP unit 7. The second heat recovery circuit is a circuit that reaches the intermediate portion of the hot water storage tank 8 from the lower part of the hot water storage tank 8 through the HP unit 7 and the primary side flow path 60a. The second heat recovery circuit passes through the HP going pipe 14 and the HP returning pipe 15. Since the first heat recovery circuit does not pass through the HP going pipe 14 and the HP return pipe 15, the circuit length is shorter than that of the second heat recovery circuit.

In the following explanation, the heat recovery operation in which water flows through the first heat recovery circuit is referred to as "first heat recovery operation", and the heat recovery operation in which water flows through the second heat recovery circuit is referred to as "second heat recovery operation". It is called.

In winter when the outside air temperature is low, the water remaining inside the HP going pipe 14 and the HP returning pipe 15 may be cooled by the outside air, so that the HP going pipe 14 and the HP returning pipe 15 may freeze. .. The possibility that the HP going pipe 14 and the HP returning pipe 15 freeze is hereinafter referred to as "freezing possibility". When executing the heat recovery operation, the control device 36 executes the first heat recovery operation when there is no possibility of freezing, and causes water to flow through the second heat recovery circuit when there is a possibility of freezing. (Ii) Perform a heat recovery operation. As a result, the following effects can be obtained.

When there is a possibility of freezing, the water in the hot water storage tank 8 can be made to flow to the HP going pipe 14 and the HP returning pipe 15 by executing the second heat recovery operation. As a result, the heat of the residual hot water can be recovered in the hot water storage tank 8 while the freezing of the HP going pipe 14 and the HP returning pipe 15 can be reliably prevented. On the other hand, when there is no possibility of freezing, the heat of the residual hot water is removed while reducing the drive load of the circulation pump 12 by executing the first heat recovery operation by the first heat recovery circuit having a short circuit length. It can be collected in the hot water storage tank 8. Therefore, the power consumption of the circulation pump 12 can be reduced.

The control device 36 may determine whether or not there is a possibility of freezing by using the temperature sensor provided in the HP unit 7. For example, the control device 36 determines that there is a possibility of freezing when the detection temperature of the hot water temperature sensor 39 or the detection temperature of the incoming water temperature sensor 40 is lower than the reference value (for example, 3 ° C.), and when not, the control device 36 determines that there is a possibility of freezing. May determine that there is no possibility of freezing.

FIG. 3 is a diagram showing the flow of hot water in the first heat recovery circuit. In the first heat recovery operation, as shown in FIG. 3, it is as follows. In the three-way valve 11, the a port and the c port communicate with each other, and the b port is closed. In the four-way valve 16, the a port and the d port communicate with each other, and the b port and the c port are closed. In the four-way valve 18, the a port and the b port communicate with each other, and the c port and the d port are closed. The circulation pump 12 is operated. For water, the water outlet 8b, the low temperature pipe 10, the three-way valve 11, the first water supply pipe 13a, the circulation pump 12, the branch 51, the second water supply pipe 13b, the four-way valve 16, the first hot water pipe 17a, the four-way valve 18, The third hot water pipe 19a, the pipe 20a, the primary side flow path 60a, the branch portion 52, the pipe 20b, the branch portion 53, and the medium temperature pipe 79 flow in this order, and flow into the intermediate portion of the hot water storage tank 8 from the medium hot water introduction outlet 8f. The circuit in which hot water circulates in this way corresponds to the first heat recovery circuit. When the first heat recovery operation is performed, the residual hot water in the pipe after the end of the repelling operation flows into the hot water storage tank 8 from the medium hot water introduction outlet 8f and is stored in the intermediate portion of the hot water storage tank 8.

FIG. 4 is a diagram showing the flow of hot water in the second heat recovery circuit. In the second heat recovery operation, as shown in FIG. 4, it is as follows. In the three-way valve 11, the a port and the c port communicate with each other, and the b port is closed. In the four-way valve 16, the b port and the d port communicate with each other, and the a port and the c port are closed. In the four-way valve 18, the a port and the b port communicate with each other, and the c port and the d port are closed. The circulation pump 12 is operated. Water is water outlet 8b, low temperature pipe 10, three-way valve 11, first water supply pipe 13a, circulation pump 12, HP going pipe 14, water refrigerant heat exchanger 3, HP return pipe 15, four-way valve 16, first hot water. Pipe 17a, four-way valve 18, third hot water pipe 19a, pipe 20a, primary side flow path 60a, branch 52, pipe 20b, branch 53, medium temperature pipe 79 flow in this order, and the hot water storage tank 8 from the medium hot water introduction outlet 8f. It flows into the middle part of. The circuit in which hot water circulates in this way corresponds to the second heat recovery circuit. When the second heat recovery operation is performed, the residual hot water in the pipe after the end of the repelling operation flows into the hot water storage tank 8 from the medium hot water introduction outlet 8f and is stored in the intermediate portion of the hot water storage tank 8.

In the present embodiment, the hot water storage circuit, the tank utilization heating circuit, the first heat recovery circuit, and the second heat recovery circuit can be switched by the three-way valve 11, the four-way valve 16, and the four-way valve 18. The three-way valve 11, the four-way valve 16, and the four-way valve 18 correspond to circuit switching means capable of switching the hot water circuit.

In the present embodiment, the circulation pump 12 is arranged in the first water supply pipe 13a which is a common flow path for the hot water storage circuit, the tank utilization heating circuit, the first heat recovery circuit, and the second heat recovery circuit. .. As a result, hot water can be circulated in any circuit with a single circulation pump 12, so that there is an advantage that the number of installed pumps can be reduced.

Before the start of the second heat recovery operation, cold water that may freeze is filled inside the HP going pipe 14, the water refrigerant heat exchanger 3, and the HP return pipe 15. This cold water is hereinafter referred to as "ultra-low temperature water". In the second heat recovery operation, assuming that the extremely low temperature water flows into the hot water storage tank 8 from the medium hot water introduction outlet 8f, the temperature of the intermediate portion of the hot water storage tank 8 may decrease, which may lead to a decrease in energy efficiency. .. In view of this point, it is preferable that the control device 36 controls so that the extremely low temperature water does not flow into the hot water storage tank 8 as much as possible in the second heat recovery operation. As a result, the above-mentioned decrease in energy efficiency can be reliably prevented. For example, the control device 36 may stop the circulation pump 12 and end the second heat recovery operation before the ultra-low temperature water flows into the hot water storage tank 8.

The control device 36 may make the time for continuing the second heat recovery operation shorter than the time for continuing the first heat recovery operation. As a result, it is possible to reliably prevent the extremely low temperature water from flowing into the hot water storage tank 8.

The control device 36 may limit the time for continuing the second heat recovery operation so as not to exceed the upper limit time. As a result, it is possible to reliably prevent the extremely low temperature water from flowing into the hot water storage tank 8.

In the following description, the position where the flow path of the second heat recovery circuit merges with the flow path of the first heat recovery circuit is referred to as a “merging position”. In the present embodiment, the four-way valve 16 corresponds to the merging position. On the downstream side of the four-way valve 16, the flow path of the first heat recovery circuit and the flow path of the second heat recovery circuit are common. In the second heat recovery operation, the control device 36 receives the water in the second heat recovery circuit upstream of the four-way valve 16 before the start of the second heat recovery operation before the water flows into the hot water storage tank 8. It is preferable to end the second heat recovery operation. That is, the control device 36 stops the circulation pump 12 before the ultra-low temperature water in the HP return pipe 15 flows into the hot water storage tank 8 before the start of the second heat recovery operation, and ends the second heat recovery operation. It is preferable to do so. As a result, it is possible to more reliably prevent the extremely low temperature water from flowing into the hot water storage tank 8.

In the heat recovery operation, the total volume of water flowing into the hot water storage tank 8 from the medium hot water introduction outlet 8f is hereinafter referred to as "recovered water amount". In the second heat recovery operation, if the amount of recovered water does not exceed the volume of the flow path from the four-way valve 16 at the confluence position to the medium hot water introduction outlet 8f, the extremely low temperature water is surely prevented from flowing into the hot water storage tank 8. it can. The volume of the flow path from the four-way valve 16 to the medium hot water introduction outlet 8f is hereinafter referred to as "total flow path volume". In the present embodiment, the first hot water pipe 17a, the four-way valve 18, the third hot water pipe 19a, the pipe 20a, the primary side flow path 60a, the branch portion 52, the pipe 20b, the check valve 50, the branch portion 53, and the medium temperature pipe. The total volume of the flow path can be calculated from the inner diameter and length of the flow path passing through 79. As an example, assuming that the inner diameter of the flow path is 10 mm and the total length is 2 m, the total volume of the flow path can be calculated by the following formula.
Total flow path volume = (1/2) ² × π × 200/1000 ≒ 0.157 [L]
In this example, assuming that the control device 36 operates the circulation pump 12 so that the water flow rate of the second heat recovery circuit is 2 L / min, the upper limit time for continuing the second heat recovery operation can be calculated by the following equation. ..
Upper limit time = 0.157 / 2 x 60 = 4.7 [seconds]
Therefore, in this example, if the circulation pump 12 is stopped before the time for continuing the second heat recovery operation exceeds the upper limit time of 4.7 seconds, the amount of recovered water is equal to or less than the total volume of the flow path. Therefore, it is possible to reliably prevent the extremely low temperature water from flowing into the hot water storage tank 8.

As described above, the control device 36 calculates the amount of recovered water in the flow path by calculating the upper limit time for continuing the second heat recovery operation based on the total volume of the flow path and the water flow rate of the second heat recovery circuit. It can be limited to less than the total volume. That is, it is possible to reliably prevent the extremely low temperature water from flowing into the hot water storage tank 8.

The water flow rate of the second heat recovery circuit changes according to the rotation speed of the circulation pump 12. The control device 36 stores in the memory the rotation speed of the circulation pump 12 so that the water flow rate of the second heat recovery circuit becomes equal to a predetermined target value as the target rotation speed, and circulates during the second heat recovery operation. The rotation speed of the pump 12 may be controlled to be equal to the target rotation speed.

The control device 36 may learn the circulation flow rate of the hot water storage circuit during the hot water storage operation, and may change the time for continuing the second heat recovery operation according to the learned circulation flow rate. Since the total length of the second heat recovery circuit is almost equal to the total length of the hot water storage circuit, if the rotation speed of the circulation pump 12 is the same, the water flow rate during the second heat recovery operation will be the circulation flow rate during the hot water storage operation. Almost equal. Therefore, the control device 36 can estimate the water flow rate during the second heat recovery operation by learning the circulation flow rate during the hot water storage operation. When the circulation flow rate during the hot water storage operation is relatively high, it can be estimated that the water flow rate during the second heat recovery operation is relatively high. Therefore, the control device 36 compares the time for continuing the second heat recovery operation. Shorten the target. As a result, it is possible to more reliably suppress the inflow of ultra-low temperature water into the hot water storage tank 8. On the contrary, when the circulation flow rate during the hot water storage operation is relatively low, it can be estimated that the water flow rate during the second heat recovery operation is relatively low, so that the second heat recovery operation is continued for a relatively long time. However, it can be said that the extremely low temperature water does not flow into the hot water storage tank 8. Therefore, in this case, the control device 36 lengthens the time for continuing the second heat recovery operation relatively long.

During the hot water storage operation, the control device 36 detects, for example, the speed at which hot water is stored in the hot water storage tank 8 using the hot water storage temperature sensors 41, 42, 43, and is based on the detected value and the capacity of the hot water storage tank 8. Therefore, the circulation flow rate of the hot water storage circuit can be calculated. In this case, the control device 36 corresponds to the circulating flow rate calculating means.

In the first heat recovery operation, there is no problem even if the water in the first heat recovery circuit upstream of the four-way valve 16 at the confluence position flows into the hot water storage tank 8. Therefore, the control device 36 may set the upper limit time for continuing the first heat recovery operation to be longer than the upper limit time for continuing the second heat recovery operation. That is, the control device 36 may make the amount of recovered water in the first heat recovery operation larger than the amount of recovered water in the second heat recovery operation. Before the start of the first heat recovery operation, the water in the water outlet 8b, the low temperature pipe 10, the first water supply pipe 13a, and the second water supply pipe 13b upstream of the four-way valve 16 was originally a hot water storage tank. It is the water stored in 8. Therefore, in the first heat recovery operation, even if the water in the first heat recovery circuit upstream of the four-way valve 16 flows into the hot water storage tank 8, the temperature inside the hot water storage tank 8 is unlikely to drop. No problem.

In the following description, the temperature detected by the hot water storage temperature sensor 41 is referred to as "tank intermediate water temperature", and the temperature detected by the hot water storage temperature sensor 43 is referred to as "tank lower water temperature". If the water temperature in the middle part of the tank becomes equal to or lower than the water temperature in the lower part of the tank during the heat recovery operation, the control device 36 ends the heat recovery operation regardless of the upper limit time. For example, the control device 36 continues the heat recovery operation when the water temperature at the lower part of the tank is 9 ° C. and the water temperature at the middle part of the tank is 40 ° C., but when the water temperature at the lower part of the tank is 15 ° C. and the water temperature at the middle part of the tank is 10 ° C. End the recovery operation.

1 Compressor, 3 Water refrigerant heat exchanger, 4 Expansion valve, 5 Refrigerator piping, 6 Air heat exchanger, 7 HP unit, 8 Hot water storage tank, 8a Water inlet, 8b Water outlet, 8c Water inlet, 8d Hot water Introductory outlet, 8e hot water inlet, 8f medium hot water inlet, 8g medium hot water inlet, 9a first water supply pipe, 9b second water supply pipe, 9c third water supply pipe, 9d fourth water supply pipe, 10 low temperature pipe, 11 three-way Valve, 12 Circulation pump, 13a 1st water supply pipe, 13b 2nd water supply pipe, 14 HP going pipe, 15 HP return pipe, 16 4-way valve, 17a 1st hot water pipe, 17b 2nd hot water pipe, 18 4-way valve, 19a 1st 3 hot water piping, 19b 4th hot water piping, 19c 5th hot water piping, 20a piping, 20b piping, 20c piping, 21 high temperature piping, 22 hot water supply mixing valve, 23 bath mixing valve, 24 hot water supply piping, 25 bath piping, 26 Electromagnetic valve for bath, 27 Bath going pipe, 28 Bath return piping, 29 Bath circulation pump, 30 Bath, 31 Pressure reducing valve, 33 Tank unit, 34 Hot water tap, 35 Hot water storage type hot water supply device, 36 Control device, 37 Bath going temperature sensor , 38 Bath return temperature sensor, 39 Outlet temperature sensor, 40 Inflow temperature sensor, 41, 42, 43 Hot water storage temperature sensor, 44 Remote control device, 45 Bath flow sensor, 46 Water level sensor, 47 Flow switch, 50 Check valve, 51 Branch part, 52 branch part, 53 branch part, 60 bath heat exchanger, 60a primary side flow path, 60b secondary side flow path, 78 medium temperature water switching valve, 79 medium temperature piping

Claims (6)

A heating means to heat water and
A hot water storage tank capable of storing hot water heated by the heating means and having an upper portion, a lower portion, and an intermediate portion between the upper portion and the lower portion.
A heat exchanger having a primary side flow path and a secondary side flow path and exchanging heat between the primary fluid flowing through the primary side flow path and the secondary fluid flowing through the secondary side flow path.
A circuit switching means that can switch the hot and cold water circuit,
A control means capable of performing a heating operation in which the secondary fluid is heated by the primary fluid in the heat exchanger and a heat recovery operation after the heating operation.
With
The circuit switching means
A tank-utilizing heating circuit that reaches the intermediate portion of the hot water storage tank from the upper part of the hot water storage tank through the primary side flow path without passing through the heating means.
A first heat recovery circuit from the lower portion of the hot water storage tank to the intermediate portion of the hot water storage tank through the primary side flow path without passing through the heating means.
A second heat recovery circuit that reaches the intermediate portion of the hot water storage tank from the lower portion of the hot water storage tank through the heating means and the primary side flow path.
Can be switched,
When the control means executes the heat recovery operation, the first heat recovery operation causes water to flow through the first heat recovery circuit when there is no possibility that the water pipe connected to the heating means freezes. A hot water storage type hot water supply device that executes a second heat recovery operation in which water flows through the second heat recovery circuit when there is a possibility of the above. The hot water storage type hot water supply device according to claim 1, wherein the control means shortens the time for continuing the second heat recovery operation to be shorter than the time for continuing the first heat recovery operation. The hot water storage type hot water supply device according to claim 1 or 2, wherein the control means does not exceed the upper limit time for continuing the second heat recovery operation. The merging position is a position where the flow path of the second heat recovery circuit merges with the flow path of the first heat recovery circuit.
The hot water storage according to claim 3, wherein the upper limit time is a time calculated based on the volume of the flow path from the confluence position to the intermediate portion of the hot water storage tank and the water flow rate of the second heat recovery circuit. Type hot water supply device. The merging position is a position where the flow path of the second heat recovery circuit merges with the flow path of the first heat recovery circuit.
In the second heat recovery operation, in the control means, the water in the second heat recovery circuit upstream of the confluence position before the start of the second heat recovery operation is the intermediate portion of the hot water storage tank. The hot water storage type hot water supply device according to any one of claims 1 to 4, wherein the second heat recovery operation is terminated before flowing into the water. The circuit switching means can be switched to a hot water storage circuit from the lower part of the hot water storage tank to the upper part of the hot water storage tank through the heating means.
A circulation pump arranged in a flow path common to the hot water storage circuit and the second heat recovery circuit,
A circulation flow rate calculation means for calculating the circulation flow rate of the hot water storage circuit during a hot water storage operation in which hot water heated by the heating means is stored in the hot water storage tank.
With
The hot water storage type hot water supply device according to any one of claims 1 to 5, wherein the control means changes the time for continuing the second heat recovery operation according to the circulating flow rate.

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