JP6129133B2 - Solar water heater and control method for solar water heater - Google Patents

Description

  The present invention relates to a solar water heater which is a water heater connected to a solar heat collector.

The solar water heater can warm the tank water stored in the hot water storage tank using the water heated by the solar heat collector. However, the solar heat collector may not be used depending on the weather, and in that case, the tank water is heated by another heat source device such as a heat pump device.
A hot water supply device such as a solar heat water supply device is provided with a protection function for preventing the tank water from becoming excessively hot. Unlike other heat source devices, the solar heat collector cannot arbitrarily adjust the heating capacity. Therefore, the water supplied from the solar heat collector may become a high temperature exceeding 90 ° C. In this case, the tank water may become locally hot. Then, although the tank water does not reach the target temperature as a whole, the operation for heating the tank water is stopped by the protection function.

  Patent Document 1 describes that the flow rate is reduced when the temperature of water supplied from a solar heat collector becomes high. Patent Document 2 describes that the water circuit on the solar heat collector side and the water circuit on the hot water supply apparatus side are separated by a three-way valve.

JP 2012-93061 A JP 2010-175143 A

In the techniques described in Patent Documents 1 and 2, when the water supplied from the solar heat collector becomes high temperature, it becomes impossible to heat the tank water using the solar heat collector, or The rate at which tank water is heated using a solar heat collector will be significantly reduced.
An object of the present invention is to continue operation using a solar heat collector as much as possible while avoiding that the operation of heating tank water is stopped by the protection function.

The solar water heater according to this invention is
A first heat exchanger that heats the tank water by exchanging heat between the first fluid heated by the solar heat collector and the tank water stored in the hot water storage tank;
A forward pipe that is radiated by the first heat exchanger and through which the first fluid directed to the solar heat collector flows;
A branch pipe branched from the forward pipe and a part of the first fluid flowing through the forward pipe;
A return pipe through which the first fluid heated by the solar heat collector flows;
A merging device for merging the first fluid flowing through the return pipe and the first fluid flowing through the branch pipe;
A return merging pipe that joins at the merging device and flows through the first fluid toward the first heat exchanger;
A supply temperature detector that detects the temperature of the first fluid flowing through the return junction pipe as a supply temperature;
The merging device is controlled according to the supply temperature detected by the supply temperature detection unit, and the first fluid flowing through the return pipe and the first fluid flowing through the branch pipe in the first fluid flowing through the return merging pipe. A ratio control unit for adjusting the ratio.

In this invention, the ratio of the 1st fluid which flows through the return piping in the 1st fluid which merged, and the 1st fluid which flows through the branch piping is adjusted according to supply temperature. By adjusting this ratio, the temperature of the first fluid flowing into the first heat exchanger can be prevented from becoming excessively high, and the tank water can be prevented from becoming locally high.
As a result, it is possible to avoid stopping the operation for heating the tank water by the protection function. In addition, since the first fluid is continuously supplied to the first heat exchanger, the operation using the solar heat collector can be continued.

1 is a configuration diagram of a solar hot water supply device 100 according to Embodiment 1. FIG. FIG. 3 is a configuration diagram of a solar circuit 63 according to the first embodiment. FIG. 3 is a configuration diagram of a control device 50 according to the first embodiment. 5 is a flowchart showing the operation of the control device 50 according to the first embodiment. FIG. 5 is a diagram illustrating an example of a mixing ratio according to the first embodiment. The figure which shows the example different from FIG. 5 of the mixing ratio which concerns on Embodiment 1. FIG.

Embodiment 1 FIG.
*** Explanation of configuration ***
FIG. 1 is a configuration diagram of a solar hot water supply apparatus 100 according to the first embodiment.
The solar water heater 100 includes an outdoor unit 10, an indoor unit 20, a solar system 40, and a control device 50.

The outdoor unit 10 includes a compressor 11 that compresses the refrigerant 81, an expansion valve 12 that expands the refrigerant 81, and an outside air-refrigerant heat exchanger 13 that exchanges heat between the outside air and the refrigerant 81.
The compressor 11, the refrigerant-fluid heat exchanger 21 included in the indoor unit 20, the expansion valve 12, and the outside air-refrigerant heat exchanger 13 are sequentially connected by piping, and a refrigerant circuit 61 in which the refrigerant 81 circulates is configured. The That is, the compressor 11, the refrigerant-fluid heat exchanger 21, the expansion valve 12, and the outside air-refrigerant heat exchanger 13 constitute a heat pump device 70 serving as a heat source device.

The indoor unit 20 includes a refrigerant-fluid heat exchanger 21 that exchanges heat between the refrigerant 81 and the second fluid 83 such as water, an auxiliary heater 22 that supplementarily heats the second fluid 83 as necessary, and a second A pump 23 for circulating the fluid 83 and a hot water storage tank 30 for storing water are provided. Hereinafter, the water stored in the hot water storage tank 30 is referred to as tank water 84.
The hot water storage tank 30 includes a first heat exchanger 31 and a second heat exchanger 32 for heating the tank water 84, and a tank temperature detection unit 33 that is a sensor for detecting the temperature of the tank water 84. Is provided. The first heat exchanger 31 heats the tank water 84 by exchanging heat between the first fluid 82 heated by solar heat in the solar heat collector 42 and the tank water 84 stored in the hot water storage tank 30. The second heat exchanger 32 heats the tank water 84 by exchanging heat between the second fluid 83 heated by the heat pump device 70 and the tank water 84 stored in the hot water storage tank 30.
The pump 23, the refrigerant-fluid heat exchanger 21, the auxiliary heater 22, and the second heat exchanger 32 are sequentially connected by piping, and a fluid circuit 62 in which the second fluid 83 circulates is configured.

  The indoor unit 20 flows between the second heat exchanger 32 and the pump 23 in the fluid circuit 62, the flow sensor 24 that detects the flow rate of the second fluid 83 circulating in the fluid circuit 62, and the fluid circuit 62. And a strainer 25 for discharging dust and the like. In addition, the indoor unit 20 includes a pressure relief valve 26 for reducing the pressure of the fluid circuit 62, an air vent valve 27 for venting the air in the fluid circuit 62, and a fluid circuit in a pipe branched from the vicinity of the auxiliary heater 22. And an expansion tank 28 for temporarily storing surplus water circulating in 62.

  A pipe 34 for supplying tank water 84 to a sanitary facility such as a shower is connected to the upper part of the hot water storage tank 30, and the tank water 84 is supplied to the hot water storage tank 30 from the water supply at the lower part of the hot water storage tank 30. For this purpose, a pipe 35 is connected. A discharge port 36 for discharging the tank water 84 is provided in the lower part of the hot water storage tank 30.

The solar system 40 includes a solar kit 41, a solar heat collector 42 that is a solar panel, and a three-way valve 43 that is a junction device 71. The solar kit 41 includes a pump 44 for circulating the first fluid 82 such as water.
The pump 44, the solar heat collector 42, the three-way valve 43, and the first heat exchanger 31 are sequentially connected by piping, and the solar circuit 63 in which the first fluid 82 circulates is configured.

  FIG. 2 is a configuration diagram of the solar circuit 63 according to the first embodiment.

The solar circuit 63 includes a forward pipe 64, a branch pipe 65, a return pipe 66, a return pipe as pipes connecting the pump 44, the solar heat collector 42, the three-way valve 43, and the first heat exchanger 31. And a junction pipe 67.
The forward pipe 64 is a pipe connecting the first heat exchanger 31 and the solar heat collector 42, and the first fluid 82 that radiates heat in the first heat exchanger 31 and moves toward the solar heat collector 42 flows. The branch pipe 65 branches from a branch point 68 in the middle of the forward pipe 64 and is connected to the three-way valve 43, and a part of the first fluid 82 that flows through the forward pipe 64 flows. The return pipe 66 is a pipe connecting the solar heat collector 42 and the three-way valve 43, and the first fluid 82 heated by the solar heat collector 42 flows through the return pipe 66. The first fluid 82 flowing through the branch pipe 65 and the first fluid 82 flowing through the return pipe 66 merge at the three-way valve 43. The return merge pipe 67 is a pipe connecting the three-way valve 43 and the first heat exchanger 31. The return merge pipe 67 merges at the three-way valve 43, which is the merge device 71, and the first fluid 82 toward the first heat exchanger 31 flows. .
The solar circuit 63 includes a supply temperature detection unit 45 that detects the temperature of the first fluid 82 that flows through the return junction pipe 67 as a supply temperature TS, and the temperature of the first fluid 82 that flows through the return pipe 66 as a return temperature TB. A return temperature detection unit 46 for detection is provided.

FIG. 3 is a configuration diagram of the control device 50 according to the first embodiment.
When the tank water 84 becomes excessively hot, the control device 50 stops only the operation control unit 51 that stops the operation of heating the tank water 84 and only a part of the tank water 84 in the hot water storage tank 30. Therefore, it has an avoidance unit 52 for avoiding that the operation of heating the tank water 84 is stopped by the operation control unit 51.
The operation control unit 51 stops the operation of the compressor 11 of the outdoor unit 10 and the operation of the pump 44 of the solar kit 41 when the temperature of the tank water 84 detected by the tank temperature detection unit 33 exceeds the reference value. For example, the operation of heating the tank water 84 is stopped.
The avoidance unit 52 includes a supply temperature acquisition unit 53 and a ratio control unit 54. The supply temperature acquisition unit 53 acquires the supply temperature TS detected by the supply temperature detection unit 45. The ratio control unit 54 controls the three-way valve 43 that is the merging device 71 based on the supply temperature TS acquired by the supply temperature acquisition unit 53, and flows through the return pipe 66 in the first fluid 82 that flows through the return merging pipe 67. The mixing ratio of the first fluid 82 and the first fluid 82 flowing through the branch pipe 65 is adjusted. The ratio control unit 54 controls the temperature of the first fluid 82 flowing into the first heat exchanger 31 by adjusting the mixing ratio.

*** Explanation of operation ***
The basic operation of solar water heating apparatus 100 according to Embodiment 1 will be described.
As shown in FIG. 1, in the refrigerant circuit 61, the high-temperature / high-pressure refrigerant 81 discharged from the compressor 11 flows into the refrigerant-fluid heat exchanger 21. Then, the refrigerant-fluid heat exchanger 21 exchanges heat between the refrigerant 81 and the second fluid 83, the refrigerant 81 is cooled, and the second fluid 83 is heated. The cooled refrigerant 81 passes through the expansion valve 12, is decompressed, and flows into the outside air-refrigerant heat exchanger 13. Then, heat is exchanged between the refrigerant 81 and the outside air in the outside air-refrigerant heat exchanger 13, and the refrigerant 81 is heated. The heated refrigerant 81 is compressed by the compressor 11 and becomes a high-temperature / high-pressure refrigerant 81 again.
The second fluid 83 heated by the refrigerant-fluid heat exchanger 21 is further heated by the auxiliary heater 22 as necessary. And the 2nd fluid 83 is heat-exchanged with the tank water 84 by the 2nd heat exchanger 32, the 2nd fluid 83 is cooled, and the tank water 84 is heated. The cooled second fluid 83 is heated again by the refrigerant-fluid heat exchanger 21 via the pump 23 and the like.
That is, the tank water 84 stored in the hot water storage tank 30 is heated by the second fluid 83 heated by the heat pump device 70 in the second heat exchanger 32.

If the solar system 40 can be used, the pump 44 operates and the first fluid 82 circulates through the solar circuit 63.
In the solar circuit 63, the first fluid 82 heated by solar heat in the solar heat collector 42 flows into the first heat exchanger 31. Then, the first fluid 82 and the tank water 84 are subjected to heat exchange in the first heat exchanger 31, the first fluid 82 is cooled, and the tank water 84 is heated. The cooled first fluid 82 again flows into the solar heat collector 42 via the pump 44 and is heated.
That is, the tank water 84 stored in the hot water storage tank 30 is heated by the first fluid 82 heated by the solar heat collector 42 in the first heat exchanger 31.

  With the above operation, the tank water 84 is gradually heated until the temperature of the tank water 84 detected by the tank temperature detection unit 33 reaches a preset target temperature. Then, the tank water 84 that has reached the target temperature is supplied from the pipe 34 to the sanitary equipment. Further, when the tank water 84 is reduced, the tank water 84 is supplied from the pipe 35.

  When the solar system 40 can be used, the tank water 84 is heated using the heat pump device 70 and the solar system 40 in combination. However, the solar system 40 may not be used depending on the weather. When the solar system 40 cannot be used, the tank water 84 is heated only by the heat pump device 70.

As described above, the operation control unit 51 of the control device 50 stops the operation of heating the tank water 84 when the temperature of the tank water 84 detected by the tank temperature detection unit 33 exceeds the reference value. The operation control unit 51 works not only when the tank water 84 is heated only by the outdoor unit 10 but also when the tank water 84 is heated together with the solar system 40.
The first fluid 82 heated by the solar heat collector 42 may become a high temperature such as over 90 ° C. In this case, as a result of heat exchange between the first fluid 82 and the tank water 84 in the second heat exchanger 32, the tank water 84 locally becomes hot. Then, the operation control unit 51 operates, and there is a possibility that the operation of the solar hot water heater 100 is stopped. That is, although the tank water 84 in the hot water storage tank 30 does not reach the target temperature as a whole, only a part of the tank water 84 in the hot water storage tank 30 has become hot, so the solar water heater 100 Will be stopped.
The avoidance unit 52 of the control device 50 performs an operation to avoid the operation control unit 51 from stopping the operation of the solar water heater 100 when the first fluid 82 becomes high temperature.

Operation | movement of the avoidance part 52 of the control apparatus 50 is demonstrated.
As shown in FIG. 2, in the solar circuit 63, the first fluid 82 heated by solar heat by the solar heat collector 42 flows through the return pipe 66. Then, in the three-way valve 43, the first fluid 82 flowing through the return pipe 66 and the first fluid 82 flowing through the branch pipe 65 join together, flow through the return joint pipe 67, and flow into the first heat exchanger 31. The first heat exchanger 31 exchanges heat between the first fluid 82 and the tank water 84. Then, the first fluid 82 heat-exchanged with the tank water 84 by the first heat exchanger 31 flows through the outgoing pipe 64. A part of the first fluid 82 flowing through the outgoing pipe 64 branches and flows to the branch pipe 65 at the branch point 68, and the rest flows into the solar heat collector 42 and is heated.
The supply temperature acquisition unit 53 of the avoidance unit 52 acquires the supply temperature TS detected by the supply temperature detection unit 45. And the ratio control part 54 is based on the supply temperature TS acquired by the supply temperature acquisition part 53, the opening degree by the side of the return pipe 66 of the three-way valve 43 which is the junction apparatus 71, and the opening degree by the side of the branch pipe 65 And the mixing ratio of the first fluid 82 flowing through the return pipe 66 and the first fluid 82 flowing through the branch pipe 65 in the first fluid 82 flowing through the return junction pipe 67 is adjusted.
The first fluid 82 flowing through the branch pipe 65 is radiated by the first heat exchanger 31 and has a low temperature. Therefore, the temperature of the first fluid 82 flowing through the return junction pipe 67 can be adjusted by adjusting the mixing ratio. By adjusting the temperature of the first fluid 82 flowing through the return junction pipe 67, the temperature of the first fluid 82 flowing into the first heat exchanger 31 can be prevented from becoming high. As a result, it is possible to avoid stopping the operation of the solar water heater 100 due to the protection function.

FIG. 4 is a flowchart showing the operation of the avoidance unit 52 according to the first embodiment.
When the pump 44 operates and the first fluid 82 starts to circulate, the supply temperature acquisition unit 53 acquires the supply temperature TS detected by the supply temperature detection unit 45 (S1). Ratio control unit 54, the supply temperature TS acquired in S1, compared theta ₂ to the first threshold value theta ₁ and the second threshold value (S2).
Feed temperature TS is of less than the second threshold value theta ₂ first threshold value theta ₁ or more, the rate control unit 54 advances the process to S3. If the supply temperature TS is in the first threshold value θ _1, less than the rate control unit 54 advances the process to S4. Feed temperature TS is in the second threshold value theta ₂ or more, the rate control unit 54 advances the process to S5.

If the supply temperature TS is the second threshold value theta less than ₂ first threshold value theta ₁ or more in S2, the rate control unit 54, as the feed temperature TS rises, the proportion of the first fluid 82 flowing through the branch pipe 65 is increased, the return The three-way valve 43 which is the merging device 71 is controlled so that the ratio of the first fluid 82 flowing through the pipe 66 is reduced (S3). By controlling in this way, the temperature of the first fluid 82 flowing through the return junction pipe 67 can be kept substantially constant.

If the supply temperature TS is in the first threshold value θ less than ₁ in S2, the rate control unit 54, to flow merging pipe 67 by a first fluid 82 flowing in the return line 66 returns the three-way valve 43 is a merging device 71 Control (S4). That is, the ratio control unit 54 closes the mouth of the three-way valve 43 on the branch pipe 65 side. By controlling in this way, the temperature of the first fluid 82 flowing through the return junction pipe 67 is prevented from becoming unnecessarily low.

If the supply temperature TS is the second threshold value theta ₂ or more S2, the rate control unit 54, to flow merging pipe 67 by a first fluid 82 flowing through the branch pipe 65 is returned, the three-way valve 43 is a merging device 71 Control (S5). That is, the ratio control unit 54 closes the mouth of the three-way valve 43 on the return pipe 66 side. By controlling in this way, the temperature of the first fluid 82 flowing through the return junction pipe 67 is prevented from becoming excessively high.

When the port on the return pipe 66 side of the three-way valve 43 is closed in S5, the supply temperature acquisition unit 53 acquires the return temperature TB detected by the return temperature detection unit 46 (S6). Then, the ratio control unit 54, return temperature TB is determined whether a third less than the threshold value theta ₃ (S7), if the return temperature TB is lower than the third threshold value theta _3, the three-way valve 43 the return line The opening on the 66 side is opened, and the first fluid 82 that has flowed through the return pipe 66 is also allowed to flow into the return junction pipe 67 (S8). Return temperature TB is in the case where the third threshold value theta ₃ above, the process of re-S6 after a predetermined time has elapsed is performed.

  After the processes of S3, S4, and S8, the process of S1 is executed again with a certain time interval. The certain time interval is the time taken for the three-way valve 43 to be controlled, the mixing ratio to change, and the supply temperature TS to stabilize.

Here, the first threshold value θ ₁ and the second threshold value θ ₂ can be determined as follows.
The first threshold θ ₁ may be an operating temperature that is the temperature of the tank water 84 on which the operation control unit 51 operates. That is, if the operation controller 51 operates to stop the operation of heating the tank water 84 when the tank water 84 becomes 90 ° C. or higher, the first threshold θ ₁ may be about 90 ° C. This is because if the supply temperature TS is lower than the operating temperature, the temperature of the tank water 84 does not exceed the operating temperature because the tank water 84 is heated by the first heat exchanger 31.
The second threshold value θ ₂ circulates through the solar circuit 63 controlled by the pump length of the indoor unit 20, the position of the tank temperature detection unit 33 in the hot water storage tank 30, the position of the first heat exchanger 31, and the pump 44. It is influenced by the flow rate of the first fluid 82 and the like. Therefore, it is not possible to make a general decision. However, the second threshold value θ ₂ is, for example, the temperature of the tank water 84 detected by the tank temperature detection unit 33 even if the supply temperature TS rises to a reference temperature, even if the temperature is less than 100 ° C. A reference temperature that does not increase to a temperature at which the can operate may be used.
The third threshold θ ₃ may be a temperature slightly higher than the second threshold θ ₂ .

FIG. 5 is a diagram illustrating an example of the mixing ratio according to the first embodiment.
The mixing ratio in FIG. 5 means the ratio of the first fluid 82 that has flowed through the return pipe 66 in the first fluid 82 that flows through the return merging pipe 67. That is, when the mixing ratio is 100%, it means that the ratio of the first fluid 82 that has flowed through the return pipe 66 in the first fluid 82 that flows through the return merge pipe 67 is 100%. When the mixing ratio is 0%, it means that the ratio of the first fluid 82 that has flowed through the return pipe 66 in the first fluid 82 that flows through the return merge pipe 67 is 0%.
If the supply temperature TS is in the first threshold value θ less than _1, the mixing ratio of 100%. If the supply temperature TS is in the first threshold value theta ₁ or more second threshold theta less than _2, in accordance with the supply temperature TS approaches the first threshold value theta ₁ to the second threshold value theta _2, the mixing ratio is gradually decreased linearly. If the supply temperature TS is the second threshold value theta ₂ or more, the mixing ratio is 0%.

FIG. 6 is a diagram showing an example different from FIG. 5 of the mixing ratio according to the first embodiment.
In FIG. 6, as in FIG. 5, the mixing ratio means the ratio of the first fluid 82 that has flowed through the return pipe 66 in the first fluid 82 that flows through the return junction pipe 67.
If the supply temperature TS is in the first threshold value theta less than _1, and the supply temperature TS is in the case of the second threshold value theta ₂ or more, the same as in FIG. When the supply temperature TS is greater than or equal to the first threshold θ _{1 and} less than the second threshold θ ₂ , the mixing ratio decreases step by step as the supply temperature TS approaches the second threshold θ ₂ from the first threshold θ ₁ .

*** Explanation of effects ***
As described above, in the solar water heating apparatus 100 according to Embodiment 1, the ratio of the fluid flowing through the return pipe 66 and the fluid flowing through the branch pipe 65 is adjusted in accordance with the supply temperature TS. By adjusting this ratio, the temperature of the fluid flowing into the first heat exchanger 31 can be prevented from becoming excessively high, and the tank water 84 can be prevented from becoming locally high.
As a result, it is possible to prevent the operation of heating the tank water 84 from being stopped by the operation control unit 51 even though the tank water 84 has not reached the target temperature as a whole. In addition, since the first fluid 82 continues to be supplied to the first heat exchanger 31, the operation using the solar heat collector 42 can be continued.

Moreover, it replaces with the process of S2 to S5 of FIG. 4, and the ratio control part 54 may control the three-way valve 43 so that supply temperature TS may enter into a certain temperature range.
Specifically, when the supply temperature TS is within the temperature range, the ratio control unit 54 keeps the opening degree of each port of the three-way valve 43 as it is. When the supply temperature TS is higher than the upper limit of the temperature range, the ratio control unit 54 controls the three-way valve 43 so that the ratio of the first fluid 82 flowing through the return pipe 66 decreases, and the supply temperature TS is the temperature. Try to be in range. On the other hand, when the supply temperature TS is lower than the lower limit of the temperature range, the ratio control unit 54 controls the three-way valve 43 so that the ratio of the first fluid 82 flowing through the return pipe 66 is increased, thereby supplying the supply temperature TS. To be in the temperature range.

In the above description, the name indoor unit 20 is used. However, the indoor unit 20 may not be installed indoors but may be installed outdoors.
In the above description, the three-way valve 43 is used as the junction device 71. However, the merging device 71 may be configured by, for example, a combination of valves instead of the three-way valve 43.

  DESCRIPTION OF SYMBOLS 100 Solar hot water supply apparatus, 10 Outdoor unit, 11 Compressor, 12 Expansion valve, 13 Outside air-refrigerant heat exchanger, 20 Indoor unit, 21 Refrigerant-fluid heat exchanger, 22 Auxiliary heater, 23 Pump, 24 Flow sensor, 25 Strainer , 26 Pressure relief valve, 27 Air vent valve, 28 Expansion tank, 30 Hot water storage tank, 31 1st heat exchanger, 32 2nd heat exchanger, 33 Tank temperature detection part, 34, 35 Piping, 36 outlet, 40 Solar system , 41 Solar kit, 42 Solar collector, 43 Three-way valve, 44 Pump, 45 Supply temperature detection unit, 46 Return temperature detection unit, 50 Control device, 51 Operation control unit, 52 Avoidance unit, 53 Supply temperature acquisition unit, 54 Ratio control unit, 61 refrigerant circuit, 62 fluid circuit, 63 solar circuit, 64 forward piping, 65 branch piping 66 return line 67 returns converging tube, 70 heat pump unit, 71 merging device 81 refrigerant, 82 first fluid, 83 second fluid, 84 tank water.

Claims (9)

A first heat exchanger that heats the tank water by exchanging heat between the first fluid heated by the solar heat collector and the tank water stored in the hot water storage tank;
A forward pipe that is radiated by the first heat exchanger and through which the first fluid directed to the solar heat collector flows;
A branch pipe branched from the forward pipe and a part of the first fluid flowing through the forward pipe;
A return pipe through which the first fluid heated by the solar heat collector flows;
A merging device for merging the first fluid flowing through the return pipe and the first fluid flowing through the branch pipe;
A return merging pipe that joins at the merging device and flows through the first fluid toward the first heat exchanger;
A supply temperature detector that detects the temperature of the first fluid flowing through the return junction pipe as a supply temperature;
The merging device is controlled according to the supply temperature detected by the supply temperature detection unit, and the first fluid flowing through the return pipe and the first fluid flowing through the branch pipe in the first fluid flowing through the return merging pipe. A solar hot water supply apparatus provided with the control apparatus which adjusts a mixing ratio. The said control apparatus controls the said confluence | merging apparatus so that the ratio of the 1st fluid which flows through the said branch piping increases, so that the said supply temperature becomes high, when the said supply temperature is more than 1st threshold value and less than 2nd threshold value. Item 2. The solar water heater according to Item 1. The said control apparatus is a solar hot water supply of Claim 2 which controls the said confluence | merging apparatus so that only the 1st fluid which flows through the said return piping flows through the said return merging pipe when the said supply temperature is less than the said 1st threshold value. apparatus. 4. The control device according to claim 2, wherein when the supply temperature is equal to or higher than the second threshold, the control device controls the merging device such that only the first fluid flowing through the branch pipe flows through the return merging pipe. Solar water heater. As the supply temperature approaches the second threshold value from the first threshold value, the control device linearly decreases the ratio of the first fluid flowing through the return pipe in the first fluid flowing through the return merge pipe. To control the merging device
The solar-powered hot-water supply apparatus of Claim 2. As the supply temperature approaches the second threshold value from the first threshold value, the control device gradually decreases the ratio of the first fluid flowing through the return pipe in the first fluid flowing through the return merge pipe. To control the merging device
The solar-powered hot-water supply apparatus of Claim 2. The solar water heater further includes:
A heat pump device for heating the second fluid;
The solar hot water supply apparatus of any one of Claim 1-6 provided with the 2nd heat exchanger which heats the said tank water with the said 2nd fluid heated with the said heat pump apparatus. The solar water heater further includes:
A tank temperature detector for detecting the temperature of the tank water;
Wherein the control device, when the temperature of the tank water the tank temperature detecting section detects exceeds the reference value, according to any one of claims 1 to 7 for stopping the operation for heating the tank water Solar water heater. A first heat exchanger that heats the tank water by exchanging heat between the first fluid heated by the solar heat collector and the tank water stored in the hot water storage tank;
A forward pipe that is radiated by the first heat exchanger and through which the first fluid directed to the solar heat collector flows;
A branch pipe branched from the forward pipe and a part of the first fluid flowing through the forward pipe;
A return pipe through which the first fluid heated by the solar heat collector flows;
A merging device for merging the first fluid flowing through the return pipe and the first fluid flowing through the branch pipe;
A control method for a solar water heater comprising a return merging pipe that joins at the merging device and flows a first fluid toward the first heat exchanger;
A supply temperature detection step of detecting the temperature of the first fluid flowing through the return junction pipe as a supply temperature;
The merging device is controlled according to the supply temperature detected in the supply temperature detecting step, and the first fluid flowing through the return pipe and the first fluid flowing through the branch pipe in the first fluid merged by the merging device. A control method for a solar water heater, comprising: a ratio control step of adjusting a mixing ratio.

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