JP2013079752A - Heat pump water heater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently prevent freezing of a plurality of pipes without installing a heater for antifreezing at each part of the pipes.SOLUTION: An antifreezing bypass pipe 40 is connected between a mixing hot water supply pipe 5 and a four-way valve 31 of this heat pump water heater. An antifreezing circulation water passage 49 is constituted of a lower part of a hot water storage tank 10, a part of a water supply pipe 2, a water supply branch pipe 4, a hot water supply mixing valve 6, the mixing hot water supply pipe 5, the antifreezing bypass pipe 40, the four-way valve 31, a circulation pump 21, a heat pump inlet pipe 41, a boiling heat exchanger 62, a heat pump outlet pipe 42, a four-way valve 32, and a tank return pipe 44. When an execution condition for antifreezing operation is achieved, while the four-way valve 31 is switched to an a-d route and the second four-way valve 32 is switched to a c-a route, the circulation pump 21 is operated. Thus, freezing of water at each part of the antifreezing circulation water passage 49 can be prevented.

Description

  The present invention relates to a heat pump water heater, and more particularly, to a heat pump water heater having a function of preventing piping from freezing.

  As a prior art, for example, as described in Patent Document 1, a heat pump water heater provided with a heater for preventing freezing is known. In the prior art, when a hot water heater is used in a low temperature environment such as a cold region or in winter, the heater is operated to prevent freezing of the water supply pipe or the hot water supply pipe.

  As another conventional technique, as described in Patent Document 2, a bypass pipe is provided for returning the hot water flowing into the upper part of the hot water storage tank to the lower part of the tank, and the bypass pipe is connected to the water supply pipe. What was done is also known. In this prior art, a part of the bypass circulation path passing through the bypass pipe and the water supply pipe are shared, and the hot water taken out from the hot water storage tank is circulated to the water supply pipe via the bypass pipe, thereby freezing the water supply pipe. Try to prevent.

JP 2004-271102 A Japanese Patent No. 4368846

  However, in the prior art of Patent Document 1, in order to prevent the pipe from being frozen only by the heater, it is necessary to arrange the heaters at a plurality of places where there is a possibility of freezing. As a result, there is a problem that the total power consumption of the heater increases and the economic efficiency of the water heater is impaired. Moreover, in the prior art of patent document 2, although it becomes possible to prevent freezing of a water supply piping by distribute | circulating the hot water taken out from the hot water storage tank to a water supply piping via a bypass piping, other than water supply piping is used. Hot water does not circulate in the piping (hot water supply piping or branch piping). For this reason, even in the prior art of Patent Document 2, it is necessary to provide a heater for preventing freezing in other piping portions where hot water does not circulate, and there is a problem that power consumption for preventing freezing increases.

  The present invention has been made in order to solve the above-described problems, and it is possible to efficiently prevent freezing of a plurality of pipes without installing freezing prevention heaters in the respective parts of the pipes. It aims at providing the heat pump water heater which can reduce power consumption and can improve economical efficiency.

  A heat pump water heater according to the present invention includes a hot water storage tank for storing hot water, a heating heat exchanger for heating water in the hot water storage tank, one end side connected to a lower part of the hot water storage tank, and the other end side for heating heat. Boiling piping connected to the upper part of the hot water storage tank via the exchanger and water extracted from the lower part of the hot water storage tank are connected to the hot water storage tank via the heating heat exchanger. Mixing the circulation pump that returns to the upper part, the water supply pipe that supplies water to the lower part of the hot water storage tank, the water supply branch pipe that branches off from the water supply pipe, and the hot water taken out from the upper part of the hot water storage tank and the cold water supplied from the water supply branch pipe A mixing valve that generates hot water with adjusted hot water temperature, a mixed hot water supply pipe that supplies hot water whose temperature has been adjusted by the mixing valve to the outside, one end branching from the mixed hot water supply pipe, and the other end is heated for boiling Exchanger and circulation pump Freezing prevention bypass piping connected to the piping for boiling on the upstream side, opening / closing means for opening and closing the anti-freezing bypass piping, opening the freezing prevention bypass piping by the opening / closing means, and driving the circulation pump Freezing prevention that performs freeze prevention operation to distribute the water taken out from the lower part of the tank to the freeze prevention circulation waterway including at least part of the water supply pipe, water supply branch pipe, mixed hot water supply pipe, freeze prevention bypass pipe and boiling pipe Control means.

  According to the present invention, a freeze prevention circulation water channel is constituted by a plurality of pipes, valves, pumps, etc. including at least a boiling pipe, a water supply pipe, a water supply branch pipe, a mixed hot water supply pipe, etc., and a temperature environment in which there is a possibility of freezing Then, it is possible to prevent freezing of each part by flowing water through the freeze prevention circulation channel. Therefore, it is possible to easily prevent the freezing of a large number of pipes with one freezing prevention circulation water channel without installing freezing prevention heaters in each part of the pipes. Can be made.

In Embodiment 1 of this invention, it is a whole block diagram which shows the structure of a heat pump water heater. It is operation | movement explanatory drawing which shows the standby state of a heat pump water heater. It is operation | movement explanatory drawing which shows the starting operation of a heat pump water heater. It is operation | movement explanatory drawing which shows the boiling independent operation | movement of a heat pump water heater. It is operation | movement explanatory drawing which shows the reheating operation of a heat pump water heater. It is operation | movement explanatory drawing which shows the hot water supply driving | operation of a heat pump water heater. It is operation | movement explanatory drawing which shows the freeze prevention driving | operation of a heat pump water heater. It is operation | movement explanatory drawing which shows the freeze prevention driving | operation of heat pump piping.

Embodiment 1 FIG.
Hereinafter, Embodiment 1 of the present invention will be described with reference to FIGS. In each drawing, common elements are denoted by the same reference numerals, and redundant description is omitted. FIG. 1 is an overall configuration diagram showing the configuration of a heat pump water heater in Embodiment 1 of the present invention. The water heater according to the present embodiment includes a tank unit 1 in which various parts and pipes described later are incorporated, and a heat pump unit 60. These units 1 and 60 are connected to each other by a heat pump inlet pipe 41 and a heat pump outlet pipe 42.

  First, the heat pump unit 60 will be described. The heat pump unit 60 heats the low-temperature water introduced from the tank unit 1. The heat pump unit 60 includes devices such as a compressor 61, a boiling heat exchanger 62, an expansion valve 63, an air heat exchanger 64, and a refrigerant circulation pipe 65. These devices are connected in a ring shape using a refrigerant circulation pipe 65 to constitute a refrigeration cycle. An example of this refrigeration cycle includes a supercritical heat pump cycle using carbon dioxide as a refrigerant. Since the heat pump unit 60 uses carbon dioxide as a refrigerant, the low-temperature water introduced from the tank unit 1 can be boiled to a high temperature of about 90 ° C. without using an electric heater.

  The boiling heat exchanger 62 performs heat exchange between the low-temperature water introduced from the tank unit 1 and the refrigerant flowing through the refrigerant circulation pipe 65. Thereby, the boiling heat exchanger 62 can heat (boiling) water in the hot water storage tank 10 described later. The boiling heat exchanger 62 includes a water inlet through which low-temperature water flows from the tank unit 1 to the boiling heat exchanger 62, and a water outlet through which water flows out from the boiling heat exchanger 62. Yes.

  The heat pump unit 60 includes an HP outlet side thermistor 66, an HP inlet thermistor 67, and an outside temperature thermistor 69. The HP outlet-side thermistor 66 is provided in the heat pump outlet pipe 42 and detects the temperature of the high-temperature water heated by the boiling heat exchanger 62 (high-temperature water flowing through the heat pump outlet pipe 42). The HP inlet thermistor 67 is provided in the heat pump inlet pipe 41 and detects the temperature of the low-temperature water flowing into the boiling heat exchanger 62 (low-temperature water flowing through the heat pump inlet pipe 41). The outside air temperature thermistor 69 detects the outside air temperature around the heat pump unit 60. These thermistors 66, 67, and 69 constitute a temperature sensor that detects the atmospheric temperature of the water heater as will be described later.

  Next, the configuration of the tank unit 1 will be described. The tank unit 1 includes a hot water storage tank 10 that stores hot water. The hot water storage tank 10 is configured such that high-temperature water heated by the heat pump unit 60 flows from the upper part of the tank, and low-temperature water obtained by water supply or the like flows from the lower part of the tank. As a result, hot water is stored in the hot water storage tank 10 so that a temperature difference occurs between the upper part and the lower part in the tank. Further, remaining hot water thermistors 11 and 12 for detecting the temperature distribution of hot water in the hot water storage tank 10 are provided on the upper surface and the lower surface of the hot water storage tank 10.

  The tank unit 1 also includes a water supply pipe 2, a hot water supply pipe 3, a water supply branch pipe 4, a mixed hot water supply pipe 5, a hot water supply mixing valve 6, and the like. The water supply pipe 2 is branched from the water pipe and connected to the lower part of the hot water storage tank 10, and always supplies tap water to the hot water storage tank 10. Since the supply pressure from the city water varies depending on the region, a pressure reducing valve 7 is connected in the middle of the water supply pipe 2, and the pressure reducing valve 7 keeps the pressure applied to the hot water storage tank 10 at a certain value or less. The hot water supply pipe 3 takes out high-temperature water stored on the upper side of the hot water storage tank 10, and one end thereof is connected to the upper part of the hot water storage tank 10. The other end of the hot water supply pipe 3 is connected to the b port of the hot water supply mixing valve 6. One end side of the water supply branch pipe 4 branches from the middle of the water supply pipe 2, and the other end side is connected to the a port of the hot water supply mixing valve 6. The mixed hot water supply pipe 5 supplies hot water whose temperature is adjusted by the hot water supply mixing valve 6 to an external supply destination (faucet 80, shower, etc.), one end of which is connected to the c port of the hot water supply mixing valve 6. Yes.

  The hot water mixing valve 6 generates hot water with adjusted temperature by mixing the high temperature water supplied from the hot water supply pipe 3 and the low temperature water supplied from the water supply branch pipe 4 while adjusting the flow rate ratio between them. Then, this hot water is supplied to the mixed hot water supply pipe 5. The hot water mixing valve 6 is constituted by an electromagnetically driven three-way valve or the like, and is controlled by a control unit 70 described later. The hot water supply mixing valve 6 has a function of supplying hot water at the temperature of the low temperature water by setting the flow rate of the low temperature water to the maximum and setting the flow rate of the high temperature water to the minimum. By setting the flow rate of low-temperature water to the minimum, the function of supplying hot water at the temperature of high-temperature water is provided. The mixed hot water supply pipe 5 includes a hot water supply flow rate sensor 8 that detects a flow rate of hot water (hot water supply flow rate) supplied to the outside via the mixed hot water supply pipe 5 and a hot water supply that detects the temperature of the hot water flowing through the mixed hot water supply pipe 5. A piping thermistor 9 is provided. The feed water pipe 2 is provided with a feed water thermistor 15 for detecting the feed water temperature. It is desirable that the water supply pipe thermistor 15 be attached to a portion where the water temperature of the water supply pipe 2 is lowest.

  On the other hand, the tank unit 1 uses high-temperature water taken out from the upper part of the hot water storage tank 10 or high-temperature water heated by the heat pump unit 60 to heat the water to be heated, such as bathtub water or heating circulation water, for example. A heat exchanger 22 is provided. In addition, in this Embodiment, the case where the bathtub water stored by the bathtub 50 is used as heating object water is illustrated. On the primary side of the use side heat exchanger 22, a later-described use side heat exchanger primary side inlet pipe 45 and a use side heat exchanger primary side outlet pipe 46 are connected. A secondary circulation pipe 51 through which bath water circulates is connected to the secondary side of the use side heat exchanger 22. The secondary circulation pipe 51 includes a secondary circulation pump 52 that circulates bathtub water, and a bathtub outlet thermistor 53 that detects the temperature of the bathtub water flowing out of the bathtub 50 at a position inside the tank unit 1. Is provided.

  Next, the boiling piping 39 mounted on the heat pump water heater and each device provided in the boiling piping 39 will be described. The boiling piping 39 has one end connected to the lower part of the hot water storage tank 10 and the other end connected to the upper part of the hot water storage tank 10 via the boiling heat exchanger 62. That is, the boiling pipe 39 is a circulation path for returning the water taken out from the lower part of the hot water storage tank 10 to the upper part of the hot water storage tank 10 via the boiling heat exchanger 62, and includes a heat pump inlet pipe 41, a heat pump. The outlet pipe 42, the tank upper pipe 43 and the tank lower pipe 48 are configured. In the middle of the boiling piping 39, a circulation pump 21, first and second four-way valves 31 and 32, and a boiling heat exchanger 62 are provided.

  The circulation pump 21 is a pump for circulating hot water (water) through the boiling piping 39 and is controlled by the control unit 70. The circulation pump 21 is connected in the middle of the heat pump inlet pipe 41 in the tank unit 1, is downstream of the first four-way valve 31 in the flow direction of water flowing into the boiling heat exchanger 62, and It arrange | positions in the position used as the upstream of the heat exchanger 62 for raising (and heat pump bypass piping 47 mentioned later). With this arrangement, the circulation pump 21 is also used as a pump that circulates hot water in other flow paths in accordance with the switching positions of the four-way valves 31 and 32. That is, using the single circulation pump 21, it is possible to execute a startup operation, a boiling-only operation, a reheating operation, and a freeze prevention operation which will be described later.

  The four-way valves 31 and 32 are switching-controlled by the control unit 70 as the first and second control valves in the present embodiment, and each have an a port, a b port, a c port, and a d port. . More specifically, the first four-way valve 31 has three inflow ports (a port, b port, and c port) and one outflow port (d port), and any one of the inflow ports is defined as an outflow port. Communicate. That is, the four-way valve 31 can switch the water flow path to any one of the ad path, the bd path, and the cd path. Further, the four-way valve 31 holds other ports in a closed state except for a set of ports that are communicated with each other. As an example, when the four-way valve 31 is switched to the a-d route, the a port and the d port communicate with each other, and the b port and the c port are closed.

  The a port of the four-way valve 31 is connected to the hot water supply / mixing pipe 5 through a freeze prevention bypass pipe 40 described later, and the b port is connected to the lower part of the hot water storage tank 10 through a tank lower pipe 48. The c port of the four-way valve 31 is connected to the downstream side of the use side heat exchanger 22 via the use side heat exchanger primary side outlet pipe 46, and the d port connects the heat pump inlet pipe 41 and the circulation pump 21. And connected to the water inlet of the boiling heat exchanger 62.

  On the other hand, the second four-way valve 32 has two inflow ports (b port and c port) and two outflow ports (a port and d port), and has either one of the inflow ports or one of the outflow ports. Communicate. That is, the four-way valve 32 can switch the water flow path to any of the ba route, the dd route, the ca route, and the cd route. Further, the four-way valve 32 holds the other ports in a closed state except for the set of connected ports. As an example, when the four-way valve 32 is switched to the ba route, the a port and the b port communicate with each other, and the c port and the d port are closed. The a port, b port, c port, and d port of each of the four-way valves 31, 32 are the first port, the second port, the third port, and the fourth port of the first and second control valves in claim 2, respectively. It corresponds to.

  The a port of the four-way valve 32 is connected to a predetermined portion between the intermediate portion and the lower portion of the hot water storage tank 10 via a tank return pipe 44. The tank return pipe 44 and the tank lower pipe 48 are connected to the hot water storage tank 10 at different positions. Further, the b port of the four-way valve 32 is connected to the heat pump inlet pipe 41 via the heat pump bypass pipe 47, and this connecting portion is connected to the circulation pump 21 in the flow direction of the water flowing into the boiling heat exchanger 62. It is arranged at a position downstream of the boiling heat exchanger 62 and upstream of the boiling heat exchanger 62 (between the circulation pump 21 and the boiling heat exchanger 62). The c port of the four-way valve 32 is connected to the water outlet of the boiling heat exchanger 62 via the heat pump outlet pipe 42, and the d port is connected to the upper part of the hot water storage tank 10 via the tank upper pipe 43. .

  The use side heat exchanger primary side inlet pipe 45 has one end branched from the tank upper pipe 43 and the other end connected to the primary side inlet of the use side heat exchanger 22. The use side heat exchanger primary side outlet pipe 46 has one end connected to the primary outlet of the use side heat exchanger 22 and the other end connected to the c port of the four-way valve 31. The tank upper pipe 43 may be branched from the hot water supply pipe 3 to connect the hot water supply pipe 3 and the d port of the four-way valve 32.

(Anti-freezing bypass piping)
Next, the freeze prevention bypass piping 40 that is a feature of the present invention will be described. First, since hot water is stored in the hot water storage tank 10 in a stacked manner from the upper part, the hot water stays in the upper part of the tank, and the cold water stays in the lower part. When the temperature of the lower part of the hot water storage tank 10 is low, the pipes (for example, the water supply pipe 2, the water supply branch pipe 4, the mixed hot water supply pipe 5 etc.) arranged at the lower part of the tank unit 1 tend to be low in temperature. There is a risk that these pipes will freeze in the ground and in winter. Further, the heat pump inlet pipe 41 and the heat pump outlet pipe 42 connecting the tank unit 1 and the heat pump unit 60 are easily frozen because they are exposed to the outside air.

  Therefore, in the present embodiment, a freeze prevention bypass pipe 40 for connecting the mixed hot water supply pipe 5 and the boiling pipe 39 is provided on the lower side of the tank unit 1, and mixing is performed according to the switching positions of the four-way valves 31 and 32. The hot water for preventing freezing is circulated from the hot water supply pipe 5 to the boiling pipe 39. More specifically, the freeze prevention bypass pipe 40 has one end branched from the mixed hot water supply pipe 5 and the other end connected to the a port of the four-way valve 31 on the upstream side of the boiling heat exchanger 62 and the circulation pump 21. . That is, the other end side of the freeze prevention bypass pipe 40 is connected to the boiling-up pipe 39 (the connection part between the heat pump inlet pipe 41 and the tank lower pipe 48) via the four-way valve 31. In this configuration, the four-way valve 31 constitutes an opening / closing means for opening and closing the freeze prevention bypass pipe 40 with respect to the boiling pipe 39. In the present invention, the opening / closing means may be constituted by a valve mechanism different from the four-way valve 31, and this valve mechanism may be arranged in the middle or one end side of the freeze prevention bypass pipe 40.

  Further, one end side of the freeze prevention bypass pipe 40 is located as far as possible from the hot water supply mixing valve 6 in the tank unit 1 (position as close as possible to the drawing portion of the mixed hot water supply pipe 5 drawn to the outside from the tank unit 1). To the mixed hot water supply pipe 5. Thereby, at the time of freeze prevention operation of the heat pump water heater, the pipe length of the part located upstream of the freeze prevention bypass pipe 40 in the mixed hot water supply pipe 5 is secured as long as possible, and hot water for freeze prevention is provided in this part. Can be circulated. The freeze prevention operation will be described later together with other operations.

  On the other hand, the tank unit 1 is equipped with a control unit 70 that controls the operating state of the water heater. On the input side of the control unit 70, temperature sensors such as a hot water supply thermistor 9, remaining hot water thermistors 11 and 12, a hot water supply thermistor 15, an HP outlet thermistor 66, an HP inlet thermistor 67, and an outside temperature thermistor 69, and a hot water flow rate sensor. 8 is connected. Further, the hot water mixing valve 6, the circulation pump 21, the four-way valves 31 and 32, the secondary-side circulation pump 52, and the like are connected to the output side of the control unit 70. The control unit 70 executes the start-up operation, the boiling-only operation, the reheating operation, the hot water supply operation, and the freeze prevention operation described below as necessary based on the output of each sensor and the setting contents of a remote controller (not shown). To do. The control unit 70 constitutes the freeze prevention control unit of the present embodiment.

(Standby state)
FIG. 2 is an operation explanatory view showing a standby state of the heat pump water heater. The standby state indicates a state in which any of various operations described later is not executed. As shown in this figure, in the standby state, first, the first four-way valve 31 is held in the bd path, and the a port and the c port are closed. That is, the tank lower pipe 48 and the heat pump inlet pipe 41 are made to communicate with each other by the four-way valve 31, and the use side heat exchanger primary side outlet pipe 46 and the freeze prevention bypass pipe 40 are closed to use the use side heat exchanger. 22 and the flow path from the mixed hot water supply pipe 5 are shut off.

  In the standby state, the second four-way valve 32 is held in the ca path, and the b port and the d port are closed. That is, the heat pump outlet pipe 42 and the tank return pipe 44 are communicated, and the tank upper pipe 43 and the heat pump bypass pipe 47 are closed. In the standby state, all of the circulation pump 21, the heat pump unit 60, and the secondary side circulation pump 52 are held in a stopped state.

(Start-up operation)
FIG. 3 is an operation explanatory diagram showing the start-up operation of the heat pump water heater. In the following drawings, the flow path of warm water (water) flowing through the pipe is indicated by a bold line. Due to its operating characteristics, the heat pump unit 60 requires a certain amount of time from when it is started until a predetermined output is obtained. For this reason, the start-up operation is executed before starting the boiling-only operation. In the start-up operation, the circulation pump 21 and the heat pump unit 60 are operated in a state where the four-way valves 31 and 32 are held at the same switching position as in the standby state. Thus, when the low temperature water flows out from the lower part of the hot water storage tank 10, the low temperature water flows into the heat pump unit 60 via the tank lower pipe 48, the first four-way valve 31, the circulation pump 21 and the heat pump inlet pipe 41. It is heated by the heat pump unit 60 to become high temperature water. The hot water flows out of the heat pump unit 60 and is returned to the lower part from the intermediate portion of the hot water storage tank 10 via the heat pump outlet pipe 42, the second four-way valve 32 and the tank return pipe 44.

  According to the start-up operation, the half-temperature hot water that has been boiled up until the predetermined output is reached after the heat pump unit 60 is started is applied to a predetermined portion between the intermediate portion and the lower portion of the hot water storage tank 10. Returned. Thereby, at the start of the boiling-only operation, it is not necessary to allow the intermediate temperature hot water to flow into the upper part of the hot water storage tank 10, so that the hot water temperature distribution in the hot water storage tank 10 can be stabilized. Moreover, since the circulation of the hot water with respect to the use side heat exchanger 22 is interrupted in the start-up operation, the heat exchange with the bath water is not executed.

(Boiling only operation)
FIG. 4 is an operation explanatory diagram showing a single boiling operation of the heat pump water heater. The boiling-only operation is to heat the water in the hot water storage tank 10 by the heat pump unit 60, and the control unit 70 detects the amount of hot water in the hot water storage tank 10 based on the detected temperature of the remaining hot water thermistors 11 and 12. When it is determined that the residual amount of high-temperature water is small based on the detection result, the boiling-only operation is executed. During the boiling-only operation, the first four-way valve 31 is switched to the bd route, and its a port and c port are closed. Further, the second four-way valve 32 is switched to the cd path, and its a port and b port are closed. Then, the circulation pump 21 and the heat pump unit 60 are operated.

  Thus, when the low temperature water flows out from the lower part of the hot water storage tank 10, the low temperature water flows into the heat pump unit 60 via the tank lower pipe 48, the first four-way valve 31, the circulation pump 21 and the heat pump inlet pipe 41. It is heated by the heat pump unit 60 to become high temperature water. The hot water flows out of the heat pump unit 60 and is returned to the upper part of the hot water storage tank 10 via the heat pump outlet pipe 42, the second four-way valve 32, and the tank upper pipe 43. According to this boiling-only operation, the hot water layer can be gradually thickened while storing hot water in the upper layer portion of the hot water storage tank 10.

(Driving operation)
FIG. 5 is an operation explanatory diagram showing a chasing operation of the heat pump water heater. In the chasing operation, from the standby state shown in FIG. 2, the first four-way valve 31 is switched to the cd path, and the second four-way valve 32 is switched to the ba path. And the circulation pump 21 and the bathtub water circulation pump 52 are operated. Thereby, the high temperature water taken out from the upper part of the hot water storage tank 10 distribute | circulates the tank upper piping 43, the primary side of the utilization side heat exchanger 22, and the utilization side heat exchanger primary side exit piping 46, and at this time The bathtub water is heated by exchanging heat with the bathtub water in the use side heat exchanger 22. Then, the hot water whose temperature has been lowered by heating the bath water flows into the heat pump inlet pipe 41 via the first four-way valve 31 and the circulation pump 21. However, since the c and d ports of the second four-way valve 32 are closed, the hot water flowing into the heat pump inlet pipe 41 flows into the heat pump bypass pipe 47 after flowing through a part thereof, and the second four-way valve. 32 and the tank return pipe 44, the hot water storage tank 10 is returned to a predetermined portion between the middle part and the lower part.

  On the other hand, since the secondary circulation pump 52 is operated on the bathtub 50 side, the hot water stored in the bathtub circulates on the secondary side of the use side heat exchanger 22 via the secondary circulation pipe 51. Heated (chased) by high temperature water flowing on the primary side. Thus, according to the chasing operation, the bath water can be chased using the high-temperature water stored in the hot water storage tank 10.

(Hot water operation)
FIG. 6 is an operation explanatory diagram illustrating a hot water supply operation of the heat pump water heater. In the hot water supply operation, when the user of the water heater opens the faucet 80, hot water whose hot water temperature is adjusted to a preset temperature (for example, 40 ° C.) preset by a remote controller or the like is supplied to the faucet 80. Specifically, first, when the user opens the faucet 80 and hot water flows into the mixed hot water supply pipe 5 from the hot water supply mixing valve 6, the control unit 70 has a predetermined flow rate of hot water (hot water supply flow rate) detected by the hot water supply flow rate sensor 8. When the flow rate exceeds the hot water supply determination flow rate, it is determined that “the hot water supply operation is present”, and the control of the hot water supply mixing valve 6 is started. In this control, high temperature water (about 65 to 90 ° C.) taken from the upper part of the hot water storage tank 10 via the hot water supply pipe 3 and low temperature water taken from the water supply pipe 2 via the water supply branch pipe 4 are used. Mix in the hot water supply mixing valve 6. At this time, the control unit 70 controls the hot water supply mixing valve 6 to adjust the mixing ratio of high temperature water and low temperature water so that the hot water temperature after mixing detected by the hot water supply pipe thermistor 9 becomes the set temperature. Execute feedback control. Thereby, the user can obtain hot water adjusted to a desired temperature from the faucet 80.

(Freeze prevention operation)
Next, FIG. 7 is an operation explanatory view showing a freeze prevention operation of the heat pump water heater. In the freeze prevention operation, the first four-way valve 31 is switched to the a-d path and the second four-way valve 32 is switched to the c-a path from the standby state shown in FIG. On the other hand, the use side heat exchanger primary side outlet pipe 46, the heat pump bypass pipe 47, and the tank lower pipe 48 are blocked from the freeze prevention circulation water channel 49 by the four-way valves 31 and 32. Accordingly, as shown in FIG. 7, the heat pump water heater is provided with a freeze prevention circulation water channel 49 that circulates freezing prevention water starting from the lower part of the hot water storage tank 10.

  That is, the freeze prevention circulation water channel 49 starts from the lower part of the hot water storage tank 10, a part of the water supply pipe 2, the water supply branch pipe 4, the hot water supply mixing valve 6, the mixed hot water supply pipe 5, the freeze prevention bypass pipe 40, and the first four directions. The valve 31, the circulation pump 21, the heat pump inlet pipe 41, the boiling heat exchanger 62, the heat pump outlet pipe 42, the second four-way valve 32, and the tank return pipe 44 are connected from the middle part to the lower part of the hot water storage tank 10. It is a waterway which returns to a predetermined part in between. Note that the freeze prevention circulation water channel 49 includes the lower side in the hot water storage tank 10. Thus, when the circulation pump 21 is operated in a state where the freeze prevention circulation water channel 49 is formed, water flows out from the lower part of the hot water storage tank 10, and this water flows through the freeze prevention circulation water channel 49, and then the hot water storage tank. Return to 10.

  Further, in the freeze prevention operation, the flow rate ratio of the low temperature water supplied from the water supply branch pipe 4 to the mixed hot water supply pipe 5 is larger than the flow rate ratio of the high temperature water supplied from the hot water supply pipe 3 to the mixed hot water supply pipe 5. The hot water mixing valve 6 is controlled so that the flow rate ratio of the low temperature water is maximized and the flow rate ratio of the high temperature water is minimized. At this time, the flow rate ratio of the high-temperature water is set to a minimum flow rate that does not lower the temperature of the water circulating in the freezing prevention circulation channel 49 to below the freezing point. Thereby, the water flowing out from the lower part of the hot water storage tank 10 circulates in the freeze prevention circulation water channel 49 in a state where a small amount of high temperature water is mixed by the hot water supply mixing valve 6. According to this configuration, the temperature of the water circulating in the freezing prevention circulation water channel 49 can be kept at a low temperature that does not freeze. Therefore, energy consumed for preventing freezing can be minimized while preventing freezing of water.

  Next, execution conditions for the freeze prevention operation will be described. The freeze prevention operation is executed when both of the following conditions (1) and (2) are satisfied.

(1) When the atmospheric temperature of the water heater is lowered below a predetermined freezing critical temperature Here, the atmospheric temperature of the water heater is, for example, the temperature of the heat pump inlet pipe 41 and the heat pump outlet pipe 42 detected by the thermistors 66 and 67, It means at least one of the temperature of the water supply pipe 2 detected by the water supply pipe thermistor 15, the temperature of the mixed hot water supply pipe 5 detected by the hot water supply pipe thermistor 9, and the outside air temperature detected by the outside air temperature thermistor 69. Moreover, freezing danger temperature is temperature which the water which distribute | circulates (stays) in each said piping may freeze. When the atmospheric temperature of the water heater is higher than the freezing danger temperature, it is considered that the water in the piping will not freeze even if the water for freezing prevention is not circulated, so the freezing prevention operation is not executed.

(2) When not in hot water supply operation The controller 70 detects the flow rate of hot water (hot water supply flow rate) flowing through the mixed hot water supply pipe 5 by the hot water supply flow rate sensor 8. When the hot water supply flow rate is equal to or higher than the predetermined hot water supply determination flow rate, it is determined that the hot water supply operation is in progress (with hot water supply). ). The hot water supply determination flow rate is set to a minimum flow rate considering, for example, an error of the hot water supply flow rate sensor 8. During the hot water supply operation, it is considered that the hot water flowing in the pipe is not frozen, so the freeze prevention operation is not executed. The hot water supply determination flow rate may be set to zero, or may be set to a value of about several liters as necessary.

  That is, the control unit 70 performs the freeze prevention operation when the atmospheric temperature of the water heater is equal to or lower than the freezing danger temperature and the hot water flow rate is less than the hot water determination flow rate. When the freeze prevention operation is executed, the low-temperature water flowing out from the lower part of the hot water storage tank 10 is part of the water supply pipe 2, the water supply branch pipe 4, the hot water supply mixing valve 6, the mixed hot water supply pipe 5, and the freeze prevention bypass pipe 40. The first four-way valve 31, the circulation pump 21, the heat pump inlet pipe 41, the boiling heat exchanger 62, the heat pump outlet pipe 42, the second four-way valve 32, and the tank return pipe 44 are returned to the hot water storage tank 10. It is. Since this low temperature water is mixed with a small amount of high temperature water by the hot water supply mixing valve 6, the low temperature water flows through the freeze prevention circulation water channel 49 while maintaining a temperature that does not freeze.

  On the other hand, when the hot water supply flow rate becomes equal to or higher than the hot water supply determination flow rate during the execution of the freeze prevention operation, the freeze prevention operation is stopped at that time and the normal hot water supply operation is started. For example, the control unit 70 opens the faucet 80 (or increases the opening of the faucet 80) when the hot water supply flow rate changes from 3 liters per minute to 5 liters per minute, for example, during the freeze prevention operation. It is determined that the operation has been performed. In this case, the control unit 70 stops the circulation pump 21 and switches the first four-way valve 31 from the a-d path to the b-d path in order to stop the flow of water for freezing prevention. The port and c port are closed. Thereby, as shown in FIG. 6, the freeze prevention bypass piping 40 can be interrupted | blocked and a hot water supply operation can be started.

  As described above in detail, according to the present embodiment, freezing prevention is provided by a plurality of pipes, valves 31, 32, pump 21, and the like that are disposed on the lower side of the tank unit 1 and are easily frozen by being exposed to the outside air. A circulation channel 49 can be formed. In a temperature environment where there is a possibility of freezing, water (warm water) can continue to flow through the freezing prevention circulation channel 49 by performing the freezing prevention operation, and freezing is prevented in each part of the freezing prevention circulation channel 49. be able to. Therefore, it is possible to efficiently prevent freezing of a large number of pipes by one freezing prevention circulation water channel 49 without installing anti-freezing heaters in each part of the pipes, and it is possible to reduce power consumption by the heaters and improve economy. Can be improved.

  In addition, in the present embodiment, the freeze prevention circulation water channel 49 is configured by using only one circulation pump 21 and the two four-way valves 31 and 32 only by installing the freeze prevention bypass pipe 40 in the tank unit 1. be able to. For this reason, the freeze prevention function of many piping is realizable only by making a comparatively small design change with respect to the existing heat pump water heater.

  In the present embodiment, the freeze prevention operation can be executed only when the hot water supply flow rate through the mixed hot water supply pipe 5 is less than the predetermined hot water supply determination flow rate. Even in the freeze prevention operation, when the user performs the hot water supply operation, it is possible to quickly shift from the freeze prevention operation to the hot water supply operation. Therefore, the freeze prevention operation can be executed without impairing the convenience of the user who uses the hot water supply function.

  On the other hand, in the present embodiment, not only the anti-freezing operation described above, but also other anti-freezing operation for the heat pump inlet pipe 41 and the heat pump outlet pipe 42 (hereinafter referred to as a heat pump pipe anti-freezing operation) is executed. be able to. FIG. 8 is an operation explanatory view showing the freeze prevention operation of the heat pump pipe. This anti-freezing operation is executed in the same manner as the anti-freezing operation described above, but differs from the anti-freezing operation described above in that the first four-way valve 31 is switched to the b-d route instead of the ad route. Yes. When the circulation pump 21 is operated in this state, the low-temperature water flowing out from the lower part of the hot water storage tank 10 is the tank lower pipe 48, the first four-way valve 31, the circulation pump 21, the heat pump inlet pipe 41, and the heat exchange for boiling. It is returned to the hot water storage tank 10 via the vessel 62, the heat pump outlet pipe 42, the second four-way valve 32 and the tank return pipe 44. Thereby, it is possible to prevent the water in the heat pump inlet pipe 41, the heat pump outlet pipe 42, and the boiling heat exchanger 62 having a particularly high possibility of freezing from being frozen.

  In the first embodiment, the four-way valves 31 and 32 each having four ports have been described as examples of the first and second control valves. However, the present invention is not limited to a four-way valve. For example, the functions of the first and second control valves may be realized by combining a plurality of electromagnetic valves.

  Moreover, in the said Embodiment 1, bathtub water was employ | adopted as heating object water, and the bathtub water shall be heated by a chasing operation. However, the present invention is not limited to this. For example, circulating water for heating supplied to an external heating device or the like may be adopted as water to be heated, and the heating operation may be performed according to each operation mode.

  In the first embodiment, the heat pump cycle configured by the heat pump unit 60 is a supercritical heat pump cycle in which the refrigerant pressure is equal to or higher than the critical pressure. However, the present invention is not limited to this, It may be a heat pump cycle that operates below pressure. In this case, chlorofluorocarbon gas, ammonia or the like may be used as the refrigerant.

DESCRIPTION OF SYMBOLS 1 Tank unit 2 Water supply piping 3 Hot water supply piping 4 Water supply branch piping 5 Mixed hot water supply piping 6 Hot water supply mixing valve (mixing valve)
8 Hot water flow rate sensor 9 Hot water supply thermistor (temperature sensor)
10 Hot water storage tank 15 Water supply piping thermistor (temperature sensor)
21 Circulating pump 22 Use side heat exchanger 31 Four-way valve (first control valve, opening / closing means)
32 Four-way valve (second control valve)
39 Boiling piping 40 Freezing prevention bypass piping 41 Heat pump inlet piping 42 Heat pump outlet piping 44 Tank return piping 48 Tank lower piping 49 Freezing prevention circulation water channel 60 Heat pump unit 62 Boiling heat exchanger 66 HP outlet side thermistor (temperature sensor)
67 HP inlet thermistor (temperature sensor)
69 Outside temperature thermistor (temperature sensor)
70 Control unit (freezing prevention control means)

Claims (4)

A hot water storage tank for storing hot water;
A boiling heat exchanger for heating water in the hot water storage tank;
One end side is connected to the lower part of the hot water storage tank, and the other end side is connected to the upper part of the hot water storage tank via the boiling heat exchanger;
A circulating pump that is provided in the piping for boiling and returns the water taken out from the lower part of the hot water storage tank to the upper part of the hot water tank via the boiling heat exchanger;
A water supply pipe for supplying water to the lower part of the hot water storage tank;
A water supply branch pipe branched from the water supply pipe;
A mixing valve that mixes high temperature water taken out from the upper part of the hot water storage tank and low temperature water supplied from the water supply branch pipe, and generates hot water adjusted in hot water temperature;
A mixed hot water supply pipe for supplying hot water whose temperature is adjusted by the mixing valve to the outside;
One end side is branched from the mixed hot water supply pipe, and the other end side is connected to the boiling pipe on the upstream side of the boiling heat exchanger and the circulation pump, and a freeze prevention bypass pipe,
Opening and closing means for opening and closing the freeze prevention bypass pipe;
By opening the freezing prevention bypass pipe by the opening and closing means and driving the circulation pump, water taken from the lower part of the hot water storage tank is at least the water supply pipe, the water supply branch pipe, the mixed hot water supply pipe, the freeze A freeze prevention control means for performing a freeze prevention operation for circulating in a freeze prevention circulation channel including a part of the prevention bypass pipe and the boiling pipe;
Heat pump water heater equipped with. A use-side heat exchanger that heats water to be heated using high-temperature water extracted from the upper part of the hot water storage tank;
A four-way valve constituting the opening / closing means, a first port connected to the freeze prevention bypass passage, and a second port connected to a lower portion of the hot water storage tank through a part of the boiling piping The third port connected to the downstream side of the use side heat exchanger, the other part of the piping for boiling, and the upstream side of the boiling heat exchanger via the circulation pump A first control valve having a fourth port;
A boiling port between the first port, which is constituted by a four-way valve and is connected to the middle or lower part of the hot water storage tank via a tank return pipe, and the circulation pump and the boiling heat exchanger. A second port connected, a third port connected to the downstream side of the boiling heat exchanger via a part of the boiling piping, and a fourth port connected to the upper part of the hot water storage tank A second control valve having
The freeze prevention control means communicates the first port of the first control valve with the fourth port when executing the freeze prevention operation, and the first port of the second control valve It is configured to communicate with the third port,
The said freeze prevention circulation water channel becomes a structure containing the said water supply piping, the said water supply branch piping, the said mixed hot water supply piping, the said freeze prevention bypass piping, a part of said piping for boiling, and the said tank return piping. Heat pump water heater. A temperature sensor that detects at least the temperature of the boiling piping;
A hot water supply flow rate sensor for detecting a flow rate of hot water flowing through the mixed hot water supply pipe,
When the temperature of the boiling piping is equal to or lower than a predetermined freezing danger temperature and the flow rate of hot water flowing through the mixed hot water supply piping is less than a predetermined hot water supply determination flow rate, the freeze prevention control means The preventive operation is performed, and when the flow rate of hot water flowing through the mixed hot water supply pipe becomes equal to or higher than the hot water supply determination flow rate during execution of the freeze prevention operation, the freeze prevention operation is stopped. The heat pump water heater described in 1.   The freezing prevention control means is configured to mix, with the mixing valve, a minimum amount of hot water that does not freeze the water flowing through the freezing prevention circulation channel. The heat pump water heater according to item 1.

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