JP6599274B2 - Hot water storage water heater - Google Patents

Description

  The present invention relates to a hot water storage type hot water heater that performs a circulation operation for preventing freezing.

  Conventionally, in this type of hot water storage type hot water heater, as described in Patent Document 1, the hot water in the hot water storage tank is transferred to the lower part of the tank → the outgoing pipe → the heat exchanger → the middle part of the return pipe → the return bypass pipe → the lower part of the tank. There are some which circulate while switching between the route that circulates like this and the route that circulates like the lower tank → outward pipe → heat exchanger → return pipe → upper tank.

JP 2003-214700 A

  When performing the circulation operation, it is necessary to shorten the time for performing the circulation operation as much as possible because a drop in the temperature of the hot water in the hot water storage tank is unavoidable in any of the above two routes. For this purpose, it is conceivable that all the pipes of the two routes are made of a pipe material having a low thermal conductivity to suppress the cooling from outside the pipe to the hot water flowing in the pipe.

  However, usually, a drain pipe for draining hot water in the hot water storage tank is connected to the lower part of the hot water storage tank, and at least one branch pipe (hot water in an emergency) is connected to the forward pipe communicating with the lower part of the hot water storage tank. Intake pipes for obtaining water and protective pipes for protecting hot water tank cans are connected. Each of the drainage pipe and the branch pipe is provided with appropriate opening / closing valves (a drainage plug provided in the drainage pipe, an emergency intake cock provided in the intake pipe, a can body protection valve provided in the protection pipe, etc.). ing. Therefore, when all the pipes have a low thermal conductivity as described above, there is a problem that the amount of heat released from the hot water in the pipes with respect to the on-off valves decreases, and the on-off valves may be frozen.

In order to solve the above-mentioned problem, in claim 1 of the present invention, in the hot water storage type hot water supply apparatus provided with a hot water storage tank for storing hot water in the hot water storage tank unit, in the hot water storage tank unit, A forward pipe for connecting to a heat exchanger for exchanging heat between the hot water in the hot water storage tank and the heated refrigerant is provided , and a return pipe for connecting the heat exchanger to the upper part of the hot water storage tank is provided. provided, wherein the return pipe provided with a three-way valve, the return bypass pipe communicating into the lower portion of the hot water storage tank from the three-way valve is provided, the place-off valve near the lower portion of the hot water storage tank, the hot water storage tank unit wherein a first value is the thermal conductivity of the pipe member constituting the said return bypass pipe and the first section up to the three-way valve from the heat exchanger out of the return pipe, the hot water storage tank unit of It is those wherein the small second value than the hot water storage the first value is the thermal conductivity of the pipe member constituting the second section up to the top of the tank from the three-way valve of the return pipe.

  Moreover, in Claim 2, the said 1st area of the said return pipe and the said bypass pipe are comprised by the copper pipe, and the said 2nd area of the said return pipe is comprised by the SUS pipe. .

Further, in claim 3, a circulation pump provided in the forward pipe for circulating hot water, and at least one branch pipe that is branched and connected from between the hot water storage tank and the circulation pump in the forward pipe, has, the on-off valve is one which is the first on-off valve provided in said branch pipe.

According to a fourth aspect of the present invention, there is provided a drain pipe branched and connected from the return bypass pipe, and the on-off valve is a second on-off valve provided on the drain pipe.

According to a fifth aspect of the present invention, the three-way valve includes a first state in which the first section and the return bypass pipe communicate with each other for a first period, and a first state in which the first section and the second section communicate with each other for a second period. Control means for periodically switching between two states is provided.

  According to the first aspect of the present invention, the hot water heated by exchanging heat with the refrigerant in the heat exchanger is stored in the hot water storage tank. That is, at the time of boiling operation, the low temperature water in the hot water storage tank is taken out from the forward pipe connected to the lower part of the hot water storage tank, led to the heat exchanger, and heated by the heat exchange with the refrigerant to become high temperature water. . This high temperature water is returned from the heat exchanger to the upper part of the hot water storage tank through a return pipe, and as a result, the hot water is stored in layers from the upper part of the hot water storage tank.

  Here, in the above-described pipe connection structure, for example, circulating operation of hot water in the hot water storage tank is performed in order to prevent freezing in winter. At this time, a three-way valve is provided in the middle of the return pipe, and the three-way valve and the lower part of the hot water storage tank are connected by a return bypass pipe. In the circulation operation for preventing freezing, a two-route circulation operation is selectively executed by switching the three-way valve. In the first route, the three-way valve is switched to a state (first state) in which the first section of the return pipe from the heat exchanger to the three-way valve communicates with the return bypass pipe. In this state, the hot water in the hot water tank circulates in the following manner: hot water tank lower part → outward pipe → heat exchanger → return pipe first section → three-way valve → return bypass pipe → hot water tank lower part. In the second route, the three-way valve communicates the first section with the second section from the three-way valve of the return pipe to the upper part of the hot water storage tank (second state. In other words, the return pipe is entirely connected. To pass through). In this state, the hot water in the hot water tank circulates in the following order: hot water tank lower part → outward pipe → heat exchanger → first section of return pipe → three-way valve → second section of return pipe → upper hot water tank. Usually, the three-way valve is alternately switched between the first state and the second state, so that the circulation operation by the two routes is alternately performed periodically. Accordingly, it is possible to suppress the temperature drop of the hot water in the upper part of the hot water storage tank, which can occur when the circulation operation is performed only in the second route (similar to the boiling operation).

  According to claim 1, the first section from the heat exchanger to the three-way valve in the return pipe, and the return bypass pipe from the three-way valve to the lower part of the hot water storage tank are thermally conductive. Is constituted by a piping material having a first value (that is, high thermal conductivity), while the second section from the three-way valve to the upper part of the hot water storage tank in the return pipe has a second value of thermal conductivity ( That is, it is constituted by a piping material having a low thermal conductivity. As a result, a relatively large heat dissipation amount is ensured in the first return pipe section and the return bypass pipe, and the on-off valves respectively provided in the drain pipe communicating with the lower part of the hot water storage tank and the branch pipe branched from the forward pipe are provided. While preventing the freezing, the cooling of the remaining second section of the return pipe can be suppressed to shorten the circulation operation.

  According to the second aspect of the present invention, the return pipe first section and the return bypass pipe are made of copper pipes, so that a large amount of heat radiation can be ensured, and the return pipe second section is made of a SUS pipe. Therefore, it is possible to reliably suppress cooling from outside the pipe to hot water flowing through the pipe.

  Further, according to claim 3, for example, when a water intake pipe for acquiring hot water in an emergency, a protective pipe for protecting the can of the hot water storage tank, etc. are provided, the emergency water intake arranged in them. It is possible to reliably prevent the stopper and the can body protection valve from freezing.

  According to the fourth aspect of the present invention, when a drain pipe branched from the return bypass pipe is provided, it is possible to reliably prevent the drain plug arranged in the drain pipe from freezing.

  According to the fifth aspect of the present invention, the three-way valve is alternately switched between the first state and the second state by the control of the control means, whereby the circulation operation by the two routes is alternately performed periodically. As a result, it is possible to reliably suppress the temperature drop of the hot water in the upper part of the hot water storage tank, which may occur when the circulation operation is performed only on the second route. Further, by reducing the thermal conductivity of the second section, the heat radiation from the second section is reduced, and the temperature of the hot water in the second section is maintained for a relatively long time. Thereby, when the control means alternately switches between the first state and the second state as described above, the frequency of the second state communicating the first section to the second section may be relatively reduced. it can. As a result, the amount of low-temperature hot water flowing into the upper part of the hot water storage tank can be reduced, and a temperature drop in the upper part of the hot water storage tank can be prevented.

1 is an overall schematic configuration diagram of a hot water storage type water heater according to an embodiment of the present invention. A perspective view of the tank device and its surrounding piping and functional parts The figure explaining the state before the operation of the circulation operation for freeze prevention The figure explaining the operation of the circulation operation (the 1st route) for freeze prevention The figure explaining the operation of the circulation operation (second route) for freeze prevention Diagram explaining details of switching behavior of three-way valve in comparison with comparative example

  Next, an embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 shows an overall schematic configuration of a hot water storage type water heater of the present embodiment. In FIG. 1, this hot water storage type hot water heater 100 is a device that boils hot water in the midnight hours when the unit price of contracted electric power by time zone is low, stores the hot water, and uses the stored hot water for hot water supply. The hot water storage tank unit 1, the heat pump unit 3 as a heating means for heating the hot water in the can body 2 (hot water storage tank), and the hot water taps 4 respectively provided in the kitchen, the washroom, etc. (shower is shown in this example) And a bathtub 6.

  As shown in FIGS. 1 and 2, the tank device TA includes the can body 2 that is installed inside an exterior case (not shown) that serves as a housing and stores hot water therein. The can body 2 is connected to a hot water discharge pipe 8 at the upper end, connected to a water supply pipe 9 at the lower end, further connected to the lower part of the heat pump forward pipe 10 constituting the heat pump circulation circuit, and returned to the upper part of the heat pump constituting the heat pump circulation circuit. A pipe 11 (in detail, a return pipe second section 11B, details will be described later) is connected.

  The can body 2 is a metal hollow can having a substantially cylindrical shape as a whole, and four foam heat insulating materials 53, 54, 55, and 56 for heat insulation are provided around the can body 2 so as to cover the entire can body 2. (In FIG. 1, it is schematically shown by a one-dot chain line for preventing complexity).

  The hot water in the can body 2 taken out from below the can body 2 through the heat pump forward pipe 10 is boiled up by the heat pump unit 3 and then from the upper end of the can body 2 through the heat pump return pipe 11. It is returned to the body 2 and stored. Further, hot water in the can body 2 is pushed up by the water supply from the water supply pipe 9 so that the high-temperature water in the upper part of the can body 2 is pushed out from the hot water discharge pipe 8 and hot water is supplied. At this time, the water supply pipe 9 is provided with a water supply temperature sensor (not shown) for detecting the temperature of the water supply, and the hot water discharge pipe 8 is provided with an overpressure relief valve 45 for releasing the overpressure of the can body 2. Is provided.

  The heat pump unit 3 includes a heat pump circuit 16, a heat pump circulation pump 17, and a heat pump control unit (not shown) that controls driving of the heat pump circuit 3. The heat pump circuit 16 includes a compressor 12, a refrigerant-water heat exchanger 13 as a condenser, an electronic expansion valve 14, an intermediate heat exchanger 18, and a forced air-cooled evaporator 15. . The heat pump circulation pump 17 circulates hot water in the can 2 into the refrigerant-water heat exchanger 13 through the heat pump forward pipe 10 and the heat pump return pipe 11.

  Carbon dioxide is used as a refrigerant in the heat pump circuit 16 to constitute a supercritical heat pump cycle. In general, in the supercritical heat pump cycle, the refrigerant is condensed in a supercritical state during heat exchange, but in the refrigerant-water heat exchanger 13, the refrigerant and hot water in the can body 2 that is heated water flow opposite to each other. The counter flow system is employed, whereby heated water can be efficiently heated to a high temperature. For example, low-temperature water can be boiled to a high temperature of about 90 ° C. without an electric heater.

  The heat expansion control unit 14 is configured so that the temperature difference between the inlet temperature of the refrigerant-water heat exchanger 13 and the outlet temperature of the refrigerant-water heat exchanger 13 is constant. Alternatively, the compressor 12 is controlled. Thereby, especially when the inlet temperature of the refrigerant-water heat exchanger 13 of the water to be heated is a low temperature of about 5 to 20 ° C., for example, the water to be heated is heated with a very good COP (energy consumption efficiency). can do.

  On the other hand, the heat pump return pipe 11 in the hot water storage tank unit 1 is provided with a three-way valve 5 whose switching is controlled by a hot water supply control unit 44 (control means). In the heat-pump return pipe 11, the second section 11B closer to the can body 2 (in other words, between the three-way valve 5 and the can body 2) than the three-way valve 5 has a first value with relatively low thermal conductivity. A certain piping material, for example, stainless steel (SUS; see the abbreviation of the triple line in FIG. 1) is used. In contrast, the first section 11A of the heat-pump return pipe 11 closer to the refrigerant-water heat exchanger 13 than the three-way valve 5 (in other words, between the refrigerant-water heat exchanger 13 and the three-way valve 5) A pipe material having a second value higher than the first value in thermal conductivity, for example, copper (refer to a single thin solid line in FIG. 1). Its technical significance will be described later. In addition, the piping material which comprises the other various piping shown by FIG. 1 is copper, unless it mentions specially (refer the schematic illustration of the single thin solid line in FIG. 1).

  In the three-way valve 5, a return bypass pipe 7 is connected which branches from the heat-pump return pipe 11 and reaches the water supply pipe 9 (in other words, communicates with the lower part of the can body 2). The three-way valve 5 includes an upstream connection port 5a connected to the first section 11A of the heat-pump return pipe 11, a downstream connection port 5b connected to the second section 11B of the heat-pump return pipe 11, and the return A bypass side connection port 5c connected to the bypass pipe 7 is provided. The three-way valve 5 communicates the upstream connection port 5a and the downstream connection port 5b, for example, at the time of boiling operation performed at midnight. Accordingly, the can body 2 → the heat pump forward pipe 10 → the circulation pump 17 → the refrigerant-water heat exchanger 13 → the first section 11A of the heat pump return pipe 11 → the three-way valve 5 → the second section 11B of the heat pump return pipe 11 → the can body. The boiling operation is performed by two routes.

  Further, a water intake pipe 57 provided with an emergency water intake faucet 58 (first on-off valve) is branched and provided between the stop cock 46 provided in the middle of the heat pump forward pipe 10 and the circulation pump 17. The tip of this emergency water intake tap 58 is provided exposed from an exterior case (not shown) serving as a casing of the tank apparatus TA. The bottom of the can body 2 and the water intake pipe 57 are communicated with each other, and hot water stored in the can body 2 can be easily taken out from the emergency water intake tap 58 as domestic water. Further, from the upstream side of the stop cock 46 in the heat pump forward pipe 10, a protective pipe 62 for branching a protective pipe 62 for protecting the can body 2 provided with a can body protection valve 61 (first on-off valve) is provided. Yes. Further, a drain pipe 59 is connected to the bottom of the can body 2 through the water supply pipe 9. In the middle of the drain pipe 59, a drain plug 60 (second on-off valve) for opening and closing the drain pipe 59 is provided.

  On the other hand, a heat exchanger 19 made of, for example, stainless steel (SUS; see the abbreviation of the triple line in FIG. 1) for heating hot water in the bathtub 6 is provided in the can body 2. Yes. The heat exchanger 19 is connected to the bath pipes 20a and 20b and the bath return pipes 22a, 22b and 22c provided with the bath circulation pump 21 and the three-way valve 36 so that the hot water in the bathtub 6 can be circulated. It has become. That is, hot water in the bathtub 6 guided through the bath return pipes 22 a to 22 c is heated by the high-temperature water in the can 2 in the heat exchanger 19, and then returned to the bath 6 through the bath pipe 20. Insulation or memorialization is performed. The bath return pipes 22a to 22c are provided with bath temperature sensors (for example, thermistors; the same applies hereinafter) 23 for detecting the temperature of the hot water in the tub 6 that circulates.

  Further, an intermediate tap pipe 24 is connected to an intermediate position of the can body 2 (not limited to a substantially central position in the vertical direction). The intermediate hot water discharge pipe 24 is medium-temperature water whose temperature has been lowered by exchanging heat with hot water from the bathtub 6 in the heat exchanger 19, intermediate-temperature water whose temperature has been lowered (or increased in temperature) in the vicinity of the boundary layer of hot water and water, etc. The hot water stored in the intermediate position of the can body 2 (not limited to the substantially central position in the vertical direction) is discharged from the can body 2.

  Furthermore, the intermediate hot water led from the vicinity of the intermediate position of the can body 2 through the intermediate hot water pipe 24 and the upper end of the can body 2 are connected to the downstream side joining position of the intermediate hot water pipe 24 and the hot water pipe 8. An intermediate mixing valve 25 composed of an electric mixing valve that mixes high temperature water guided through the hot water discharge pipe 8 is provided. An intermediate hot water supply pipe 27 is connected to the downstream side of the intermediate mixing valve 25, and an intermediate temperature sensor 26 is provided. The mixing ratio of the medium temperature water and the high temperature water in the intermediate mixing valve 25 is such that the hot water temperature detected by the intermediate temperature sensor 26 is higher by a predetermined temperature than the hot water supply set temperature set by the user with a remote controller (not shown). Controlled to be at temperature.

  Furthermore, hot water led from the intermediate mixing valve 25 through the intermediate hot water pipe 27 and the hot water bypass pipe 29a, to the downstream side joining position of the intermediate hot water pipe 27 and the water supply bypass pipe 29 branched from the water supply pipe 9 are provided. A hot water supply mixing valve 28 composed of an electric mixing valve for mixing with low-temperature water led from 29b is provided. A hot water supply pipe 30 is connected to the downstream side of the hot water supply mixing valve 28, and a hot water supply temperature sensor 31 is provided. The mixing ratio of the hot water and the low temperature water in the hot water mixing valve 28 is controlled such that the hot water temperature detected by the hot water temperature sensor 31 becomes the hot water setting temperature set by the user with a remote controller (not shown). The hot water supply pipe 30 is further provided with a hot water flow rate sensor 47 for counting the amount of hot water to be supplied.

  Further, the hot water led through the branch intermediate hot water pipe 33 is located at the downstream side joining position of the branch intermediate hot water pipe 33 branched from the intermediate hot water pipe 27 and the branch water supply bypass pipe 34 branched from the water supply bypass pipe 29b. And a low temperature water led from the branch water supply bypass pipe 34 is provided with a bath mixing valve 32 composed of an electric mixing valve. A hot water filling pipe 35 communicating with the bath return pipes 22 a and 22 b is connected to the downstream side of the hot water mixing valve 32, and a hot water temperature sensor 39 is provided. The mixing ratio of the hot water and the low temperature water in the bath mixing valve 32 is controlled such that the hot water temperature detected by the hot water temperature sensor 39 becomes the bath set temperature set by the user with a remote controller (not shown). The hot water filling pipe 35 is provided with a hot water filling valve 37 for starting / stopping hot water filling to the bathtub 6 and a double check valve 48 for preventing the hot water in the bathtub 6 from flowing backward. ing. The pipe 64 branched from the branch water supply bypass pipe 34 is provided with a pressure reducing valve 64 for reducing the pressure of the water supply.

  Further, the hot water supply control unit 44 is connected to the remote controller by wireless communication or wired communication. The hot water supply control unit 44 receives input from each sensor (the bath temperature sensor 23, the intermediate temperature sensor 26, the hot water supply temperature sensor 31, the hot water temperature sensor 36, etc.) in the hot water storage tank unit 1 and is an actuator (electric mixing valve). Intermediate mixing valve 25, hot water supply mixing valve 28, actuator of bath mixing valve 32, actuator of hot water filling valve 37, etc.) and a hot water supply set temperature arbitrarily set by the user on the remote controller And the preset temperature is realized by driving the actuators. Specifically, the hot water supply control unit 44 detects the intermediate mixing valve 25 so that the temperature detected by the intermediate temperature sensor 26 becomes a mixing target temperature that is a predetermined temperature higher than the higher one of the hot water supply set temperature and the bath set temperature. The valve opening of the hot water supply mixing valve 28 is feedback controlled so that the temperature detected by the hot water supply temperature sensor 31 becomes the set temperature for hot water supply, and further, the temperature of the hot water temperature sensor 39 detects. The valve opening of the bath mixing valve 32 is feedback-controlled so that the temperature becomes the bath setting temperature.

  The hot water storage type water heater 100 having the above basic configuration is usually provided outside a building such as a house or a building, and is often exposed to a severe cold climate especially in winter. In such a case, if each pipe connected to the can 2 is frozen, there is a concern about damage to the pipe due to freezing and expansion of the internal water. Therefore, it is preferable to take some measures to prevent freezing.

  Therefore, in this embodiment, the circulating operation of the hot water in the can body 2 is performed to prevent freezing. That is, the three-way valve 5 can communicate the upstream side connection port 5a and the bypass side connection port 5c under the control of the hot water supply control unit 44 (first state). In this case, the hot water in the can body 2 is transferred from the state shown in FIG. 3 to the can body 2 → the heat pump forward pipe 10 → the circulation pump 17 → the refrigerant-water heat exchanger 13 → the heat pump return pipe 11 as shown in FIG. The first section 11A → the three-way valve 5 → the return bypass pipe 7 → the water supply pipe 9 → circulates along the path below the can body 2 (first path). That is, only the hot water in the lower part in the can body 2 (refer to the area A shown by the double diagonal lines in FIG. 4) flows.

  Further, in the three-way valve 5, during the circulation operation, in addition to the above, the upstream connection port 5 a and the downstream connection port 5 b are communicated with each other by the control of the hot water supply control unit 44 as in the boiling operation. Is also performed (second state). In this case, similar to the above-described boiling operation, the can body 2 → the heat pump forward pipe 10 → the circulation pump 17 → the refrigerant-water heat exchanger 13 → the first section 11A of the heat pump return pipe 11 → the three-way valve as shown in FIG. 5 → 2nd section 11B of the heat-pump return pipe 11 → circulates along the path above the can body 2 (second path). That is, hot water is supplied to the upper part in the can body 2 and flows (refer to region (a) shown by the double diagonal lines in FIG. 5). Actually, since hot water supplied to the upper part in the can body 2 is relatively low in temperature, it flows downward in the can body 2, and the flow reaches a wide range in the can body 2.

  The hot water supply control unit 44 controls the three-way valve 5 so that the two states are alternately switched periodically, and the circulation operation by the first route and the second route is alternately performed periodically. (Details will be described later).

  By the way, when performing the said circulating operation, since the temperature fall of the hot water in the can 2 is unavoidable in any of the two said routes, it is necessary to shorten the time for performing the said circulating operation as much as possible. For that purpose, for example, all the pipes of the two routes (the heat pump forward pipe 10, the heat pump return pipe 11 and the return bypass pipe 7) are made of a pipe material having a low thermal conductivity, and from outside the pipe to the hot water flowing in the pipe. It is conceivable to suppress cooling.

  However, as described above with reference to FIG. 1, the drain pipe 59 for draining hot water in the can body 2 is connected to the lower portion of the can body 2 and further communicated with the lower portion of the can body 2. At least one branch pipe (in this example, the water intake pipe 57 and the protective pipe 62) is also connected to the heat pump forward pipe 10. The drain pipe 59, the intake pipe 57, and the protection pipe 62 are provided with a drain plug 60, an emergency intake cock 58, and a can body protection valve 61, which are on-off valves, respectively. Therefore, when all the pipes have a low thermal conductivity as described above, the amount of heat released from the hot water in the pipes to the drain plug 60, the emergency water intake plug 58, and the can body protection valve 61 is reduced, and these valves are frozen. There is a fear. Moreover, there is a similar concern with respect to the stop cock 46 provided in the heat-feeding pipe 10.

  Therefore, in the present embodiment, as described above, the first section 11A from the refrigerant-water heat exchanger 13 to the three-way valve 5 in the heat pump return pipe 11 and the water supply from the three-way valve 5 to the lower part of the can body 2 are provided. The second section from the three-way valve 5 to the upper part of the can body 2 in the heat-pump return pipe 11 while the return bypass pipe 7 to the pipe 9 is made of a piping material (copper in this example) having a high thermal conductivity. 11B is constituted by a piping material (in this example, stainless steel) having a low thermal conductivity. Accordingly, a relatively large heat radiation amount is ensured in the first section 11A of the heat-pump return pipe 11 and the return bypass pipe 7, and the drain plug 60, the emergency intake plug 58, the can body protection valve 61, and the water stop valve are secured. While preventing the plug 46 from freezing, the cooling of the remaining second section 11B of the heat-pump return pipe 11 from the outside of the pipe with respect to the hot water flowing through the pipe can be suppressed to shorten the circulation operation (described later). FIG. 6).

  Further, in the present embodiment, the hot water supply control unit 44 controls the three-way valve 5 so that the first state and the second state are alternately switched periodically, thereby the first route. (Can body 2 → heat-pump forward pipe 10 → circulation pump 17 → refrigerant-water heat exchanger 13 → first section 11A of the heat-pump return pipe 11 → three-way valve 5 → return bypass pipe 7 → water supply pipe 9 → lower part of the can body 2; 4) and the second route (can body 2 → heat-pump forward pipe 10 → circulation pump 17 → refrigerant-water heat exchanger 13 → first section 11A of heat-pump return pipe 11 → three-way valve 5 → heat-pump return pipe 11) In the second section 11B → the upper portion of the can body 2; see FIG. 5).

  Details of the switching behavior of the three-way valve 5 will be described with reference to FIG. In the present embodiment, as shown in FIG. 6A, for example, the three-way valve 5 switches to the first state (denoted as “bypass side” in the figure) for constructing the first route 149 ( The operation for a total of 150 minutes, in which the switching to the second state (indicated as “boiling side” in the figure) is performed for one minute (second period) after the first period) is performed. This is repeated as 3 sets (450 minutes in total).

  At this time, in the present embodiment, as described above, by reducing the thermal conductivity of the second section 11B of the heat-pump return pipe 11, heat radiation from the second section 11B is reduced, and the second section 11B is reduced. The temperature of the hot and cold water is kept for a relatively long time. Thereby, when the three-way valve 5 switches alternately between the second state and the first state, the first state 11A of the heat-pump return pipe 11 communicates with the second region 11B side. The frequency can be reduced relatively.

  For example, FIG. 6B shows a comparative example in which the thermal conductivity of the second section 11B of the heat-pump return pipe 11 is not lowered as described above, and is equal to the thermal conductivity of the first section 11A. . As shown in the figure, in this comparative example, the effect of reducing the heat radiation from the second section 11B as described above cannot be obtained, so it is necessary to switch to the second state with a relatively high frequency. In this example, the three-way valve 5 performs switching to the first state (bypass side in the figure) for 119 minutes and then switching to the second state (“boiling side in the figure”) for 1 minute. The operation for a total of 120 minutes is set as one set, and this is repeated for four sets (total 480 minutes). In this comparative example, “switching time to the first state”: “switching time to the second state” = 119: 1 (ie, switching frequency to the second state 1/120), and for freezing prevention for 480 minutes In the circulation operation, the state is switched to the second state for 4 minutes.

On the other hand, “switching time to the first state”: “switching time to the second state” = 149: 1 in the present embodiment shown in FIG. 150), and the frequency of switching to the second state is reduced as compared with the comparative example. As a result, in the circulation operation for freezing prevention for 4500 minutes, the switching to the second state is shortened to only 3 minutes. ing. Thereby, since the quantity of the low-temperature hot water which flows into the upper part of the can body 2 via the said 2nd route | root in the said 2nd state can be reduced, the temperature fall of the can body 2 upper part can be prevented. In addition, since the second section 11B is made of stainless steel, the entire circulation operation can be shortened (480 minutes → 450 minutes), so that the temperature drop of the hot water in the can 2 can be suppressed. .

  In addition, this invention is not limited to the said embodiment, A various change is possible in the range which does not change the summary of invention. For example, in the above-described embodiment, the case where the heat exchanger 19 is the internal heat exchange system installed in the hot water storage tank 2 has been described as an example, but the present invention is not limited thereto. That is, an external heat exchange type heat exchanger in which hot water in the tank and the bathtub water exchange heat outside the hot water storage tank 2 may be used.

  Moreover, although the said embodiment demonstrated as an example the case where a heating means was comprised with the heat pump unit 3, it is not restricted to this. That is, a hot water heater using solar heat, gas or liquid fuel, an electric water heater using an electric heater, a waste heat recovery device of a cogeneration system, or the like may be used as the heating means.

  Furthermore, in the said embodiment, the refrigerant | coolant-water heat exchanger 13 as said condenser is provided in the heat pump unit 3, and the heat pump forward pipe 10 and the heat pump return pipe 11 are extended and connected with respect to this from the hot water storage tank unit 1. However, it is not limited to this. Conversely, a refrigerant-water heat exchanger 13 is provided in the hot water storage tank unit 1, and a pipe line from the heat pump circuit 16 side of the heat pump unit 3 is extended to the refrigerant-water heat exchanger 13 in the hot water storage tank unit 1 for connection. You may make it do.

2 Can body (hot water storage tank)
5 Three-way valve 7 Return bypass pipe 10 Heaton return pipe 11 Heaton return pipe 11A 1st section 11B 2nd section 13 Refrigerant-water heat exchanger 17 Circulation pump 44 Hot water supply control part (control means)
57 Intake pipe (branch pipe)
58 Emergency intake tap (first on-off valve)
59 Drain pipe 60 Drain plug (second on-off valve)
61 Can body protection valve (first on-off valve)
62 Protection tube (branch tube)
100 Hot water storage water heater

Claims (5)

In a hot water storage water heater equipped with a hot water storage tank that stores hot water in a hot water storage tank unit ,
The hot water storage tank unit includes a forward pipe for connecting a lower portion of the hot water storage tank to a heat exchanger for exchanging heat between the hot water in the hot water storage tank and the heated refrigerant, and the heat exchanger Provide a return pipe to connect to the upper part of the hot water storage tank,
Provided with a three-way valve in the return pipe, provided the return bypass pipe communicating into the lower portion of the hot water storage tank from the three-way valve,
An on-off valve is arranged near the lower part of the hot water tank,
Among the return pipes in the hot water storage tank unit, the thermal conductivity of the piping material constituting the first section from the heat exchanger to the three-way valve and the return bypass pipe is the first value,
Among the return pipes in the hot water storage tank unit, the thermal conductivity of the piping material constituting the second section from the three-way valve to the upper part of the hot water storage tank is a second value smaller than the first value. Hot water storage type water heater characterized by. The first section of the return pipe and the bypass pipe are made of a copper pipe,
The hot water storage type hot water supply device according to claim 1, wherein the second section of the return pipe is configured by a SUS pipe. A circulation pump provided in the forward pipe for circulating hot water;
At least one branch pipe branched and connected from between the hot water storage tank and the circulation pump among the forward pipes;
Have
The on-off valve, a hot water storage type hot water supply apparatus according to claim 1 or claim 2, wherein said a first on-off valve provided in the branch pipe <br/>. Having a drain pipe branched and connected from the return bypass pipe ;
The on-off valve, a hot water storage type hot water supply apparatus according to any one of claims 1 to 3, characterized in that said a second on-off valve provided in the drain pipe <br/>. Periodically, the three-way valve is in a first state in which the first section and the return bypass pipe communicate with each other for a first period, and in a second state in which the first section and the second section communicate with each other for a second period. The hot water storage type hot water supply device according to any one of claims 1 to 4, further comprising a control means for switching between the two.

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