JP6090907B2 - Hot water system - Google Patents

Description

  The present invention relates to a hot water supply system including a hot water circulation circuit for enabling immediate hot water supply.

  In a hot water supply system that stores hot water produced by a heat source device such as a heat pump in a hot water storage tank, and that hot water can be discharged from a faucet, shower head, or other hot water supply terminal when necessary, for example, immediately when the faucet is opened In order to supply hot water at a required temperature, a hot water supply system is known in which a hot water circulation circuit is provided between a heat source machine and a hot water storage tank and a hot water supply terminal, and a plurality of hot water supply terminals are attached to the hot water circulation circuit. For example, see Patent Document 1).

  As described above, in a hot water supply system equipped with a hot water circulation circuit, a dedicated closed circulation tank independent from the hot water storage tank is generally installed in the hot water circulation circuit, and the hot water circulating in the hot water circulation circuit and the hot water storage tank Usually, the hot water stored in the hot water is not mixed in the hot water storage tank.

  On the other hand, in order to omit the circulation tank provided in the hot water circulation circuit, when a part of the hot water storage tank is also used as a circulation hot water storage tank and the temperature of the hot water in the hot water circulation circuit decreases, A hot water supply system that can maintain an immediate hot water supply function is provided by circulating the part back and maintaining the hot water temperature in the hot water circulation circuit at a constant temperature.

JP 2008-145096 A

  However, as described above, if the hot water circulation circuit is equipped with a dedicated circulation tank, a circulation tank must be installed in addition to the hot water storage tank having the required capacity. As a result, it is not only unavoidable that the system becomes larger, the configuration becomes complicated, and the cost is increased, but also the circulating tank can store the hot water whose temperature has dropped. There were issues such as being unable to do so.

  In addition, if the dedicated circulation tank is omitted and a part of the hot water storage tank is also used as a circulating hot water storage tank, the system can be downsized and simplified. If hot water is not supplied to the hot water storage tank, the hot water temperature in the hot water circulation circuit that has gradually decreased due to natural heat dissipation cannot be raised even though hot water is stored in other hot water storage tanks. There were problems such as high temperature hot water supply being disabled.

  The present invention has been made in view of such circumstances, and omits a dedicated circulation tank to simplify the hot water circulation circuit, to reduce the size of the system, and to enable high-temperature hot water storage. An object of the present invention is to provide a hot water supply system capable of effectively using hot water as hot water supply hot water even when the temperature of the hot water in the hot water circulation circuit is reduced.

In order to solve the above problems, the hot water supply system of the present invention employs the following means.
That is, a hot water supply system according to the present invention includes a heat source unit that heats low-temperature water to produce high-temperature water, and a high-temperature unit that is connected to the heat source unit via a low-temperature water pipe and a high-temperature water pipe. At least two or more hot water storage tanks connected in series to sequentially store water from an upstream hot water storage tank to a downstream hot water storage tank, and a hot water discharge pipe to the uppermost hot water storage tank to which the high temperature water pipe is connected And a hot water circulation circuit which is connected via a mixing valve and circulates hot water constantly adjusted to a predetermined temperature and is provided with one or more hot water supply terminals, wherein the hot water circulation circuit comprises comprising a hot water return pipe returning a certain amount of circulating hot water in the bottom of the particular storage tank located the other of the hot water storage tank on the downstream side of the at least two or more of the hot water storage tank, the return hot water The pipe detects a hot water temperature of the specific hot water storage tank, and when the temperature drops below a set temperature, a return pipe and a switching valve that return the circulating hot water to the bottom of the hot water storage tank downstream from the specific hot water storage tank. It is characterized by having.

According to the present invention, by providing a hot water return pipe for returning a certain amount of circulating hot water circulating through the hot water circulation circuit to the bottom of the specific hot water storage tank , the hot water storage tank is also used as a circulation tank to constitute the hot water circulation circuit, When the hot water temperature in the hot water storage tank drops below the set temperature, the return hot water and the switching valve are used to return the circulating hot water to the bottom of the hot water storage tank downstream from the specific hot water tank. Alternatively, it is possible to configure the hot water circulation circuit by sharing all of them as a circulation tank, and a dedicated circulation tank independent from the hot water circulation circuit can be omitted. Therefore, when compared with a hot water supply system having the same hot water storage capacity, the system can be increased in size by the amount that does not require a dedicated circulation tank, and the configuration can be simplified and the cost can be reduced. In addition, since the circulating hot water is stored in a hot water storage tank that also serves as a circulation, it is possible to store hot water and hot water at higher temperatures than those in which hot water whose temperature has been lowered is stored in a dedicated circulating tank.

Furthermore, the hot water supply system of the present invention is the above-described hot water supply system, wherein the hot water storage tank , the return pipe and the switching valve for returning a certain amount of circulating hot water from the hot water circulation circuit are arranged in three stages from the upstream side to the downstream side. More than provided

  According to the present invention, in accordance with the number of hot water storage tanks, there are provided three or more stages of hot water storage tanks, return pipes and switching valves for returning a predetermined amount of circulating hot water from the hot water circulation circuit from the upstream side to the downstream side. Therefore, for example, when six or eight hot water storage tanks are connected in series, the return destination of the circulating hot water is divided into three or more stages, and is sequentially switched to the downstream stage. All the hot water storage tanks can be used as a circulation tank. Therefore, the hot water in all the hot water storage tanks can be effectively used to adjust the temperature of the circulating hot water and to supply hot water, thereby ensuring the required hot water supply temperature.

Furthermore, the hot water supply system of the present invention is characterized in that, in the hot water supply system described above, a plurality of return destination hot water storage tanks are provided in each stage.

  According to the present invention, since each stage is provided with a plurality of hot water storage tanks for return, even when the hot water circulation circuit is long or installed in an environment where heat dissipation is easy, By securing a suitable hot water storage tank for circulation, the hot water circulation circuit can function properly. Accordingly, the required hot water supply performance can be obtained while increasing the degree of design freedom for the hot water circulation circuit side.

Furthermore, the hot water supply system of the present invention is the above-described hot water supply system with respect to a hot water storage tank in which a plurality of hot water storage tanks provided at three or more stages from the upstream side to the downstream side are located on the downstream side. The return pipe is connected to the bottom of the hot water storage tank of the other stage on the downstream side, and the hot water temperature of the hot water storage tank of the upstream stage near the hot water side is used for switching determination of the return destination. It is characterized by.

According to the present invention, among the plurality of hot water storage tanks provided in three or more stages from the upstream side to the downstream side, the hot water storage tank in which the other stage hot water storage tank is located on the downstream side is different from the hot water storage tank in the other downstream stage. A return pipe is connected to the bottom of the tank, and the hot water temperature of the upstream stage hot water storage tank close to the hot water side is used for switching judgment of the return destination. It returned to circulation hot water medium temperature returned from the hot water circulation circuit in the hot water storage tank of another stage on the downstream side, among which can be tapped Te sequentially extruded hot water is hot water storage in the hot water storage tank with hot water, also upstream When the hot water temperature of the hot water storage tank of the second stage falls below the set temperature, the return destination can be switched to the next stage. Therefore, the hot water and the intermediate temperature water from the hot water circulation circuit are not mixed in the hot water storage tank, and all the high temperature water and intermediate temperature water stored in the hot water storage tank of that stage are used for temperature adjustment and hot water supply of the circulating hot water. Can be provided.

Furthermore, the hot water supply system of the present invention is the hot water supply system according to any one of the above, wherein when the hot water temperature of the hot water storage tank on the most downstream side falls below a set temperature , the hot water storage tank on the most downstream side and the heat source machine are The hot water storage pump provided in the low-temperature water pipe connecting the heat source and the heat source unit are operated, and the hot water storage operation is performed until a target hot water storage amount is obtained.

According to the present invention, when the hot water temperature of the hot water storage tank on the most downstream side of each stage falls below the set temperature, the low temperature water pipe that connects between the hot water storage tank on the most downstream side and the heat source unit is provided. Since the hot water storage pump and heat source unit are operated and the hot water storage operation is performed until the target amount of hot water is obtained, when the temperature of the hot water storage tank at the most downstream side falls below the set temperature, all the hot water storage tanks The hot water stored in the hot water and the medium hot water are judged to be used effectively, and hot water storage operation is performed by operating the hot water storage pump and heat source machine to store hot water at the target temperature in each hot water storage tank. Can do. Thus, efficient operation can be performed by appropriately repeating hot water storage operation and hot water supply operation.

  According to the present invention, a part or all of a plurality of hot water storage tanks can also be used as a circulation tank to constitute a warm water circulation circuit, and a dedicated circulation tank independent from the warm water circulation circuit can be omitted. When compared with a hot water supply system having the same hot water storage capacity, the system can be increased in size by the amount that does not require a dedicated circulation tank, and the configuration can be simplified and the cost can be reduced. In addition, since the circulating hot water is stored in a hot water storage tank that also serves as a circulation, it is possible to store hot water and hot water at higher temperatures than those in which hot water whose temperature has been lowered is stored in a dedicated circulating tank.

It is a basic lineblock diagram of a hot-water supply system concerning one embodiment of the present invention. It is a control flowchart of the hot water supply system shown in FIG. It is a block diagram of the practical application form of the said hot-water supply system. FIG. 4 is a control flow diagram of the hot water supply system shown in FIG. 3.

An embodiment according to the present invention will be described below with reference to FIGS.
FIG. 1 shows a basic configuration diagram of a hot water supply system according to an embodiment of the present invention.
The hot water supply system 1 of the present embodiment includes a heat source device 2 that heats low temperature water to produce high temperature water, at least two or more hot water storage tanks 3 that store hot water produced by the heat source device 2, and a heat source device 2. Alternatively, when the hot water discharged from the hot water storage tank 3 is circulated as hot water of a predetermined temperature and a plurality of hot water supply terminals 5 such as a faucet and a shower head are opened, hot water of the required temperature is immediately supplied from the hot water supply terminal 5. The hot water circulation circuit 4 is provided.

  As the heat source device 2, a known heat pump equipped with a refrigerant / water heat exchanger 6 can be used, and supplied to the refrigerant / water heat exchanger 6 from the hot water storage tank 3 side through the low temperature water pipe 7 and the hot water storage pump 8. The low-temperature water (cold water) thus heated is heated to high-temperature water having a predetermined temperature, and the high-temperature water is sent to the high-temperature water pipe 9. In addition to the heat pump, other heat source devices such as a hot water boiler can be used as the heat source device 2.

  As the hot water storage tank 3, in the present embodiment, for example, at least two sealed hot water storage tanks 3 having a capacity of 500 L and N connected in series with each other by the connecting pipe 10 are used. Regarding the hot water storage tank 3, the hot water storage tank 3 on the upstream side to which the high temperature water pipe 9 from the heat source device 2 is connected is referred to as a first hot water storage tank 3A, and the hot water storage tank 3 connected to the downstream side via the connection pipe 10 is provided. It demonstrates as the 2nd hot water storage tank 3B. In this case, the high temperature water pipe 9 from the heat source unit 2 is connected to the upper part of the first hot water storage tank 3A, and the bottom of the first hot water storage tank 3B is connected to the upper part of the second hot water storage tank 3B by the connecting pipe 10. A low-temperature water pipe 7 to the heat source unit 2 and a water supply pipe 11 from the water supply are connected to the bottom of the hot water storage tank 3B.

  Further, a hot water discharge pipe 12 is connected to an upper portion of the first hot water storage tank 3A on the most upstream side to which the high temperature water pipe 9 is connected, and the hot water circulation circuit 4 is connected via a mixing valve 13 provided in the hot water discharge pipe 12. It is connected. The hot water circulation circuit 4 is configured such that a plurality of hot water supply terminals 5 are installed in a pipe 4 </ b> A connected to the outlet side of the mixing valve 13, and a circulation pump 14 is installed on the downstream side thereof.

  A pipe 4A of the hot water circulation circuit 4 is branched downstream of the circulation pump 14, and one of the pipes 4B is a circulation pipe 4B connected to the mixing valve 13 via the flow rate adjusting valve 15, and the other pipe 4B is connected to the mixing valve 13. The piping 4 </ b> C is a hot water return piping (return piping) 4 </ b> C connected to the first hot water storage tank 3 </ b> A via the flow rate adjustment valve 16. Thus, the first hot water storage tank 3A is configured to be used as a circulating hot water storage tank in which a part of the hot water circulating in the hot water circulation circuit 4 is circulated.

  The flow rate adjusting valves 15 and 16 are the flow rate ratios of the circulating hot water to the circulation pipe 4B and the return pipe 4C according to the piping length of the hot water circulation circuit 4 connected via the tap pipe 12 and the mixing valve 13, the installation environment, and the like. It is for adjusting. That is, the hot water circulation circuit 4 is circulated with the hot water (1) adjusted to a temperature (eg, 55 ° C.) that does not cause burns even if the hot water is supplied immediately by the mixing valve 13, but the hot water supply terminal 5 does not supply hot water. When it is circulated, the temperature gradually decreases due to natural heat dissipation. For this reason, the ratio of the recirculation amount is set to a certain ratio according to the pipe length, the installation environment, etc. by the flow rate adjusting valves 15 and 16, and the hot water discharged from the first hot water storage tank 3A by the mixing valve 13 is set. And the temperature is adjusted to the above temperature.

  The temperature adjustment by the mixing valve 13 is as described above when the hot water is not recirculated from the hot water supply terminal 5, but, in addition, when the hot water is discharged from the hot water supply terminal 5, the first hot water storage tank 3 </ b> A is used. Alternatively, the high temperature water discharged from the heat source device 2 through the hot water discharge pipe 12 is mixed with the low temperature water from the water supply pipe 11 so as to supply the hot water circulation circuit 4 as the circulating hot water at the set temperature. Yes.

  In the present embodiment, the circulation pump 14 is turned ON by the hot water supply operation, and during the circulation operation in which a part of the hot water circulating in the hot water circulation circuit 4 is returned to the first hot water storage tank 3A by the return pipe 4C. When the hot water is circulated for a long time without supplying hot water and the temperature of the hot water in the first hot water storage tank 3A falls below the set temperature, the return destination of the circulating hot water is switched from the first hot water storage tank 3A to the second hot water storage tank 3B on the downstream side. The second return pipe 4D, the first switching valve 17 and the second switching valve 18 are provided.

  As described above, when the temperature of the hot water in the first hot water storage tank 3A falls below the set temperature during the circulation operation, the first switching valve 17 is closed, the second switching valve 18 is opened, and a part of the circulating hot water is Then, after passing through the flow rate adjusting valve 16, the return pipe 4C, the second return pipe 4D, and the second switching valve 18 are returned to the bottom of the second hot water storage tank 3B. In this case, the high temperature water stored in the second hot water storage tank 3B is sequentially pushed out to the first hot water storage tank 3A via the connection pipe 10, whereby the high temperature water and medium temperature water stored in the first hot water storage tank 3A. As shown in (2) in FIG. 1, the hot water is discharged to the hot water circulation circuit 4 side through the hot water discharge pipe 12 and the mixing valve 13.

  Accordingly, the hot water stored in the first hot water storage tank 3 </ b> A and the second hot water storage tank 3 </ b> B is used as hot water sequentially supplied from the hot water supply terminal 5 or hot water circulating in the hot water circulation circuit 4. In each of the first hot water storage tank 3A and the second hot water storage tank 3B, the temperature sensor T1 detects the temperature of the hot water stored in each of the first hot water storage tank 3A and switches the return destination of the circulating hot water (1) as described above. , T2 are provided.

FIG. 2 shows a control flow diagram thereof.
During the hot water supply operation after the hot water storage operation is completed, as shown in FIG. 2, in step S <b> 1, the heat source device 2 is turned off and the circulation pump 14 is turned on, whereby the hot water circulation circuit 4 is turned on by the mixing valve 13. The adjusted hot water having a predetermined temperature is circulated. At this time, a part of the circulating hot water is returned to the bottom of the first hot water storage tank 3A through the flow rate adjusting valve 16, the return pipe 4C, and the first switching valve 17, and high temperature water necessary for temperature adjustment is returned to the first hot water storage tank 3A. By being supplied to the mixing valve 13 from the upper part via the hot water discharge pipe 12, the temperature of the circulating hot water (1) is adjusted.

When the hot water supply terminal 5 provided in the hot water circulation circuit 4 is opened and the hot water is consumed, high temperature water is discharged from the first hot water storage tank 3A sequentially, and mixed with cold water or the like by the mixing valve 13 so that the predetermined temperature is reached. To be supplied to the hot water circulation circuit 4.
During this time, in step S2, the temperature of the hot water in the first hot water storage tank 3A and the second hot water storage tank 3B is detected by the temperature sensors T1, T2. While hot water from the second hot water storage tank 3B is being supplied to the first hot water storage tank 3A by hot water supply from the hot water supply terminal 5, the detected value T1 of the temperature sensor T1 is usually higher than the set temperature SP1 in step S3. It does not become low, and it is determined as YES in the determination of “T1 ≧ SP1”, the process proceeds to step S4, the first switching valve 17 is kept on, the second switching valve 18 is kept off, and the process returns to step S2.

  On the other hand, when the state where hot water is not supplied from the hot water supply terminal 5 continues for a long time, the medium hot water whose temperature returned from the hot water circulation circuit 4 is reduced accumulates at the bottom of the first hot water storage tank 3A. If NO is determined in the determination of “T1 ≧ SP1” in step S3, the process proceeds to step S5, the first switching valve 17 is turned off, the second switching valve 18 is turned on, and the process proceeds to step S6. Further, when the first switching valve 17 and the second switching valve 18 are switched in step S5, the return destination of the circulating hot water (1) returned from the hot water circulation circuit 4 is switched to the second hot water storage tank 3B. .

Thereafter, the hot water stored in the second hot water storage tank 3B is supplied to the first hot water storage tank 3A via the connection pipe 10, and the hot water and the intermediate hot water in the first hot water storage tank 3A are supplied to the hot water pipe 12 and the mixing valve. The hot water is discharged to the hot water circulation circuit 4 through 13 and supplied to the hot water supply from the hot water supply terminal 5 sequentially. Subsequently, in step S6, it is determined whether or not the temperature of the hot water in the second hot water storage tank 3B detected by the temperature sensor T2 is equal to or higher than the set temperature SP2 (T2 ≧ SP2). If YES, the process returns to step S2, during this time. The circulating hot water (2) returning from the hot water circulation circuit 4 is circulated as shown in (2) in FIG. 1, and the above operation is repeated.

  If the hot water temperature in the 2nd hot water storage tank 3B falls below preset temperature SP2, and it determines with NO by step S6, it will transfer to step S7. In step S7, both the heat source unit 2, that is, the hot water storage pump 8 and the compressor of the heat pump are turned on, and low temperature water (cold water) is supplied to the heat source unit 2 through the second hot water storage tank 3B as shown in (3). Hot water storage operation is started. The hot water storage operation is continued until the high-temperature water (3) produced by the heat source device 2 is stored in a target amount of hot water in the first hot water storage tank 3A and the second hot water storage tank 3B. In step S8, when it is determined that the temperature sensors T1 and T2 have reached the target temperature and it is determined that the target amount of hot water has been stored, the heat source device 2 is turned off in step S9, and the hot water storage operation is performed. Will be terminated.

  In the above basic form, the sealed hot water storage tank 3 has been described in which two first hot water storage tanks 3A and a second hot water storage tank 3B are connected in series. However, in practical use, as shown in FIG. Depending on the required amount of hot water storage, there are at least two or more N-type sealed hot water storage tanks 3A, 3B, 3C, 3D, 3E and 3N having a capacity of 500L as described above (6 in this example). ), Connected in series via the connecting pipe 10. In this case, the hot water storage tanks 3A to 3N are provided with temperature sensors T1 to T6.

  In addition, as shown in FIG. 3, a hot water storage tank 3 for circulating a part of the circulating hot water is returned from the hot water circulation circuit 4 via the return pipe 4C according to the pipe length of the hot water circulation circuit 4, the installation environment, etc. For example, a plurality of first hot water storage tanks 3A and a second hot water storage tank 3B including a first hot water storage tank 3A closest to the hot water discharge pipe 12 are provided, and a first switching valve 17 is provided at the bottom of the second hot water storage tank 3B. It is good also as a structure which connected 4 C of return piping.

  In this case, the circulating and hot water storage tank 3 to which the return destination is switched is the third hot water storage tank 3C and the fourth hot water storage tank 3D, and further the fifth hot water storage tank 3E and the sixth hot water storage tank 3N, and the second switching valve. The second return pipe 4D provided with 18 and the third return pipe 4E provided with the third switching valve 19 are connected to the bottom of the fourth hot water storage tank 3D and the bottom of the sixth hot water storage tank 3N, respectively. The switching of the return destination is determined based on the detection values of temperature sensors T3 and T5 provided in the third hot water storage tank 3C and the fifth hot water storage tank 3E, which are close to the hot water side, respectively, among the plurality of hot water storage tanks. become.

  Thus, when the number of hot water storage tanks 3 connected in series is increased to 6 or 8 in order to secure the hot water storage capacity, the return destination of the circulating hot water from the hot water circulation circuit 4 is 3 stages. The plurality of stages described above may be used, and the number of the hot water storage tanks 3 in each stage may be plural. In this case, as described above, the circulating hot water return circuit is provided on the downstream side of each stage of the hot water storage tank 3. The temperature sensor used for determining the return destination switching uses the detection value of the temperature sensor provided in the upstream hot water storage tank 3 near the hot water side.

FIG. 4 shows a control flow diagram of the system shown in FIG.
In step S11 to step S14, temperatures T1, T3, and T5 are measured by temperature sensors T1, T3, and T5 in step S12. In step S12, the first switching valve 17 is turned on, and the second and third switching valves 18 and 19 are turned on. The process is the same as step S1-step S4 except that it is turned OFF. If NO is determined in step S13 and the process proceeds to step S15, it is determined whether or not the detected value T3 of the temperature sensor T3 is “T3 ≧ SP2 (set temperature)”. If YES is determined, the process proceeds to step S16. Then, the second switching valve 18 is turned on, and the first and third switching valves 17 and 19 are turned off.

  Thereby, the return destination of circulating hot water is switched from the 2nd hot water storage tank 3B to the 4th hot water storage tank 3D, and it returns to step S12 and repeats said operation | movement. Further, if NO is determined in step S15, the process proceeds to step S17, the third switching valve 19 is turned on, the first and second switching valves 17, 18 are turned off, and the process proceeds to step S18. As a result, the return destination of the circulating hot water is switched from the fourth hot water storage tank 3D to the sixth hot water storage tank 3N. In step S18, it is determined whether the detected value T5 of the temperature sensor T5 is “T5 ≧ SP3 (set temperature)”. If it is determined YES, the process returns to step S12 and the above operation is repeated.

  On the other hand, if NO is determined in step S18, the process proceeds to step S19, and similarly to steps S7 to S9, the hot water storage operation is started by turning on the heat source unit 2 in step S19, and in step S20, the temperature sensor is started. When all of T1 to T6 detect the target temperature and it is detected that the target amount of high-temperature water is stored, in step S21, the heat source unit 2 is turned off, and the hot water storage operation is ended. Yes.

With the configuration described above, according to the present embodiment, the following operational effects can be obtained.
In the hot water supply system 1, when the heat source device 2 such as a heat pump and the hot water storage pump 8 are operated during the hot water storage operation, the second hot water storage tank 3B in FIG. Low temperature water (cold water) is supplied to the heat source unit 2 through the hot water storage tank 3N. The high-temperature water heated to a predetermined temperature by the heat source device 2 is sent to the high-temperature water pipe 9 and from the first hot water storage tank 3A in FIG. 1 or the first hot water storage tank 3A in FIG. When the hot water is sequentially stored in the hot water storage tanks 3B, 3C, 3D, 3E,.

  Hot water storage operation is usually performed at night using inexpensive late-night power, and hot water stored in the hot water storage tank 3 by hot water storage operation is consumed by hot water supply operation during other usage hours. become. The hot water supply operation is performed in a state where hot water of a predetermined temperature is circulated in the hot water circulation circuit 4 by stopping the heat source device 2 and the hot water storage pump 8 and operating the circulation pump 14, and when the hot water supply terminal 5 is opened, Immediate hot water supply is possible by supplying hot water at a required temperature immediately.

  During the hot water supply operation, part of the hot water in the hot water circulation circuit 4 returns to the first hot water storage tank 3A in FIG. 1 or the second hot water storage tank 3B in FIG. 3 via the flow rate adjustment valve 16, the return pipe 4C, and the first switching valve 17. Then, a part of the hot water is circulated from the first hot water storage tank 3A to the hot water circulation circuit 4 side through the mixing valve 13 to be used for temperature adjustment of the circulating hot water.

  At this time, there is no hot water supply from the hot water supply terminal 5 for a long time, and the state where the temperature of the circulating hot water decreases due to natural heat dissipation continues, and the first hot water storage tank 3A of FIG. 1 or the first hot water storage tank 3A of FIG. When the temperature sensor T1 detects that the hot water temperature has dropped below the set temperature SP1, the first switching valve 17 is closed and the second switching valve 18 is opened, thereby circulating hot water from the hot water circulation circuit 4 Is switched to the second hot water storage tank 3B in FIG. 1 or the fourth hot water storage tank 3D in FIG.

  Therefore, the hot water stored in the second hot water storage tank 3B of FIG. 1 or the third hot water storage tank 3C and the fourth hot water storage tank 3D of FIG. 3 is sequentially pushed out to the upstream tank, and the first hot water storage tank of FIG. Hot water and intermediate hot water in the hot water storage tank 3A or the first hot water storage tank 3A and the second hot water storage tank 3B in FIG. 3 are sequentially discharged to the hot water circulation circuit 4 through the hot water discharge pipe 12 and supplied to the hot water supply from the hot water supply terminal 5. Is done. Here, the medium-temperature water is still sufficiently high in temperature, and low-temperature warm water is not supplied with hot water.

  Similarly, in the case of FIG. 3, the temperature sensor indicates that the temperature of the hot water in the third hot water storage tank 3C has dropped to the set temperature SP2 during the hot water supply operation after the return destination of the circulating hot water is switched to the fourth hot water storage tank 3D. When detected at T3, the second switching valve 18 is closed and the third switching valve 19 is opened. Thus, the return destination of the circulating hot water from the hot water circulation circuit 4 is switched from the fourth hot water storage tank 3D to the sixth hot water storage tank 3N, and the operation according to the above is repeated.

  When the temperature sensor T2 or T5 detects that the hot water temperature in the second hot water storage tank 3B in FIG. 1 or the fifth hot water storage tank 3E in FIG. 3 has reached the set temperature SP2 or SP3, the operation of the heat source device 2 is performed. The hot water storage operation will be started. Of course, during this hot water storage operation, a part of the high temperature water from the high temperature water pipe 9 can be discharged to the hot water circulation circuit 4 side through the hot water discharge pipe 12 and the mixing valve 13 and supplied for hot water supply.

  Thus, according to the present embodiment, the hot water circulation circuit 4 can be configured by partially using the hot water storage tank 3 as a circulation tank, and a dedicated circulation tank independent from the hot water circulation circuit 4 can be omitted. Can do. Therefore, when compared with a hot water supply system having the same hot water storage capacity, the system can be enlarged by the amount not requiring a dedicated circulation tank, and the configuration can be simplified and the cost can be reduced. In addition, since the circulating hot water is stored in the hot water storage tank 3 that also serves as a circulation, the hot water having a lowered temperature can be stored in a dedicated circulating tank, so that it is possible to store hot water (hot water).

  Further, when the temperature of the hot water in the hot water storage tank 3 that has been used as the circulating hot water storage tank 3 drops due to a state in which hot water is not supplied from the hot water supply terminal 5 for a long time, the return destination of the circulating hot water is changed. Since the hot water storage tank 3 can be switched to the downstream side, the hot water temperature in the hot water circulation circuit gradually decreases due to natural heat radiation even though high temperature water is stored in other hot water storage tanks. The hot water stored in the hot water storage tank 3 can be effectively used, and at the same time, the medium temperature water whose temperature has dropped can be effectively used for hot water supply. it can.

  In particular, when a large number of hot water storage tanks 3, for example, six or eight tanks are connected in series, the return destination of the circulating hot water is divided into three or more stages and sequentially switched to the downstream stage. By going, all the hot water storage tanks 3A to 3N can be used as a circulation tank. Therefore, the hot water in all the hot water storage tanks 3A to 3N can be effectively used to adjust the temperature of the circulating hot water and supply hot water, thereby ensuring the required hot water supply temperature.

  Further, in each of the above stages, by providing a plurality of hot water storage tanks 3 for return, even when the hot water circulation circuit 4 becomes long or when it is installed in an environment where heat is easily radiated, the capacity corresponding to that is obtained. By securing the hot water storage tank 3 for circulation, the hot water circulation circuit 4 can be appropriately functioned, thereby obtaining the required hot water supply performance while increasing the degree of freedom of design for the hot water circulation circuit 4 side. it can.

  Further, the medium-temperature circulating hot water returned from the hot water circulation circuit 4 to the plurality of hot water storage tanks 3 in each stage is returned to the downstream hot water storage tank 3, and the hot water stored in each hot water storage tank 3 with the intermediate hot water is used. The hot water can be extruded by being sequentially discharged, and when the temperature of the hot water in the upstream hot water storage tank 3 falls below the set temperature, the return destination can be switched to the next stage. Therefore, the hot water and the intermediate temperature water from the hot water circulation circuit 4 are not mixed in the hot water storage tank 3, and the temperature of the high temperature water and the intermediate temperature water stored in the hot water storage tank 3 at that stage is all circulated. Can be used for adjustment and hot water supply.

  Further, when the hot water temperature of the hot water storage tank 3 at the most downstream side falls below the set temperature, it is determined that the hot water and the intermediate hot water stored in all the hot water storage tanks 3A to 3N are used effectively, respectively. By operating the pump 8 and the heat source device 2 to perform hot water storage operation, hot water having a target temperature can be stored in each of the hot water storage tanks 3A to 3N. Thus, efficient operation can be performed by appropriately and appropriately repeating hot water storage operation and hot water supply operation.

  In addition, this invention is not limited to the invention concerning the said embodiment, In the range which does not deviate from the summary, it can change suitably. For example, in the above embodiment, two or three first to third switching valves 17, 18, and 19 are used as valves for switching the return destination of the circulating hot water. One or two three-way switching valves can be substituted. Similarly, the flow rate adjusting valves 15 and 16 may be replaced by a single three-way flow rate adjusting valve.

DESCRIPTION OF SYMBOLS 1 Hot water supply system 2 Heat source machine 3 Hot water storage tank 3A First hot water storage tank (hot water storage tank)
3B 2nd hot water storage tank (hot water storage tank)
3C 3rd hot water storage tank (hot water storage tank)
3D 4th hot water storage tank (hot water storage tank)
3E 5th hot water storage tank (hot water storage tank)
3N 6th hot water storage tank (hot water storage tank)
4 Hot water circulation circuit 4C, 4D, 4E Hot water return piping (return piping)
5 Hot water supply terminal 7 Low temperature water pipe 8 Hot water storage pump 9 High temperature water pipe 10 Connecting pipe 12 Hot water pipe 13 Mixing valve 14 Circulating pumps 15 and 16 Flow rate adjusting valve 17 First switching valve (switching valve)
18 Second switching valve (switching valve)
19 3rd switching valve (switching valve)
T1, T2, T3, T4, T5, T6 Temperature sensor

Claims (5)

A heat source machine for producing high-temperature water by heating low-temperature water;
Connected to the heat source unit via a low temperature water pipe and a high temperature water pipe, and connected in series with each other to store hot water produced by the heat source unit from an upstream hot water storage tank to a downstream hot water storage tank in sequence. Two or more hot water storage tanks,
Connected to the hot water storage tank on the most upstream side to which the high temperature water pipe is connected via a hot water pipe and a mixing valve, hot water adjusted to a predetermined temperature is always circulated and at least one hot water supply terminal is provided. A hot water supply system comprising a hot water circulation circuit,
The hot water circulation circuit includes a hot water return pipe for returning a certain amount of circulating hot water to the bottom of a specific hot water storage tank in which another hot water storage tank is located downstream of the at least two hot water storage tanks ,
The hot water return pipe detects a hot water temperature of the specific hot water storage tank, and when the temperature drops below a set temperature, a return pipe that returns the circulating hot water to the bottom of the hot water storage tank downstream from the specific hot water storage tank; A hot water supply system comprising a switching valve. The return hot water storage tank that returns a certain amount of circulating hot water from the hot water circulation circuit, the return pipe, and the switching valve are provided in three or more stages from the upstream side to the downstream side. Hot water system. The hot water supply system according to claim 2, wherein a plurality of the return destination hot water storage tanks are provided in each stage. Among a plurality of hot water storage tanks provided in three or more stages from the upstream side to the downstream side, with respect to the hot water storage tank in which the hot water storage tank of the other stage is located on the downstream side, the bottom of the hot water storage tank of the other stage on the downstream side The hot water supply system according to claim 3, wherein a return pipe is connected, and the hot water temperature of the upstream hot water storage tank close to the hot water side is used for switching determination of the return destination. When the hot water temperature of the hot water storage tank on the most downstream side falls below a preset temperature, the hot water storage pump provided in the low temperature water pipe connecting the hot water storage tank on the most downstream side and the heat source machine and the heat source machine The hot water supply system according to any one of claims 1 to 4, wherein the hot water storage operation is performed until a target hot water storage amount is obtained.

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