JP5436933B2 - Hot water system - Google Patents

Description

The present invention relates to a hot water supply system capable of heating hot water using a heat exchanger using hot water in a bathtub as a heat source.

Conventionally, a hot water supply system that heats hot water in a hot water storage tank using hot water in a bathtub as a heating source has been proposed, and a specific example thereof is described in Patent Document 1, for example.
In the hot water supply system described in Patent Document 1, hot water is taken out from the lower part of the hot water storage tank by operating the circulation pump, and the hot water is heated by a heat exchanger using the hot water in the bathtub as a heating source, and then returned to the upper part of the hot water storage tank.

JP 2008-111574 A

However, in this hot water supply system, when the circulation pumps (P2, P3) are stopped, the hot water stored in the heat exchanger is cooled, so that convection occurs in the pipe connecting the upper and lower parts of the hot water storage tank. Since the hot water in the upper part of the hot water storage tank has a higher temperature and specific gravity than the hot water in the lower part, when the entire hot water in the pipe connecting the upper and lower parts of the hot water tank becomes low temperature hot water, It flows into the hot water storage tank from the lower part of the tank, and the temperature of the hot water in the hot water storage tank drops.
This invention is made | formed in view of this situation, and it aims at provision of the hot water supply system which suppresses the temperature of the hot water in a hot water storage tank resulting from being cooled with a heat exchanger.

The hot water supply system according to the present invention that meets the above-mentioned object is provided with a tap water inlet for supplying tap water at the bottom, a hot water storage tank for sending out stored hot water from the top, and a pipe connection to a water outlet provided at the bottom of the hot water storage tank The hot water in the bathtub is circulated to heat the hot water discharged from the water outlet, and the hot water taken out from the water intake provided in the lower part of the hot water tank is heated, External heating means for supplying hot water to the upper part, and a controller for controlling heating of hot water by the heat exchanger and heating of hot water by the external heating means, respectively, at the lower part of the hot water storage tank , starting from the outlet A water inlet that is an end point of a circuit that passes through the heat exchanger and that is filled with hot water heated by the heat exchanger is provided.

In the hot water supply system according to the present invention, the hot water storage tank includes first and second tanks arranged in parallel, and an upper portion of the first tank is connected to a lower portion of the second tank via a connecting pipe. Preferably, the upper part of the hot water storage tank functions as the upper part of the second tank, and the lower part of the hot water storage tank functions as the lower part of the first tank.

In the hot water supply system according to the present invention, the control device detects the temperature A of the hot water in the bathtub and the temperature B of hot water discharged from the outlet, and the temperature A is higher than the temperature B by a predetermined temperature or more. In addition, it is preferable to have control means 1 for heating the hot water with the heat exchanger.

In the hot water supply system according to the present invention, the control device can include control means 2 for starting heating of hot water by the heat exchanger during a midnight power discount time period on condition that a heat recovery start input has been made. .

In the hot water supply system according to the present invention, the control device sets a standby time zone before the midnight power discount time zone, and if there is a heat recovery start input in the standby time zone, Wait and heat the hot water using the heat exchanger. If there is a heat recovery start input before the waiting time period, heat the hot water using the heat exchanger when the heat recovery start input is received. Control means 3 can be provided.

In the hot water supply system according to the present invention, the water inlet is disposed closer to the water inlet than the water outlet, and hot water is heated by the heat exchanger in synchronization with heating of the hot water by the external heating means. The hot water heated by the heat exchanger can be positively taken out from the intake port.

The hot water supply system according to any one of claims 1 to 6 is provided with a water outlet for discharging hot water into the heat exchanger and a water inlet for receiving hot water heated by the heat exchanger at the lower portion of the hot water storage tank. The temperature difference between hot and cold water at the height of the water inlet and outlet is small, and the water in the heat exchanger is cooled without heating the hot water in the heat exchanger, and the circuit connects the inlet and outlet. Even if the entire interior has low-temperature hot water, it is possible to prevent the low-temperature hot water from flowing in from the water inlet or outlet, and to suppress the temperature drop of the entire hot water stored in the hot water storage tank.

In particular, since the hot water supply system according to claim 2 includes the first and second tanks in which the hot water storage tanks are arranged in parallel, it is possible to save the space for installing the hot water storage tank.

In the hot water storage system according to claim 3, since the temperature A of the hot water in the bathtub is higher than the temperature B of the hot water discharged from the outlet by a predetermined temperature or more, the hot water is heated by the heat exchanger. It is possible to avoid the hot water heating operation from being performed in a situation where the heating cannot be performed or the heating efficiency is low.

Since the hot water storage system according to claim 4 starts heating the hot water by the heat exchanger in the late-night power discount time zone, it is possible to reduce the power cost required for the hot water heating.

In the hot water storage system according to claim 5, when there is a heat recovery start input in the standby time zone, the hot water is heated by the heat exchanger after waiting for the midnight power discount time zone, so the power cost required for heating the hot water is reduced. If there is a heat recovery start input before the standby period, the hot water is heated by the heat exchanger at that time before the temperature of the hot water in the bathtub drops significantly. Hot water can be heated by a heat exchanger.

In the hot water storage system according to claim 6, since hot water heated by the heat exchanger is actively taken out from the water intake, the temperature rise of the hot water in the hot water storage tank is suppressed, and a low temperature hot water storage tank is sent to the heat exchanger, It is possible to increase the heating efficiency of the heat exchanger.

It is a schematic explanatory drawing which shows the hot water supply system which concerns on one embodiment of this invention. It is a block diagram which shows the connection of the control apparatus of the hot-water supply system. It is a flowchart figure which shows the time of the start of the heat recovery of the hot-water supply system.

Next, embodiments of the present invention will be described with reference to the accompanying drawings for understanding of the present invention.
As shown in FIGS. 1 and 2, a hot water supply system 10 according to an embodiment of the present invention includes a tap water inlet 16 into which tap water is placed at the bottom, and a hot water storage tank 13 for sending out stored hot water from the top, The hot water in the bathtub 38 is circulated to be taken out from the heat exchanger 56 for heating the hot water discharged from the water outlet 67 provided in the lower part of the hot water storage tank 13 and the water intake 17 provided in the lower part of the hot water storage tank 13. An external heating means 20 for heating the hot water and supplying hot water to the upper part of the hot water storage tank 13, and a controller 34 for controlling heating of the hot water by the heat exchanger 56 and heating of the hot water by the external heating means 20, respectively. .

The hot water storage tank 13 includes first and second tanks 11 and 12 arranged in parallel to store hot water, and the upper portion of the first tank 11 is connected to the lower portion of the second tank 12 via a connecting pipe 14. Thus, the hot water in the first tank 11 and the hot water in the second tank 12 can go back and forth via the connecting pipe 14.
A tap water inlet 16 that is connected to the water pipe 15 and feeds tap water into the first tank 11 is provided at the bottom (lower part) of the first tank 11.
A water intake 17 is provided in the lower part of the first tank 11, and the water intake 17 is connected to the upper part of the second tank 12 through a heating circulation pump 18 and a heat pump heat exchanger 19.

The external heating means 20 having the heating circulation pump 18, the heat pump heat exchanger 19 and the heat pump heat source device 23 operates the heating circulation pump 18 to take out hot water from the water intake 17, and the taken hot water is used as heat pump heat. It is sent to the exchanger 19. The heat pump heat exchanger 19 is connected to a heat pump heat source device 23 which is an example of a heat source device via a heat medium circulation circuit 22 in which the heat medium circulates, and the heat medium heated by the heat pump heat source device 23 is connected to the heat pump heat exchanger 19. Hot water sent from the first tank 11 is heated by heat exchange as a heat source.

The hot water heated by the heat pump heat exchanger 19 is supplied to the upper part of the second tank 12, and the second tank 12 has the hottest hot water in the upper part and the temperature of the hot water as it approaches the lower part from the upper part. Becomes lower and has the coldest hot water at the bottom. The hot water contained in the second tank 12 was connected to the lower part of the second tank 12 as the hot water heated by the heat pump heat exchanger 19 was supplied to the second tank 12. The first tank 11 flows into the first tank 11 via the connecting pipe 14, and the first tank 11 also has the hottest hot water in the upper part, like the second tank 12, and the temperature of the hot water decreases as it approaches the lower part from the upper part. It will be in the state which has the coldest hot water.

The first tank 11 includes first, second, third, and fourth remaining hot water thermistors 24, 25, 26, and 27, which are examples of temperature sensors that measure the water temperature, from the upper part to the lower part of the first tank 11. It is attached at different height positions in order toward the, and the temperature of the hot water at each attachment position is measured. The second tank 12 is provided with fifth, sixth, and seventh remaining hot water thermistors 28, 29, and 30 at different heights in order from the upper part to the lower part. Measure the temperature.

A heating three-way valve 32 is arranged between the heat pump heat exchanger 19 and the upper part of the second tank 12, and the heating three-way valve 32 is connected to the lower part of the first tank 11 via a bypass pipe 33. The heating three-way valve 32 can switch between flowing hot water flowing from the heat pump heat exchanger 19 to the second tank 12 or flowing to the lower portion of the first tank 11 via the bypass pipe 33. is there.

A controller 34 for controlling heating of hot water by the external heating means 20 is connected to the heating three-way valve 32 and the heating circulation pump 18, and the controller 34 controls the heat medium circulation circuit 22 immediately after the heat pump heat source device 23 is operated. When the circulating heat medium does not reach the temperature at which the hot water taken out from the water intake port 17 can be heated, the hot water flowing from the heat exchanger 19 for heat pump is switched to the lower part of the first tank 11 by switching the heating three-way valve 32. The low temperature hot water is supplied to the upper part of the second tank 12 to prevent the temperature of the hot water in the second tank 12 from decreasing.

Further, when the heat medium circulating in the heat medium circuit 22 reaches a temperature at which the hot water taken out from the water intake port 17 can be heated, the control device 34 performs heating of the hot water by the external heating means 20 and also for heating. The hot water sent from the heat pump heat exchanger 19 is sent to the upper part of the second tank 12 by switching the three-way valve 32.
A hot water storage tank mixing valve 35 connected to the upper part of the first tank 11 and the upper part of the second tank 12 is provided. The hot water storage tank mixing valve 35 is connected to the upper part of the first tank 11 and the second tank 12. Each hot water sent out from the upper part of is mixed and adjusted so as to be hot water having a predetermined temperature T or higher.

When the temperature of the hot water in the first tank 11 and the second tank 12 is both equal to or higher than the predetermined temperature T, the hot water in the first tank 11 is preferentially used and the hot water in the second tank 12 is preserved. Therefore, the second tank 12 is easily brought into a state having high-temperature hot water that can be recharged later.
The hot water fed through the hot water tank mixing valve 35 is mixed with tap water, and 1) hot water at a hot water supply set temperature set as the temperature of hot water supplied to the kitchen and washbasin faucet, etc., and 2) Since it is supplied as hot water having a hot water setting temperature set as the temperature of hot water filling the bathtub 38, the higher one of the hot water supply setting temperature and the hot water setting temperature is defined as a predetermined temperature T. To do.

In addition, a first thermistor 37, which is an example of a temperature sensor that measures the hot water temperature, is attached in the vicinity of the outlet 36 side of the hot water tank mixing valve 35, and the first thermistor 37 is sent out from the hot water tank mixing valve 35. Since the temperature of the hot water is measured, it is possible to detect whether or not the temperature of the hot water fed from the hot water tank mixing valve 35 is actually equal to or higher than the predetermined temperature T.

The water channel on the outlet 36 side of the hot water storage tank mixing valve 35 is branched, one of the branched water channels is directed to the inlet 43 side of the hot water mixing valve 42 and the other is directed to the inlet 40 side of the bathtub mixing valve 39. Form.
A water pipe 15 is connected to the hot water mixing valve 42, and the hot water mixing valve 42 mixes tap water with the hot water in the first tank 11 and the second tank 12 that flows in via the hot water storage tank mixing valve 35. Hot water having a hot water supply set temperature is used, and the hot water having the hot water set temperature is sent to a hot water supply pipe 44 connected to a kitchen, a faucet of a sink, or the like.

A water pipe 15 is also connected to the mixing valve 39 for the bathtub, and the mixing valve 39 for the bathtub taps the tap water into the hot water of the first tank 11 and the second tank 12 that flows through the hot water tank mixing valve 35. Are mixed to obtain hot water with a hot water filling set temperature, and hot water with this hot water filling set temperature is supplied to the bathtub 38 (hot water filling).

In the vicinity of the inlet 43 side of the hot water mixing valve 42, the hot water does not flow from the hot water mixing valve 42 to the hot water tank mixing valve 35, respectively, toward the water pipe 15 from the first check valve 45 and the hot water mixing valve 42. And a second check valve 46 for preventing hot water from flowing, and between the bathtub mixing valve 39 and the hot water tank mixing valve 35, the hot water tank mixing valve 35 is connected to the hot water tank mixing valve 35. A third check valve 47 is provided so that hot water does not flow in the direction.

A hot water filling circuit 52 that reaches the bathtub 38 through the opening / closing valve 48, the fourth check valve 49, and the bathtub circulation pump 50 is formed starting from the bathtub mixing valve 39. The hot water supply system 10 includes the opening / closing valve 48. By making it open, hot water adjusted in temperature by the bathtub mixing valve 39 is supplied to the bathtub 38. The on-off valve 48 and the bathtub circulation pump 50 are connected to the control device 34, and the control device 34 controls the opening and closing of the on-off valve 48 and the operation and stop of the bathtub circulation pump 50, respectively. The fourth check valve 49 prevents hot water from flowing from the bathtub 38 side to the bathtub mixing valve 39.

The bathtub 38 is connected to a bathtub circulation circuit 53 that shares a part with the hot water filling circuit 52 and circulates the hot water (hot water) in the bathtub 38. In the bathtub circulation circuit 53, a second thermistor 54 that measures the temperature of hot water in the bathtub 38 and a water level sensor 55 that measures the amount of hot water in the bathtub 38 are attached in the vicinity of the bathtub 38. A bathtub circulation pump 50 for circulating hot water in the bathtub 38 is provided.

Heat recovery for heating hot water discharged from the hot water storage tank 13 (first tank 11) using the hot water as a heat source is circulated in the bathtub circulation circuit 53, and hot water storage tank 13 (second tank 12). A heat exchanger 56 is provided that performs hot water from the hot water discharged from the hot water in the bathtub 38 and heats the hot water in the bathtub 38, and a bathtub-side flow path 57 through which the hot water in the bathtub 38 formed in the heat exchanger 56 flows is provided. A part of the bathtub circulation circuit 53 is configured.

Hot water is taken out from the bathtub 38 by operating the bathtub circulation pump 50 with the open / close valve 48 closed by the control device 34, and the hot water taken out circulates through the bathtub circulation circuit 53 and flows into the bathtub 38.
An upper part of the second tank 12 is provided with a hot water outlet 58 for discharging hot water, and the hot water discharged from the hot water outlet 58 of the second tank 12 is sent to the three-way valve 63 for heat exchange. It is done.

The three-way valve 63 for heat exchange has a reheating side inlet 59 connected to the reheating hot water outlet 58 and a heat recovery side inlet 60 to which hot water is supplied from the first tank 11. One of the heat recovery side inlet 60 and the heat recovery side inlet 60 is in a state where hot water (or hot water) passes to the heat exchange side outlet 61 provided in the heat exchange three-way valve 63, and the other is hot water on the heat exchange side outlet 61 side. Make it not pass. The heat exchange side outlet 61 is connected to a water inlet 65 provided at the lower part of the first tank 11 via a heat exchanger 56 and a heat exchange circulation pump 64.

When the heat exchanging pump 64 is operated in a state where the hot water inlet 59 can pass hot water, hot water in the upper part of the second tank 12 is discharged from the hot water outlet 58 and sent to the water inlet 65.
Further, a water outlet 67 for discharging hot water is provided at the lower part of the first tank 11, and the water outlet 67 is connected to the heat recovery side inlet 60 by piping and connected to the heat exchanger 56 through the heat exchange three-way valve 63. It is connected.

In addition, since the water inlet 65 is arrange | positioned in the position close | similar to the tap water inlet 16 and the water outlet 67 with respect to the water inlet 17, for example, it arrange | positions adjacent to the water inlet 17, the hot water supply system 10 is the heat exchanger 56. When the hot water is heated by the external heating means 20 in synchronization with the heat recovery by the hot water, the hot water that is heated by the heat exchanger 56 and flows into the first tank 11 through the water inlet 65 is positively taken in. Can be taken out from.

The circuit having the water inlet 65 as the end point via the heat exchange three-way valve 63, the heat exchanger 56, and the heat exchange circulation pump 64 is referred to as a heat recovery circuit 68, and the water outlet 58 for reheating is provided. Assuming that the circuit having the water inlet 65 as the end point via the heat exchange three-way valve 63, the heat exchanger 56, and the heat exchange circulation pump 64 at the start point is the follow-up circuit 66, the follow-up circuit 66 and the heat recovery circuit 68 are The part from the heat exchange side outlet 61 to the water inlet 65 is shared.

In addition, a hot water storage tank side flow path 69 constituting a reheating circuit 66 and a heat recovery circuit 68 is formed inside the heat exchanger 56, and hot water flowing out from the heat exchange side outlet 61 is supplied to the hot water storage tank side flow path. Pass through 69.
The heat exchange three-way valve 63 and the heat exchange circulation pump 64 are connected to the control device 34, and the control device 34 supplies hot water in the bathtub 38 to a predetermined level by the heat of the hot water discharged from the second tank 12. A tracking request signal for requesting tracking (heating) to temperature can be received from the outside.

When the control device 34 receives the reheating request signal, the hot water passes through the retreating side inlet 59 of the heat exchanging three-way valve 63, and further operates the heat exchanging circulation pump 64 to start from the reheating outlet 58. The hot water in the second tank 12 is taken out, and this hot water is poured into the first hot water storage tank 11 from the water inlet 65 via the hot water tank side channel 69. Moreover, the control apparatus 34 is connected also to the circulation pump 50 for bathtubs, will operate | move the circulation pump 50 for bathtubs, if the chasing request signal is received, circulate the hot water in the bathtub 38 in the bathtub circulation circuit 53, The hot water in the bathtub 38 flowing in the bathtub side flow path 57 is heated by heat exchange using the hot water in the second tank 12 flowing in the hot water storage tank side flow path 69 as a heat source.

The heat exchange is a condition that the heat source is at a higher temperature than the object to be heated, and the higher the temperature difference is, the more efficient and the object to be heated can be heated in a short time. Even if the temperature C of the hot water discharged from the hot water outlet 58 is higher than the bath set temperature set as the temperature of the hot water in the bathtub 38 in order to avoid replacement, the temperature difference is set in advance. If the difference is smaller than X, for example, 5 deg (° C.), no tracking is performed.

Here, the fifth remaining hot water thermistor 28 is arranged at the same height as the arrangement position of the hot water outlet 58 of the second tank 12, and the temperature C is measured by the fifth remaining hot water thermistor 28. The temperature A is measured by the second thermistor 54. In addition, the chasing ends when the temperature A reaches the set temperature by heating the hot water in the bathtub 38 in the heat exchanger 56. In addition, when no reheating is performed, the retreating side inlet 59 is in a state where hot water does not pass.

The control device 34 can receive a heat recovery start input signal for starting heating the hot water in the first tank 11 discharged from the water outlet 67 to a predetermined temperature using hot water in the bathtub 38 as a heat source. Yes, heating of hot water by the heat exchanger 56 is controlled based on this heat recovery start input. Upon receiving this heat recovery start input, the control device 34 puts hot water through the heat recovery side inlet 60 of the heat exchange three-way valve 63, operates the heat exchange circulation pump 64, and operates the first through the water outlet 67. The hot water is taken out from the first tank 11 and flows into the first hot water storage tank 11 from the water inlet 65 via the hot water storage tank side channel 69 and the hot water in the bathtub 38 is operated by operating the circulation pump 50 for the bathtub. Heat recovery is performed by heating the hot water in the first hot water storage tank 11 flowing in the hot water storage tank side channel 69 by heat exchange using the hot water flowing in the bathtub side flow channel 57 as a heat source.

The control device 34 sets the temperature A of the hot water in the bathtub 38 higher than the temperature B of the hot water discharged from the water outlet 67 and is set to a preset temperature Y (for example, 7 deg). Heating, that is, heat recovery is performed. The fourth remaining hot water thermistor 27 is arranged at the same height as the arrangement position of the water outlet 67 of the first tank 11, and the temperature B is measured by the fourth remaining hot water thermistor 27. Further, the heat recovery ends when the temperature A does not become higher than the preset temperature Z (for example, 5 deg) higher than the temperature B due to heating of the hot water in the hot water storage tank 13 by the heat exchanger 56.
The control device 34 is constituted by, for example, a microcomputer, can detect the temperature measured by the second thermistor 54, and the fourth and fifth remaining hot water thermistors 27, 28, and the heating circulation pump 18, A program for controlling the operation of the bathtub circulation pump 50 and the heat exchange circulation pump 64 and the operation of the heating three-way valve 32, the on-off valve 48, and the heat exchange three-way valve 63 is stored.

The hot water heated by the heat exchanger 56 by heat recovery flows into the first tank 11 from the water inlet 65, so that the hot water that has flowed in the first tank 11 flows from the lower part to the upper part while flowing through the first tank 11. It diffuses throughout the hot water contained in the tank 11.
Here, since the water inlet 65 is disposed adjacent to the water inlet 17, the control device 34 performs heat recovery in synchronization with the heating of the hot water by the external heating means 20, so that the heating flowing in from the water inlet 65 is performed. The hot water taken out from the water intake port 17 is actively taken out, and the hot water flowing in from the water inlet port 65 is diffused in the first tank 11 to prevent the temperature of the entire hot water in the first tank 11 from rising, thereby recovering heat. The efficiency of (heat exchange) can be increased.

Furthermore, when hot water is heated by the external heating means 20, the hot water of the first tank 11 taken out from the water intake port 17 is sent to the second tank 12, and the lower part of the second tank 12. This hot water flows into the upper part of the first tank 11 via the connecting pipe 14, and the hot water in the lower part of the second tank 12 is lower than the temperature of the upper part of the first tank 11. The hot water contained in the first tank 11 is prevented from rising in temperature due to heat recovery.

When reheating or heat recovery is not performed, the heat recovery side inlet 60 is in a state in which hot water passes and the reheating side inlet 59 is in a state in which hot water does not pass, and both the water inlet 65 and the water outlet 67 are first. The temperature difference between the hot water in the vicinity of the water inlet 65 and the water outlet 67 is a slight difference, so that the hot water in the hot water tank side channel 69 is cooled over time to recover heat. The amount of hot water flowing through the circuit 68 and flowing into the first tank 11 from the water inlet 65 or the water outlet 67 can be limited.

As shown in FIG. 3, the controller 34 detects whether or not heating of hot water by the external heating means 20 is being executed (step S2) on the condition that a heat recovery start input has been received (step S1). If hot water is being heated by the heating means 20, heat recovery is immediately started on condition that the temperature A is higher than the temperature B by a set temperature Y or higher and that there is a certain level of hot water in the bathtub 38 (step S3). ). The control device 34 has control means 1 that performs heat recovery on condition that the temperature A is higher than the temperature B by a set temperature Y or more.

Further, when the control device 34 detects in step S2 that the hot water is not heated by the external heating means 20, it is determined whether or not the current time is a midnight power discount time zone in which the power charge is cheap. (Step S4), and in the late-night power discount time zone, heat recovery starts immediately on condition that the temperature A is higher than the temperature B by a set temperature Y or higher and that there is a certain amount of hot water in the bathtub 38. (Step S5). Note that the control device 34 includes control means 2 that performs heat recovery in the midnight power discount time zone on condition that a heat recovery start input has been received.

Here, the control device 34 can set the start time (hereinafter also referred to as “N hour”) and the end time of the midnight power discount time zone in advance, and normally, 23:00 to 7:00 are set as the midnight power discount time zone. The The control device 34 can be set to start heat recovery at N time without immediately starting heat recovery at step S3, and until the start of heating of hot water by the external heating means 20 at step S4. It is also possible to set the start of heat recovery at the start of hot water heating by the external heating means 20 without starting the heat recovery.

Further, the control device 34 has a control means 3 that can set a standby time zone W in which heat recovery is not performed before the midnight power discount time zone , and when the control means 3 receives a heat recovery start input, Even if the temperature A is higher than the temperature B by a set temperature difference Y or more, heat recovery is not started in the standby time zone W. It should be noted that the end of the standby time zone W is always the start time of the midnight power discount time zone set in the control device 34, and a specific setting value for setting the standby time zone W is a time length (for example, 3 hours). It becomes.

Moreover, the longest value that can be set as the set value of the standby time zone W can be determined in advance, and when the longest value that can be set is determined, the time interval from the time when the heat recovery start input is input to N o'clock is long, It can be avoided that the temperature of the hot water in the bathtub 38 decreases with time, and the temperature at which heat cannot be recovered, that is, the temperature A is not higher than the set temperature Y compared to the temperature B.

When it is detected in step S4 that the current time is not the midnight power discount time zone, the control means 3 of the control device 34 detects whether or not the current time is the standby time zone W (step S6). If it is W, heat recovery is started at N hours without recovering heat until N hours (step S7).

On the other hand, when the control means 3 of the control device 34 detects that the current time is not the standby time zone W (in front of the standby time zone W, it is not the midnight power discount time zone) in step S6, the heat recovery start input is received. Immediately after that, heat recovery is started (step S8). For example, when the bath is taken in the morning and the heat is recovered after waiting for the midnight power discount time, the hot water in the bathtub 38 is cooled.
Further, the control device 34 can set in advance whether or not to start heating of hot water by the external heating means 20 when heat recovery is started in step S5, step S7, and step S8. It is also possible to execute hot water heating by a heat exchanger in synchronization with the above.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and all changes in conditions and the like that do not depart from the gist are within the scope of the present invention.
For example, the external heating means may use an electric heater or a heat source device using gas or petroleum as fuel instead of providing a heat pump heat source as a heat source. Further, the hot water storage tank may be a single tank without having two tanks. In this case, the hot water storage tank is not less than the hot water supply set temperature and the hot water set temperature from the hot water supply port provided at one upper portion. Pour hot water.

10: Hot water supply system, 11: First tank, 12: Second tank, 13: Hot water storage tank, 14: Connection pipe, 15: Water pipe, 16: Tap water inlet, 17: Water intake, 18: Circulation for heating Pump: 19: Heat exchanger for heat pump, 20: External heating means, 22: Heat medium circulation circuit, 23: Heat pump heat source device, 24: First remaining hot water thermistor, 25: Second remaining hot water thermistor, 26: Third remaining hot water thermistor, 27: fourth remaining hot water thermistor, 28: fifth remaining hot water thermistor, 29: sixth remaining hot water thermistor, 30: seventh remaining hot water thermistor, 32: three-way valve for heating, 33: Bypass pipe, 34: Control device, 35: Hot water storage tank mixing valve, 36: Outlet, 37: First thermistor, 38: Bathtub, 39: Bathtub mixing valve, 40: Inlet, 42 Hot water mixing valve, 43 : Entrance, 44: Hot water supply pipe, 45: 1 check valve, 46: second check valve, 47: third check valve, 48: on-off valve, 49: fourth check valve, 50: circulation pump for bathtub, 52: hot water filling circuit 53: Bath circulation circuit, 54: Second thermistor, 55: Water level sensor, 56: Heat exchanger, 57: Bath side flow path, 58: Hot water outlet, 59: Hot water inlet, 60: Heat Recovery side inlet, 61: Heat exchange side outlet, 63: Heat exchange three-way valve, 64: Heat exchange circulation pump, 65: Water inlet, 66: Reheating circuit, 67: Water outlet, 68: Heat recovery circuit, 69 : Hot water storage tank side flow path

Claims (6)

A hot water storage tank that has a tap water inlet at the bottom for tap water, and delivers stored hot water from the top,
A heat exchanger connected to a water outlet provided at a lower portion of the hot water storage tank, circulating hot water in a bathtub, and heating hot water discharged from the water outlet;
An external heating means for heating hot water taken out from a water intake provided at a lower portion of the hot water storage tank and supplying hot water to the upper portion of the hot water storage tank;
A controller for controlling heating of hot water by the heat exchanger and heating of hot water by the external heating means,
A hot water supply comprising a water inlet at a lower portion of the hot water storage tank , which is an end point of a circuit passing through the heat exchanger starting from the water outlet and into which hot water heated by the heat exchanger enters. system. The hot water supply system according to claim 1, wherein the hot water storage tank includes first and second tanks arranged in parallel, and an upper portion of the first tank is connected to a lower portion of the second tank via a connecting pipe. An upper part of the hot water storage tank functions as an upper part of the second tank, and a lower part of the hot water storage tank functions as a lower part of the first tank. 3. The hot water supply system according to claim 1, wherein the control device detects a temperature A of hot water in the bathtub and a temperature B of hot water discharged from the outlet, and the temperature A is higher than the temperature B by a predetermined temperature or more. A circulation type hot water supply system characterized by comprising control means 1 for heating hot water by the heat exchanger on the condition of 4. The hot water supply system according to claim 3, wherein the control device includes a control unit 2 that starts heating the hot water by the heat exchanger during a midnight power discount time period on condition that a heat recovery start input has been made. A hot water supply system that is characteristic. 4. The hot water supply system according to claim 3, wherein the control device sets a standby time zone before the late-night power discount time zone, and when there is a heat recovery start input in the standby time zone, the late-night power discount time zone. When the heat recovery start input is received before the waiting time period, the hot water is heated by the heat exchanger when the heat recovery start input is received. A hot water supply system having a control means 3 for performing. 3. The hot water supply system according to claim 1, wherein the water inlet is disposed closer to the water inlet than the water outlet, and is synchronized with heating of the hot water by the external heating means. A hot water supply system that performs heating and actively takes out hot water heated by the heat exchanger from the water intake.

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