JP5126433B1 - Water heater - Google Patents

Abstract

An object of the present invention is to provide an energy-saving hot water supply apparatus that does not have an energy saving effect due to heat recovery or prevents a heat recovery operation in a small state.
A hot water storage tank, a bathtub, a heat exchanger for exchanging heat between the hot water in the hot water tank and the hot water in the bathtub, and a hot water temperature detection for detecting the temperature of the hot water tank. Means 28, and when the temperature of the hot water in the bathtub 3 is equal to or lower than the temperature of the hot water tank 1 or the temperature of the hot water flowing into the heat exchanger 4 from the hot water tank 1, the heat exchanger 4 In the hot water supply device, the heat recovery operation for recovering the heat of the hot water in the bathtub 3 to the hot water in the hot water storage tank 1 is not performed. Even if the heat recovery operation is started, the stop condition is reached immediately. In this case, the heat recovery operation can be prevented from operating.
[Selection] Figure 1

Description

  The present invention relates to a hot water supply apparatus having a heat recovery function.

  Conventionally, this type of hot water supply apparatus includes a reheating operation for heating the hot water in the bathtub and a heat recovery operation for recovering heat from the hot water in the bathtub (for example, see Patent Document 1).

  FIG. 16 shows a hot water supply device having a heat recovery operation as a function. 1 is a hot water storage tank, 2 is a heat pump unit, 3 is a bathtub, 4 is a heat exchanger, 5a is a hot water tank water transport pump, and 5b is a bath water transport pump. , 6 is a heat recovery branch pipe, 7 is a three-way valve, 8 is a high temperature water supply pipe, 9 is a low temperature water supply pipe, 10 is a hot water supply pipe, 11 is a mixing valve, 12 is a bath water circulation pipe, 13 is an on-off valve, 14 is A water supply pipe, 15 is a hot water supply branch pipe, and 16 is a heat exchange return pipe.

  The bathtub water circulation pipe 12 is configured by connecting the forward pipe and the return pipe of the bathtub 3 in an annular shape, and includes a heat exchanger 4 and a bathtub water conveyance pump 5b on the circuit.

  The mixing valve 11 is configured to connect the high temperature water supply pipe 8 and the low temperature water supply pipe 9 to the inlet side, and connect the hot water supply pipe 10 to the outlet side, and the bathtub water circulation pipe 12 via the on-off valve 13. Connected. Further, a bathtub water temperature detecting means 17 for detecting the water temperature in the bathtub is provided in the middle of the bathtub water circulation pipe 12.

  When this hot water supply apparatus performs bath automatic operation, first, hot water stored in the hot water storage tank 1 and water supplied from the water supply pipe 14 are mixed with hot water at a desired temperature by the mixing valve 11 to supply hot water to the bathtub 3. . After the hot water is supplied to the bathtub 3, a heat retaining operation is performed in order to keep the temperature of the hot water constant for a certain period of time.

  The heat insulation operation is performed when the bath water temperature falls below a certain temperature. The hot water storage tank water transport pump 5a and the bath water transport pump 5b are operated, and the heat exchanger 4 performs hot water (for example, The hot water (for example, about 35 ° C.) in the bathtub 3 is heated by about 80 ° C.).

  Moreover, in order to judge whether the water temperature of the bathtub 3 has fallen below the fixed temperature, the bathtub water temperature detection operation | movement which drives only the bathtub water conveyance pump 5b is performed intermittently.

  When the bath water temperature detecting means 17 detects that the water temperature of the bathtub 3 is lowered below a certain temperature, the heat retaining operation is performed, and when the bath water temperature detecting means 17 is not lowered, it waits as it is. After a certain period of time has elapsed, automatic bath operation is automatically terminated.

  Next, when the reheating operation is performed, the hot water storage tank water transfer pump 5a and the bathtub water transfer pump 5b operate, and the hot water (for example, about 80 ° C.) in the hot water storage tank 1 is stored in the bathtub in the heat exchanger 4. The hot water in 3 (for example, about 35 ° C.) is heated. As a result, the water temperature in the bathtub 3 rises, and the amount of heat (heat storage amount) stored as hot water in the hot water tank 1 decreases.

  Finally, in the case of performing the heat recovery operation, the hot water tank water transfer pump 5a and the bath water transfer pump 5b are similarly operated. In the heat exchanger 4, the water in the hot water tank 1 (for example, about 10 ° C.) Cools the water (for example, about 35 ° C.) in the bathtub 3 and recovers heat.

  As a result, the water temperature in the bathtub 3 drops and the amount of heat (heat storage amount) stored as hot water in the hot water tank 1 increases, so that the amount of heat heated up by the heat pump unit 2 can be reduced.

  In addition, as one of the methods for controlling such operation, there is a method of setting a time until the heat recovery operation is started after stopping the automatic bath operation, and performing the heat recovery operation when this time expires. (For example, refer to Patent Document 2).

  FIG. 17 shows a control block of a conventional hot water supply apparatus described in Patent Document 2.

  The operation control means 18 operates the timer 20 which measures the time until the heat recovery operation is started after the bath automatic operation detection unit 19 detects the stop of the automatic bath operation, and the preset time has expired. The heat recovery operation control means 21 starts the heat recovery operation.

JP 2009-198115 A JP 2007-278578 A

  However, in the conventional configuration, if there is a relatively large amount of remaining hot water in the hot water tank after the automatic bath function is stopped, the heat recovery function may be started in a state where the stop condition is reached immediately even if the heat recovery operation is started. However, there is a problem that the energy saving effect by heat recovery is small, or conversely, useless energy may be consumed for the operation of the pump or the like.

  An object of the present invention is to solve the above-described conventional problems, and to provide an energy-saving hot water supply apparatus that does not have an energy saving effect due to heat recovery or prevents a heat recovery operation in a small state. To do.

In order to solve the conventional problems, a hot water supply apparatus of the present invention includes a hot water storage tank, a bathtub, a heat exchanger for exchanging heat between the hot water in the hot water tank and the hot water in the bathtub, and the hot water tank. Multiple in the height direction
Is arranged, the hot water storage temperature detecting means for detecting the temperature of the hot water storage tank, a first tapping tube connected to an upper portion of the hot water tank, a water supply pipe connected to the lower portion of the hot water tank, the hot water tank The user gives an instruction to start a heat pump apparatus that heats the hot water in the hot water, and a heat recovery operation in which the hot water is taken out from the lower part of the hot water tank and the heat of the hot water in the bathtub is recovered by the heat exchanger and returned to the hot water tank. Means and a control means, in the hot water supply apparatus configured to take out hot water from the lower part of the hot water tank and heat it with the heat pump device and then return it to the upper part of the hot water tank, between the substantially central part and the bottom part of the hot water tank When the temperature of the hot water of the hot water exceeds a predetermined value, or the temperature of the hot water of the bathtub is the temperature of the hot water between the substantially central part and the bottom of the hot water tank or the hot water flowing into the heat exchanger from the hot water tank of in the case of a temperature below, With not performing serial heat recovery operation, when executing the heat recovery operation, so that the input of the heat pump apparatus during operation after the heat recovery operation stop is substantially minimized, cold water to the bottom of the hot water tank The heat recovery operation is stopped in a state where the water is stored .

  As a result, when the stop condition is reached immediately after starting the heat recovery operation, the heat recovery operation can be prevented from operating.

  ADVANTAGE OF THE INVENTION According to this invention, the energy saving effect by heat recovery is not provided, or an energy-saving hot water supply apparatus can be provided by preventing the heat recovery operation operation in a small state.

Configuration diagram of hot water supply apparatus in Embodiment 1 of the present invention Block diagram of the heat recovery operation control means Conceptual diagram of control method for automatic bath operation and heat recovery operation Conceptual diagram of the control method for the chasing operation and heat recovery operation Circuit configuration diagram showing the flow of water and hot water when hot water is supplied to the bathtub during automatic bath operation Circuit configuration diagram showing the flow direction of water and hot water during warm-up operation and chasing operation during automatic bath operation Circuit configuration diagram showing the flow direction of water and hot water during bath water temperature detection operation during automatic bath operation Circuit configuration diagram showing the flow direction of water and hot water during the heat recovery operation The figure which showed the change of the temperature distribution in the hot water tank by the heat recovery operation Diagram showing the efficiency of the heat pump unit Diagram showing the relationship between the heat recovery amount and heat pump unit input Flow chart of the heat recovery operation control operation The block diagram of the hot-water supply apparatus in Embodiment 2 of this invention Circuit configuration diagram showing the flow direction of water and hot water during the heat recovery operation Circuit configuration diagram showing the flow direction of water and hot water during the same boiling operation Configuration diagram of conventional hot water supply equipment Block diagram of the same control

The first invention includes a hot water storage tank, a bathtub, a heat exchanger for exchanging heat between the hot water in the hot water tank and the hot water in the bathtub, and a plurality of the hot water storage tanks in the height direction of the hot water storage tank. Hot water temperature detecting means for detecting the temperature of the tank, a first hot water pipe connected to the upper part of the hot water tank, a water supply pipe connected to the lower part of the hot water tank, and hot water in the hot water tank are heated. A heat pump device, means for instructing the user to start a heat recovery operation in which hot water is taken out from the lower part of the hot water tank and the heat of the hot water in the bathtub is recovered by the heat exchanger and returned to the hot water tank, and control means; The hot water is taken out from the lower part of the hot water tank, heated by the heat pump device, and then returned to the upper part of the hot water tank.
In the hot water device, when the temperature of the hot water between the approximate center and the bottom of the hot water tank exceeds a predetermined value, or the temperature of the hot water in the bathtub is between the approximate center and the bottom of the hot water tank . When the temperature is not more than the temperature of hot water or the temperature of hot water flowing from the hot water storage tank to the heat exchanger, the heat recovery operation is not performed, and when the heat recovery operation is performed, the heat recovery operation is stopped. The hot water supply device stops the heat recovery operation in a state where low temperature water is stored in the bottom of the hot water storage tank so that the input during the operation of the heat pump device is substantially minimized .

As a result, when the stop condition is reached immediately after starting the heat recovery operation, the heat recovery operation can be prevented from operating .

Moreover, when there is a lot of hot water in the temperature stratified hot water storage tank, it is possible to prevent a heat recovery operation that is less effective .

Thus , based on the temperature distribution of the hot water storage tank during the heat recovery operation, the time point at which the heat consumption (power consumption) for boiling up the predetermined hot water storage amount by the heating means is judged to be minimum, and the heat recovery operation is stopped. Therefore, it is possible to improve the efficiency of the entire system, which is the original purpose, and to improve energy saving.

Further , the heat recovery operation can be started when the user determines that the subsequent bathing does not occur regardless of the activation schedule of the heat recovery operation set automatically or the like.

Thereby , the useless heat dissipation from a bathtub is suppressed and there exists an effect that energy saving property improves .

2nd invention WHEREIN: The 2nd hot-water pipe connected between the position where the said 1st hot-water pipe was connected in the up-down direction of the said hot water tank, and the position where the said water supply pipe was connected, and the said heat exchange A heat exchange return pipe connected to the heat exchanger and the hot water storage tank so that the hot water in the hot water storage tank exchanged heat with the hot water in the bathtub is returned to the hot water storage tank. The hot water storage tank at a position between the position where the first hot water discharge pipe is connected to the hot water storage tank and the position where the second hot water discharge pipe is connected to the hot water storage tank in the vertical direction of the hot water storage tank. It is characterized by being connected to.

As a result, it is possible to effectively use water at a medium temperature (hereinafter referred to as medium hot water) between the hot water at the upper part of the hot water tank and the cold water at the lower part, which is unavoidable in the temperature stratified hot water tank. The amount of heat recovered from the bath water can be increased because a large amount of low-temperature water can be secured below the hot water tank.

In addition, flowing the warm water generated by the heat recovery into the relatively upper part of the hot water tank means that the hot water that moves below the hot water tank while increasing the temperature of the hot water that is below the inflow position of the hot water recovered. Since it can be used for hot water supply through the hot water outlet, the amount of heat stored in the hot water can be used to the maximum extent possible.

At the same time, when the heating means is a heat pump unit, the efficiency of the entire system can be prevented by reducing the medium temperature water in the hot water tank that causes a decrease in the boiling efficiency, and the good use of the heat quantity is good. Realize usability and high energy saving.

In addition, when there is a lot of hot water and heat recovery operation is started in a state close to the stop condition, the second hot water pipe and the heat exchange return pipe are installed at appropriate positions to make good use of the medium hot water at the bottom of the hot water tank. Regardless of the configuration that secures a lot of low-temperature water, operating the first transport pump increases the amount of medium-temperature water in the hot water storage tank.

In this case, the effect of heat recovery cannot be obtained, and the efficiency is reduced when boiling in the heat pump unit, but since the temperature state of the hot water tank is detected to determine the execution of the heat recovery operation, The high energy saving property obtained by optimizing the connection position between the second hot water discharge pipe and the heat exchange return pipe is not impaired.

A third invention is the high temperature water supply pipe connected to supply hot water savings tundish, so as to supply cold water, cold water supply pipe connected to said hot water tank bottom or the water supply pipe A mixing valve for connecting the high temperature water supply pipe and the low temperature water supply pipe to the inlet side to mix the high temperature water and the low temperature water, and the hot exchanger in the heat exchanger and the bathtub circulate. A hot water pipe connected to the outlet side of the mixing valve and the hot water pipe so as to supply hot water of a predetermined temperature to the hot water bath, and a hot water pipe connected to the hot water pipe in the middle of the hot water pipe. and an opening and closing valve, and upstream in the branch connected to the hot water supply branch pipe to the heat exchanger of the on-off valve, a first conveying pump for circulating the hot water in front Symbol hot water storage tank and the heat exchanger, the bathtub and a second conveying pump for circulating the hot water in the heat exchanger, the control Stage, closing the on-off valve, by adjusting the mixing valve to the opening to supply preferentially the water from the cold water supply pipe to the hot water supply pipe than hot water from the hot water supply pipe, and the second One transport pump and the second transport pump are operated to perform the heat recovery operation.

  As a result, the three functions of hot water supply, reheating and heat recovery can be realized by controlling the opening of the mixing valve, so that there is an effect that the control is simplified and malfunctions such as malfunctions are reduced.

A fourth invention is the savings to be substantially lower in the hot water tundish flows into the heat exchanger, the heat pump device, and the heat recovery forward pipe connected to the heat exchanger through sequentially the switching means, said heat pump as hot water heated by the device is returned to the hot water storage tank, e Bei a boiling return pipe connected to the hot water storage tank from said switching means, the heat of the hot water of the bathtub by the heat exchanger When performing a heat recovery operation for recovering the hot water in the hot water tank, hot water from the hot water tank flows in the order of the heat recovery forward pipe, the heat pump device , the switching means, the heat exchanger, and the heat exchange return pipe. said, also when performing a boiling operation for heating hot water in the hot water storage tank by the heat pump system, the heat recovery forward pipe, the heat pump apparatus, said switching means, in the order of the water heating return pipe As flow water from tundishes, a hot water supply device, characterized in that said control means has a configuration for switching the switching means.

Thereby, it can be set as the structure which uses a part of piping used at the time of heat recovery also at the time of the boiling operation of the hot water in a hot water tank, and can provide the hot water supply apparatus which implement | achieved cost reduction .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a diagram showing a configuration of a hot water supply apparatus according to Embodiment 1 of the present invention.

  In FIG. 1, a hot water supply apparatus includes a hot water tank 1, a heat pump unit 2 as a heating means for heating the water in the hot water tank 1, a bathtub 3 to be subjected to heat recovery, water in the bathtub 3, and the hot water tank 1. A heat exchanger 4 configured to exchange heat with water, a water supply pipe 14 connected to the hot water tank 1, a first hot water pipe 22 connected to substantially the upper part of the hot water tank 1, and a first It is comprised from the position where the hot water pipe 22 and the water supply pipe 14 were connected, ie, the 2nd hot water pipe 23 connected to the trunk | drum approximate center part of the hot water storage tank 1 in the height direction.

The hot water supply device is connected to the high temperature water mixing valve 24 in which the first hot water discharge pipe 22 and the second hot water discharge pipe 23 are connected to the inlet side, and to the outlet side of the high temperature water mixing valve 24. A high-temperature water supply pipe 8 for supplying high-temperature water therein, a low-temperature water supply pipe 9 branched from the water supply pipe 14 and supplying low-temperature water in the hot water tank 1 or from the water supply pipe 14, and these high-temperature water supply pipes 8 A mixing valve 11 connected to the inlet side of the low-temperature water supply pipe 9, a hot water supply pipe 10 connected to the outlet side of the mixing valve 11, an on-off valve 13 connected in the middle of the hot water pipe 10, and an on-off valve The hot water branch pipe 15 branched upstream of 13 and connected to the first flow path of the heat exchanger 4, and the water in the hot water tank 1 that exchanged heat with the water in the bathtub 3 in the heat exchanger 4 are again stored in the hot water tank 1. The hot water storage tank is located at a position between the first hot water discharge pipe 22 and the second hot water discharge pipe 23 of the heat exchanger 4 in the height direction so as to return to And a connected thermal 交戻 Ri tube 16. in and.

  Furthermore, the hot water supply device includes a hot water tank water transfer pump 5a as a first transfer pump that circulates water in the first flow path of the hot water tank 1 and the heat exchanger 4, and a second flow of the heat exchanger 4. Bathtub water conveyance as a second conveyance pump for circulating water in the second flow path of the bathtub 3 and the heat exchanger 4 and the bathtub water circulation pipe 12 connected so that the water of the bathtub 3 circulates in the road And a pump 5b.

  Here, the heat exchange return pipe 16 is connected to the hot water tank 1 at a position between the first hot water pipe 22 and the second hot water pipe 23 in the vertical direction of the hot water tank 1. Moreover, the hot water supply pipe 10 is connected in the middle of the bathtub water circulation pipe 12, and this hot water supply pipe 12 is used when hot water is supplied to the bathtub 3.

  The remote controller 25 installed in the bathroom is provided with a heat recovery operation start switch 26 for the user to arbitrarily start the heat recovery operation, and the bathtub water circulation pipe 12 measures the water pressure as a bath water amount detection means. Thus, a water level sensor 27 for detecting the water level of the hot water in the bathtub 3 and a bathtub water temperature detecting means 17 for detecting the water temperature of the bathtub 3 are provided, and the water temperature in the hot water tank 1 is set in the hot water tank 1. Several hot water storage temperature detection means 28a-28e for detecting are provided.

  Furthermore, based on the outputs of the plurality of hot water storage temperature detection means 28a to 28e, the water level sensor 27, the bath water temperature detection means 17 and the operation of the heat recovery operation start switch 26, the hot water supply to the bathtub 3 and the time set in advance thereafter Only bath automatic operation control means 29 as hot water supply control means for controlling automatic bath operation for maintaining the temperature of the bathtub water and maintaining the amount of water, and reheating operation control means 30 for controlling the reheating operation for heating the water in the bathtub 3. The hot water storage tank 1 is provided with operation control means 18 including heat recovery operation control means 21 for controlling the heat recovery operation for recovering the heat of the water in the bathtub 3.

  FIG. 2 shows a block diagram of the heat recovery operation control means 21, in which the output of the hot water storage temperatures 28 c and 28 d of the water level sensor 27 and the hot water storage temperature detection means 28 a to 28 e and the operating state of the bath automatic operation control means 29 or the heat recovery operation control. The heat recovery operation start determination unit 31 for determining the start of the heat recovery operation from the heat recovery operation start time set in advance by the means 21 and the heat recovery operation start switch 26 and the like, and the boiling operation by the heat pump unit 2 are controlled. Hot water storage temperature distribution which measures hot water storage temperature distribution by required hot water storage heat quantity acquisition part 32 and hot water storage temperature detection means 28a-28e which acquire hot water storage calorie required for use of hot water supply after hot water from boiling operation control means (not shown) It is necessary to calculate the required amount of boiling heat based on the measurement unit 33 and the results obtained by the required hot water storage amount acquisition unit 32 and the hot water temperature distribution measurement unit 33. It consists of an upper heat amount calculation unit 34 and a hot water storage temperature distribution estimation unit 35 at the time of completion of boiling that estimates the current temperature distribution by the hot water storage temperature distribution measurement unit 33 and the temperature distribution at the time of completion of boiling from the required boiling heat amount calculation unit 34. .

  Further, the boiling required for estimating the input to the heat pump unit 2 from the current temperature distribution by the hot water storage temperature distribution measuring unit 33 to the estimated temperature distribution at the completion of boiling by the hot water storage temperature distribution estimating unit 35 at the completion of boiling. The input estimation part 36 and the pump control part 37 which controls the hot water tank water conveyance pump 5a and the bathtub water conveyance pump 5b based on the time change of the input estimated value by this boiling required input estimation part 36 are comprised.

  About the hot water supply apparatus comprised as mentioned above, the operation | movement and an effect | action are demonstrated below.

  As a basic operation in the use of hot water in a general home, hot water for the day is stored in the hot water tank 1 in the morning, and is sequentially used for hot water supply during an active time. When the amount of hot water storage is insufficient during use of hot water, the heat pump unit 2 may be operated as necessary, and an additional hot water storage operation may be performed.

  In recent years, there have been an increasing number of hot water supply apparatuses having a function of automatic bath operation that automatically performs from hot water supply to the bathtub 3 to heat insulation. When the bath automatic operation control means 29 performs hot water supply to the bathtub 3 and heat insulation operation, the hot water stored in the hot water storage tank 1 is used to supply hot water to the bathtub 3, and when the bath water temperature decreases, the hot water storage tank A heat insulation operation is performed using the heat of hot water stored in 1, and the bath water temperature is maintained at a preset temperature. In addition, when the reheating operation is performed by the reheating operation control means 30 and the hot water in the bathtub 3 is heated, the heat of the hot water stored in the hot water tank 1 is used.

  Most of the hot water in the hot water storage tank 1 is replaced with hot water at the time when heat use such as hot water supply for one day is finished, and hot water storage operation for the next use is performed again at midnight thereafter. At this time, the hot water supplied to the bathtub 3 for bathing is often left at a relatively high temperature with respect to the water temperature in the hot water tank 1 at the end of use of the hot water supply. A heat recovery operation is performed before or during the midnight boiling operation by the heat pump unit 2 to recover heat in the hot water tank 1.

  Next, a control method for bath automatic operation, chasing operation, and heat recovery operation will be described. The bath automatic operation control means 29 automatically supplies a predetermined amount of hot water to the bathtub 3 at a predetermined temperature, and then intermittently performs a heat retaining operation so as to maintain the bath water temperature at a preset temperature for a preset time. Perform (automatic bath operation).

  During bath automatic operation, in order to determine whether or not it is necessary to perform a heat retaining operation, a bath water temperature detecting operation is periodically performed to detect the bath water temperature. The bath water temperature is detected by the bath water temperature detection means 17, and as a result, when the bath water temperature is lower than a preset temperature by a predetermined temperature or more (for example, 1K or more), a heat insulation operation is performed to maintain the bath water temperature. If it is less than 1, do not keep warm.

  During this preset time, automatic bath operation is prioritized and the heat recovery operation control means 21 is automatically operated or the heat recovery operation start switch 26 is operated by the user even when receiving an instruction to start the heat recovery operation. Control is performed so that the heat recovery operation is performed after a preset time has elapsed without performing the recovery operation.

  On the contrary, when the bath automatic operation control means 29 receives an instruction to start the bath automatic operation during the heat recovery operation, the heat recovery operation control means 21 stops the heat recovery operation, giving priority to the bath automatic operation. The automatic operation control means 29 starts bath automatic operation (conceptual diagram is shown in FIG. 3).

  The reheating operation control means 30 circulates and warms the hot water in the bathtub 3 and ends when the bath water temperature detected by the bath water temperature detection means 17 reaches a predetermined temperature or when a predetermined time elapses from the start of the operation (refreshing). operation).

  While the reheating operation control means 30 is performing the reheating operation, the renewal operation is prioritized, the heat recovery operation control means 21 does not perform the heat recovery operation, and after the reheating operation is completed, the heat recovery operation is performed. Control to do.

Conversely, even when the reheating operation control means 30 receives an instruction for reheating operation during the heat recovery operation, the recuperation operation is given priority, and the heat recovery operation control means 21 stops the heat recovery operation and retreats. The operation control means 30 starts a chasing operation (a conceptual diagram is shown in FIG. 4).

  The operation of the valve and the pump when performing each operation and the flow of water and hot water associated therewith will be described with reference to FIGS. In the figure, the flow path is indicated by a bold line.

  First, the operation when the bath automatic operation control means 29 performs bath automatic operation will be described. FIG. 5 shows the flow of water and hot water in the circuit when hot water is first supplied to the bathtub 3. From the hot water storage tank 1, hot water from the first hot water discharge pipe 22 and the second hot water discharge pipe 23 is mixed by the high temperature water mixing valve 24 and supplied to the high temperature water supply pipe 8.

  The hot water supplied to the high-temperature water supply pipe 8 and the water supplied from the water supply pipe 14 to the low-temperature water supply pipe 9 are mixed with hot water having a desired hot water supply temperature by the mixing valve 11 and supplied to the hot water supply pipe 10. The Here, the temperature of the hot water supplied from the high-temperature water mixing valve 24 to the high-temperature water supply pipe 8 is higher than the above-mentioned desired hot water supply temperature by a predetermined temperature or more (for example, 45 ° C. or more when the desired hot water supply temperature is 40 ° C.). ) Is adjusted.

  The on-off valve 13 is opened, and hot water having a desired temperature supplied to the hot water supply pipe 10 is supplied to the bathtub 3 from the bathtub water circulation pipe 12. The opening degree of the high temperature water mixing valve 24 and the mixing valve 11 is generally feedback controlled based on the temperature of hot water supplied to the high temperature water supply pipe 8 and the hot water supply pipe 10 respectively connected to the outlet side. For the high temperature water mixing valve 24, the hot water from the first outlet pipe 22 and the second outlet pipe, and for the mixing valve 11, the hot water from the high temperature water supply pipe 8 and the temperature of the feed water from the low temperature water supply pipe 9. It depends on.

  FIG. 6 shows the flow of water and hot water in the circuit when the hot water in the bathtub 3 is kept warm. The hot water storage tank water transfer pump 5a and the bathtub water transfer pump 5b start operation, and the hot water storage tank water transfer pump 5a starts operation from the upper part of the hot water storage tank 1 through the first hot water discharge pipe 22 through the high temperature water mixing valve 24. Hot water is supplied to the hot water supply pipe 8 and further supplied to the hot water supply pipe 10 via the mixing valve 11.

  At this time, the on-off valve 13 is closed and the hot water supplied to the hot water supply pipe 10 is supplied to the hot water supply branch pipe 15 to heat the hot water in the bathtub 3 circulating through the bathtub water circulation pipe 12 in the heat exchanger 4. Increase the bath water temperature.

  On the other hand, the hot water that has left the heat exchanger 4 and has a relatively low temperature returns to the hot water tank 1 through the heat exchange return pipe 16. At this time, the opening degree of the high temperature water mixing valve 24 and the mixing valve 11 is such that the first hot water outlet pipe 22 and the high temperature water supply pipe 8 side are fully opened, and the hot water in the upper part of the hot water tank 1 is supplied to the heat exchanger 4. It is generally controlled so that a certain amount of hot water or water flows from the second hot water outlet pipe 23 and the low temperature water supply pipe 9 and mixes them.

  FIG. 7 shows the flow of water and hot water in the circuit when the bathtub water temperature detection operation for detecting the water temperature in the bathtub 3 is performed. The bathtub water conveyance pump 5b starts operation, and the hot water in the bathtub 3 circulates in the bathtub water circulation pipe 12. At this time, the on-off valve 13 is closed and the hot water tank water transfer pump 5a does not operate. The bathtub water temperature detection means 17 detects the bathtub water temperature and determines whether or not to perform a heat retaining operation.

  Next, the operation when the reheating operation control means 30 performs the reheating operation, the flow of water and hot water in the circuit when the reheating operation is performed, when the bath automatic operation control means 29 performs the heat retaining operation. Since this is the same as shown in FIG.

Finally, FIG. 8 shows the flow of water and hot water in the circuit when the heat recovery operation control means 21 performs the heat recovery operation of the hot water remaining in the bathtub 3. When the heat recovery operation is started, water is supplied from a substantially lower portion of the hot water tank 1 to the low-temperature water supply pipe 9 by the operation of the hot water tank water transfer pump 5 a, and supplied to the hot water supply pipe 10 through the mixing valve 11.

  At this time, the on-off valve 13 is closed, and the water supplied to the hot water supply pipe 10 is supplied to the hot water supply branch pipe 15 and exchanges heat with the hot water of the bathtub 3 circulating through the bathtub water circulation pipe 12 in the heat exchanger 4. To recover heat. On the other hand, the water that has left the heat exchanger 4 and has reached a relatively high temperature returns to the hot water tank 1 through the heat exchange return pipe 16. At this time, the opening degree of the mixing valve 11 is generally controlled so that the low temperature water supply pipe 9 side is fully opened, but a certain amount of hot water flows from the high temperature water supply pipe 8 and mixes. There may be.

  The temperature distribution in the hot water tank 1 when the heat recovery operation is performed changes in the order of 38, 39, and 40 shown in FIG. That is, the temperature of the water 41 that exchanges heat with the bathtub 3 and flows into the hot water tank 1 from the heat exchange return pipe 16 is often lower than the hot water temperature of the hot water tank 1, and the hot water tank is caused by the action of the hot water tank water transfer pump 5a. It moves toward the lower side of the hot water tank 1 while being mixed with the hot water of No. 1.

  Since the connection position of the second hot water discharge pipe 23 is below the connection position of the heat exchanger return pipe 16, when hot water is generated, the medium-temperature water 42 that has come down is discharged from the second hot water discharge pipe 23, 1 can be used by mixing with hot water 43 from the hot water outlet pipe. Reference numeral 44 shown in FIG. 3 indicates a temperature distribution when hot water is generated after heat recovery. Thus, since the 2nd hot water discharge pipe 23 exists below the connection position to the hot water storage tank of the heat exchange return pipe 16, the collect | recovered heat | fever can be utilized effectively.

  The occurrence of hot water supply is relatively small, and the medium-temperature water that remains without being used up is reheated and used by the heat pump unit 2, but the operating efficiency of the heat pump unit 2 is as shown in FIG. The higher the water temperature, the lower it.

  As can be seen from the temperature distribution of the hot water tank 1 shown in FIG. 9, the required heating amount by the heat pump unit 2 after the heat recovery operation decreases as the amount of recovered heat from the bathtub 3 increases. Since the water temperature before heating becomes high and the operation efficiency at the time of reheating is reduced, it is not necessarily energy saving to perform as much heat recovery as possible.

  That is, the input (heat consumption or power consumption) to the heat pump unit 2 is obtained by subtracting the recovered heat amount obtained by the heat recovery operation from the necessary heat amount before heat recovery for obtaining the required hot water storage heat amount. As shown in FIG. 11, this value may have a minimum value for the recovered heat amount.

  Therefore, in order to obtain a higher energy saving effect, it is necessary to stop the heat recovery operation from the bathtub 3 at the time when the input to the heat pump unit 2 becomes substantially minimum in the reheating operation performed after the heat recovery operation is stopped. It is.

  As a specific method for finding the time point at which the minimum value is reached, the change of the input value to the heat pump unit 2 that is predicted based on the temperature distribution of the hot water tank 1 measured at predetermined time intervals is obtained. Judgment is made when the degree of decrease in the value is small or no longer decreases, or starts to increase.

As shown in FIG. 10, when the hot water in the hot water tank 1 is heated by the heat pump unit 2, the temperature at the site where water is transported from the hot water tank 1 to the heat pump unit 2 (in this embodiment, the hot water tank 1 The operating efficiency of the heat pump unit 2 increases as the temperature of the lower part of the heat pump unit 2 decreases. However, when the heat recovery operation from the bathtub 3 is performed, the water recovered from the bathtub 3 flows into the hot water tank 1. There is a state in which the temperature of the part that transports water from the hot water tank 1 to the heat pump unit 2 starts to rise.

  Therefore, at the time of the heat recovery operation from the bathtub 3, the temperature of the part that transports water to the heat pump unit 2 of the hot water tank 1 is measured, and the heat recovery operation operation from the bathtub 3 is performed in the vicinity where the increase in the temperature starts to increase. By stopping the operation, it is possible to achieve substantially the maximum operating efficiency of the heat pump unit 2 during the heating operation after the heat recovery operation.

  A control method of the heat recovery operation control means 21 for obtaining a high energy saving effect in consideration of the above will be described.

  FIG. 12 is a flowchart of the operation of the heat recovery operation control means 21. When the heat recovery operation start determination unit 31 determines the start of the heat recovery operation, such as the operation of the heat recovery operation start switch 26 by the user or the elapse of a predetermined time after the end of the automatic bath operation by the bath automatic operation control means 29, first The hot water storage temperature detection means 28c and the hot water storage temperature detection means 28d disposed between the substantially central portion and the bottom portion in the height direction of the hot water storage tank 1, and the temperature difference (Tc−Td) between these values. Is less than a predetermined value α (for example, 3 deg) and the value Td of the hot water storage temperature detecting means 28d on the lower side exceeds the predetermined value β (for example, 38 ° C.) (step 1), the heat recovery operation is started. It ends without doing (step 2).

  This is a process for avoiding an operation in which there is hot water up to the position of the hot water storage temperature detection means 28d and the heat recovery is stopped and the effect is not improved even if the heat recovery is started.

  In the present embodiment, the determination is made by using the temperature difference between the two detection means of the hot water storage temperature detection means 28c and the hot water storage temperature detection means 28d, but more hot water storage temperature detection means are used. In this case, the temperature may be determined using a plurality of hot water storage temperature detection means.

  However, in the temperature-stratified hot water tank 1 in which hot water is stored higher in the hot water tank 1 than in the lower side, the hot water tank 1 is disposed at least between the center and the bottom in the height direction of the hot water tank 1. It is desirable to determine the temperature using the temperature of the stored hot water temperature detecting means 28d.

  Next, if the above conditions are not met, the water level sensor 27 detects the water level proportional to the amount of hot water in the bathtub (step 3), and the water level is below a predetermined value σ (eg, 200 mm). However, as a condition in which there is too little hot water in the bathtub 3 and the effect of heat recovery cannot be obtained, the heat recovery operation is terminated without starting (step 2).

  In addition, even if it is not the water level sensor 27, the bathtub water conveyance pump 5b may be operated, the flow of hot water in the bathtub 3 may be detected by a flow rate detection switch or the like, and any means capable of detecting the amount of hot water in the bathtub may be used.

  Further, in (Step 3), the bathtub water transport pump 5b is operated, the hot water temperature of the bathtub 3 is detected by the bathtub water temperature detecting means 17, and then the hot water storage tank water transport pump 5a is operated, and the hot water temperature of the bathtub 3 is detected. However, if the hot water temperature detection means 28d is below the value Te of the hot water storage temperature detecting means 28e disposed further downward in the height direction of the hot water storage tank 1, the hot water temperature of the bathtub 3 is lower than the hot water storage tank 1. Since the heat recovery effect cannot be obtained because the temperature is equal to or lower than the temperature, the heat recovery operation is terminated without starting (step 2).

In the above description, the temperature of the lower part of the hot water tank 1 is used. However, temperature detecting means is provided in the low temperature water supply pipe 9 and the hot water supply branch pipe 15 that flow into the heat exchanger 4 from the lower part of the hot water tank 1, and the hot water May be used.

  If these conditions are not satisfied, the operation proceeds to the operation of heat recovery, the required hot water storage amount acquired by the required hot water storage amount acquisition unit 31, and the current temperature distribution of the hot water tank 1 measured by the hot water storage temperature detection means 28a to 28e, When the temperature distribution in the hot water tank 1 at the time of completion of the hot water storage operation is predicted from the operating conditions such as the boiling temperature of the heat pump unit 2 and compared with the current temperature distribution, the heat pump unit 2 is heated from that time The remaining heating amount Qr is obtained (step 4).

  Next, the average water temperature before boiling in the heat pump unit 2 is estimated from the measured current temperature distribution until reaching the predicted temperature distribution at the time of completion of the hot water storage operation (step 5).

  Further, the average efficiency during hot water storage operation is obtained from the average water temperature obtained in step 5 and the characteristics of the heat pump unit 2 shown in FIG. 4, and the remaining heating amount Qr obtained in step 4 is divided by this average efficiency to obtain hot water storage water. The input Qin during operation is estimated (step 6).

  Qin obtains a difference from Qin−f which is a value obtained at the previous evaluation time, and when it is smaller than a predetermined deviation q, that is, when a change in estimated input gradually becomes smaller and it is determined to be the minimum value (step 7) In Step 2, the hot water storage tank water transfer pump 5a and the bathtub water transfer pump 5b are stopped to end the heat recovery operation. When the difference between Qin and Qin−f is greater than or equal to q, the heat recovery operation is continued, and when the next evaluation time is reached (step 9), the above operation is repeated.

  In addition, as a supplement, at the first operation after the start of the heat recovery operation, step 8 is executed without performing the comparison at step 7.

  Here, the operation based on the water level at the start of the heat recovery operation has been described. In Step 1, after the heat recovery operation is started, the difference Tc−Td between the hot water temperature detection means 28c and the hot water temperature detection means 28d is calculated. Even when the temperature is less than 3 ° C., the heat recovery operation is stopped (step 2).

  Further, although not shown in this flowchart, the amount of hot water in the hot water storage tank 1 changes due to hot water supply or the like, and the difference Tc−Td between the hot water temperature detecting means 28c and the hot water temperature detecting means 28d becomes 3 ° C. or more. If this happens, the heat recovery operation is resumed by executing this procedure again, and the above operation is performed.

  The above is the explanation of the operation. The stop of the heat recovery operation that does not depend on the difference between the hot water temperature detecting means 28c and the hot water temperature detecting means 28d or the amount of hot water in the bathtub 3 is judged as the minimum value of the input of the heat pump unit 2. This is done by reducing the degree of decrease.

  In addition to this method, when the input difference q between the evaluation times is 0, or when the sign of q is reversed from the previous evaluation time, that is, when the estimated input starts to increase, the heat recovery operation is set to the minimum value. May be stopped.

  In addition, the estimated input often increases or decreases while reaching the minimum value due to a measurement error of the temperature value of the hot water tank 1 to be measured. Therefore, by storing the estimated input at the latest several evaluation times, and determining whether the minimum value has been reached by using the moving average value, the determination accuracy of whether the minimum value has been reached is further improved. Can be increased.

  Furthermore, as described above, the method of evaluating the temperature distribution each time and obtaining the input is highly accurate, but the calculation is complicated and the load on the heat recovery operation control means 21 is large.

  In that case, when a change in hot water storage temperature at a position that most affects the input is grasped in advance, and one of the hot water storage temperature detection means 28a to 28e corresponding to that position starts to rise. When the temperature rises or a predetermined temperature is detected, or while the temperature detected by the hot water storage temperature detection means 28d rises and the temperature detected by the hot water storage temperature detection means 28e does not increase, the heat recovery operation is continued. The stop may be determined according to a combination of two or more temperatures.

  Specifically, by detecting that the temperature relatively close to the lower part of the hot water tank 1 is rising and stopping the heat recovery operation, the efficiency of the heat pump unit 2 is less likely to be impaired, and a desired effect is obtained. Can be obtained. Furthermore, if the change of the temperature of the upper part of the hot water tank 1 is taken into consideration, it is possible to simultaneously evaluate the amount of recovered heat by the heat recovery operation, and the accuracy is improved.

  Thus, according to the embodiment of the present invention, there is hot water having the same temperature up to a relatively low position of the hot water tank 1, that is, there is a large amount of remaining hot water, and there is little room for heat recovery of the bathtub 3, If the stop condition is reached immediately after starting the recovery operation, the heat recovery operation is not performed.

  Therefore, according to the present invention, the hot water tank water transfer pump 5a and the bath water transfer pump 5b move wastefully by preventing the energy recovery effect by heat recovery or preventing the heat recovery operation in a small state. It can be prevented and energy saving is not impaired.

  At this time, if there is a lot of hot water in the hot water tank 1 at the timing of starting the heat recovery operation, the heat recovery operation is not started, and the hot water is increased in the hot water tank 1 during the heat recovery operation. The heat recovery operation is also stopped when it becomes. Furthermore, if the remaining hot water decreases due to hot water supply or the like, the heat recovery operation can be started or restarted to perform operation without impairing the energy saving performance.

  The heat recovery operation can be resumed automatically after a certain amount of time has elapsed after the amount of hot water has recovered, but after the user has supplied hot water, the amount of remaining hot water in the hot water storage tank 1 is confirmed. Since it can be restarted immediately by operating the start switch 26, wasteful heat radiation from the bathtub 3 over time is suppressed, and energy saving is improved.

  Further, in the configuration of the piping system for realizing the automatic bath operation, the reheating operation, and the heat recovery operation, they are switched by adjusting the opening of one mixing valve 11, so that the function is improved in the housing. In addition, it is not necessary to secure an installation space for new members, and there is no increase in weight, material, and standby power, contributing to resource and energy savings.

  In addition, the heat exchanger 4 is a plate type with high heat exchange efficiency, and is installed near the connection position of the heat exchange return pipe 16 of the hot water tank 1 to make the heat exchanger 4 itself compact. As a minimum pipe length, it will save resources as well.

  When the heat recovery operation is performed, the heat recovery operation is stopped when the input to the heat pump unit 2 for boiling up the required hot water storage amount is minimized, so that the efficiency of the entire system, which is the original purpose, is reduced. Improvement can be realized and energy saving can be improved.

  As a configuration, water stored in the lower part of the hot water tank 1 is collected from the tap water, heated by the heat exchanger 4 and returned to the upper part of the hot water tank 1, but the hot water tank 1 by the heat recovery operation is used. The temperature distribution varies depending on the difference between the take-out position and the return position.

  Furthermore, the heat recovery speed and the like can be controlled by controlling the capacity of the hot water tank water transfer pump 5a, and the operation efficiency changes depending on the difference in configuration and control.

  Therefore, in this embodiment, an optimized design is made such that an appropriate take-out position and return position can be set in consideration of usage, the capacity of the hot water tank 1, and the capacity control of the hot water tank water transfer pump 5a can be performed. Since the degree of freedom is high, it can be easily applied to a plurality of different models, and as a result, a large energy saving effect can be obtained by providing it to many users.

  Furthermore, in hot water supply from the hot water tank 1, hot water from the first hot water discharge pipe 22 and the second hot water discharge pipe 23 is appropriately mixed by the high temperature water mixing valve 24 to effectively use the medium temperature water in the hot water storage tank 1. In addition, by making the connection position of the heat exchange return pipe 16 to the hot water storage tank 1 higher than the second hot water discharge pipe 23, the hot water in the upper part of the hot water tank and the lower temperature in the lower part are inevitable in the temperature stratified hot water tank. As a result of the effective use of the medium-temperature water that can be formed between the water and the water, the amount of heat recovered from the bath water can be increased because a large amount of low-temperature water can be secured below the hot water tank even with the same heat storage amount.

  In addition, the flow of the intermediate warm water generated by the heat recovery into the relatively upper portion of the hot water storage tank 1 means that the intermediate warm water that moves below the hot water storage tank 1 while increasing is lower than the inflow position of the hot recovered hot water. Since it can be used for hot water supply through the two hot water outlet pipes 23, the amount of stored hot water can be used to the maximum extent possible.

  At the same time, the reduction of the medium temperature water in the hot water tank 1 that leads to a decrease in the heating efficiency of the heat pump unit 2 can prevent a decrease in the efficiency of the entire system. Good usability and high energy savings due to effective use of heat quantity Realize.

  Further, when the heat recovery operation is started when there is no or little bath water, the second hot water discharge pipe 23 and the heat exchange return pipe 16 are installed at appropriate positions, so that the hot water can be used well and the lower part of the hot water tank 1 In spite of the configuration of securing a large amount of low-temperature water, the hot water storage tank 5 is operated to increase the amount of hot water in the hot water storage tank.

  In this case, the effect of heat recovery cannot be obtained, and the efficiency is lowered when the heat pump unit 2 is heated. However, since the amount of hot water in the bath is detected in advance to determine the execution of the heat recovery operation, The high energy-saving property obtained by optimizing the connection position of the hot water return pipe 23 and the heat exchange return pipe 16 is not impaired.

  That is, it is possible to provide a hot water supply apparatus that appropriately controls the heat recovery operation and realizes high energy saving performance.

(Embodiment 2)
FIG. 13 is a diagram showing a configuration of a hot water supply apparatus according to the second embodiment of the present invention.

  In FIG. 13, the difference from the first embodiment is that a switching means 51 is provided, and a reheating branch branched from the first outlet pipe 22 through the switching means 51 to the primary inlet of the heat exchanger 4. A heat transfer pipe 52 serving as a flow path for operation is connected, and a lower part of the hot water tank 1 and the switching means 51 are connected via a heat pump unit 2 by a heat recovery forward pipe 53.

  Furthermore, the upper part of the hot water tank 1 and the switching means 51 are connected by a boiling return pipe 54, and the hot water tank water transfer pump 5 a is disposed in the heat recovery forward pipe 53.

  About the hot water supply apparatus comprised as mentioned above, the operation | movement and an effect | action are demonstrated below. The entire operation is the same as that described in the first embodiment, and a portion in which the hot water path differs depending on the circuit will be described.

When performing a heat recovery operation in which the heat of the hot water of the bathtub 3 is recovered by the heat exchanger 4 into the hot water of the hot water tank 1, the hot water of the bathtub 3 is transferred to the secondary side flow path of the heat exchanger 4 as shown in FIG. The bathtub water conveyance pump 5b is operated in order to convey the water.

  Thereafter, from the lower part of the hot water storage tank 1, the hot water storage pipe 53, the heat pump unit 2, the switching means 51, the primary flow path of the heat exchanger 4, the heat exchange return pipe 16, and the substantially central part of the hot water storage tank 1 are sequentially stored. The hot water storage tank water conveyance pump 5a is operated so that the hot water from the tank 1 flows. Thereby, the heat which the hot water of the bathtub 3 has is collect | recovered by the hot water of the hot water tank 1.

  In addition, the required flow volume by the bathtub water conveyance pump 5b is ensured by making the conveyance amount of the hot water by the bathtub water conveyance pump 5b larger than the conveyance amount of the hot water by the hot water tank water conveyance pump 5a, and the temperature distribution in the bathtub 3 is It is made uniform and heat can be stably recovered from the bathtub 3, and the flow rate by the hot water tank water transfer pump 5a becomes excessive, so that the hot water in the hot water tank 1 is not stirred and the temperature stratification is performed. Since it can hold | maintain, it becomes possible to perform the boiling operation of the hot water in the hot water storage tank 1 mentioned later efficiently.

  Further, when performing the boiling operation for heating the hot water in the hot water tank 1 by the heat pump unit 2, as shown in FIG. 15, the operation control means 18 changes the flow direction of the switching means 51 during the heat recovery operation described above. Are switched to different directions and the hot water tank water transfer pump 5a is operated, so that the heat recovery forward pipe 53, the heat pump unit 2, the switching means 51, the boiling return pipe 54, and the hot water tank 1 are Hot water from the hot water storage tank 1 is flowed to the upper part in order, and the hot water transfer amount by the hot water tank water transfer pump 5a is controlled so that the hot water after passing through the heat pump unit 2 reaches a predetermined boiling temperature.

  Thereby, the water in the lower part of the hot water tank 1 is heated by the heat pump unit 2 and returned to the upper part of the hot water tank 1, and the hot water is stored from above the hot water tank 1.

  Note that, in both the heat recovery operation and the boiling operation, the hot water storage tank water transport pump 5a provided in the heat recovery forward pipe 53 in order to transport the hot water in the lower part of the hot water storage tank 1 to the primary side of the heat exchanger 4. However, when performing the heat recovery operation, a pump provided in the heat exchange return pipe 16 may be used as in the first embodiment.

  In this embodiment, since a considerable part of the flow path of the heat recovery operation and the boiling operation can be shared by using the switching means 51, the number of piping members to be used can be reduced, thus realizing resource saving and cost reduction. There is an effect that can be done.

  As described above, the hot water supply device according to the present invention performs appropriate control in consideration of the hot water temperature in the hot water storage tank during the heat recovery operation from the hot water in the bathtub. In addition to being applicable, it can also be applied to large-scale applications such as commercial use, and can provide a hot water supply device control system with excellent practicality.

1 Hot water tank 2 Heating means (heat pump unit)
3 Bathtub 4 Heat exchanger 5a First transfer pump (hot water storage tank transfer pump)
5b Second transfer pump (tub water transfer pump)
DESCRIPTION OF SYMBOLS 8 High temperature water supply pipe 9 Low temperature water supply pipe 10 Hot water supply pipe 11 Mixing valve 12 Bath water circulation pipe 13 On-off valve 14 Water supply pipe 15 Hot water branch pipe 16 Heat exchange return pipe 17 Bath water temperature detection means 18 Operation control means 21 Heat recovery operation control means DESCRIPTION OF SYMBOLS 22 1st hot water pipe 23 2nd hot water pipe 24 High temperature water mixing valve 25 Remote control 26 Heat recovery operation start switch 28 Hot water storage temperature detection means 29 Bath automatic operation control means 30 Reheating operation control means 51 Switching means 52 Heat transfer pipe 53 Heat recovery pipe 54 Heating return pipe

Claims (4)

A hot water tank, a bathtub, a heat exchanger for exchanging heat between the hot water in the hot water tank and the hot water in the bathtub, and a plurality of heat exchangers arranged in the height direction of the hot water tank, and detecting the temperature of the hot water tank. Hot water storage temperature detection means, a first hot water pipe connected to the upper part of the hot water storage tank, a water supply pipe connected to the lower part of the hot water storage tank, a heat pump device for heating hot water in the hot water storage tank, and the hot water storage The hot water storage tank is provided with means for instructing a user to start a heat recovery operation in which hot water is taken out from the lower part of the tank and the heat of the hot water in the bathtub is recovered by the heat exchanger and returned to the hot water storage tank. In the hot water supply apparatus configured to take out hot water from the lower part and heat it with the heat pump device and return it to the upper part of the hot water tank, when the temperature of the hot water between the substantially central part and the bottom part of the hot water tank exceeds a predetermined value, or , hot water temperature of the bathtub, the savings When the hot water temperature or the hot water storage tank between the substantially central portion and the bottom portion of the bath of hot water temperature below that flows into the heat exchanger, as well it does not perform the heat recovery operation, performing the heat recovery operation When the heat recovery operation is stopped, the heat recovery operation is stopped in a state where low-temperature water is stored at the bottom of the hot water storage tank so that the input during the operation of the heat pump device after the heat recovery operation is substantially minimized. A water heater. A second hot water discharge pipe connected between a position where the first hot water discharge pipe is connected and a position where the water supply pipe is connected in the vertical direction of the hot water storage tank; A heat exchange pipe connected to the heat exchanger and the hot water storage tank so that the hot water of the hot water tank exchanged with the hot water tank is returned to the hot water storage tank, and the heat exchange return pipe is connected to the hot water storage tank. In the vertical direction, the hot water storage tank is connected to the hot water storage tank at a position between the position where the first hot water discharge pipe is connected to the hot water storage tank and the position where the second hot water discharge pipe is connected to the hot water storage tank. The hot water supply apparatus according to claim 1 . A hot water supply pipe connected to supply hot water in the savings tundish, so as to supply cold water, and cold water supply pipe connected to the hot water tank bottom or the water supply pipe, the inlet side A mixing valve for connecting the high temperature water supply pipe and the low temperature water supply pipe to mix the high temperature water and the low temperature water, and a bathtub circulation connected to circulate the heat exchanger and the hot water in the bathtub. A hot water pipe connected to an outlet side of the mixing valve and the bathtub circulation pipe so as to supply hot water of a predetermined temperature to the bathtub, an on-off valve connected in the middle of the hot water pipe, off valve upstream hot water supply branch pipe connected to the heat exchanger branches in the, by said heat exchanger before Symbol hot water storage tank and the first conveying pump for circulating the hot water, in the heat exchanger and the bath and a second conveying pump for circulating the hot water, wherein, the open The valve is closed, the mixing valve is adjusted to an opening degree that supplies water from the low-temperature water supply pipe to the hot water pipe with priority over hot water from the high-temperature water supply pipe, and the first transport pump and The hot water supply apparatus according to claim 2, wherein the second recovery pump is operated to perform the heat recovery operation. It said to be substantially lower in the hot water savings tundish flows into the heat exchanger, the heat pump device, and the heat recovery forward pipe connected to the heat exchanger through sequentially the switching means, which is heated by the heat pump apparatus as hot water returns to the hot water storage tank, e Bei a boiling return pipe connected to the hot water storage tank from said switching means, the heat of the hot water of the bathtub by the heat exchanger to the hot water of the hot water tank when performing the heat recovery operation recovering, the heat recovery forward pipe, the heat pump apparatus, said switching means, said heat exchanger, so that hot water flows from the hot water tank in the order of the heat交戻Ri tube, also, the heat pump when the device performs a boiling operation for heating hot water in the hot water storage tank, the heat recovery forward pipe, the heat pump apparatus, said switching means, hot water from the hot water tank in the order of the water heating return pipe Flowing manner, water heater according to claim 2, characterized in that said control means has a configuration for switching the switching means.