JPH11141974A - Hot water supply device for bath - Google Patents

Abstract

PROBLEM TO BE SOLVED: To economically and comfortably take a bath by providing a heat retaining start means for starting a bathtub water heat retaining means, when the temperature detected by a bath sensor is not higher than second setting temperature which is obtained by subtracting constant temperature from the setting temperature of an external input device. SOLUTION: A hot water supply device for a bath is provided with a heat retaining start means 26 for starting a bathtub water heat retaining means 27 for controlling an operation of supplementary burning, when the temperature detected by a temperature sensor 9 is not higher than second setting temperature which is obtained by subtracting constant temperature from the setting temperature of an external input device 24. Further, an interval for detecting the temperature of bathtub water for supplementary burning by the bathtub water heat retaining means 27 is made longer when the temperature is high by a temperature sensor 23, and is made shorter when the temperature is low. Further, an interval for detecting the temperature of bathtub water for supplementary burning by the bathtub water heat retaining means 27 is made longer when the temperature of water is high by a water temperature sensor 2 and made shorter when it is low.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bath water heater capable of filling a bathtub with hot water and reheating.

[0002]

2. Description of the Related Art Generally, the temperature of a hot water in a bath tub decreases with time due to natural heat radiation. In addition, the temperature of the hot water in the bathtub decreases even when a person takes a bath. Therefore, it is necessary to reheat the hot water in the bathtub to keep the temperature constant in order to maintain a desired set temperature and to take a comfortable bath.

[0003] Therefore, the conventional bath water heater detects the temperature of the bathtub at regular time intervals, for example, every 10 minutes. If the detected temperature is lower than the set temperature, additional heating is performed until the temperature reaches the set temperature. The operation is to be executed.

The configuration of a conventional general bath water heater is shown in FIG. 5 and will be described in detail.

The water passes through a water supply sensor 30 and a water temperature sensor 2 provided in a pipe 31 from a water supply port 30 of a water heater main body 29, absorbs heat in a hot water supply heat exchanger 3, and receives a heat supply sensor 4, a hot water supply control valve 5 Through the hot water outlet 32. The gas enters through a gas inlet 33, passes through a gas source solenoid valve 6 provided in a pipe 34, and passes through a hot water supply burner 8 through a hot water supply proportional valve 7 to heat the hot water supply heat exchanger 3.

The hot water is supplied to the bathtub 35 by the hot water filling means 25 by controlling the hot water supply amount control valve 5, the gas source solenoid valve 6, the gas hot water supply proportional valve 7, the hot water supply solenoid valve 20, and the two-way valve 21. Hot water, which supplies water and gas and is heated by the hot water supply heat exchanger 3 to the set temperature of the external input device 24, passes through the hot water supply amount control valve 5, the hot water supply solenoid valve 20, and passes from the two-way valve 21 to the outgoing passage 12. The water is branched into the return passage 13 and enters the bathtub 35 from the bath connection adapter 19.

[0007] Then, at predetermined time intervals (in this example, 10 minute intervals) by the heat retention start means 28, the bathtub water heat retention means 2
Start 7 That is, the water flow switch 10 and the circulation pump 22 are controlled by the bath water keeping means 27, and the bath water is supplied to the bath connection adapter 19, the return passage 13, the water level sensor 14, the switching three-way valve 15, the bath sensor 9, The water is circulated through a circulation path 36 including a water flow switch 10, a bath heat exchanger 11, an outgoing passage 12, and a bath connection adapter 19. The circulation path 3 is detected by the bath sensor 9.
The temperature of the hot water in the bath tub circulating through 6 is detected, and the detected temperature is compared with the set temperature of the external input device 24. At this time, if the detected temperature is equal to or higher than the set temperature of the external input device 24, the operation of the circulation pump 22 is stopped. However, when the detected temperature is lower than the set temperature of the external input device 24, the bathtub water warming means 27 causes the bath solenoid valve 1 of the gas.
6. The bath proportional valve 17 is controlled to supply gas to the bath burner 18 through the bath source electromagnetic valve 16 and the bath proportional valve 17 for combustion, and the bath heat exchanger 11 is heated and the external input device 24 The reheating operation is performed until the set temperature is reached.

When the temperature of the circulating bath water reaches the set temperature of the external input device 24, upon receiving a signal from the bath sensor 9 detecting the temperature, the reheating operation of the bath water warming means 27 is stopped and the circulation pump is turned on. Operation of 22 is stopped.

Next, a supplementary heating operation of the conventional bath water heater will be described in detail with reference to FIG.

(Step 1) The bath tub water keeping means 27 is started by the heat keeping start means 28, and the bath tub water is supplied to the circulation pump 22.
Circulates through a circulation path 36 consisting of a bath connection adapter 19, a return passage 13, a water level sensor 14, a switching three-way valve 15, a bath sensor 9, a water flow switch 10, a bath heat exchanger 11, an outgoing passage 12, and a bath connection adapter 19. Let it.

(Step 2) The bath sensor 9 detects the temperature of the hot water in the bathtub circulating in the circulation path 36.

(Step 3) The detected temperature of the bath sensor 9 is compared with the set temperature of the external input device 24.

(Step 4) When the detected temperature is equal to or higher than the set temperature, the operation of the circulation pump is stopped.

(Step 5) If the detected temperature is lower than the set temperature, a reheating operation is started.

(Step 6) The additional heating operation is performed until the detected temperature reaches the set temperature. (Step 7) When the detected temperature reaches the set temperature, the reheating operation is stopped.

(Step 4) After the reheating operation is stopped, the operation of the circulation pump 22 is stopped.

(Step 8) If the heat retention is to be continued, proceed to step 14. (Step 14) The bathtub water keeping means 27 is restarted every 10 minutes.

[0018]

As described above, in the conventional bath water heater, bathtub water is circulated at regular time intervals by the circulating pump 22 by the bathtub water warming means 27, and the temperature detected by the bath sensor 9 becomes external. If the temperature is lower than the set temperature of the input device 24, the additional heating operation is executed until the set temperature is reached.

However, in the conventional bath water heater, the circulating pump 22 is always operated at a constant time interval by the bath water keeping means 27 to detect the hot water temperature of the bath tub. Even when the temperature of the bathtub is hardly lowered and the bathtub water need not be kept so frequently, the circulation pump 22 can be used to detect the temperature of the bathtub.
Operation is uneconomical. Further, every time the circulation pump 22 is operated, hot water whose temperature is lower than the hot water of the bathtub due to heat radiation remaining in the water heater main body 29, the outgoing passage 12, and the return passage 13 is transferred from the bath connection adapter 19 to the bathtub 35. Since the water is released, hot water at a low temperature hits the bather, and there is a problem that the bath cannot be comfortably taken.

Conversely, if the time interval is set to be long, the temperature of the hot water in the bathtub tends to decrease in winter or the like, and even when the temperature of the bathtub needs to be maintained more frequently than in summer, the temperature of the hot water in the bathtub is low. Since the state lasts for a long time, the user often feels warm when taking a bath, and thus has a problem that the bath cannot be comfortably taken.

In order to solve the above-mentioned problems, the present invention can change the time interval for detecting the temperature of the bathtub for keeping the temperature of the bathtub depending on the hot water temperature of the bathtub and weather conditions such as the outside air temperature or the incoming water temperature. Accordingly, an object of the present invention is to provide a bath water heater capable of performing an economical and comfortable bathing.

[0022]

The bath water heater according to the present invention is provided with a bath water when the temperature detected by the bath sensor falls below a second set temperature obtained by subtracting a certain temperature from the set temperature of the external input device. There is provided a heat keeping start means for starting the heat keeping means.

Further, there is provided a heat retention start means for starting the bathtub water heat retention means at predetermined time intervals determined by an air temperature sensor provided in the water heater for detecting the outside air temperature.

Further, there is provided a heat-retaining start means for starting the bath-tub water heat-retaining means at a predetermined time interval determined by a water temperature sensor provided in the water heater for detecting the incoming water temperature.

That is, according to the present invention, the bathtub water preservation means is performed when the temperature becomes equal to or lower than the second set temperature, regardless of the predetermined time interval, so that useless operation of the circulation pump can be reduced. Therefore, it is possible to take a bath economically and comfortably.

Further, the time interval at which the bathtub water insulation means is started can be changed according to weather conditions such as the outside air temperature or the incoming water temperature. Can be done at intervals. On the other hand, in the case of summer, for example, where the temperature of the bathtub is hard to decrease, the bathtub heat retention means can be performed at long intervals,
Bathing can be performed economically and comfortably.

[0027]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A bath water heater according to a first aspect of the present invention is provided with a hot water supply heat exchanger for heating water supply, a water temperature sensor for detecting water supply temperature and a water supply flow rate for detecting water supply temperature. A water sensor, a hot water supply sensor for detecting hot water temperature and a hot water supply control valve for controlling the flow rate of hot water, a bath heat exchanger for heating the circulating bath water to hot water, and a circulating water flow from the bath to the bath heat exchanger. A return passage, a circulating pump that circulates bath water, a bath sensor that detects the temperature of the bath water, a hot water supply electromagnetic valve provided in a passage connecting the hot water supply passage and the return passage, and the bath heat exchanger. A hot water heated by the hot water supply heat exchanger is provided from the bath hot water supply electromagnetic valve to the bath hot water supply passage, provided with a downstream passage provided on the downstream side, and an external input device that can input a set temperature and display an operation state. And return passage Hot water filling means for supplying to the bath tub, and circulating pump circulates hot water in the bath tub from the return passage to the bath heat exchanger and the outgoing passage at regular time intervals, and the temperature of the circulating water detected by the bath sensor is reduced. When the temperature is lower than the temperature set by the external input device, the bath heat exchanger heats bath water until the temperature reaches the temperature set by the external input device. Is provided with a heat retention starting means for starting when the temperature becomes equal to or lower than a second set temperature obtained by subtracting a certain temperature from the set temperature of the external input device. The temperature detection for keeping the water warm is performed at short time intervals, and the bathtub water warming means can be performed at long time intervals in summer, etc. And, it is possible to carry out a comfortable bathing.

The bath water heater according to a second aspect of the present invention includes a heat retention start means for starting the bath water retention means at a predetermined time interval determined by weather conditions such as an outside air temperature or an incoming water temperature. As a result, the temperature of the bathtub can be detected at short intervals in winter, for example, when the temperature of the bathtub is likely to fall. Since the heat retaining means can be performed at long time intervals, it is possible to take a bath economically and comfortably.

Further, the bath water heater according to claim 3 of the present invention is provided when the detected temperature of the bath sensor becomes equal to or lower than a second set temperature obtained by subtracting a certain temperature from the set temperature of the external input device. In the case of a winter season or the like, where the temperature of the bathtub is likely to decrease due to the provision of the heat retention start means for starting the bathtub water retention means even at certain time intervals determined by weather conditions such as the outside air temperature or the incoming water temperature, for example. In the case, the temperature detection for keeping the bathtub water warm is performed at short time intervals, and in the case of summer months when the temperature of the bathtub water is hard to decrease, the bathtub water warming means can be performed at long time intervals,
Bathing can be performed economically and comfortably.

A bath water heater according to a fourth aspect of the present invention directly determines a weather condition by an air temperature sensor provided in the water heater and detects an outside air temperature, and a predetermined time interval determined thereby. Accordingly, the same operation as the bath water heater according to the second aspect can be obtained by providing the heat retention starting means for starting the bath water keeping means.

According to a fifth aspect of the present invention, there is provided a bath water heater in which weather conditions are indirectly determined by a water temperature sensor for detecting a water supply temperature, and the bath tub water heat insulation is performed at predetermined time intervals determined thereby. By providing the heat retention start means for starting the means in the bath water heater, the same operation as the bath water heater according to claim 2 can be obtained.

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first embodiment of the present invention. Water passes through a water supply sensor 30 and a water temperature sensor 2 provided in a pipe 31 from a water supply port 30 of a water heater main body 29, and absorbs heat in a hot water supply heat exchanger 3. Then, hot water is supplied from hot water outlet 32 through hot water supply sensor 4 and hot water supply amount control valve 5. The gas passes from the gas inlet 33 through the gas source solenoid valve 6, the gas supply proportional valve 7, burns in the hot water supply burner 8, and heats the hot water supply heat exchanger 3.

The hot water is supplied to the bathtub 35 by the hot water filling means 25 by controlling the hot water supply amount control valve 5, the gas source solenoid valve 6, the gas hot water supply proportional valve 7, the hot water supply solenoid valve 20, and the two-way valve 21. Hot water, which supplies water and gas and is heated by the hot water supply heat exchanger 3 to the set temperature of the external input device 24, passes through the hot water supply amount control valve 5, the hot water supply solenoid valve 20, and passes from the two-way valve 21 to the outgoing passage 12. The water is branched into the return passage 13 and enters the bathtub 35 from the bath connection adapter 19.

The warming of the bath water is started when the temperature of the bath sensor 9 falls below the second set temperature obtained by subtracting a certain temperature from the set temperature of the external input device 24 by the warming start means 26. That is, the water flow switch 10 and the circulation pump 22 are controlled by the bath water keeping means 27, and the bath water is supplied to the bath connection adapter 19, the return passage 13, the water level sensor 14, the switching three-way valve 15, and the bath sensor 9 by the circulation pump 22. The water is circulated through a circulation path 36 including a water flow switch 10, a bath heat exchanger 11, an outgoing passage 12, and a bath connection adapter 19. The circulation path 3 is detected by the bath sensor 9.
The temperature of the hot water in the bath tub circulating through 6 is detected, and the detected temperature is compared with the set temperature of the external input device 24. At this time,
When the detected temperature is higher than the set temperature of the external input device, the operation of the circulation pump 22 is stopped. When the detected temperature falls below the set temperature of the external input device 24, the gas passes through the bath solenoid valve 16 and the bath proportional valve 17 of the gas.
The fuel is burned by the bath burner 18, the heat is absorbed by the bath heat exchanger 11, and the bath water is reheated to a temperature set by the external input device 24.

When the temperature of the circulating water reaches the set temperature of the external input device, the reheating operation is stopped and the operation of the circulating pump 22 is stopped.

Next, according to the first aspect of the present invention, using the above configuration,
Will be described in detail with reference to FIG.

(Step 1) The bath tub water keeping means 27 is started by the heat keeping start means 26, and the bath tub water is supplied to the circulation pump 22.
Circulates through a circulation path 36 consisting of a bath connection adapter 19, a return passage 13, a water level sensor 14, a switching three-way valve 15, a bath sensor 9, a water flow switch 10, a bath heat exchanger 11, an outgoing passage 12, and a bath connection adapter 19. Let it.

(Step 2) The bath sensor 9 detects the temperature of the hot water in the bathtub circulating in the circulation path 36.

(Step 3) The detected temperature of the bath sensor 9 is compared with the set temperature of the external input device 24.

(Step 4) When the detected temperature is equal to or higher than the set temperature, the operation of the circulation pump is stopped.

(Step 5) If the detected temperature is lower than the set temperature, the reheating operation is started.

(Step 6) The additional heating operation is performed until the detected temperature reaches the set temperature. (Step 7) When the detected temperature reaches the set temperature, the reheating operation is stopped.

(Step 4) After the reheating operation is stopped, the circulation pump 22 is stopped. (Step 8) If the heat retention is to be continued, proceed to Step 9.

(Step 9) By the bath sensor 9,
While the circulation pump 22 is stopped, the temperature of the hot water staying in the circulation path 36 is detected.

(Step 10) The detected temperature detected in step 9 is compared with a second set temperature obtained by subtracting a fixed temperature from the set temperature of the external input device 24, and the detected temperature is determined as the second set temperature. In the case of the following, the process returns to Step 1 and the bath water keeping means 27 is started again.
Conversely, when the detected temperature is higher than the second set temperature, the process returns to step 9 again.

(Embodiment 2) FIG. 1 shows Embodiment 2 of the present invention. The second embodiment is different from the first embodiment in that the second embodiment is related to the heat retention start means 26.
Therefore, detailed description is omitted.

The heat retention of the bathtub is started by the heat retention start means 26, and by judging weather conditions directly from the temperature sensor 23 provided in the water heater main body 29, the bathtub water heat retention means 27 is performed when the temperature is high. The time interval is lengthened, and when the outside air temperature is low, the time interval for performing the bathtub water warming means 27 is shortened. In addition, instead of the temperature sensor 23, by indirectly judging weather conditions from the water temperature sensor 2, when the water temperature is high, the time interval for performing the bathtub water insulation means 27 is lengthened,
If the supply water temperature is low, the interval at which the bathtub water insulation means 27 is performed is shortened.

Next, the second aspect of the present invention will be described using the above configuration.
The reheating operation according to claims 4 and 5 will be described in detail with reference to FIG.

Steps 1 to 8 are the same as those in the first embodiment.
The same operation as in the flowchart of FIG.

(Step 11) If the detected temperature is equal to the second
If the temperature is higher than the set temperature and a certain time interval determined by the temperature sensor 23 or the water temperature sensor 2 indicating the weather condition directly or indirectly has elapsed, the process returns to step 1 and the bathtub water heat retaining means 27 again. To start. Conversely, if the certain time interval determined by the temperature sensor 23 or the water temperature sensor 2 has not elapsed, step 11 is repeated until the certain time interval has elapsed.

(Embodiment 3) FIG. 1 shows Embodiment 3 of the present invention. The third embodiment differs from the first embodiment in that the third embodiment is related to the heat retention start means 26, and the other parts are the same as those in the first embodiment.
Therefore, detailed description is omitted.

The bath water is kept warm when the detected temperature of the bath sensor 9 falls below the second set temperature obtained by subtracting a certain temperature from the set temperature of the external input device 24 by the warm start means 26. Temperature sensor 2 provided on body 29
By directly determining the weather condition from 3, the time interval for performing the bathtub water heat retaining means 27 is increased when the temperature is high, and the time interval for performing the bathtub water thermal insulating means 27 is shortened when the outside temperature is low. I do. In addition, instead of the temperature sensor 23, the weather condition is indirectly determined from the water temperature sensor 2,
When the water temperature is high, the time interval for performing the bathtub water insulation means 27 is lengthened, and when the supply water temperature is low, the bathtub water insulation means 27 is increased.
To shorten the interval.

Next, the third aspect of the present invention will be described using the above configuration.
The reheating operation according to claims 4 and 5 will be described in detail with reference to FIG.

Steps 1 to 8 are the same as those in the first embodiment.
The same operation as in the flowchart of FIG.

(Step 9) The bath sensor 9 detects the temperature of the hot and cold water staying in the circulation path 36 while the circulation pump is stopped.

(Step 12) The detected temperature detected in step 9 is compared with a second set temperature obtained by subtracting a certain temperature from the set temperature of the external input device 24 to determine that the detected temperature is equal to the second set temperature. In the case of the following, the process returns to Step 1 and the bath water keeping means 27 is started again.
Conversely, when the detected temperature is higher than the second set temperature, the process returns to step 9 again.

(Step 13) If the detected temperature is equal to the second
If the temperature is higher than the set temperature and a predetermined time interval determined by the temperature sensor 23 or the water temperature sensor 2 has elapsed, the process returns to step 1 and the bathtub water warming means 2 is returned again.
Start 7 Conversely, if the predetermined time interval determined by the temperature sensor 23 or the water temperature sensor 2 has not elapsed, the flow returns to step 9 and the circulation path in a state where the circulation pump is stopped again. The temperature of the hot and cold water staying at 36 is detected.

According to the first embodiment, there is provided the heat retention start means 26 for starting when the temperature detected by the bath sensor 9 becomes equal to or lower than the second set temperature obtained by subtracting a certain temperature from the set temperature of the external input device. Due to this, in the case of winter, for example, where the temperature of the bathtub water tends to fall, the bathtub water insulation is performed at short time intervals, and in the case of summer, where the temperature of the bathtub water is difficult to decrease, the bathtub water insulation is turned on for a long time. Since it can be performed at intervals, it is possible to take a bath economically and comfortably.

According to the second embodiment, the time interval at which the bathtub water warming means is started can be changed according to weather conditions such as the outside air temperature or the incoming water temperature. The bath tub water heat retaining means is performed at short time intervals, and in the case of summer, etc., where the temperature of the bath tub water is difficult to decrease, the bath tub water heat retaining means can be performed at a long time interval, so that the bath can be carried out economically and comfortably. .

According to the third embodiment, the bath sensor 9
Is lower than a second set temperature obtained by subtracting a certain temperature from the set temperature of the external input device, or at a certain time interval determined by weather conditions such as outside air temperature or incoming water temperature. In the case of winter, etc. where the temperature of the bathtub is likely to decrease due to the provision of the heat retention start means 26 for starting the means, the bathtub water retention means is performed at short time intervals, and in the case of summer, etc., where the temperature of the bathtub water is difficult to decrease. In this case, the bathtub water warming means can be performed at long time intervals, so that bathing can be performed economically and comfortably.

[0062]

As described above, according to the first aspect of the present invention, when the temperature detected by the bath sensor falls below the second set temperature obtained by subtracting a certain temperature from the set temperature of the external input device. In the case of the winter season where the temperature of the bathtub is likely to fall, the temperature detection for keeping the bathtub warm is performed at short time intervals. In the summer or the like where it is difficult to decrease the temperature, the temperature can be detected at a long time interval for keeping the bathtub water warm, so that the user can bathe economically and comfortably.

Further, according to the second aspect of the present invention, the time interval for starting the bath tub water warming means can be changed according to weather conditions such as the outside air temperature or the incoming water temperature. In the case, the bathtub water heat retaining means is performed at short time intervals, and in the case of summer, for example, where the temperature of the bathtub water is hard to decrease, the bathtub water heat retaining means can be performed at long time intervals, so that bathing can be performed economically and comfortably. be able to.

Further, according to the third aspect of the present invention, in addition to the case where the temperature detected by the bath sensor 9 becomes equal to or lower than the second set temperature obtained by subtracting a certain temperature from the set temperature of the external input device, In addition, in the case of winter time when the temperature of the bathtub is likely to decrease, the bathtub water temperature is kept low by providing the bathtub water warming means 26 at a fixed time interval determined by weather conditions such as the incoming water temperature. In the case of summer, for example, in which the means is performed at short time intervals and the temperature of the bath water is hard to decrease, the bath water keeping means can be performed at long time intervals, so that bathing can be performed economically and comfortably.

According to the fourth aspect of the present invention, there is provided a warming start means for starting the bathtub water warming means at predetermined time intervals determined by an air temperature sensor provided in the water heater and detecting an outside air temperature. As a result, the temperature of the bathtub is detected at short intervals in winter, when the temperature of the bathtub is likely to fall, and in summer, when the temperature of the bathtub is difficult to fall. Since the temperature detection for keeping the temperature can be performed at a long time interval, the bathing can be performed economically and comfortably.

Further, according to the fifth aspect of the present invention, the bathtub water warming means is started at a predetermined time interval determined by a water temperature sensor for detecting a water supply temperature. In winter, when the temperature of the hot water tends to fall, the temperature detection for keeping the bathtub warm is performed at short intervals, and in summer, when the temperature of the bathtub water is hard to fall, the bathtub can be kept warm at long intervals. Therefore, bathing can be performed economically and comfortably.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a bath water heater showing Embodiment 1, Embodiment 2, and Embodiment 3 of the present invention.

FIG. 2 is a flowchart for explaining the operation of the bath water heater in Embodiment 1 of the present invention.

FIG. 3 is a flowchart illustrating an operation of a bath water heater in Embodiment 2 of the present invention.

FIG. 4 is a flowchart for explaining the operation of a bath water heater in Embodiment 3 of the present invention.

FIG. 5 is a configuration diagram of a conventional bath water heater.

FIG. 6 is a flowchart for explaining the operation of a conventional bath water heater.

[Explanation of symbols]

 2 Water temperature sensor 3 Hot water supply heat exchanger 9 Bath sensor 11 Bath heat exchanger 12 Outgoing passage 13 Return passage 19 Bath connection adapter 20 Hot water supply solenoid valve 22 Circulation pump 23 Temperature sensor 24 External input device 25 Hot water filling means 26 Heat retention start means 27 Bathtub Water insulation means 35 Bath tub 36 Circulation route

Claims (5)

[Claims] 1. A hot water supply heat exchanger for heating supply water, a water temperature sensor for detecting supply water temperature and a water amount sensor for detecting supply flow rate, a hot water supply sensor for detecting hot water temperature and a supply water control valve for controlling tap water flow rate. A bath heat exchanger for heating the circulating bath water, a return passage through which the circulating water flows from the bath to the bath heat exchanger, a circulation pump for circulating the bath water, and a bath sensor for detecting the temperature of the bath water, A hot water supply solenoid valve provided in a passage connecting the hot water supply passage and the return passage,
An outgoing passage provided downstream from the bath heat exchanger,
An external input device for inputting a set temperature and displaying an operation state; hot water filling means for supplying hot water heated by the hot water supply heat exchanger from the bath hot water supply solenoid valve to the bathtub through the bath passage and return passage; When the hot water in the bathtub is circulated from the return passage to the bath heat exchanger by the circulation pump to the outgoing passage at regular time intervals, and the detected temperature of the bath sensor is lower than the set temperature of the external input device, A bath water warming means for heating the bath water until the set temperature of the external input device is reached in the bath heat exchanger; and the bath water warming means, wherein the temperature detected by the bath sensor is further constant than the set temperature of the external input device. A water heater that starts when the temperature becomes equal to or lower than a second set temperature obtained by subtracting the temperature. 2. A hot water supply heat exchanger for heating supply water, a water temperature sensor for detecting supply water temperature and a water amount sensor for detecting supply water flow rate, a hot water supply sensor for detecting hot water temperature and a supply water control valve for controlling tap water flow rate. A bath heat exchanger for heating the circulating bath water, a return passage through which the circulating water flows from the bath to the bath heat exchanger, a circulation pump for circulating the bath water, and a bath sensor for detecting the temperature of the bath water, A hot water supply solenoid valve provided in a passage connecting the hot water supply passage and the return passage,
An outgoing passage provided downstream from the bath heat exchanger,
An external input device capable of inputting a set temperature and displaying an operation state, and hot water filling means for supplying hot water heated by the hot water supply heat exchanger to the bathtub from the bath hot water supply solenoid valve through the outgoing passage and the return passage of the bath. When the hot water in the bathtub is circulated from the return passage to the bath heat exchanger by the circulation pump to the outgoing passage at regular time intervals, and the detected temperature of the bath sensor is lower than the set temperature of the external input device, A bath water keeping means for heating the bath water until the temperature reaches a set temperature of the external input device in the bath heat exchanger; and a heat keeping start means for starting the bath water keeping means at a fixed time interval determined based on weather conditions. Bath water heater with. 3. The bath water heater according to claim 1, further comprising a heat retention start means for starting the bath water retention means at a predetermined time interval determined based on weather conditions. 4. The bath water heater according to claim 2, further comprising a heat retention start means for starting the bath water keeping means at a predetermined time interval determined by an air temperature sensor provided in the water heater. 5. The bath water heater according to claim 2, further comprising a heat retention start means for starting the bath water retention means at a predetermined time interval determined by a water temperature sensor provided in the water heater.