Hot water storage type water heater

Abstract

To prevent air from accumulating at an upper part in a hot water storage tank for a long time.SOLUTION: A hot water storage type water heater includes a control device 34 which controls a first air bleeding operation in which, during a water filling operation into a bathtub 31, a medium temperature water mixing valve 5 is fully opened on the high temperature side and the air accumulated in a hot water storage tank 2 is delivered to the bathtub 31 together with hot water filling, and a second air bleeding operation in which, during a hot water supply operation into a hot water supply plug, the opening of the medium temperature water mixing valve 5 is fully opened on the high temperature side and the air accumulated in the hot water storage tank 2 is delivered to the hot water supply plug together with hot water supply. At the control device 34, determination means 36 is provided for determining whether or not elapsed time from the completion of the previous first or second air bleeding operation is equal to or longer than predetermined elapsed time. In the case where the determination means 36 has determined that the elapsed time is equal to or longer than predetermined time, the control device 34 performs the second air bleeding operation during the hot water supply operation, and in the case where the elapsed time has been determined to be below predetermined elapsed time, the control device 34 performs the first air bleeding operation during the hot water filling operation.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] This invention relates to a hot water storage type water supply device having a heating means.

Background Art

[0002] Conventionally, in this type of hot water storage type water supply device, a hot water storage tank and a heating means are provided, and a heating forward pipe for sending water from the lower part of the hot water storage tank to the heating means and a heating return pipe for sending water from the heating means to the hot water storage tank are used to connect the hot water storage tank and the heating means to form a heating circulation circuit. A circulation pump provided in the heating circulation circuit circulates the hot water in the hot water storage tank and the heating means to heat the water in the hot water storage tank. The heated hot water is stored in the hot water storage tank by a boiling operation, and hot water at a set temperature is supplied while sequentially mixing the high-temperature water and the supply water in the hot water storage tank to achieve economical water supply.

[0003] Also, by disposing a pressure relief valve that opens when the pressure in the hot water storage type water supply device exceeds a predetermined pressure at a position where low-temperature water flows, when discharging the pressure outside the hot water storage type water supply device, low-temperature water is discharged, so it has been known to prevent the high-temperature water stored in the hot water storage tank from being discharged outside the hot water storage type water supply device (for example, Patent Document 1).

[0004] Also, in order to release the air accumulated in the hot water storage tank to the water supply use terminal, it has been known to open the high-temperature side of the opening degree of the medium-temperature water mixing valve to facilitate air escape (for example, Patent Document 2).

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, by arranging a pressure relief valve at the bottom of the hot water storage tank as in Patent Document 1, it is possible to prevent the discharge of high-temperature water when the pressure in the hot water storage tank increases during the boiling operation. However, since the pressure relief valve is arranged at the bottom of the hot water storage tank, there is a problem that air that was discharged together with the pressure accumulating in the upper part of the hot water storage tank cannot be discharged.

[0007] In addition, there is a method of discharging air during the hot water supply operation as in Patent Document 2. However, when air is mixed into the hot water supply, there are problems such as water splashing from the hot water supply faucet and abnormal noises. Therefore, it is desirable to remove air at the initial stage of the hot water filling operation into the bathtub where there are few people as much as possible. However, there is a problem that air accumulates in the upper part of the hot water storage tank when the hot water filling operation is not performed for a long time.

Means for Solving the Problems

[0008] According to the present invention, there are provided a hot water storage tank for storing hot water, heating means for boiling the hot and cold water in the hot water storage tank, a heating circulation circuit that circulably connects the hot water storage tank and the heating means, a water supply pipe connected to the lower part of the hot water storage tank for supplying water to the hot water storage tank, a water supply bypass pipe branched from the water supply pipe, a pressure relief valve provided in a pipe connected to the lower part of the hot water storage tank for releasing the pressure outside the hot water storage tank when the pressure in the hot water storage tank exceeds a predetermined pressure, a medium-temperature water mixing valve for mixing the high-temperature water taken out from the upper part of the hot water storage tank and the medium-temperature water taken out from the middle part of the hot water storage tank, a bath mixing valve for mixing the medium-temperature water mixed by the medium-temperature water mixing valve and the water supply from the water supply bypass pipe and supplying it to a bathtub, a hot water supply mixing valve for mixing the medium-temperature water mixed by the medium-temperature water mixing valve and the water supply from the water supply bypass pipe and supplying it to a hot water supply faucet, a first air bleeding operation for opening the medium-temperature water mixing valve fully on the high-temperature side during the bathtub filling operation to send the air accumulated in the hot water storage tank to the bathtub together with the filling water, and a second air bleeding operation for opening the medium-temperature water mixing valve fully on the high-temperature side during the hot water supply operation to the hot water supply faucet to send the air accumulated in the hot water storage tank to the hot water supply faucet together with the hot water supply, and a control device for controlling the above, wherein the control device is provided with a determination means for determining whether or not the elapsed time since the completion of the previous first or second air bleeding operation is equal to or more than a predetermined elapsed time. When the determination means determines that the elapsed time is equal to or more than the predetermined elapsed time, the control device performs the second air bleeding operation during the hot water supply operation. When the determination means determines that the elapsed time is less than the predetermined elapsed time, the control device performs the first air bleeding operation during the bathtub filling operation.

Effect of the Invention

[0009] According to the present invention, the determination means determines whether air has accumulated in the upper part of the hot water storage tank for a long time, and the control device performs the first air bleeding operation or the second air bleeding operation according to the determination result. In the first air bleeding operation, it is possible to safely discharge air into the bathtub at the initial stage of starting the hot water filling operation. In the second air bleeding operation, air that has accumulated in the upper part of the hot water storage tank without performing the hot water filling operation is discharged during the hot water supply operation, thereby preventing the continuous accumulation of air. These effects can be achieved at appropriate timings.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0011] Next, a hot water storage type hot water supply device according to an embodiment of the present invention will be described with reference to the drawings. Reference numeral 1 denotes a hot water storage tank unit, which includes a hot water storage tank 2 for storing hot water and hot water in its interior, a high-temperature side hot water outlet pipe 3 connected to the upper part of the hot water storage tank 2, a medium-temperature side hot water outlet pipe 4 connected to the middle part of the hot water storage tank 2, a medium-temperature water mixing valve 5 for mixing high-temperature water from the high-temperature side hot water outlet pipe 3 and medium-temperature water from the medium-temperature side hot water outlet pipe 4, a water supply pipe 6 connected to the lower part of the hot water storage tank 2, a hot water supply mixing valve 8 for mixing mixed water from the medium-temperature water mixing valve 5 and low-temperature water from a water supply bypass pipe 7 branched from the water supply pipe 6, a hot water supply temperature sensor 10 provided in a hot water supply pipe 9 connected to the downstream of the hot water supply mixing valve 8, and a hot water supply flow sensor 11 for detecting the hot water supply flow rate.

[0012] Reference numeral 12 denotes a heat pump unit, which comprises a heat pump heating means 18 composed of a compressor 13, a water-cooled refrigerant heat exchanger 14 as a condenser, an electronic expansion valve 15, an outdoor fan 16, and an air heat exchanger 17 as an evaporator for heat exchange with air, a circulation pump 22 for circulating the hot water in the hot water storage tank 2 through a heating circulation circuit 21 composed of a heating supply pipe 19 and a heating return pipe 20 to the heating means 18, and a heat pump control unit 23 for controlling the driving thereof. Carbon dioxide is used as the refrigerant in the heating means 18 to constitute a transcritical heat pump cycle. Further, since carbon dioxide is used as the refrigerant, it is possible to boil low-temperature water up to a high temperature of about 90° C. without an electric water heater.

[0013] Here, the water-cooled refrigerant heat exchanger 14 employs a counterflow method in which the refrigerant and the hot water in the hot water storage tank 2 as the water to be heated flow in opposite directions. In the transcritical heat pump cycle, since the refrigerant is condensed while remaining in the supercritical state during heat exchange, the water to be heated can be efficiently heated to a high temperature. By controlling the expansion valve 15 or the compressor 13 so that the temperature difference between the inlet temperature of the water-cooled refrigerant heat exchanger 14 of the water to be heated and the outlet temperature of the refrigerant becomes constant, it is possible to heat the water to be heated in a state where the COP (energy consumption efficiency) is very good when the inlet temperature of the water-cooled refrigerant heat exchanger 14 of the water to be heated is as low as about 5 to 20° C.

[0014] A heating bypass valve 24 is provided in the middle of the heating return pipe 20. During freeze prevention, the heating bypass valve 24 is switched to communicate with the heating bypass pipe 25 side, which is a heating bypass path connected to the water supply pipe 6 at the lower part of the hot water storage tank 2, to prevent freezing by means of a short-circuit circulation using the lower part inside the hot water storage tank 2. This heating bypass valve 24 is arranged at the branch position from the heating return pipe 20 to the heating bypass pipe 25.

[0015] Also, when circulating hot water that is not sufficiently heated at the initial stage of heating by the heating means 18, the hot water is not returned to the upper part of the hot water storage tank 2, but is returned to the lower part of the hot water storage tank 2 through a bypass circulation path via the heating bypass pipe 25. When circulating hot water that has been sufficiently heated thereafter, the heating bypass valve 24 is switched to the upper part side of the hot water storage tank 2.

[0016] 26 is a pressure reducing valve provided in the water supply pipe 6.

[0017] 27 is a pressure relief valve provided in the heating bypass pipe 25 for relieving the pressure in the hot water storage tank 2 and the heating circulation circuit 21.

[0018] This pressure relief valve 27 is such that when the hot water in the hot water storage tank 2 and the heating circulation circuit 21 becomes high temperature due to the boiling operation, the pressure in the storage type water heater rises, and when it exceeds a predetermined pressure, the valve opens, and the hot water is discharged outside the storage type water heater together with the pressure.

[0019] 28 is a bath mixing valve that mixes the mixed water from the medium-temperature water mixing valve 5 and the low-temperature water from the water supply bypass pipe 7 branched from the water supply pipe 6.

[0020] Also, 29 is a filling valve that connects the filling pipe 30 to the bathtub 31 to supply hot water to the bathtub 31, 32 is a filling temperature sensor that detects the filling temperature of the hot water supplied to the bath, and 33 is a bath flow sensor that detects the flow rate passing through the filling pipe 30. Also, the filling path is a path for supplying hot water to the bathtub 31 in the order of the hot water storage tank 2, the medium-temperature water mixing valve 5, the bath mixing valve 28, and the filling pipe 30.

[0021] 47 is a hot water storage temperature sensor provided outside the hot water storage tank 2, and is provided at predetermined intervals from the upper part to the lower part of the hot water storage tank 2, and are respectively the upper hot water storage temperature sensor 47a, the middle hot water storage temperature sensor 47b, the second middle hot water storage temperature sensor 47c, and the lower hot water storage temperature sensor 47d from the top. The middle hot water storage temperature sensor 47b detects the temperature of the medium-temperature water in the hot water storage tank 2.

[0022] 48 is a mixed water temperature sensor that detects the temperature of the mixed water from the medium-temperature water mixing valve 5, and 49 is a feed water temperature sensor that detects the feed water temperature provided in the water supply pipe 6.

[0023] 34 is a control device composed of a microcomputer or the like, which controls the heat pump control unit 23 to perform temperature control of hot water supply, such as boiling-up operation and boiling-up additional operation of the hot water storage tank 2 by the heating circulation circuit 21, and operation control such as filling the bathtub, reheating, and heat preservation.

[0024] Further, the control device 34 is provided with an opening degree control means 35 for controlling the opening degrees of the medium-temperature water mixing valve 5 and the bathtub mixing valve 28. Specifically, the opening degree control means 35 calculates the opening degrees of the medium-temperature water mixing valve 5 and the bathtub mixing valve 28, and drives the valve so as to achieve the calculated opening degrees.

[0025] For example, the opening degree control means 35 can fix the opening degree by instructing the ratio of the opening degree on the high-temperature side to the opening degree on the low-temperature side of the medium-temperature water mixing valve 5 and the bathtub mixing valve 28.

[0026] Further, the opening degree control means 35 can also use the feed-forward opening degree calculated as the control of the opening degree. For example, regarding the bathtub mixing valve 28, the opening degree control means 35 calculates the feed-forward opening degree of the bathtub mixing valve 28 according to the mixed water temperature detected by the mixed water temperature sensor 48, the feed water temperature detected by the feed water temperature sensor 49, and a predetermined filling set temperature, and controls the opening degree of the bathtub mixing valve 28 so as to achieve the calculated feed-forward opening degree.

[0027] Regarding the medium-temperature water mixing valve 5, the opening degree control means 35 calculates the feed-forward opening degree of the medium-temperature water mixing valve 5 according to the temperatures detected by the upper hot water storage temperature sensor 47a and the intermediate hot water storage temperature sensor 47b provided outside the hot water storage tank 2 and the mixed water set temperature, which is the set temperature of the mixed water mixed by the medium-temperature water mixing valve 5, and controls the opening degree of the medium-temperature water mixing valve 5 so as to achieve the calculated feed-forward opening degree.

[0028] In addition, the feed-forward opening degree calculates the opening degree of the medium-temperature water mixing valve 5 according to the temperatures detected by the upper hot water storage temperature sensor 47a and the intermediate hot water storage temperature sensor 47b. When the temperature near the intermediate-temperature side hot water outlet pipe 4 detected by the intermediate hot water storage temperature sensor 47b is higher than the hot water supply set temperature or the water filling set temperature, the medium-temperature water mixing valve 5 is set to an opening degree of 100% on the intermediate-temperature side. When the temperature detected by the intermediate hot water storage temperature sensor 47b is lower than the hot water supply set temperature or the water filling set temperature, the medium-temperature water mixing valve 5 opens the high-temperature side so that the mixed water temperature detected by the mixed water temperature sensor 48 becomes equal to or higher than the hot water supply set temperature or the water filling set temperature. In this way, the medium-temperature water is used more actively than the high-temperature water at the upper part of the hot water storage tank 2 by the feed-forward control of the medium-temperature water mixing valve 5.

[0029] In addition, the opening degree control means 35 can also use the feedback opening degree calculated as the control of the opening degree. For example, when explaining the bath mixing valve 28, the feedback opening degree is calculated so that the actual water filling temperature mixed by the bath mixing valve 28 becomes the water of the preset water filling set temperature, and the feedback opening degree of the bath mixing valve 28 is controlled so that the temperature detected by the water filling temperature sensor 32 becomes the water of the preset water filling set temperature.

[0030] In addition, the control device 34 is provided with a determination means 36 that counts the elapsed time after the completion of the first air bleeding operation or the second air bleeding operation described later, and determines whether or not the elapsed time is equal to or longer than a predetermined elapsed time.

[0031] Regarding the counting of the elapsed time in detail, when the first air bleeding operation or the second air bleeding operation is performed, the air accumulated in the upper part of the hot water storage tank 2 is discharged, so the count is set to 0, and the determination means 36 starts the count. Then, the determination means 36 counts the elapsed time and determines whether or not the elapsed time is equal to or longer than a predetermined elapsed time (here, 72 hours or more). Also, if the first air bleeding operation or the second air bleeding operation is executed during the counting of the elapsed time, the air accumulated in the upper part of the hot water storage tank 2 is discharged, so the count is reset and the count is started again.

[0032] When the determination means 36 determines that the elapsed time is equal to or longer than a predetermined elapsed time, the control device 34 performs a second air bleeding operation together with the hot water supply operation during the hot water supply operation. When the determination means 36 determines that the elapsed time is less than the predetermined elapsed time, the hot water filling operation control means 37 of the control device 34 performs a first air bleeding operation together with the hot water filling operation during the hot water filling operation.

[0033] The control device 34 is further provided with a hot water filling operation control means 37 for controlling a hot water filling operation described later, and a boiling-up operation control means 38 for controlling a boiling-up operation described later.

[0034] Furthermore, the remote controller 39 includes a temperature setting switch 40 for setting a hot water supply set temperature, a hot water filling switch 41 for instructing hot water filling into the bathtub 31, and a hot water filling amount setting switch 42 for setting a hot water filling amount. The remote controller 39 is further provided with a display unit 43 composed of a dot matrix type fluorescent display tube, and a remote controller control unit 44 configured by a microcomputer that controls the display unit 43 and communicates with the control device 34.

[0035] Next, the boiling-up operation will be described. When there is a request for boiling-up due to a decrease in the stored hot water heat amount or during a late-night time zone, the boiling-up operation control means 38 sets the heating bypass valve 24 to a first state in which it communicates with the lower side of the hot water storage tank 2, and the control device 34 drives the circulation pump 22 located in the middle of the pipe connecting the hot water storage tank 2 and the heating means 18 to pump up water from the lower part inside the hot water storage tank 2, warm it with the heating means 18, and return it to the lower part of the hot water storage tank 2. Then, the control device 34 sets it to a second state in which it communicates with the upper side of the hot water storage tank 2, and continues the operation of returning it to the upper part of the hot water storage tank 2, so that the water inside the hot water storage tank 2 is gradually boiled up to high-temperature water.

[0036] By performing the boiling-up operation, the water inside the hot water storage tank 2 becomes high-temperature, and the pressure inside the hot water storage tank 2 rises. Therefore, during the boiling-up operation, hot water is discharged outside the storage type hot water supply device together with the pressure from the pressure relief valve 27. At this time, the air dissolved in the water accumulates in the upper part of the hot water storage tank 2.

[0037] Next, the hot water supply operation will be described. When the hot water faucet is opened, water is supplied from the water supply pipe 6 and flows into the lower part of the hot water storage tank 2. At the same time, it passes through the water supply bypass pipe 7 on the side of the hot water mixing valve 8, and the high-temperature water pushed out from the upper part of the hot water storage tank 2 and the medium-temperature water pushed out from the middle part of the hot water storage tank 2 are mixed by the medium-temperature water mixing valve 5. The mixed water mixed by the medium-temperature water mixing valve 5 and the water supply from the water supply bypass pipe 7 on the side of the hot water mixing valve 8 are mixed by the hot water mixing valve 8, and the hot water adjusted so that the set hot water temperature is the same as the temperature detected by the hot water temperature sensor 10 is supplied from the hot water faucet.

[0038] Next, the hot water filling operation will be described. When the hot water filling switch 41 of the remote control 39 or an automatic operation switch (not shown) is pressed, the hot water filling operation control means 37 opens the hot water filling valve 29, supplies water from the water supply pipe 6, and flows into the lower part of the hot water storage tank 2. At the same time, it passes through the water supply bypass pipe 7 on the side of the bath mixing valve 28, and the high-temperature water pushed out from the upper part of the hot water storage tank 2 and the water supply from the water supply bypass pipe 7 on the side of the bath mixing valve 28 are mixed by the bath mixing valve 28. The hot water adjusted so that the set hot water filling temperature is the same as the temperature detected by the hot water filling temperature sensor 32 flows into the bathtub 31, and the hot water filling starts. Then, the flow rate flowing through the bath flow sensor 33 is detected, and when the total integrated value of the flowing flow rate is diverted by the set hot water filling amount, the hot water filling operation control means 37 closes the hot water filling valve 29 to end the hot water filling operation.

[0039] Next, the first air bleeding operation will be described. In the first air bleeding operation, at the time of a predetermined amount of hot water filling at the initial stage of the hot water filling operation, the opening degree control means 35 sets the high-temperature side of the medium-temperature water mixing valve 5 connected to the upper part of the hot water storage tank 2 to 100%, and sets the bath mixing valve 28 to the feedback opening degree, and sends the air accumulated in the hot water storage tank 2 to the bathtub 31 together with the hot water filling.

[0040] Next, the second air bleeding operation will be described. In the second air bleeding operation, during the hot water supply operation, the opening degree control means 35 sets the high-temperature side of the medium-temperature water mixing valve 5 connected to the upper part of the hot water storage tank 2 to 100%, and sets the hot water mixing valve 8 to the feedback opening degree, and sends the air accumulated in the hot water storage tank 2 to the hot water faucet together with the hot water supply.

[0041] Next, a case of discharging the air accumulated in the upper part of the hot water storage tank 2 by the first air bleeding operation will be described in detail based on the flowchart of FIG. 2. When the hot water filling switch 41 of the remote control 39 or an automatic operation switch (not shown) is pressed, the hot water filling operation control means 37 starts the hot water filling operation (S1 is Yes).

[0042] The opening degree control means 35 controls the opening degree of the high-temperature side connected to the upper part of the hot water storage tank 2 of the medium-temperature water mixing valve 5 to 100%, and controls the opening degree of the medium-temperature side connected to the middle part of the hot water storage tank 2 at a ratio of 0% (S2). The opening degree of the bath mixing valve 28 is controlled by the feedback opening degree that controls the opening degree based on the detected temperature of the hot water filling temperature sensor 32 (S3). When starting a hot water filling operation of a predetermined amount (here, 5L), the first air bleeding operation is started (S4). Then, the hot water filling operation control means 37 checks whether there is pre-existing remaining hot water in the bathtub 31 by the hot water filling operation of the predetermined amount (S5).

[0043] When there is no remaining hot water (S6 is Yes), the opening degree control means 35 controls the opening degree of the medium-temperature water mixing valve 5 such that the high-temperature side connected to the upper part of the hot water storage tank 2 is 100%, and the medium-temperature side connected to the middle part of the hot water storage tank 2 is 0% (S7). The opening degree of the bath mixing valve 28 is controlled by the feedback opening degree that controls the opening degree based on the detected temperature of the hot water filling temperature sensor 32 (S8). When starting a hot water filling operation of a predetermined amount (here, 5L), the first air bleeding operation is started (S9).

[0044] When the hot water filling operation of the predetermined amount (here, 5L) is completed, the opening degree control means 35 switches the medium-temperature water mixing valve 5 to an opening degree for actively using medium-temperature water (here, the feed-forward opening degree) (S10), and sets the opening degree of the bath mixing valve 28 to the feed-forward opening degree (S11).

[0045] The hot water filling operation control means 37 starts a hot water filling operation of 170L obtained by subtracting the predetermined amount (here, 10L = 5L + 5L) filled with hot water previously from the predetermined bathtub setting amount (here, 180L) so as to reach the predetermined bathtub setting amount (S12).

[0046] When the hot water filling operation control means 37 determines that the bathtub 31 has reached the bath set quantity and the bath set temperature (S13 is Yes), it completes the hot water filling operation (S14).

[0047] Here, an embodiment for venting the air at the upper part of the hot water storage tank 2 will be described in detail. Since the air in the hot water storage tank 2 accumulates at the upper part of the hot water storage tank 2, by setting the opening degree of the medium-temperature side of the medium-temperature hot water mixing valve 5 that does not contribute to the air discharge to 0% and the opening degree of the high-temperature side of the medium-temperature hot water mixing valve 5 that enables air discharge to 100%, the air in the hot water storage tank 2 can be efficiently discharged into the bathtub 31.

[0048] Also, at the initial stage of the hot water filling operation, since only the air accumulated at the upper part of the hot water storage tank 2 is sent out from the medium-temperature hot water mixing valve 5, the temperature detected by the hot water filling temperature sensor 32 becomes the temperature of the water supply from the water supply bypass pipe 7. Therefore, by controlling the opening degree of the bath mixing valve 28 with the feedback opening degree, since the hot water filling temperature detected by the hot water filling temperature sensor 32 is less than the bath set temperature, the opening degree of the medium-temperature hot water mixing side of the bath mixing valve 28 opens widely, and the air accumulated at the upper part of the hot water storage tank 2 can be easily discharged from the medium-temperature hot water mixing valve 5.

[0049] In this way, during the initial predetermined amount of the hot water filling operation, the air accumulated at the upper part of the hot water storage tank 2 can be discharged into the bathtub 31. Therefore, at the initial stage of the hot water filling operation when there is no one in the bathtub 31 yet, the air in the bathtub 31 can be safely discharged, and the air accumulated at the upper part of the hot water storage tank 2 at the initial stage of the hot water filling operation can be completely discharged.

[0050] Also, by setting the opening degree of the medium-temperature hot water mixing valve 5 to 100% on the high-temperature side and setting the bath mixing valve 28 to the feedback opening degree, the air accumulated at the upper part of the hot water storage tank 2 can be quickly discharged.

[0051] Also, when there is remaining hot water (S6 is No), the opening degree control means 35 controls the opening degree of the medium-temperature water mixing valve 5 such that the high-temperature side connected to the upper part of the hot water storage tank 2 is 100%, and the medium-temperature side connected to the middle part of the hot water storage tank 2 is 0% (S16). The opening degree of the bath mixing valve 28 is controlled at a feedback opening degree based on the detected temperature of the hot water filling temperature sensor 32 (S17), and a first air bleeding operation is started together with a hot water filling operation of a predetermined amount (here, 5 L) (S18).

[0052] When the hot water filling operation of the predetermined amount (here, 5 L) is completed, the opening degree control means 35 switches the opening degree of the medium-temperature water mixing valve 5 to an opening degree for actively using medium-temperature water (here, a feed-forward opening degree) (S19), and sets the opening degree of the bath mixing valve 28 to the feed-forward opening degree (S20).

[0053] The hot water filling operation control means 37 starts a hot water filling operation (make-up water operation) of an amount obtained by subtracting the predetermined amount of hot water filled previously and the remaining hot water amount in the bathtub 31 from a predetermined bathtub setting amount (here, 180 L) so as to reach the predetermined bathtub setting amount (S21).

[0054] When the bathtub 31 reaches the bathtub setting amount and the bathtub setting temperature (S22 is Yes), the hot water filling operation control means 37 completes the hot water filling operation (S23).

[0055] In this way, when there is remaining hot water, at the initial stage of starting the hot water filling operation (make-up water operation), the air accumulated in the upper part of the hot water storage tank 2 in the bathtub 31 can be completely discharged. Therefore, it is possible to prevent the user from feeling uncomfortable by hearing the gurgling sound generated when air is discharged into the bathtub 31 during bathing.

[0056] Next, the case of discharging the air accumulated in the upper part of the hot water storage tank 2 by a second air bleeding operation will be described in detail based on the flowchart of FIG. 3. When the hot water supply faucet is opened and the hot water supply operation is started (S24 is Yes), the determination means 36 determines whether the elapsed time since the completion of the previous first air bleeding operation or second air bleeding operation is equal to or more than a predetermined elapsed time (here, 72 hours or more) (S25).

[0057] When the determination means 36 determines that the elapsed time since the completion of the previous first air bleeding operation or second air bleeding operation is equal to or longer than a predetermined elapsed time (S25 is Yes), the opening degree control means 35 sets the high-temperature side connected to the upper part of the hot water storage tank 2 of the medium-temperature water mixing valve 5 to 100%, and controls the opening degree of the medium-temperature side connected to the middle part of the hot water storage tank 2 at a rate of 0% (S26). The opening degree of the hot water supply mixing valve 8 is controlled at a feed-forward opening degree according to the temperatures detected by the upper hot water storage temperature sensor 47a and the intermediate hot water storage temperature sensor 47b and the mixed water set temperature (S27), the hot water supply operation is started, and the second air bleeding operation is started (S28).

[0058] When the hot water supply faucet is closed, the hot water supply operation is terminated (S29).

[0059] When the determination means 36 determines that the elapsed time since the completion of the previous first air bleeding operation or second air bleeding operation is less than the predetermined elapsed time (S25 is No), the opening degree control means 35 switches the medium-temperature water mixing valve 5 to an opening degree for actively using medium-temperature water (here, the feed-forward opening degree) (S30), the opening degree of the hot water supply mixing valve 8 is set at the feed-forward opening degree (S31), and the hot water supply operation is started (S32).

[0060] When the hot water supply faucet is closed, the hot water supply operation is terminated (S33).

[0061] In this way, only when the determination means 36 determines that the hot water filling operation has not been performed for a predetermined elapsed time or longer and air has accumulated in the upper part of the hot water storage tank 2, the air bleeding operation is performed together with the hot water supply operation, so that problems caused by air accumulating over a long period of time can be suppressed.

[0062] In addition, by the determination means 36 determining the execution of the first air bleeding operation and the second air bleeding operation, in the first air bleeding operation, air can be safely discharged from the bathtub 31 at the initial stage of the hot water filling operation when there is still no one in the bathtub 31, and in the second air bleeding operation, it is possible to prevent air from continuously accumulating in the upper part of the hot water storage tank 2 without performing the hot water filling operation.

[0063] Note that the present invention is not limited to the embodiments, and it does not prevent modifications within the scope of not changing the gist. For example, in the embodiment, the pressure relief valve 27 is provided in the heating bypass pipe 25, but the pressure relief valve 27 may be provided in the water supply pipe 6 connected to the lower part of the hot water storage tank 2.

[0064] Also, the criterion for the determination by the determination means 36 has been described in terms of whether or not the elapsed time since the completion of the previous first air bleeding operation or second air bleeding operation is equal to or longer than a predetermined elapsed time, but it may be whether or not it is equal to or longer than a predetermined number of days (3 days), as long as it can detect that air has accumulated in the upper part of the hot water storage tank 2 due to the long time during which the hot water filling operation is not executed.

[0065] Also, in the embodiment, when performing the second air bleeding operation and the hot water supply operation, in order to suppress the fluctuation of the hot water supply temperature due to the opening degree change even after a predetermined amount of hot water supply is performed, the opening degrees of the medium-temperature water mixing valve 5 and the hot water supply mixing valve 8 are maintained. However, if it is determined that a predetermined amount of hot water (here, 5 L) has been supplied and the air in the upper part of the hot water storage tank 2 has been discharged, the opening degrees of the medium-temperature water mixing valve 5 and the hot water supply mixing valve 8 may be switched to the opening degrees for actively using the medium-temperature water.

[0066] Also, in the embodiment of the present invention, the opening degree for actively using the medium-temperature water has been described using the feedback opening degree, but the medium-temperature water mixing valve 5 may use a fixed opening degree such as 100% on the medium-temperature side, and by reducing the medium-temperature water in the hot water storage tank 2, the boiling efficiency of the boiling operation can be improved.

Explanation of Reference Numerals

[0067] 2 Hot water storage tank 3 High-temperature side hot water outlet pipe 4 Medium-temperature side hot water outlet pipe 5 Medium-temperature water mixing valve 6 Water supply pipe 7 Water supply bypass pipe 8 Hot water supply mixing valve 27 Pressure relief valve 28 Bath mixing valve 29 Hot water filling valve 30 Hot water filling pipe 31 Bathtub 34 Control device 35 Opening control means 36 Determination means 37 Filling operation control means

Claims

【Claim 1】 A hot water storage tank for storing hot water, heating means for boiling the hot water in the hot water storage tank, a heating circulation circuit that connectably circulates the hot water storage tank and the heating means, a water supply pipe connected to the lower part of the hot water storage tank for supplying water to the hot water storage tank, a water supply bypass pipe branched from the water supply pipe, a pressure relief valve provided in a pipe connected to the lower part of the hot water storage tank, which releases the pressure outside the hot water storage tank when the pressure in the hot water storage tank exceeds a predetermined pressure, a medium-temperature water mixing valve for mixing the high-temperature water taken out from the upper part of the hot water storage tank and the medium-temperature water taken out from the middle part of the hot water storage tank, a bath mixing valve for mixing the medium-temperature water mixed by the medium-temperature water mixing valve and the water supply from the water supply bypass pipe and supplying it to the bathtub, a hot water supply mixing valve for mixing the medium-temperature water mixed by the medium-temperature water mixing valve and the water supply from the water supply bypass pipe and supplying it to the hot water supply faucet, a control device that controls a first air bleeding operation of opening the medium-temperature water mixing valve fully on the high-temperature side during the water filling operation of the bathtub to send the air accumulated in the hot water storage tank to the bathtub together with the water filling, and a second air bleeding operation of opening the medium-temperature water mixing valve fully on the high-temperature side during the hot water supply operation to the hot water supply faucet to send the air accumulated in the hot water storage tank to the hot water supply faucet together with the hot water supply, The control device is provided with: judgment means for judging whether the elapsed time since the completion of the previous first or second air bleeding operation is equal to or more than a predetermined elapsed time, When the judgment means: judges that the elapsed time is equal to or more than the predetermined elapsed time, the control device performs the second air bleeding operation during the hot water supply operation, When the judgment means judges that the elapsed time is less than the predetermined elapsed time, the control device performs the first air bleeding operation during the water filling operation. A hot water storage type hot water supply device characterized by this.

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