Bath water heater

Abstract

To suppress an increase in medium-temperature hot water in a hot water storage tank.SOLUTION: A control unit 28 includes: residual hot water filling operation control means 38 of controlling residual hot water filling operation performed upon the instruction of hot water filling action from the control unit 28 in a state where residual hot water is in a bathtub 3; residual hot water amount calculating means 34 of calculating a residual hot water amount x from a previously stored cross sectional area a of the bathtub 3, and a residual hot water level h of residual hot water detected by a water level sensor 23; and residual hot water temperature detection means 35 of detecting a residual hot water temperature t based on a detection value of a bath temperature sensor 22. The residual hot water filling operation control means 38 calculates based on the residual hot water amount calculating means 34 and residual hot water temperature detection means 35, a drainage volume b of residual hot water in the bathtub 3 so as to bring to a bath set temperature T when a bath set water level H is attained only by additional hot water of a hot water supply temperature A higher than the bath set temperature, and drains the drainage volume b calculated by drainage volume calculating means 36 followed by performing residual hot water filling operation only by additional hot water of the hot water supply temperature A.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a hot water supply device for a bath that fills a bathtub with hot water. [Background technology]

[0002] Conventionally, this type of bath hot water supply device has been known to heat water supplied from a water supply pipe using a heating means, store the heated hot water in a hot water storage tank or the like, and fill the bath with the hot water in the hot water storage tank.

[0003] For example, as described in Patent Document 1, if there is remaining hot water in the bathtub, high-temperature hot water is added at the maximum hot water supply temperature, and if the bath temperature does not reach the set bath temperature even after the bath water level has reached the set bath temperature, a reheating operation is performed (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 4-283349 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in a system like that described in Patent Document 1, depending on the temperature of the remaining hot water, even if high-temperature water is added at the maximum hot water supply temperature, the set bath temperature may not be reached. The bath is filled to the set temperature by reheating the water, but with a storage-type bath water heating device, there is an issue that the amount of medium-temperature water in the storage tank increases. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides a bath hot water supply device comprising a hot water storage tank for storing hot water, a heating means for heating the hot water in the hot water storage tank, a bath heat exchanger capable of a reheating operation for exchanging heat between the hot water in the hot water storage tank and bathtub water to heat the bathtub water to a preset bath set temperature T, a bath supply pipe from the bathtub leading to the bath heat exchanger and a bath return pipe from the bath heat exchanger to the bathtub, a bath circulation circuit connecting the bath heat exchanger and the bathtub in a circulatory manner, a mixing valve for mixing the high-temperature water in the hot water storage tank and the water supplied from the water supply pipe to obtain hot water at a desired temperature, a water filling pipe connecting the mixing valve and the bath circulation circuit, an electric drain plug capable of draining the bathtub water in the bathtub, a bath temperature sensor for detecting the bath temperature in the bathtub, a water level sensor for detecting the water level from the water pressure of the hot water in the bathtub, and a control device for controlling a plurality of operations including the reheating operation, The control device is equipped with a remaining hot water filling operation control means which, when instructed by the control device to perform a filling operation, controls the remaining hot water filling operation which is performed when there is remaining hot water in the bathtub; a remaining hot water amount calculation means which calculates the remaining hot water amount x from the pre-stored cross-sectional area a of the bathtub and the remaining hot water level h of the remaining hot water detected by the water level sensor; a remaining hot water temperature detection means which detects the remaining hot water temperature t based on the detection value of the bath temperature sensor; and a drainage amount calculation means which, when performing the remaining hot water filling operation, calculates a drainage amount b of the remaining hot water in the bathtub based on the remaining hot water amount calculation means and the remaining hot water temperature detection means so that the bath set temperature T is reached when the bath set water level H is reached only by adding hot water at a high temperature hot water supply temperature A which is higher than the bath set temperature T. When it is necessary to drain the bath water, the remaining hot water filling operation control means opens the electric drain valve to drain the drainage amount b calculated by the drainage amount calculation means, and then performs the remaining hot water filling operation by only adding hot water at the high temperature hot water supply temperature A.

[0007] Further, the drainage amount calculation means calculates the drainage amount b by b = ((TA) x (H x a) + (At) x x) / (At), and the remaining hot water filling operation control means, based on the calculation result of the drainage amount b, if b>0, the remaining hot water filling operation control means opens the electric drain valve, drains the drainage amount b calculated by the drainage amount calculation means, and then performs a first remaining hot water filling operation in which only hot water is added at the high temperature hot water supply temperature A, if b=0, the remaining hot water filling operation control means performs a second remaining hot water filling operation in which only hot water is added at the high temperature hot water supply temperature A until the bath water level reaches the set water level H, and if b<0, the remaining hot water filling operation control means performs a third remaining hot water filling operation at a predetermined temperature lower than the high temperature hot water supply temperature A.

[0008] In addition, the amount of water discharged (b) is divided by the cross-sectional area (a) to calculate the amount of water level drop in the drainage. When the amount of water level drop from the start of drainage reaches the amount of water level drop in the drainage, drainage is terminated.

[0009] During drainage, the drainage amount b / s per unit time is learned, and the drainage amount b is drained using the learned drainage amount b / s per unit time. Effect of the Invention

[0010] According to the invention, the residual hot water filling operation control means 38 drains only the drainage volume b from the residual hot water in the bathtub 3, and fills the bath to the set water level H only by adding hot water at the high temperature hot water supply temperature A, so that re-heating can be performed without performing re-heating operation, thereby suppressing the generation of medium-temperature water. [Brief description of the drawings]

[0011] [Figure 1] Schematic diagram of an embodiment of the present invention. [Diagram 2] Flowchart showing the automatic bath filling operation of the present invention [Diagram 3] A graph showing the state of the bathtub based on the amount of drainage b and the remaining water temperature t of this invention DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Next, the present embodiment of the present invention will be described with reference to the drawings. Reference numeral 1 denotes a hot water storage tank that stores hot water, 2 denotes a heat pump unit as a heating means for heating the hot water, and 3 denotes a bathtub. Bathtub 3 is also equipped with an electric drain plug 300, which is a drain plug that is opened and closed remotely by the user sending an electric signal from control device 28, which will be described later, to electric drain plug 300. A drainage amount sensor 301 is provided downstream of electric drain plug 300, which can detect the amount of drained water.

[0013] In addition, the cross-sectional area a of the bathtub 3 is calculated by dividing the amount of water filled before reaching the preset bath set water level H (the preset bath set water amount L may be referenced) by the actual water level in the bathtub 3, and the calculated area is stored in advance in the control device 28.

[0014] Reference numeral 4 denotes a heating circulation circuit that connects the hot water storage tank 1 and the heat pump unit 2 in a circulatory manner, and is composed of a heat pump supply pipe connected to the bottom of the hot water storage tank 1 and a heat pump return pipe connected to the top of the hot water storage tank 1, and has a heating circulation pump 5. The cold water at the bottom of the hot water storage tank 1 is heated by the heat pump unit 2 via the heat pump supply pipe, and the heated high-temperature hot water is returned to the top of the hot water storage tank 1 via the heat pump return pipe, thereby heating and storing the hot water in the hot water storage tank 1. The hot water storage tank 1 has a hot water temperature sensor 6 on its outer periphery, and this hot water temperature sensor 6 detects the amount of stored hot water by detecting a temperature above a predetermined value.

[0015] In addition, in the heating operation of the heat pump unit 2 composed of a heat pump cycle, the temperature of the heated water flowing into the refrigerant water heat exchanger (not shown) can be set to a low temperature of 5 to 20°C, thereby enabling efficient heating operation at a high temperature and improving the COP. However, if the temperature of the flowing in heated water is medium-temperature water of 50 to 60°C, the COP will decrease.

[0016] Reference numeral 7 denotes a water supply pipe that supplies water to the hot water storage tank 1, 8 denotes a hot water outlet pipe that outputs hot water from the hot water storage tank 1, 9 denotes a water supply bypass pipe that branches off from the water supply pipe 7 and bypasses the hot water storage tank 1, 10 denotes a mixing valve that mixes the cold water from the water supply bypass pipe 9 and the hot water from the hot water outlet pipe 8 to a set temperature, 11 denotes a hot water supply pipe that supplies the mixed hot water at the set temperature, and 12 denotes a hot water tap provided at the end of the hot water supply pipe 11. Reference numeral 13 denotes a hot water supply temperature sensor provided downstream of the mixing valve 10, and 14 denotes a hot water supply flow rate sensor that counts the amount of hot water supplied. Reference numeral 15 denotes a pressure reducing valve that reduces the water pressure to a specified pressure, and 16 denotes a pressure relief valve that releases overpressure caused by heating.

[0017] Reference numeral 17 denotes a bath circulation circuit, which connects a bath heat exchanger 18, which exchanges heat between the hot water in the hot water storage tank 1 and the circulating bath hot water, to the bathtub 3, so that water can circulate through a bath supply pipe 17a leading from the bathtub 3 to the bath heat exchanger 18, and a bath return pipe 17b leading from the bath heat exchanger 18 to the bathtub 3. Reference numeral 17c denotes a heating bypass pipe that bypasses the bath heat exchanger 18. Reference numeral 19 denotes a circulation port that connects the bathtub 3 to the bath circulation circuit 17.

[0018] Reference numeral 20 denotes a bath circulation pump provided in the bath circulation circuit 17, 21 a flowing water sensor that detects the presence or absence of running water, 22 a bath temperature sensor that detects the temperature of the bath water flowing through the bath circulation circuit 17, and 23 a water level sensor that detects the water level in the bathtub 3 from the water pressure of the hot and cold water, and is provided upstream of the bath circulation pump 20 in the bath circulation circuit 17. This water level sensor 23 detects the water level in the bathtub 3 from the water pressure of the hot and cold water, and so if the circulation port 19 is exposed, the water level cannot be detected, and so the water level must be higher than the circulation port 19 in order to detect the water level.

[0019] Reference numeral 24 denotes a hot water filling pipe that branches off from the hot water supply pipe 11 and is connected to the bath circulation circuit 17 for filling the bathtub 3 with hot water, 25 denotes a hot water filling valve that is provided on this hot water filling pipe 24 and controls the start and stop of filling the bathtub 3 with hot water, and 26 denotes a bath flow sensor that counts the amount of hot water filled into the bathtub 3.

[0020] Reference numeral 27 denotes a heating control unit which controls the heating of the heat pump unit 2, and reference numeral 28 denotes a control device which controls the hot water supply and bath, and receives the detection values ​​of the hot water storage temperature sensor 6, the hot water supply temperature sensor 13, the hot water supply flow rate sensor 14, the running water sensor 21, the bath temperature sensor 22, the water level sensor 23, and the bath flow rate sensor 26, and drives the heating circulation pump 5, the mixing valve 10, the bath circulation pump 20, and the hot water filling valve 25.

[0021] Reference numeral 29 denotes a bathroom remote control installed in the bathroom and capable of communicating with the control device 28. The remote control is provided with an operation unit 30 including an automatic bath operation switch 31, a display unit 32 which displays the settings, and a sound generating unit 33 which generates sound such as a speaker as an alarm means.

[0022] Furthermore, the control device 28 is equipped with a remaining hot water amount calculation means 34 for calculating the remaining hot water amount x in the bathtub 3, a remaining hot water temperature detection means 35 for detecting the remaining hot water temperature t based on the detection result of the bath temperature sensor 22, a drainage amount calculation means 36 for calculating the drainage amount b of bath water to be drained during the remaining hot water filling operation described below, a water filling operation control means 37 for controlling the automatic water filling operation, and a remaining hot water filling operation control means 38 for controlling the remaining hot water filling operation performed when there is remaining hot water in the bathtub 3.

[0023] The remaining hot water amount calculation means 34 calculates the remaining hot water amount x using the remaining hot water level h from the water level detected by the water level sensor 23 and the cross-sectional area a of the bathtub 3 that is stored in advance.

[0024] The remaining hot water temperature detection means 35 detects the remaining hot water temperature t at the start of the remaining hot water filling operation using the bath temperature sensor 22.

[0025] Based on the remaining hot water amount calculation means 34 and the remaining hot water temperature detection means 35, the drainage amount calculation means 36 calculates the drainage amount b of the remaining hot water in the bathtub 3 so that the bath set temperature T will be achieved at the bath set water level H by simply adding hot water at the high temperature hot water supply temperature A.

[0026] When the automatic operation switch 31 is pressed, the water filling operation control means 37 checks whether or not there is remaining hot water, and if there is no remaining hot water, the water filling operation control means 37 controls the no remaining hot water filling operation described below, and if there is remaining hot water, the water filling operation control means 37 switches to the remaining hot water filling operation control means 38, and the remaining hot water filling operation control means 38 controls the remaining hot water filling operation.

[0027] Next, each of the multiple operations will be described. First, the boiling operation will be described. When a request for boiling is made, the control device 28 drives the heating circulation pump 5 located in the middle of the piping connecting the hot water storage tank 1 and the heat pump unit 2 to pump water from the bottom of the hot water storage tank 1, heat it in the heat pump unit 2, and return it to the top of the hot water storage tank 1, gradually boiling the water in the hot water storage tank 1 into high-temperature water.

[0028] Next, the hot water supply operation will be described. When the hot water tap 12 is opened, water is supplied from the water supply pipe 7, flows into the bottom of the hot water storage tank 1 and passes through the water supply bypass pipe 9. The high-temperature water pushed out from the top of the hot water storage tank 1 and the water supply from the water supply bypass pipe 9 are mixed in the mixing valve 10, and hot water adjusted so that the hot water setting temperature and the temperature detected by the hot water temperature sensor 13 are the same is supplied from the hot water tap 12.

[0029] In this case, if the hot water stored in the hot water storage tank 1 is high temperature, a smaller amount of high temperature water needs to be mixed in by the mixing valve 10, so the more high temperature water there is in the hot water storage tank 1, the higher the hot water storage efficiency will be.However, if there is a large amount of medium temperature water within the limited amount of hot water stored in the hot water storage tank 1, the amount of hot water required for hot water supply will also increase, so the hot water storage efficiency will decrease and the risk of running out of hot water will increase.

[0030] Next, the operation of filling bathtub 3 with water will be described. The control device 28 opens the filling valve 25, supplies water from the water supply pipe 7, which flows into the bottom of the hot water storage tank 1 and passes through the water supply bypass pipe 9. The high-temperature water pushed out from the top of the hot water storage tank 1 and the water supply from the water supply bypass pipe 9 are mixed in the mixing valve 10, and the filling operation begins by allowing the hot water adjusted so that the desired filling temperature and the temperature detected by the bath temperature sensor 22 are the same to flow into the bathtub 3. The flow rate is detected by the bath flow rate sensor 26, and when the water level detected by the water level sensor 23 reaches the bath set water level H, the control device 28 closes the filling valve 25, completing the filling operation.

[0031] Next, the reheating operation will be described. During the warming operation or when the user operates the operation unit 30 to start the reheating operation, the control device 28 drives the bath circulation pump 20 and detects the bath temperature of the bathtub 3 with the bath temperature sensor 22. If the detected bath temperature is lower than the bath set temperature T, the control device 28 switches the bath three-way valve (not shown) from the heating bypass pipe 17c to the bath heat exchanger 18, and the bath water and the high-temperature water in the hot water storage tank 1 exchange heat through the bath heat exchanger 18, heating the bath water. The heated bath water returns to the bathtub 3, heating the bath water in the bathtub 3. The reheating operation is performed by circulating the bathtub 3 and the bath heat exchanger 18 through the bath circulation circuit 17, and the reheating operation is completed when the bath temperature detected by the bath temperature sensor 22 reaches the bath set temperature T.

[0032] In addition, when the reheating operation is performed, heat is exchanged between the high-temperature water near the bath heat exchanger 18 and the bathtub water, so the temperature of the stored hot water near the bath heat exchanger 18 drops, and if the reheating operation is performed frequently, the amount of medium-temperature water in the hot water storage tank 1 increases.

[0033] Next, the automatic filling operation when the automatic operation switch 31 of the operation unit 30 is operated will be described with reference to the flow chart of FIG. First, when the user operates the automatic operation switch 31 of the operation unit 30 (S1: Yes), the water filling operation control means 37 provided in the control device 28 starts automatic water filling operation (S2).

[0034] In order to determine whether there is any hot water remaining in the bathtub 3, the filling operation control means 37 opens the filling valve 25, supplies water from the water supply pipe 7, and the water flows into the lower part of the hot water storage tank 1 and passes through the water supply bypass pipe 9. The high-temperature water pushed out from the upper part of the hot water storage tank 1 and the water supply from the water supply bypass pipe 9 are mixed in the mixing valve 10, and the bathtub 3 is filled with hot water at the bath setting temperature T up to a water level that can be detected by the water level sensor 23 so that the bath setting temperature T and the temperature detected by the bath temperature sensor 22 are the same, and a priming operation is performed (S3).

[0035] If, after performing the priming operation, the water level sensor 23 cannot detect the water level and it is determined that there is no remaining hot water in the bathtub 3 (S4 is No), the water filling operation control means 37 decides to perform a water filling operation without remaining hot water (S5).

[0036] Then, the filling operation control means 37 performs a no-remaining-hot-water filling operation in which hot water adjusted so that the bath set temperature T and the temperature detected by the bath temperature sensor 22 are the same is flowed into the bathtub 3 (S6).

[0037] If the current water level reaches the bath set water level H (S7 is Yes), the filling operation control means 37 completes the no-remaining-water filling operation by closing the filling valve 25, and notifies the completion of the filling operation with the sound generating unit 33 (S8).

[0038] If the water filling operation control means 37 determines in S4 that there is remaining hot water in the bathtub 3 (S4 is Yes), the control device 28 switches the water filling operation control means 37 to the remaining hot water filling operation control means 38, and the remaining hot water filling operation control means 38 decides to carry out the remaining hot water filling operation (S9).

[0039] Residual hot water temperature detection means 35 detects the remaining hot water temperature t in bathtub 3 based on the detection value of bath temperature sensor 22. At this time, if priming is being performed, it detects the remaining hot water temperature t after priming. Furthermore, remaining hot water amount calculation means 34 detects the remaining hot water level h based on the detection value of water level sensor 23, and calculates the remaining hot water amount x by multiplying this by the cross-sectional area a of bathtub 3, which was calculated in advance, using the following (Equation 1) (S10). x=h×a (Formula 1)

[0040] Next, based on the remaining hot water amount calculation means 34 and the remaining hot water temperature detection means 35, the drainage amount calculation means 36 calculates the drainage amount b of the remaining hot water in the bathtub 3 using the following (Equation 2) so that the bath set temperature T will be reached when the bath set water level H is reached only by adding hot water at a high-temperature hot water supply temperature A, which is higher than the bath set temperature T (S11). b=((TA)×(H×a)+(At)×x) / (At)...(Formula 2)

[0041] The remaining hot water filling operation control means 38 checks whether the drainage amount b calculated by the drainage amount calculation means 36 is 0 or more (S12), and if it is 0 or more (Yes in S12), proceeds to S13.

[0042] The remaining hot water filling operation control means 38 checks whether the drainage amount b calculated by the drainage amount calculation means 36 is higher than 0 (S13), and if it is higher than 0 (Yes in S13), proceeds to S14.

[0043] Then, the remaining hot water filling operation control means 38 decides to carry out the first remaining hot water filling operation (S14).

[0044] The remaining hot water filling operation control means 38 opens the electric drain valve 300 to drain the drainage amount b calculated in S11 from the bathtub 3, and starts draining (S15). Here, the flow rate after the start of draining is counted by the drainage amount sensor 301, and when the counted flow rate reaches the drainage amount b, the draining is stopped.

[0045] Then, the remaining hot water filling operation control means 38 starts the filling operation up to the bath set water level H by only adding hot water at the high temperature hot water supply temperature A (S16). Then, when the detection value of the water level sensor 23 reaches the bath set water level H (S7 is Yes), the first remaining hot water filling operation ends and the automatic filling operation is completed (S8).

[0046] In this way, if the calculated drainage volume b is greater than 0, a decision is made to carry out the first remaining hot water filling operation, and the remaining hot water filling operation control means 38 drains the drainage volume b from the remaining hot water in the bathtub 3, and fills the bath to the set water level H only by adding hot water at the high temperature hot water supply temperature A.This means that no re-heating operation is performed, and the water can be re-heated only by the filling operation by mixing the mixing valve 10, thereby suppressing the generation of medium-temperature water.

[0047] In addition, the remaining hot water filling operation control means 38 checks whether the drainage amount b calculated by the drainage amount calculation means 36 is higher than 0 (S13), and if the drainage amount b is 0 (S13 is No), proceeds to S17.

[0048] Then, the remaining hot water filling operation control means 38 decides to carry out the second remaining hot water filling operation (S14).

[0049] The remaining hot water filling operation control means 38 starts the filling operation up to the bath set water level H by only adding hot water of high temperature hot water supply temperature A (S16). Then, when the detection value of the water level sensor 23 reaches the bath set water level H (Yes in S7), the second remaining hot water filling operation ends and the automatic filling operation is completed (S8).

[0050] In this way, if the calculated drainage volume b is 0, a decision is made to carry out the second remaining hot water filling operation, and the remaining hot water filling operation control means 38 fills the bath to the set water level H only by adding hot water at the high temperature hot water supply temperature A, so no re-heating operation is performed, and re-heating can be performed only by the filling operation by mixing the mixing valve 10, thereby suppressing the generation of medium-temperature water.

[0051] In addition, the remaining hot water filling operation control means 38 checks whether the drainage amount b calculated by the drainage amount calculation means 36 is 0 or more (S12), and if the drainage amount b is lower than 0 (S12: No), proceeds to S19.

[0052] Then, the remaining hot water filling operation control means 38 decides to carry out the third remaining hot water filling operation (S19).

[0053] The remaining hot water filling operation control means 38 calculates a predetermined temperature so that the bath temperature becomes the bath set temperature T when the bath set water level H is reached (S20).

[0054] The remaining hot water filling operation control means 38 starts the filling operation with hot water mixed at a predetermined temperature up to the bath set water level H (S21). Then, when the detection value of the water level sensor 23 reaches the bath set water level H (Yes in S7), the third remaining hot water filling operation ends and the automatic filling operation is completed (S8).

[0055] In this way, if the calculated discharge volume b is a value smaller than 0, a decision is made to carry out the third remaining hot water filling operation, and the remaining hot water filling operation control means 38 determines that re-heating the water by adding hot water at the high temperature hot water supply temperature A will exceed the set bath temperature T, and performs the filling operation by adjusting the filling temperature so that the bath set temperature T is reached when the set bath water level H is reached.Therefore, no re-heating operation is performed, and re-heating can be performed only by the filling operation by mixing with the mixing valve 10, thereby suppressing the generation of medium-temperature water.

[0056] In addition, when there is remaining hot water, the remaining hot water filling operation control means 38 performs either the first remaining hot water filling operation which does not perform reheating operation, the second remaining hot water filling operation, or the third remaining hot water filling operation, so that in any operation, the generation of medium-temperature water is suppressed and efficiency can be maintained by suppressing a decrease in the heat generation efficiency (COP) and hot water storage efficiency.

[0057] Next, the relationship between the amount of wastewater b and the remaining hot water temperature t will be described with reference to the graph of FIG. Depending on the value of the drainage amount b calculated by the drainage amount calculation means 36, the residual hot water filling operation control means 38 performs either the first residual hot water filling operation, the second residual hot water filling operation, or the third residual hot water filling operation. If the value of the drainage amount b is greater than 0 and within area A, the first residual hot water filling operation is performed, if the value of the drainage amount b is 0 and on line B, the second residual hot water filling operation is performed, and if the value of the drainage amount b is less than 0 and within area C, the third residual hot water filling operation is performed.

[0058] In other words, when b = 0, the state of the bathtub 3 can be set to the bath set temperature T when the bath set water level H is reached by simply adding hot water from the high temperature hot water supply temperature A without draining the water. Also, when the state of the bathtub 3 is within area A, the state of the bathtub 3 is brought onto line B by draining the amount of drainage b, and the bath set temperature can be reached by adding hot water from the high temperature hot water supply temperature A when the bath set water level H is reached.

[0059] The present invention is not limited to this embodiment, and modifications can be made without changing the gist of the invention. For example, in this embodiment, the bath filling operation is carried out based on the bath set water level H, but the water volume rather than the water level can also be used as the basis. For example, when the user sets the bath set water volume L to 180 L, the bath filling operation can be terminated when the accumulated total flow rate through the bath flow sensor 26 reaches the bath set water volume L.

[0060] In addition, in the calculation of the drainage amount b in this embodiment, when draining the drainage amount b, the flow rate of the drainage amount sensor 301 is counted, and when the count reaches the drainage amount b, the end of drainage is detected, but the drainage amount b may be divided by the cross-sectional area a of the bathtub 3 to calculate the drainage water level drop amount, and drainage may be ended when the water level drop amount from the start of drainage reaches the drainage water level drop amount. Also, the drainage amount b / s per hour (here, the drainage amount per second) during drainage may be learned in advance and stored in the control device 28, and the end of drainage of the drainage amount b may be detected based on the elapsed time from the start of drainage.

[0061] Furthermore, during the third residual hot water filling operation, a predetermined temperature is calculated before the start of the filling operation, and the bath set temperature T is reached when the bath set water level H is reached; however, this is not limited to this, and if the state of the bathtub 3 is on line B by filling the bathtub with water at a temperature at least lower than the residual hot water temperature t, then it is possible to fill the bathtub with water at a low temperature and then add hot water at high hot water supply temperature A so that the bath set temperature T is reached when the bath set water level H is reached.

[0062] In this embodiment, the completion of the bath filling operation is when the amount of water is the bath set water level H and the bath temperature is the bath set temperature T, but the amount of water may be set not based on the water level detected by the water level sensor 23, but based on the integrated value of the flow rate counted by the bath flow rate sensor 26 reaching the bath set water amount L. For example, it may be set to fill the bath with a set water amount of 180 L at a bath set temperature of 42°C.

[0063] Furthermore, since draining the water even when the residual hot water temperature t is high results in a loss of heat, a lower limit drain temperature at which the water can be drained during the first residual hot water filling operation can be set. For example, when the bath temperature is higher than the lower limit drain temperature (for example, when the residual hot water temperature is higher than 36°C), the water can be filled to high temperature hot water supply temperature A or a specified temperature until the bath set water level H is reached, and a short reheating operation can be performed. [Explanation of symbols]

[0064] 1 Hot water tank 3. Bathtub 10 Mixing valve 22 Bath temperature sensor 23 Water level sensor 24 Hot water pipe 28 Control device 29 Bathroom remote control 34 Remaining hot water amount calculation method 35 Remaining water temperature detection means 36 Means for calculating drainage volume 37 Filling operation control means 38. Means for controlling remaining hot water filling operation 300 Electric drain plug 301 Displacement sensor

Claims

1. A hot water storage tank for storing hot water; A heating means for heating the hot water in the hot water storage tank; A bath heat exchanger capable of reheating the bath water by exchanging heat between the hot water in the hot water storage tank and the bath water to a preset bath temperature T; A bath circulation circuit is configured with a bath supply pipe from the bathtub to the bath heat exchanger and a bath return pipe from the bath heat exchanger to the bathtub, and connects the bath heat exchanger and the bathtub in a circulatory manner; a mixing valve for mixing the high-temperature water in the hot water storage tank and the water supplied from the water supply pipe to produce hot water of a desired temperature; A water filling pipe connecting the mixing valve and the bath circulation circuit; An electric drain plug capable of draining the bath water from within the bathtub; a bath temperature sensor for detecting a bath temperature in the bathtub; a water level sensor that detects the water level based on the water pressure in the bathtub; A bath hot water supply device provided with a control device for controlling a plurality of operations including the reheating operation, The control device includes: A residual hot water filling operation control means for controlling a residual hot water filling operation performed when there is residual hot water in the bathtub when the control device instructs the bathtub filling operation; A remaining hot water amount calculation means for calculating a remaining hot water amount x from a cross-sectional area a of the bathtub stored in advance and a remaining hot water level h of the remaining hot water detected by the water level sensor; A residual bath temperature detection means for detecting a residual bath temperature t based on a detection value of the bath temperature sensor; A drainage amount calculation means is provided for calculating, based on the remaining hot water amount calculation means and the remaining hot water temperature detection means, a drainage amount b of the remaining hot water in the bathtub so that the bath set temperature T is reached when the bath set water level H is reached only by adding hot water at a high temperature hot water supply temperature A, which is higher than the bath set temperature T, during the remaining hot water filling operation; This bath water heating device is characterized in that when it is necessary to drain the bathtub water, the remaining hot water filling operation control means opens the electric drain valve, drains the drainage volume b calculated by the drainage volume calculation means, and then performs the remaining hot water filling operation by only adding hot water at the high temperature hot water supply temperature A.

2. The displacement amount calculation means calculates the displacement amount b b=((TA)×(H×a)+(A-t)×x) / (A-t) Calculate it as follows: The residual hot water filling operation control means, based on the calculation result of the drainage amount b, In the case of b>0, the residual hot water filling operation control means opens the electric drain valve to drain the drainage amount b calculated by the drainage amount calculation means, and then performs a first residual hot water filling operation in which only hot water of the high temperature hot water supply temperature A is added; In the case of b=0, the residual hot water filling operation control means performs a second residual hot water filling operation in which only hot water of the high-temperature hot water supply temperature A is added so that the bath water level reaches the set bath water level H, A bath hot water supply device as described in claim 1, characterized in that when b<0, the remaining hot water filling operation control means performs a third remaining hot water filling operation at a predetermined temperature lower than the high temperature hot water supply temperature A.

3. 3. The bath hot water supply device according to claim 1, wherein the drainage amount b is divided by the cross-sectional area a to calculate the drainage water level drop amount, and drainage is terminated when the water level drop amount from the start of drainage reaches the drainage water level drop amount.

4. 3. The bath hot water supply device according to claim 1, wherein the amount of water discharged per hour b / s is learned during drainage, and the amount of water discharged b is drained using the learned amount of water discharged per hour b / s.

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