Hot water system

Abstract

To supply hot water with an appropriate temperature when supplying hot water to a first hot water supply target part during hot water supply to a second hot water supply target part in a hot water supply system in which the first hot water supply target part (hot water supply plug) is connected to both of a first water heater and a second water heater and the second hot water supply target part (bathtub) is connected to the second water heater.SOLUTION: When a request to supply hot water to a hot water supply plug CL is made while hot water is being supplied from a second water heater 2B to a bathtub BTB, at least one temperature of a target hot water supply temperature for the hot water supply plug CL and a target hot water supply temperature for the bathtub BTB is used as a common target hot water supply temperature between a first water heater 2A and the second water heater 2B. Water for hot water supply with the common target hot water supply temperature is supplied from the first water heater 2A to the hot water supply plug CL and is supplied from the second water heater 2B to the hot water supply plug CL and the bathtub BTB.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a hot water supply system in which a plurality of hot water heaters are connected. [Background technology]

[0002] Conventionally, as seen in Patent Document 1, for example, a system has been known in which multiple water heaters are connected in parallel between a main water supply line through which hot water is supplied and a main water supply line from which heated hot water is dispensed, and hot water is supplied from the main water supply line to one or more water heaters via a water supply on-off valve, and the hot water heated in the one or more water heaters can be supplied from the main water supply line to a hot water supply target such as a hot water tap (a hot water supply target common to the multiple water heaters).

[0003] In such a system, one of the multiple water heaters is typically set as the main water heater and the others as auxiliary water heaters, with the main water heater primarily supplying hot water to hot water taps and other hot water supply targets. In situations where the main water heater alone is insufficient in capacity, the auxiliary water heater additionally heats the hot water supply water in addition to the main water heater. Furthermore, the water supply on-off valve of the auxiliary water heater (an on-off valve installed in the flow path that allows hot water to flow from the main water supply line to the auxiliary water heater) is kept in a closed state when the auxiliary water heater is not heating the hot water supply water (when the auxiliary water heater is in standby mode).

[0004] Furthermore, with regard to individual water heaters, as seen in Patent Document 2, for example, it has been generally known that heated hot water can be distributed and supplied to multiple hot water supply targets, such as hot water taps and bathtubs. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2020-16409 [Patent Document 2] Japanese Patent Application Laid-Open No. 2014-152993 Summary of the Invention [Problem to be solved by the invention]

[0006] In a system capable of supplying heated hot water from one or more of a plurality of water heaters to a common hot water supply target (e.g., a hot water tap) for the plurality of water heaters, such as the system described in Patent Document 1, it is possible to connect each of the one or more water heaters to another hot water supply target (e.g., a bathtub), and construct a system in which hot water can be supplied from each water heater to the common hot water supply target, as well as hot water can be supplied from the water heater connected to the other hot water supply target.

[0007] For example, a hot water supply system can be constructed that includes at least two water heaters, a first water heater and a second water heater, the hot water supply passage of the first water heater connected to a first hot water supply target (e.g., a hot water tap) so as to supply hot water to the first hot water supply target, the hot water supply passage of the second water heater connected to the first hot water supply target and the second hot water supply target (e.g., a bathtub) so as to distribute hot water to the first hot water supply target and the second hot water supply target, and further, a water supply opening / closing valve that can open and close the water supply passage is installed in the water supply passage of the second water heater.

[0008] The inventors of the present application have discovered through their research that in such a hot water supply system, when a request for hot water supply to a first hot water supply target (e.g., a hot water tap) occurs while hot water is being supplied from a second hot water heater to a second hot water supply target (e.g., a bathtub), the following problem occurs.

[0009] In other words, when hot water is being supplied from the second water heater to the second hot water supply target area, the water supply on-off valve of the water supply line of the second water heater is controlled to be open, so when hot water supply to the first hot water supply target area begins, some of the hot water heated by the second water heater is mixed with the hot water heated by the first water heater and supplied to the first hot water supply target area.

[0010] In this case, when hot water is supplied from the second water heater to the second hot water supply target unit at a target hot water supply temperature for the second hot water supply target unit that has been set in advance by the user, and hot water is supplied from the first water heater to the first hot water supply target unit at a target hot water supply temperature for the first hot water supply target unit that has been set in advance by the user, the temperature of the hot water supplied from the second water heater to the first hot water supply target unit will be temperature-controlled to the target hot water supply temperature for the second hot water supply target unit.

[0011] Furthermore, the temperature of the hot water supplied from the first water heater to the first hot water supply target part is temperature-controlled to the target hot water supply temperature for the first hot water supply target part. Therefore, the temperature of the hot water supplied to the first hot water supply target part is a temperature different from both the target hot water supply temperature for the first hot water supply target part and the target hot water supply temperature for the second hot water supply target part (a temperature intermediate between both temperatures).

[0012] Therefore, particularly when the temperature difference between the target hot water supply temperature for the first hot water supply target unit and the target hot water supply temperature for the second hot water supply target unit is relatively large, the temperature of the hot water supply water dispensed at the first hot water supply target unit will be different from both the target hot water supply temperature for the first hot water supply target unit and the target hot water supply temperature for the second hot water supply target unit set by the user, which may cause the user to feel uncomfortable or mistakenly believe that there is a malfunction in the hot water supply system.

[0013] The present invention has been made in consideration of this background, and aims to provide a hot water supply system in which a first hot water supply target is connected to both a first hot water heater and a second hot water heater, and a second hot water supply target is further connected to the second hot water heater, which can supply hot water at an appropriate temperature when supplying hot water to the first hot water supply target while supplying hot water to the second hot water supply target. [Means for solving the problem]

[0014] In order to achieve the above-mentioned object, the hot water supply system of the present invention comprises a first water heater and a second water heater, each having a water supply passage, a hot water supply passage, and a heating unit, and each configured to heat hot water supplied through the water supply passage in the heating unit and to dispense the heated hot water through the hot water supply passage, and a control device that controls the operation of the first water heater and the second water heater, wherein the hot water supply passage of the first water heater is connected to a first hot water supply target portion so as to be able to supply hot water to the first hot water supply target portion, and the hot water supply passage of the second water heater is connected to the first hot water supply target portion and the second hot water supply target portion so as to be able to distribute the hot water to the first hot water supply target portion and the second hot water supply target portion, and further wherein a water supply on-off valve that can open and close the water supply passage is assembled to the water supply passage of the second water heater, The control device is configured to control the water supply on-off valve to open and operate only the second water heater so that hot water at a second target hot water temperature, which is the target temperature for hot water for the second hot water supply target portion, is supplied to the second hot water supply target portion, and when a request for hot water supply to the first hot water supply target portion occurs, use either the first target hot water temperature, which is the target temperature for hot water supply to the first hot water supply target portion, or the second target hot water temperature as a target hot water temperature A common to the first water heater and the second water heater, supply hot water at the target hot water temperature A from the first water heater to the first hot water supply target portion, and operate the first water heater and the second water heater so that hot water at the target hot water temperature A is supplied to the first hot water supply target portion and the second hot water supply target portion from the second water heater (first invention).

[0015] According to the first invention, when a request for hot water to a first hot water supply target occurs while hot water at a second target hot water supply temperature is being supplied to the second hot water supply target, hot water whose temperature has been controlled to either the first target hot water supply temperature, which is the target temperature of hot water supply water for the first hot water supply target, or the second target hot water supply temperature, which is the target temperature of hot water supply water for the second hot water supply target, is supplied to the first hot water supply target.

[0016] This prevents hot water at a temperature different from both the first target hot water supply temperature and the second target hot water supply temperature from being supplied to the first hot water supply target, which is common to both the first and second hot water heaters. This prevents the user from feeling uncomfortable or mistaking this for a malfunction of the hot water supply system. Therefore, according to the first aspect of the present invention, when supplying hot water to the second hot water supply target, hot water can be supplied at an appropriate temperature to the first hot water supply target.

[0017] In the first aspect of the invention, for example, the first hot water supply target portion may be a hot water tap, and the second hot water supply target portion may be a bathtub. In this case, it is preferable that the control device is configured to use the second target hot water supply temperature, or the lower of the first target hot water supply temperature and the second target hot water supply temperature, as the A target hot water supply temperature (second aspect of the invention).

[0018] This makes it possible to prevent hot water at a temperature higher than the second target hot water temperature, which is the target temperature of hot water for the bathtub (second hot water supply target portion), from being supplied to the bathtub (filling the bathtub with hot water at that high temperature). Also, when the lower of the first target hot water temperature and the second target hot water temperature is used as the A-th target hot water temperature, if the first target hot water temperature is set to a temperature equal to or lower than the second target hot water temperature, hot water whose temperature is controlled to the first target hot water temperature, which is the target temperature of hot water for the hot water tap, is supplied to the hot water tap, thereby improving the convenience of the hot water supply system.

[0019] In the first or second invention, when the hot water supply passage of the first water heater is connected to the first hot water supply object portion and the third hot water supply object portion so as to distribute hot water to the first hot water supply object portion and the third hot water supply object portion, the control device operates the first water heater to supply hot water at a third target hot water supply temperature, which is a target temperature of the hot water for the third hot water supply object portion, to the third hot water supply object portion, and controls the water supply on-off valve to open and close so as to supply hot water at the second target hot water supply temperature to the second hot water supply object portion, It is preferable that when a request for hot water supply to a unit occurs, one of the first target hot water supply temperature, the second target hot water supply temperature, and the third target hot water supply temperature is used as a Bth target hot water supply temperature common to the first water heater and the second water heater, and the first water heater and the second water heater are operated so that hot water at the Bth target hot water supply temperature is supplied from the first water heater to the first hot water supply target unit and the third hot water supply target unit, and hot water at the Bth target hot water supply temperature is supplied from the second water heater to the first hot water supply target unit and the second hot water supply target unit (third invention).

[0020] According to this, when the first water heater is operated to supply hot water at a third target hot water temperature, which is the target temperature of the hot water for the third hot water supply target portion, to the third hot water supply target portion, and the second water heater is operated by controlling the opening of the water supply on-off valve to supply hot water at the second target hot water temperature to the second hot water supply target portion, when a request for hot water supply to the first hot water supply target portion occurs, hot water whose temperature has been controlled to one of the first target hot water temperature, which is the target temperature of the hot water for the first hot water supply target portion, the second target hot water temperature, which is the target temperature of the hot water for the second hot water supply target portion, and the third target hot water temperature, which is the target temperature of the hot water for the third hot water supply target portion, is supplied to the first hot water supply target portion.

[0021] This prevents hot water at a temperature different from any of the first target hot water supply temperature, the second target hot water supply temperature, and the third target hot water supply temperature from being supplied to the first hot water supply target portion, which is common to both the first and second hot water heaters. This prevents the user from feeling uncomfortable or mistaking this for a malfunction of the hot water supply system. Therefore, according to the third aspect of the present invention, when supplying hot water to both the second and third hot water supply target portions, hot water can be supplied at an appropriate temperature to the first hot water supply target portion.

[0022] In the third invention, for example, the first hot water supply target portion may be a hot water tap, the second hot water supply target portion may be a bathtub, and the third hot water supply target portion may be a bathtub different from the second hot water supply target portion. In this case, an embodiment may be adopted in which the control device is configured to use the lower target hot water supply temperature of the second target hot water supply temperature and the third target hot water supply temperature, or the lowest target hot water supply temperature of the first target hot water supply temperature, the second target hot water supply temperature, and the third target hot water supply temperature, as the B target hot water supply temperature (fourth invention).

[0023] This prevents hot water at a temperature higher than the second target hot water temperature, which is the target temperature for hot water supply to the bathtub as the second hot water supply target part, from being supplied to the bathtub (filling the bathtub with hot water at that high temperature), and prevents hot water at a temperature higher than the third target hot water temperature, which is the target temperature for hot water supply to the bathtub as the third hot water supply target part, from being supplied to the bathtub (filling the bathtub with hot water at that high temperature).

[0024] Furthermore, when the lowest target hot water temperature among the first target hot water temperature, the second target hot water temperature, and the third target hot water temperature is used as the B target hot water temperature, if the first target hot water temperature is set to a temperature lower than the second target hot water temperature and lower than the third target hot water temperature, hot water whose temperature is controlled to the first target hot water temperature, which is the target temperature of the hot water for the hot water tap, is supplied to the hot water tap, thereby improving the convenience of the hot water supply system.

[0025] In the first or second invention, when the first hot water supply object portion is a hot water tap, the second hot water supply object portion is a bathtub, and the hot water supply path of the first hot water heater is connected to the first hot water supply object portion and the third hot water supply object portion, which is a bathtub different from the second hot water supply object portion, so as to distribute hot water to the first hot water supply object portion and the third hot water supply object portion, the control device operates the first hot water heater to supply hot water to the third hot water supply object portion at a third target hot water supply temperature, which is a target temperature of hot water for the third hot water supply object portion. and when a request for hot water supply to the first hot water supply target portion occurs in a state in which the second hot water heater is operated by controlling the water supply on-off valve to be open so as to supply hot water at the second target hot water supply temperature to the second hot water supply target portion, supply of hot water to the hot water supply target portion corresponding to the one of the third hot water supply target portion and the second hot water supply target portion is performed from one of the first and second hot water heaters, which is a water heater corresponding to the higher target hot water supply temperature of the second target hot water supply temperature and the third target hot water supply temperature. a first process for interrupting hot water supply to the hot water supply target part by blocking a flow path of hot water; and in the interrupted state, using the lower of the second target hot water supply temperature and the third target hot water supply temperature as a C-th target hot water supply temperature common to the first hot water heater and the second hot water heater, and supplying hot water at the C-th target hot water supply temperature to the first hot water supply target part from one of the first hot water heater and the second hot water heater, and supplying hot water at the C-th target hot water supply temperature to the second hot water supply target part and the previous hot water supply target part from the other of the first hot water heater and the second hot water heater. It is also possible to adopt an aspect in which the first water heater and the second water heater are configured to operate to perform a second process of supplying hot water at the Cth target hot water temperature to the hot water supply target portion corresponding to the other water heater among the third hot water supply target portions and to the first hot water supply target portion, and a third process of resuming hot water supply from the one water heater to the second hot water supply target portion and the hot water supply target portion corresponding to the one water heater among the third hot water supply target portions after hot water supply to the first hot water supply target portion is completed (5th invention).

[0026] According to this, when the first water heater is operated to supply hot water at the third target hot water supply temperature to the third hot water supply target part (bathtub), and the second water heater is operated by controlling the water supply on-off valve to open so as to supply hot water at the second target hot water supply temperature to the second hot water supply target part (bathtub), when a request for hot water supply to the first hot water supply target part (hot water tap) occurs, hot water supply from one of the water heaters (the first water heater or the second water heater), which is the water heater corresponding to the higher target hot water supply temperature of the second target hot water supply temperature and the third target hot water supply temperature, to the hot water supply target part corresponding to that one water heater (the bathtub which is the third hot water supply target part or the bathtub which is the second hot water supply target part) (the bathtub which is the second hot water supply target part) is interrupted.

[0027] Then, hot water supply to the hot water supply target portion corresponding to the one water heater is resumed after hot water supply to the first hot water supply target portion (hot water tap) is completed, so it becomes possible to supply hot water whose temperature has been controlled to the target hot water supply temperature (second target hot water supply temperature or third target hot water supply temperature) corresponding to the hot water supply target portion corresponding to the one water heater. In other words, it becomes possible to prevent hot water at a temperature lower than the target hot water temperature corresponding to the hot water supply target portion corresponding to the one water heater from being supplied to the hot water supply target portion corresponding to the one water heater.

[0028] Furthermore, hot water whose temperature is controlled to the Cth target hot water temperature is supplied to the hot water supply target (bathtub) corresponding to the other of the second and third hot water supply targets, the hot water supply target (hot water tap), and the first hot water supply target (hot water tap). In this case, the lower of the second target hot water supply temperature and the third target hot water supply temperature is used as the Cth target hot water temperature (more specifically, if the other water heater is the first water heater, the third target hot water supply temperature corresponding to the third hot water supply target (bathtub on the first water heater side); if the other water heater is the second water heater, the second target hot water supply temperature corresponding to the second hot water supply target (bathtub on the second water heater side)).

[0029] This prevents hot water at a temperature different from any of the first, second, and third target hot water supply temperatures from being supplied to the first hot water supply target portion common to both the first and second hot water heaters, thereby preventing the user from feeling uncomfortable or mistaking this for a malfunction in the hot water supply system.

[0030] In addition, when the other water heater is the first water heater, the C target hot water temperature corresponds to the third target hot water temperature corresponding to the bathtub (third hot water supply target part) on the first water heater side, and when the other water heater is the second water heater, it corresponds to the second target hot water temperature corresponding to the bathtub (second hot water supply target part) on the second water heater side.Therefore, it is possible to prevent the hot water supply target part (bathtub) corresponding to the other water heater from being supplied with hot water at a temperature lower or higher than the target hot water temperature (second target hot water supply temperature or third target hot water temperature) corresponding to the hot water supply target part (bathtub) (the hot water supply target part (bathtub) being filled with hot water at that lower or higher temperature).

[0031] Therefore, according to the fifth aspect of the present invention, when supplying hot water to both the second hot water supply target and the third hot water supply target, hot water can be supplied at an appropriate temperature to the first hot water supply target.

[0032] Another aspect of the hot water supply system of the present invention is a hot water supply system comprising a first water heater and a second water heater, each having a water supply passage, a hot water supply passage, and a heating unit, and each configured to heat hot water supplied via the water supply passage in the heating unit and to dispense the heated hot water via the hot water supply passage, and a control device that controls the operation of the first water heater and the second water heater, wherein the hot water supply passage of the first water heater is connected to the first hot water supply target portion and the third hot water supply target portion so as to distribute the hot water to the first hot water supply target portion and the third hot water supply target portion, and the hot water supply passage of the second water heater is connected to the first hot water supply target portion and the second hot water supply target portion so as to distribute the hot water to the first hot water supply target portion and the second hot water supply target portion, and further wherein a water supply on / off valve capable of opening and closing the water supply passage is assembled to the water supply passage of the second water heater, The control device operates the first water heater to supply hot water of a third target hot water supply temperature, which is a target temperature of the hot water for the third hot water supply target portion, to the third hot water supply target portion, and controls the water supply on-off valve to open and operate the second water heater to supply hot water of a second target hot water supply temperature, which is a target temperature of the hot water for the second hot water supply target portion, when a request for hot water supply to the first hot water supply target portion occurs, The sixth invention is characterized in that one of the hot water temperature, the second target hot water temperature, and the third target hot water temperature is used as a common target hot water temperature B for the first water heater and the second water heater, and the first water heater and the second water heater are operated so that hot water at the target hot water temperature B is supplied from the first water heater to the first hot water supply target portion and the third hot water supply target portion, and hot water at the target hot water temperature B is supplied from the second water heater to the first hot water supply target portion and the second hot water supply target portion (sixth invention). This can provide the same effects as the third aspect of the invention.

[0033] In the above-mentioned sixth invention, when the first hot water supply target part is a hot water tap, the second hot water supply target part is a bathtub, and the third hot water supply target part is a bathtub different from the second hot water supply target part, the control device may be configured to use the lower target hot water supply temperature of the second target hot water supply temperature and the third target hot water supply temperature, or the lowest target hot water supply temperature of the first target hot water supply temperature, the second target hot water supply temperature, and the third target hot water supply temperature as the B target hot water supply temperature (seventh invention). This can provide the same effects as the fourth aspect of the invention.

[0034] Another aspect of the hot water supply system of the present invention is a hot water supply system comprising a first water heater and a second water heater, each having a water supply passage, a hot water supply passage, and a heating unit, and each configured to heat hot water supplied via the water supply passage in the heating unit and to dispense the heated hot water via the hot water supply passage, and a control device that controls the operation of the first water heater and the second water heater, wherein the hot water supply passage of the first water heater is connected to the first hot water supply target portion and the third hot water supply target portion so as to distribute the hot water to the first hot water supply target portion and the third hot water supply target portion, and the hot water supply passage of the second water heater is connected to the first hot water supply target portion and the second hot water supply target portion so as to distribute the hot water to the first hot water supply target portion and the second hot water supply target portion, and further wherein a water supply on / off valve capable of opening and closing the water supply passage is assembled to the water supply passage of the second water heater, The first hot water supply target portion is a hot water tap, the second hot water supply target portion is a bathtub, and the third hot water supply target portion is a bathtub different from the second hot water supply target portion, The control device operates the first water heater to supply hot water to the third hot water supply target portion at a third target hot water supply temperature, which is a target temperature of the hot water for the third hot water supply target portion, and controls the water supply on-off valve to open and operate the second water heater to supply hot water to the second hot water supply target portion at a second target hot water supply temperature, which is a target temperature of the hot water for the second hot water supply target portion, and when a request for hot water supply to the first hot water supply target portion occurs, the control device performs a first process of interrupting hot water supply to the hot water supply target portion by blocking a flow path of hot water supply water from one of the first and second water heaters, which is a water heater corresponding to a higher target hot water supply temperature of the second target hot water supply temperature and the third target hot water supply temperature, to the hot water supply target portion corresponding to the one of the third hot water supply target portion and the second hot water supply target portion; and a third process of using the lower of the first target hot water supply temperature and the third target hot water supply temperature as a Cth target hot water supply temperature common to the first water heater and the second water heater, and supplying hot water at the Cth target hot water supply temperature from one of the first water heater and the second water heater to the first hot water supply target portion and the hot water supply water at the Cth target hot water supply temperature from the other of the first water heater and the second water heater to the hot water supply target portion corresponding to the other of the second hot water supply target portion and the third hot water supply target portion and the first hot water supply target portion; and a third process of resuming hot water supply from the one water heater to the hot water supply target portion corresponding to the one of the second hot water supply target portion and the third hot water supply target portion after hot water supply to the first hot water supply target portion has been completed (8th invention). This can provide the same effects as the fifth aspect of the invention. [Brief explanation of the drawings]

[0035] [Figure 1] 1 is a diagram showing the overall configuration of a hot water supply system according to an embodiment of the present invention. [Figure 2] 5 is a flowchart showing a first example of processing for controlling the operation of the main water heater (first water heater) in the first embodiment. [Figure 3]5 is a flowchart showing a first example of processing for controlling the operation of the auxiliary water heater (second water heater) in the first embodiment. [Figure 4] 6 is a flowchart showing a second example of the process for controlling the operation of the main water heater (first water heater) in the first embodiment. [Figure 5] 6 is a flowchart showing a second example of the process for controlling the operation of the auxiliary water heater (second water heater) in the first embodiment. [Figure 6] 10 is a flowchart showing an example of a process for controlling the operation of the main water heater (first water heater) in the second embodiment. [Figure 7] 10 is a flowchart showing an example of a process for controlling the operation of an auxiliary water heater (second water heater) in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0036] [First embodiment] A first embodiment of the present invention will be described below with reference to Figures 1 to 5. Referring to Figure 1, a hot water supply system 1 of this embodiment includes a plurality of (for example, two) water heaters 2A, 2B. Each of the water heaters 2A, 2B includes a heat source unit 3 having the same configuration as the other, as a heat source unit for heating water for hot water supply. A hot water tap CL located in a kitchen, washroom, bathroom, etc. is connected to the heat source unit 3 of each of the water heaters 2A, 2B as a common target for hot water supply, and a separate bathtub BTA, BTB is connected to each of the water heaters 2A, 2B as another target for hot water supply.

[0037] Here, of the water heaters 2A and 2B, the water heater 2A is the main water heater for supplying hot water to the hot water tap CL, and hereinafter may be referred to as the main water heater 2A. Furthermore, the water heater 2B is a water heater for supplying hot water to the hot water tap CL on an auxiliary basis when the hot water supply capacity of the main water heater 2A alone is insufficient, and hereinafter may be referred to as the auxiliary water heater 2B. In this embodiment, the main water heater 2A corresponds to the first water heater in the present invention, and the auxiliary water heater 2B corresponds to the second water heater in the present invention. Furthermore, the hot water tap CL, the bathtub BTB, and the bathtub BTA correspond to the first hot water supply target area, the second hot water supply target area, and the third hot water supply target area in the present invention, respectively. In the following description, when there is no need to distinguish between the water heaters 2A and 2B, they will be simply referred to as the water heater 2, and when there is no need to distinguish between the bathtubs BTA and BTB, they will be simply referred to as the bathtub BT.

[0038] The heat source unit 3 of each water heater 2 includes a water supply passage 10 to which hot water is supplied from a water supply source not shown, a first heating section 11 for heating the hot water supplied from the water supply passage 10, a hot water supply passage 12 for discharging the hot water heated by the first heating section 11, a second heating section 13 for heating bathtub water which is the hot water supplied to the bathtub BT, a circulation water passage 14 for circulating the bathtub water between the second heating section 13 and the bathtub BT, and a bath filling water passage 15 for supplying the hot water heated by the first heating section 11 from the hot water supply passage 12 to the bathtub BT via the circulation water passage 14.

[0039] The water supply passages 10 of each of the water heaters 2A and 2B branch off from a single upstream water supply passage 4, and hot water is supplied to each of the water supply passages 10 from a water supply source (not shown) via the upstream water supply passage 4. The downstream sides of the hot water supply passages 12 of each of the water heaters 2A and 2B merge into a single downstream hot water supply passage 5, the downstream end of which is connected to a hot water tap CL, and hot water is supplied from each of the hot water supply passages 12 to the hot water tap CL via the downstream hot water supply passage 5. Note that although only a single hot water tap CL is shown in FIG. 1, multiple hot water taps may be connected to the downstream hot water supply passage 5.

[0040] Although detailed illustration is omitted, first heating section 11 is configured, for example, by a known combustion-type heating device including a burner and a heat exchanger. In this case, first heating section 11 circulates hot water supplied from water supply passage 10 through hot water supply passage 12 via the heat exchanger, and heats the hot water flowing through the heat exchanger with combustion heat generated by combustion operation of the burner. Note that first heating section 11 may also be equipped with a bypass passage that flows hot water from water supply passage 10 to hot water supply passage 12 without passing through the heat exchanger, and a bypass ratio adjustment valve for adjusting a bypass ratio, which is the ratio of the flow rate of hot water flowing through the bypass passage to the flow rate of hot water flowing through the heat exchanger.

[0041] A water supply rate regulating valve 16 for regulating the water supply rate, which is the flow rate of hot water flowing through the water supply rate 10, and a flow rate sensor 17 for detecting the water supply rate are installed in the water supply line 10, and a temperature sensor 18 for detecting the hot water temperature, which is the temperature of the hot water supplied through the hot water supply line 12 to the hot water tap CL or bathtub BT downstream, are installed in the hot water supply line 12. The water supply rate regulating valve 16 is, for example, an electric servo valve, and is also capable of closing the water supply line 10. However, of the water heaters 2A and 2B, the water supply rate regulating valve 16 of the main water heater 2A does not have to have the function of closing the water supply line 10. The water supply rate regulating valve 16 of the auxiliary water heater 2B corresponds to the water supply on-off valve in this invention.

[0042] The circulation water passage 14 comprises a return water passage 14a that flows bath water from inside the bathtub BT to the second heating section 13, and an outward water passage 14b that flows bath water from the second heating section 13 into the bathtub BT, and an electric pump 19 is attached to one of the return water passage 14a and the outward water passage 14b, for example the return water passage 14a, as a power source for circulating the bath water in the circulation water passage 14. The ends of the return water passage 14a and the outward water passage 14b on the bathtub BT side are connected to a pouring spout Ba formed in the side wall near the bottom of the bathtub BT.

[0043] Although not shown in detail, second heating section 13 is composed of a known combustion-type heating device including a burner and a heat exchanger, similar to first heating section 11. In this case, the heat exchanger of second heating section 13 is connected to return water passage 14a and outward water passage 14b so that bathwater flows from return water passage 14a to outward water passage 14b. Second heating section 13 is configured so that bathwater flowing through circulation water passage 14 due to the operation of pump 19 is heated in the heat exchanger by combustion heat generated by the combustion operation of the burner.

[0044] Additionally, each of the first heating section 11 and the second heating section 13 of the heat source unit 3 of each water heater 2 is not limited to a combustion-type heating device. For example, each of the first heating section 11 and the second heating section 13 may be equipped with an electric heating device or a heat pump-type heating device instead of or in addition to a combustion-type heating device.

[0045] One of the return water passage 14a and the outward water passage 14b, for example the return water passage 14a, is fitted with a temperature sensor 20 that detects the temperature of the bathtub water, a water flow switch 21 that detects the presence or absence of water flow in the circulation water passage 14, and a water level sensor 22 that detects the water level of the bathtub water in the bathtub BT. Note that the temperature sensor 20, water flow switch 21, and water level sensor 22 may each be provided in the outward water passage 14b.

[0046] Filling water passage 15 branches off from hot water supply passage 12 and merges into one of return water passage 14a and forward water passage 14b of circulation water passage 14, for example, return water passage 14a. Filling water passage 15 is fitted with a filling solenoid valve 23 that can open and close filling water passage 15, and a flow rate sensor 24 that detects the flow rate of hot water supplied to bathtub BT from hot water supply passage 12 through filling water passage 15 to bathtub BT (the flow rate of hot water supplied to bathtub BT).

[0047] Each of water heaters 2A, 2B further includes a control device 31A, 31B having the function of controlling the operation of the respective heat source unit 3. Control devices 31A, 31B are mounted on the respective heat source units 3 of water heaters 2A, 2B. In addition, hot water supply system 1 includes, as remote controls for operating the system, a kitchen remote control 32A installed in the kitchen or the like, a bathroom remote control 33A installed in the bathroom where bathtub BTA is installed, and a bathroom remote control 33B installed in the bathroom where bathtub BTB is installed.

[0048] Although detailed illustrations are omitted, the kitchen remote control 32A is equipped with an operation unit including a switch (on / off switch) for turning on / off the hot water supply operation that supplies hot water to the hot water tap CL, an operation switch for setting a target hot water temperature, and an operation switch for instructing the execution of a hot water filling operation that fills each of the bathtubs BTA and BTA with hot water, as well as a display unit that displays various information regarding the operation of the water heaters 2A and 2B, and a sound output unit that outputs alarm sounds and audio information.

[0049] In addition, although detailed illustrations are omitted, the bathroom remote controls 33A and 33B of the water heaters 2A and 2B each include an operation unit including operation switches for setting the target temperature of the bath water in the corresponding bathtubs BTA and BTB, the target water level of the bathwater, and the target hot water temperature, as well as operation switches for instructing the execution of the bath filling operation corresponding to each of the bathtubs BTA and BTB, a display unit that displays various information related to bath filling, etc., and a sound output unit that outputs alarm sounds and audio information.

[0050] Control devices 31A and 31B are each configured with one or more electronic circuit units including a processor such as a microcomputer, memory, an interface circuit, etc., and are capable of communicating with each other. Control device 31A of water heater 2A is capable of communicating with kitchen remote control 32A and bathroom remote control 33A, and control device 31B of water heater 2B is capable of communicating with bathroom remote control 33B. Kitchen remote control 32A may be configured to communicate with control device 31B of water heater 2B instead of or in addition to control device 31A of water heater 2A.

[0051] Each of the control devices 31A, 31B has the function of controlling the operation of the heat source unit 3 of the corresponding water heater 2A, 2B through functions realized by the implemented hardware configuration and program (software configuration).

[0052] Next, the operation of the bath system 1 of this embodiment will be explained. First, the basic operations of the hot water supply operation that supplies hot water to the hot water tap CL and the bathtub filling operation that supplies hot water (fills the bathtub BTA or BTB) will be explained. When the hot water supply operation is turned on using the kitchen remote control 32A or the bathroom remote control 33A or 33B (the hot water supply system 1 is in standby mode), the water supply amount adjustment valve 16 of the main water heater 2A is controlled to be open by the control device 31A, and the water supply amount adjustment valve 16 of the auxiliary water heater 2B is controlled to be closed by the control device 31B.

[0053] In this standby state, when the hot water tap CL is opened, water begins to flow from the upstream water supply passage 4 to the hot water tap CL via the water supply passage 10, first heating section 11, and hot water supply passage 12 of the main hot water heater 2A, and the downstream hot water supply passage 5. At this time, when the control device 31A detects that the water flow rate is greater than or equal to a predetermined rate based on the output of the flow rate sensor 17 of the main hot water heater 2A, it starts the operation of the first heating section 11 (burner combustion operation).

[0054] Furthermore, control device 31A controls the amount of heat (burner combustion amount) of first heating unit 11 so that the hot water temperature detected by temperature sensor 18 of main hot water heater 2A matches or nearly matches the target hot water temperature, which is the target value for the hot water temperature. In this case, the target hot water temperature is basically the hot water setting temperature, which is the temperature most recently set by the user using kitchen remote control 32A or bathroom remote control 33A, 33B for hot water supply to hot water tap CL. As a result, hot water is supplied to hot water tap CL at the set hot water temperature.

[0055] Furthermore, when the water flow rate to the hot water tap CL is high, or when the amount of heating provided by first heating section 11 of main water heater 2A alone is insufficient to heat the hot water supply water, control device 31A commands control device 31B of auxiliary water heater 2B to perform auxiliary hot water supply operation. At this time, control device 31B controls the opening of water supply amount adjustment valve 16 of auxiliary water heater 2B, and starts operation of first heating section 11 of auxiliary water heater 2B (burner combustion operation).

[0056] Furthermore, the control device 31B controls the heating amount (burner combustion amount) of the first heating section 11 of the auxiliary water heater 2B so that the hot water temperature detected by the temperature sensor 18 of the auxiliary water heater 2B matches or nearly matches the hot water setting temperature as the target hot water temperature.

[0057] As a result, the hot water supplied to the hot water tap CL is heated not only by the main water heater 2A but also by the auxiliary water heater 2B. Ultimately, it becomes possible to raise the temperature of the hot water supplied to the hot water tap CL to the hot water set temperature. When the main water heater 2A alone is able to raise the temperature of the hot water to the hot water set temperature, the control device 31B of the auxiliary water heater 2B stops the operation of the first heating unit 11 of the auxiliary water heater 2B and controls the water supply amount adjustment valve 16 to close, in response to a command from the control device 31A of the main water heater 2A. This stops the auxiliary hot water supply operation by the auxiliary water heater 2B.

[0058] Furthermore, when the hot water tap CL is closed, the flow of hot water to the main water heater 2A is cut off. At this time, when the control device 31A of the main water heater 2A detects that the water flow rate has dropped below a predetermined flow rate based on the output of the flow sensor 17 of the main water heater 2A, it stops the operation of the first heating unit 11 of the main water heater 2A. Furthermore, if the auxiliary water heater 2B is performing auxiliary hot water supply operation, the control device 31A commands the control device 31B of the auxiliary water heater 2B to stop the auxiliary hot water supply operation. In response, the control device 31B stops the operation of the first heating unit 11 of the auxiliary water heater 2B and controls the water supply amount adjustment valve 16 to close. In the hot water supply system 1 of this embodiment, the hot water supply operation for supplying hot water to the hot water tap CL is basically carried out as described above.

[0059] Next, we will explain the bath filling operation, which fills one of the bathtubs BTA, BTB, for example, bathtub BTB. When the hot water supply system 1 is in standby mode and an operation is performed using the kitchen remote control 32A or the bathroom remote control 33B to command the execution of the bath filling operation for bathtub BTB, the control device 31B of the auxiliary water heater 2B controls the opening of the water supply adjustment valve 16 of the auxiliary water heater 2B, controls the opening of the bath filling solenoid valve 23, and also starts the operation of the first heating unit 11. This starts the supply of hot water (filling) to the bathtub BTB.

[0060] Then, control device 31B controls the amount of heat generated by first heating unit 11 so that the hot water temperature detected by temperature sensor 18 of auxiliary hot water heater 2B matches or nearly matches the target hot water temperature for filling bathtub BTB. In this case, the target hot water temperature for filling bathtub BTB is basically the bath filling set temperature, which is the temperature most recently set by the user on bathroom remote control 33B (or kitchen remote control 32A). As a result, hot water is supplied (filled) to bathtub BTB at the bath filling set temperature.

[0061] Control device 31B calculates the amount of hot water required to raise the bathtub water level in bathtub BTB to the set water level, which is the target value most recently set by bathroom remote control 33B (or kitchen remote control 32A). Then, control device 31B supplies hot water to bathtub BTB until the amount of hot water supplied to bathtub BTB (integrated flow rate) detected based on the output of flow sensor 24 of bath filling water channel 15 reaches the calculated required amount of hot water. Once the required amount of hot water is reached, control device 31B stops operation of first heating unit 11 and closes bath filling solenoid valve 23 and water supply adjustment valve 16. This completes filling bathtub BTB to the set water level.

[0062] Control device 31B then determines whether the bathtub water temperature detected by temperature sensor 20 of auxiliary water heater 2B has reached the bath filling set temperature, which is the target bathwater temperature for filling the bath. If the determination result is negative due to bathtub water remaining in bathtub BTB when the bath filling operation begins, control device 31B activates second heating section 13 and pump 19 of auxiliary water heater 2B to heat and circulate the bathtub water in bathtub BTB through circulation water path 14 (reheating the bathtub water) until the detected bathtub water temperature reaches the bathtub filling set temperature.

[0063] In the hot water supply system 1 of this embodiment, the bathtub filling operation for filling the bathtub BTB with hot water is basically performed as described above. The bathtub BTA is filled with hot water by the main hot water heater 2A in the same manner as described above. However, in this case, the water supply amount adjustment valve 16 of the main hot water heater 2A is maintained in an open state.

[0064] Incidentally, when the auxiliary water heater 2B is performing a hot water filling operation (more specifically, a hot water filling operation excluding the reheating process), the water supply volume adjustment valve 16 of the auxiliary water heater 2B is controlled to be open, so when water starts to flow to the hot water tap CL (when the hot water tap CL is opened), a portion of the hot water heated in the first heating section 11 of the auxiliary water heater 2B is mixed with the hot water heated in the first heating section 11 of the main water heater 2A in the downstream hot water supply path 5 and supplied to the hot water tap CL.

[0065] In this case, when the auxiliary water heater 2B performs the hot water filling operation and the main water heater 2A performs the hot water supply operation as described above, the hot water supply water that flows from the auxiliary water heater 2B to the downstream hot water supply path 5 is temperature-controlled to a temperature that matches or nearly matches the set temperature for filling the bathtub BTB. Also, the hot water supply water that flows from the main water heater 2A to the downstream hot water supply path 5 is temperature-controlled to a temperature that matches or nearly matches the set temperature for hot water supply. Therefore, the temperature of the hot water supply water that flows from the hot water tap CL is a temperature that is different from both the set temperature for filling the bathtub BTB and the set temperature for hot water supply (a temperature that is intermediate between both set temperatures).

[0066] Therefore, particularly when there is a relatively large temperature difference between the bathtub BTB's set temperature for filling and the hot water supply set temperature, the temperature of the hot water coming out of the hot water tap CL will be different from both the bath filling set temperature and the hot water supply set temperature set by the user, which may cause the user to feel uncomfortable or mistakenly believe that there is a malfunction in the hot water supply system 1.

[0067] Therefore, in this embodiment, the processing described below is performed while the auxiliary water heater 2B is performing a water filling operation. In the following explanation, the water filling set temperature for filling the bathtub BTA may be referred to as the main side water filling set temperature, and the water filling set temperature for filling the bathtub BTB may be referred to as the auxiliary side water filling set temperature. In the following explanation, unless otherwise specified, "water filling operation" refers to operation during the process of filling the bathtub BTA or BTB with water, and does not include operation during the reheating process that may be performed thereafter.

[0068] First, the operation when only the auxiliary water heater 2B of the main water heater 2A and the auxiliary water heater 2B is performing the water filling operation and the water filling operation of the main water heater 2A is continuously stopped will be explained with reference to Figures 2 and 3. In this case, the main water heater 2A executes the processing shown in the flowchart of Figure 2 by the control device 31A.

[0069] In STEP 1, the control device 31A executes the process of determining whether or not the supply of water to the hot water tap CL has started until the determination result becomes affirmative. In this case, the control device 31A determines whether or not the supply of water to the hot water tap CL has started based on whether or not the water flow rate detected by the flow rate sensor 17 of the main hot water heater 2A has reached or exceeded a predetermined flow rate.

[0070] If the determination result in STEP 1 is positive (if water supply to the hot water tap CL is started while the auxiliary hot water heater 2B is performing a hot water filling operation), the control device 31A starts the operation of the first heating unit 11 of the main hot water heater 2A in STEP 2, thereby starting the hot water supply operation of the main hot water heater 2A that supplies hot water to the hot water tap CL. In this hot water supply operation, the lower of the auxiliary hot water filling set temperature and the hot water supply set temperature (= min (auxiliary hot water filling set temperature, hot water supply set temperature)) is set as the main side target hot water temperature, which is the target hot water supply temperature for the main hot water heater 2A, and the heating amount of the first heating unit 11 of the main hot water heater 2A is controlled to achieve this main side target hot water supply temperature (so that the hot water supply temperature detected by the temperature sensor 18 of the main hot water heater 2A matches or nearly matches the main side target hot water supply temperature).

[0071] Next, in STEP 3, the control device 31A executes the process of determining whether the supply of water to the hot water tap CL has stopped until the determination result becomes affirmative. In this case, the control device 31A determines whether the supply of water to the hot water tap CL has stopped based on whether the water flow rate detected by the flow rate sensor 17 of the main hot water heater 2A has become equal to or less than a predetermined flow rate.

[0072] If the judgment result of STEP 3 is positive (water flow to the hot water tap CL is stopped), the control device 31A stops the operation of the first heating section 11 of the main hot water heater 2A in STEP 4, thereby stopping the hot water supply operation of the main hot water heater 2A.

[0073] In parallel with the processing in the main water heater 2A as described above, the auxiliary water heater 2B executes the processing shown in the flowchart of Figure 3 by the control device 31B. In STEP 11, the control device 31B determines whether water supply to the hot water tap CL has started. In this case, the control device 31B determines whether water supply to the hot water tap CL has started based on whether the value obtained by subtracting the hot water supply flow rate detected by flow sensor 24 from the water supply flow rate detected by flow sensor 17 of the auxiliary water heater 2B is equal to or greater than a predetermined flow rate. Alternatively, the control device 31B obtains information indicating whether water supply to the hot water tap CL has started from the control device 31A of the main water heater 2A.

[0074] If the determination result in STEP 11 is negative, control device 31B determines whether or not the water filling operation in auxiliary hot water heater 2B has finished in STEP 17. If the determination result in STEP 17 is negative, control device 31B repeats the process from STEP 11, and if the determination result is positive, in STEP 15, control device 31B stops the operation of first heating section 11 of auxiliary hot water heater 2B and controls water supply amount adjustment valve 16 to close.

[0075] On the other hand, if the judgment result in STEP 11 is positive (if water starts flowing to the hot water tap CL while the auxiliary water heater 2B is performing a hot water filling operation), in STEP 12, the control device 31B sets the auxiliary side target hot water temperature, which is the target hot water temperature in the auxiliary water heater 2B, to the lower of the auxiliary side hot water filling set temperature and the hot water set temperature (= min (auxiliary side hot water filling set temperature, hot water set temperature)), i.e., the same temperature as the main side target hot water temperature set in STEP 2, and controls the heating amount of the first heating section 11 of the auxiliary water heater 2B to achieve this auxiliary side target hot water temperature (so that the hot water temperature detected by the temperature sensor 18 of the auxiliary water heater 2B matches or nearly matches the auxiliary side target hot water temperature).

[0076] Next, in STEP 13, control device 31B determines whether the supply of water to hot water tap CL has stopped. In this case, control device 31B determines whether the supply of water to hot water tap CL has stopped based on whether the value obtained by subtracting the hot water filling flow rate detected by flow sensor 24 from the water supply flow rate detected by flow sensor 17 of auxiliary hot water heater 2B is equal to or less than a predetermined flow rate. Alternatively, control device 31B obtains information indicating whether the supply of water to hot water tap CL has stopped from control device 31A of main hot water heater 2A.

[0077] If the judgment result of STEP 13 is negative (water is continuing to flow to the hot water tap CL), the control device 31B judges in STEP 18 whether the hot water filling operation of the auxiliary hot water heater 2B has ended, and if the judgment result is negative, the processing from STEP 13 is repeated.

[0078] Furthermore, if the determination result in STEP 18 is affirmative, in STEP 15, control device 31B stops the operation of first heating unit 11 of auxiliary hot water heater 2B and controls water supply amount adjustment valve 16 to close. Note that if the determination result in STEP 18 is affirmative and there is a request for auxiliary hot water supply operation from control device 31A of main hot water heater 2A, water supply amount adjustment valve 16 may be kept open and first heating unit 11 may be operated. In this case, the auxiliary-side target hot water supply temperature for controlling the heating amount of first heating unit 11 is maintained at the current set value (the temperature set in STEP 12).

[0079] If the judgment result in STEP 13 is positive (if water supply to the hot water tap CL has stopped), the control device 31B judges in STEP 14 whether the water filling operation in the auxiliary hot water heater 2B has ended, and if the judgment result is positive, in STEP 15, the operation of the first heating section 11 of the auxiliary hot water heater 2B is stopped and the water supply volume adjustment valve 16 is controlled to close.

[0080] If the determination result in STEP 14 is negative (water supply to the hot water tap CL is stopped and the hot water filling operation in auxiliary hot water heater 2B continues), in STEP 16, control device 31B sets the auxiliary side hot water filling set temperature as the auxiliary side target hot water supply temperature and controls the amount of heat from first heating section 11 of auxiliary hot water heater 2B to achieve this auxiliary side target hot water supply temperature. Control device 31B then repeats the process from STEP 11.

[0081] In this embodiment, by controlling the operation of the main water heater 2A and the auxiliary water heater 2B as described above, if water supply to the hot water tap CL is started while only the auxiliary water heater 2B is performing hot water filling operation, hot water is supplied to the hot water tap CL at the temperature set by the user (either the auxiliary-side hot water filling set temperature or the hot water supply set temperature), preventing the user from feeling uncomfortable. Furthermore, while hot water supply to the hot water tap CL continues, both the main-side target hot water temperature and the auxiliary-side target hot water temperature are kept constant at the same temperature, preventing fluctuations in the temperature of the hot water supplied to the hot water tap CL.

[0082] In addition, the bathtub BTB is filled with water at the auxiliary side water filling set temperature or a lower hot water supply set temperature, so when the bathtub is filled with water, the temperature of the bathtub water can be prevented from becoming higher than the auxiliary side water filling set temperature.

[0083] In this case, if the auxiliary side bath filling set temperature is greater than the hot water supply set temperature, the bathtub BTB will be filled with water at a temperature lower than the auxiliary side bath filling set temperature, but after the bath filling is completed, the water will be reheated, allowing the temperature of the bathwater in the bathtub BTB to be raised to the auxiliary side bath filling set temperature.

[0084] Furthermore, if the water supply to the hot water tap CL is stopped before the auxiliary water heater 2B finishes filling the bathtub BTB with water at the auxiliary water filling set temperature while the water supply is stopped, the bathtub water temperature at the end of filling can be as close as possible to the auxiliary water filling set temperature. Therefore, even if reheating is performed after the bath is finished, the energy consumption for reheating can be reduced.

[0085] When comparing hot water supply to the bathtub BTB (or BTA) with reheating of bath water, hot water supply is generally more energy efficient than reheating. Therefore, by suppressing the energy consumption in reheating as described above, the energy efficiency of the hot water supply system 1 can be improved.

[0086] In addition, when the hot water supply setting temperature to the hot water tap CL is equal to or less than the auxiliary side hot water filling setting temperature, the hot water supply setting temperature set by the user is used, thereby improving convenience.

[0087] Next, operation when both the main water heater 2A and the auxiliary water heater 2B are performing the water filling operation will be described with reference to Figures 4 and 5. In this case, in the main water heater 2A, the control device 31A executes the process shown in the flowchart of Figure 4.

[0088] In STEP 21, control device 31A determines whether water supply to hot water tap CL has started. In this case, control device 31A determines whether water supply to hot water tap CL has started based on whether the value obtained by subtracting the water supply flow rate detected by flow sensor 24 from the water supply flow rate detected by flow sensor 17 of main hot water heater 2A is equal to or greater than a predetermined flow rate.

[0089] If the determination result in STEP 21 is negative, control device 31A determines in STEP 26 whether the water filling operation in main water heater 2A has ended. If the determination result in STEP 26 is negative, control device 31A repeats the process from STEP 21, and if the determination result is positive, control device 31A stops the operation of first heating section 11 of main water heater 2A in STEP 25. Note that if the determination results in both STEPs 21 and 26 are negative and the water filling operation in auxiliary water heater 2B has ended, control device 31A executes the process from STEP 29 described below.

[0090] If the determination result in STEP 21 is positive (if water supply to the hot water tap CL is started while both the main water heater 2A and the auxiliary water heater 2B are performing hot water filling operations), the control device 31A starts the operation of the first heating unit of the main water heater 2A in STEP 22, thereby starting the hot water supply operation of the main water heater 2A that supplies hot water to the hot water tap CL. In this hot water supply operation, the main side target hot water supply temperature is set to the lowest temperature among the main side hot water filling set temperature, the auxiliary side hot water filling set temperature, and the hot water supply set temperature (= min(main side hot water filling set temperature, auxiliary side hot water filling set temperature, hot water supply set temperature)), and the heating amount of the first heating unit 11 of the main water heater 2A is controlled to achieve this main side target hot water supply temperature.

[0091] Next, in STEP 23, controller 31A executes the process of determining whether the supply of water to hot water tap CL has stopped until the determination result becomes affirmative. In this case, controller 31A determines whether the supply of water to hot water tap CL has stopped based on whether the value obtained by subtracting the water supply flow rate detected by flow sensor 24 from the water supply flow rate detected by flow sensor 17 of main hot water heater 2A is equal to or less than a predetermined flow rate.

[0092] If the determination result in STEP 23 is affirmative (water supply to the hot water tap CL is stopped), the control device 31A determines whether the water filling operation in the main water heater 2A has ended in STEP 24. If the determination result in STEP 24 is affirmative (including when the water filling operation has ended while water supply to the hot water tap CL is continuing), the control device 31A stops operation of the first heating unit 11 of the main water heater 2A.

[0093] Furthermore, if the determination result in STEP 24 is negative (water supply to the hot water tap CL is stopped and the main hot water heater 2A is continuing to fill the water), in STEP 27, the control device 31A sets the main hot water filling set temperature as the main target hot water supply temperature and controls the heating amount of the first heating section 11 of the main hot water heater 2A to achieve this main target hot water supply temperature. Note that the processing of STEP 27 does not have to be performed immediately after the determination result in STEP 24 becomes negative. For example, if the bathtub BTA is filled with water intermittently with interruption periods in between, the processing of STEP 27 may be performed from the start of filling the water following the interruption period.

[0094] Next, in STEP 28, the control device 31A determines whether the water filling operation in the auxiliary water heater 2B has ended. If the determination result in STEP 28 is negative, the water filling operation is continuing in both the main water heater 2A and the auxiliary water heater 2B, so the control device 31A repeats the process from STEP 21.

[0095] If the determination result in STEP 28 is affirmative, then in STEP 29, control device 31A determines whether water supply to hot water tap CL has started, in the same manner as in STEP 21, and if the determination result is negative, then control device 31A determines whether the hot water filling operation in main hot water heater 2A has ended, in STEP 30. If the determination result in STEP 30 is negative, control device 31A repeats the process from STEP 29, and if the determination result is positive, then control device 31A stops the operation of first heating unit 11 of main hot water heater 2A, in STEP 25.

[0096] Furthermore, if the judgment result in STEP 29 becomes positive (when water supply to the hot water tap CL is started again while the hot water filling operation is being performed only by the main hot water heater 2A), in STEP 31, the control device 31A sets the lower of the main hot water filling set temperature and the hot water supply set temperature (= min (main hot water filling set temperature, hot water supply set temperature)) as the main target hot water supply temperature, and controls the heating amount of the first heating section 11 of the main hot water heater 2A so as to achieve this main target hot water supply temperature. Then, the control device 31A executes the processing from STEP 23 described above.

[0097] In parallel with the processing being carried out in the main water heater 2A as described above, the processing shown in the flowchart of Figure 5 is carried out in the auxiliary water heater 2B by the control device 31B. In STEP 41, the control device 31B determines whether water supply to the hot water tap CL has started. This determination process is carried out in the same manner as in STEP 11. If the determination result in STEP 41 is negative, the control device 31B determines in STEP 46 whether the water filling operation in the auxiliary water heater 2B has ended.

[0098] If the determination result in STEP 46 is negative, control device 31B repeats the process from STEP 41, and if the determination result is positive, in STEP 45, control device 31B stops the operation of first heating section 11 of auxiliary hot water heater 2B and closes water supply amount adjustment valve 16. Note that if the determination results in both STEPs 41 and 46 are negative and the hot water filling operation in main hot water heater 2A has ended, control device 31B executes the process from STEP 50 described below.

[0099] If the judgment result of STEP 41 is positive (if water starts flowing to the hot water tap CL while both the main water heater 2A and the auxiliary water heater 2B are performing hot water filling operations), the control device 31B sets the auxiliary side target hot water temperature in STEP 42 to the lowest temperature among the main side hot water filling set temperature, the auxiliary side hot water filling set temperature, and the hot water supply set temperature (= min(main side hot water filling set temperature, auxiliary side hot water filling set temperature, hot water supply set temperature)), i.e., the same temperature as the main side target hot water temperature set in STEP 22, and controls the heating amount of the first heating section 11 of the auxiliary water heater 2B to achieve this auxiliary side target hot water temperature.

[0100] Next, in STEP 43, control device 31B determines whether the supply of water to hot water tap CL has stopped, in the same manner as in STEP 13. If the result of the determination in STEP 43 is negative (if water continues to flow to hot water tap CL), control device 31B determines in STEP 47 whether the water filling operation in auxiliary hot water heater 2B has ended, and if the result of this determination is negative, repeats the processing from STEP 43.

[0101] Furthermore, if the determination result in STEP 47 is affirmative, in STEP 45, control device 31B stops the operation of first heating unit 11 of auxiliary hot water heater 2B and controls water supply amount adjustment valve 16 to close. Note that if the determination result in STEP 47 is affirmative and there is a request for auxiliary hot water supply operation from control device 31A of main hot water heater 2A, water supply amount adjustment valve 16 may be kept open and first heating unit 11 may be operated. In this case, the auxiliary-side target hot water supply temperature for controlling the heating amount of first heating unit 11 is maintained at the current set value (the temperature set in STEP 42).

[0102] If the judgment result in STEP 43 is positive (if water supply to the hot water tap CL has stopped), the control device 31B judges in STEP 44 whether the water filling operation in the auxiliary hot water heater 2B has ended, and if the judgment result is positive, in STEP 45, the operation of the first heating section 11 of the auxiliary hot water heater 2B is stopped and the water supply volume adjustment valve 16 is controlled to close.

[0103] Furthermore, if the determination result in STEP 44 is negative (water supply to the hot water tap CL is stopped and the auxiliary hot water heater 2B continues to fill the bath), in STEP 48, the control device 31B sets the auxiliary side hot water filling set temperature as the auxiliary side target hot water supply temperature and controls the amount of heat from the first heating section 11 of the auxiliary hot water heater 2B to achieve this auxiliary side target hot water supply temperature. Note that the processing of STEP 48 does not have to be performed immediately after the determination result in STEP 44 becomes negative. For example, if the bathtub BTB is filled with water intermittently with interruption periods in between, the processing of STEP 48 may be performed from the start of filling the bath following the interruption period.

[0104] Next, in STEP 49, the control device 31B determines whether the water filling operation in the main water heater 2A has ended. If the determination result in STEP 49 is negative, the water filling operation is continuing in both the main water heater 2A and the auxiliary water heater 2B, so the control device 31B repeats the process from STEP 41.

[0105] If the determination result in STEP 49 is affirmative, then in STEP 50, control device 31B determines whether water supply to hot water tap CL has started, in the same manner as in STEP 41, and if the determination result is negative, then control device 31B determines whether the water filling operation in auxiliary hot water heater 2B has ended, in STEP 52. If the determination result in STEP 52 is negative, control device 31B repeats the process from STEP 50, and if the determination result is positive, then in STEP 45, control device 31B stops operation of first heating section 11 of auxiliary hot water heater 2B and closes water supply amount adjustment valve 16.

[0106] Furthermore, if the judgment result in STEP 50 becomes positive (if water supply to the hot water tap CL is started again while the auxiliary water heater 2B is performing a hot water filling operation), in STEP 51 the control device 31B sets the auxiliary side target hot water supply temperature to the lower of the auxiliary side hot water filling set temperature and the hot water supply set temperature (= min (auxiliary side hot water filling set temperature, hot water supply set temperature)), and controls the amount of heat from the first heating section 11 of the auxiliary water heater 2B so as to achieve this auxiliary side target hot water supply temperature. Then, the control device 31B executes the processing from STEP 43 described above.

[0107] In this embodiment, by controlling the operation of the main water heater 2A and the auxiliary water heater 2B as described above, when water supply to the hot water tap CL is started while both the main water heater 2A and the auxiliary water heater 2B are performing hot water filling operations, hot water is supplied to the hot water tap CL at the temperature set by the user (either the main-side hot water filling set temperature, the auxiliary-side hot water filling set temperature, or the hot water supply set temperature), preventing the user from feeling uncomfortable. Furthermore, while hot water supply to the hot water tap CL continues, both the main-side target hot water temperature and the auxiliary-side target hot water temperature are kept constant at the same temperature, preventing fluctuations in the temperature of the hot water supplied to the hot water tap CL.

[0108] Furthermore, since bathtub BTA is filled at the main-side bath filling temperature setting or a lower auxiliary-side bath filling temperature or hot water supply temperature setting, the bathtub water temperature will not be higher than the main-side bath filling temperature when bathtub BTA is filled. Similarly, bathtub BTB is filled at the auxiliary-side bath filling temperature or a lower main-side bath filling temperature or hot water supply temperature setting, the bathtub water temperature will not be higher than the auxiliary-side bath filling temperature when bathtub BTB is filled.

[0109] In this case, when filling bathtub BTA, if the main-side bath filling temperature setting is higher than the auxiliary-side bath filling temperature setting or the hot water supply temperature setting, the bathtub BTA will be filled at a temperature lower than the main-side bath filling temperature setting, but after filling is complete, the water will be reheated to raise the temperature of the bathtub water in bathtub BTA to the main-side bath filling temperature setting. Similarly, when filling bathtub BTB, if the auxiliary-side bath filling temperature setting is higher than the main-side bath filling temperature setting or the hot water supply temperature setting, the bathtub BTB will be filled at a temperature lower than the auxiliary-side bath filling temperature setting, but after filling is complete, the water will be reheated to raise the temperature of the bathtub water in bathtub BTB to the auxiliary-side bath filling temperature setting.

[0110] Furthermore, if the water supply to the hot water tap CL is stopped before the main water heater 2A finishes filling the bathtub, and the auxiliary water heater 2B finishes filling the bathtub BTA with water at the main filling temperature while the water supply is stopped, the bathtub water temperature at the end of filling can be as close as possible to the main filling temperature. Therefore, even if reheating is performed after the bathtub BTA has finished filling, the energy consumption for this reheating can be reduced.

[0111] Similarly, if the water supply to the hot water tap CL is stopped before the auxiliary water heater 2B finishes filling the bathtub, and the main water heater 2A finishes filling the bathtub, the water supply to the hot water tap CL will be stopped and the bathtub will be filled with water at the auxiliary filling temperature setting. This allows the bathtub water temperature at the end of filling to be as close as possible to the auxiliary filling temperature setting. Therefore, even if reheating is performed after the bathtub BTB has been filled, the energy consumption for this reheating can be reduced.

[0112] Therefore, energy consumption in reheating, which is generally less energy efficient than hot water supply, can be reduced, and the energy efficiency of the hot water supply system 1 can be improved.

[0113] In addition, when the hot water supply setting temperature to the hot water tap CL is equal to or less than the main side hot water filling setting temperature and the hot water supply setting temperature is equal to or less than the auxiliary side hot water filling setting temperature, the hot water supply setting temperature will be the hot water supply setting temperature set by the user, thereby increasing convenience. [Second embodiment]

[0114] Next, a second embodiment of the present invention will be described below with reference to Figures 6 and 7. Note that this embodiment differs from the first embodiment only in the control processing when both the main water heater 2A and the auxiliary water heater 2B are performing hot water filling operations, and therefore, a description of the same matters as in the first embodiment will be omitted.

[0115] When both the main water heater 2A and the auxiliary water heater 2B are performing the hot water filling operation, the control device 31A executes the process shown in the flowchart of Figure 6 in the main water heater 2A. In STEP 61, the control device 31A determines whether water supply to the hot water tap CL has started. This determination process is performed in the same manner as STEP 21 described above. If the determination result in STEP 61 is negative, the control device 31A determines in STEP 72 whether the hot water filling operation in the main water heater 2A has ended. If the determination result in STEP 72 is negative, the control device 31A repeats the process from STEP 61; if the determination result is positive, the control device 31A stops the operation of the first heating section 11 of the main water heater 2A in STEP 76. Note that if the determination results in both STEPs 61 and 72 are negative and the hot water filling operation in the auxiliary water heater 2B has ended, the control device 31A executes the process from STEP 70 described below.

[0116] If the judgment result in STEP 61 is positive (if water supply to the hot water tap CL is started while both the main water heater 2A and the auxiliary water heater 2B are performing hot water filling operations), the control device 31A judges in STEP 62 whether the main side hot water filling set temperature is higher than the auxiliary side hot water filling set temperature. If the judgment result in STEP 62 is negative (if the main side hot water filling set temperature is less than or equal to the auxiliary side hot water filling set temperature), the control device 31A starts hot water supply operation of the main water heater 2A, which supplies hot water to the hot water tap CL, in STEP 73. In this hot water supply operation, the main side hot water filling set temperature is set as the main side target hot water supply temperature, and the heating amount of the first heating section 11 of the main water heater 2A is controlled to achieve this main side target hot water supply temperature.

[0117] Next, in STEP 74, the control device 31A executes the process of determining whether or not the supply of water to the hot water tap CL has stopped until the determination result becomes affirmative. This determination process is performed in the same manner as in STEP 23.

[0118] If the determination result in STEP 74 becomes positive (water supply to the hot water tap CL is stopped), the control device 31A determines whether the hot water filling operation in the main hot water heater 2A has ended in STEP 75. If the determination result in STEP 75 is positive, the control device 31A stops the operation of the first heating unit 11 of the main hot water heater 2A in STEP 76.

[0119] Furthermore, if the determination result in STEP 75 is negative (water supply to the hot water tap CL has stopped and the hot water filling operation in the main hot water heater 2A is continuing), the control device 31A maintains the main target hot water temperature at the current set value (= main hot water filling set temperature) and determines in STEP 69 whether the hot water filling operation in the auxiliary hot water heater 2B has ended. If the determination result in STEP 69 is negative, the hot water filling operation is being performed in both the main hot water heater 2A and the auxiliary hot water heater 2B, so the control device 31A repeats the processing from STEP 61.

[0120] If the determination result in STEP 69 is affirmative, then in STEP 70, control device 31A determines whether water supply to hot water tap CL has started, in the same manner as in STEP 61, and if the determination result is negative, then control device 31A determines whether the hot water filling operation in main hot water heater 2A has ended, in STEP 71. If the determination result in STEP 71 is negative, control device 31A repeats the process from STEP 70, and if the determination result is positive, then control device 31A stops the operation of first heating unit 11 of main hot water heater 2A, in STEP 76.

[0121] Furthermore, if the determination result in STEP 70 is positive (if water supply to the hot water tap CL is started while the hot water filling operation is being performed only by the main hot water heater 2A), the control device 31A repeats the process from STEP 73. In this case, the hot water supply operation is started while the main target hot water supply temperature is maintained at the current set value (= main hot water filling set temperature).

[0122] On the other hand, if the judgment result in STEP 62 is positive (the main side bath filling set temperature is greater than the auxiliary side bath filling set temperature), the control device 31A interrupts the bath filling operation in the main water heater 2A in STEP 63. In this case, the control device 31A interrupts the bath filling operation by controlling the bath filling solenoid valve 23 to close while continuing the operation of the first heating section 11 of the main water heater 2A (burner combustion operation).

[0123] Next, in STEP 64, the control device 31A starts the hot water supply operation of the main water heater 2A that supplies hot water to the hot water tap CL. In this hot water supply operation, the auxiliary side hot water filling set temperature is set as the main side target hot water supply temperature, and the heating amount of the first heating unit 11 of the main water heater 2A is controlled to achieve this main side target hot water supply temperature.

[0124] Next, in STEP 65, the control device 31A executes the process of determining whether or not the supply of water to the hot water tap CL has stopped until the determination result becomes affirmative. This determination process is performed in the same manner as in STEP 23.

[0125] If the determination result in STEP 65 becomes positive (if the flow of water to the hot water tap CL is stopped), the control device 31A stops the operation of the first heating section 11 of the main hot water heater 2A in STEP 66, and then resumes the hot water filling operation in the main hot water heater 2A in STEP 67. In this case, in STEP 67, the control device 31A controls the hot water filling solenoid valve 23 of the main hot water heater 2A to be open and resumes the operation of the first heating section 11, thereby restarting the hot water filling operation. Note that the processing of STEP 66 may be omitted, and the hot water filling operation may be resumed by controlling the hot water filling solenoid valve 23 to be open while the operation of the first heating section 11 continues.

[0126] Furthermore, in STEP 68, control device 31A sets the main-side water filling set temperature as the main-side target hot water supply temperature, and controls the amount of heat from first heating section 11 of main hot water heater 2A to achieve this main-side target hot water supply temperature. Then, control device 31A executes the process from STEP 69 described above.

[0127] In parallel with the processing being carried out in the main water heater 2A as described above, the processing shown in the flowchart of Figure 7 is carried out in the auxiliary water heater 2B by the control device 31B. In STEP 81, the control device 31B determines whether water supply to the hot water tap CL has started. This determination processing is carried out in the same manner as in STEP 11 described above. If the determination result in STEP 81 is negative, the control device 31B determines in STEP 92 whether the water filling operation in the auxiliary water heater 2B has ended.

[0128] If the determination result in STEP 92 is negative, control device 31B repeats the process from STEP 81, and if the determination result is positive, in STEP 96, control device 31B stops the operation of first heating section 11 of auxiliary hot water heater 2B and closes water supply amount adjustment valve 16. Note that if the determination results in both STEPs 81 and 92 are negative and the hot water filling operation in main hot water heater 2A has ended, control device 31B executes the process from STEP 90 described below.

[0129] If the judgment result in STEP 81 is positive (if water supply to the hot water tap CL is started while both the main water heater 2A and the auxiliary water heater 2B are performing hot water filling operations), the control device 31B judges in STEP 82 whether the main side hot water filling set temperature is lower than the auxiliary side hot water filling set temperature. If the judgment result in STEP 82 is negative (if the main side hot water filling set temperature is equal to or greater than the auxiliary side hot water filling set temperature), the control device 31B sets the auxiliary side hot water filling set temperature as the auxiliary side target hot water supply temperature in STEP 93, and controls the heating amount of the first heating section 11 of the auxiliary water heater 2B to achieve this auxiliary side target hot water supply temperature.

[0130] Next, in STEP 94, control device 31B determines whether the supply of water to hot water tap CL has stopped, in the same manner as in STEP 13. If the result of the determination in STEP 94 is negative (if water continues to flow to hot water tap CL), control device 31B determines in STEP 97 whether the water filling operation in auxiliary hot water heater 2B has ended, and if the result of this determination is negative, repeats the processing from STEP 94.

[0131] Furthermore, if the determination result in STEP 97 is affirmative, in STEP 96, control device 31B stops the operation of first heating unit 11 of auxiliary hot water heater 2B and controls water supply amount adjustment valve 16 to close. Note that if the determination result in STEP 97 is affirmative and there is a request for auxiliary hot water supply operation from control device 31A of main hot water heater 2A, water supply amount adjustment valve 16 may be kept open and first heating unit 11 may be operated. In this case, the auxiliary-side target hot water supply temperature for controlling the heating amount of first heating unit 11 is maintained at the current set value (the temperature set in STEP 93).

[0132] If the judgment result in STEP 94 is positive (if water supply to the hot water tap CL has stopped), the control device 31B judges in STEP 95 whether the water filling operation in the auxiliary hot water heater 2B has ended, and if the judgment result is positive, in STEP 96, the operation of the first heating section 11 of the auxiliary hot water heater 2B is stopped and the water supply volume adjustment valve 16 is controlled to close.

[0133] Furthermore, if the determination result in STEP 95 is negative (water supply to the hot water tap CL has stopped and the hot water filling operation in the auxiliary hot water heater 2B is continuing), the control device 31B maintains the auxiliary side target hot water temperature at the current set value (= auxiliary side hot water filling set temperature) and determines in STEP 89 whether the hot water filling operation in the main hot water heater 2A has ended. If the determination result in STEP 89 is negative, the hot water filling operation is continuing in both the main hot water heater 2A and the auxiliary hot water heater 2B, so the control device 31B repeats the processing from STEP 81.

[0134] If the determination result in STEP 89 is affirmative, then in STEP 90, control device 31B determines whether water supply to hot water tap CL has started, in the same manner as in STEP 81, and if the determination result is negative, then control device 31B determines whether the water filling operation in auxiliary hot water heater 2B has ended, in STEP 91. If the determination result in STEP 91 is negative, control device 31B repeats the process from STEP 90, and if the determination result is positive, then in STEP 96, control device 31B stops operation of first heating section 11 of auxiliary hot water heater 2B and closes water supply adjustment valve 16.

[0135] Also, if the judgment result of STEP 90 becomes positive (if water supply to the hot water tap CL is started again while the hot water filling operation is being performed only by the auxiliary hot water heater 2B), the control device 31B repeats the processing from STEP 94 described above while maintaining the auxiliary side target hot water temperature at the current set value (= auxiliary side hot water filling set temperature).

[0136] On the other hand, if the judgment result in STEP 82 is positive (the main side bath filling set temperature is less than the auxiliary side bath filling set temperature), the control device 31B interrupts the bath filling operation in the auxiliary water heater 2B in STEP 83. In this case, the control device 31B interrupts the bath filling operation by controlling the bath filling solenoid valve 23 to close while continuing to operate the first heating section 11 of the auxiliary water heater 2B.

[0137] Furthermore, in STEP 84, control device 31B controls water supply amount adjustment valve 16 of auxiliary water heater 2B to close. Note that in STEP 84, if there is a request for auxiliary hot water supply operation from control device 31A of main water heater 2A, water supply amount adjustment valve 16 may be kept open and first heating unit 11 may be operated. In this case, the same temperature as the main target hot water supply temperature set in STEP 73 is set as the auxiliary-side target hot water supply temperature, and the heating amount of first heating unit 11 is controlled to achieve that auxiliary-side target hot water supply temperature.

[0138] Next, in STEP 85, the control device 31B executes the process of determining whether or not the supply of water to the hot water tap CL has stopped until the determination result becomes affirmative. This determination process is performed in the same manner as in STEP 94.

[0139] If the determination result in STEP 85 becomes positive (water supply to the hot water tap CL is stopped), the control device 31B controls the water supply amount adjustment valve 16 of the auxiliary hot water heater 2B to open in STEP 86, and then resumes the hot water filling operation in the auxiliary hot water heater 2B in STEP 87. In this case, in STEP 87, the control device 31B controls the hot water filling solenoid valve 23 of the auxiliary hot water heater 2B to open and resumes the operation of the first heating section 11, thereby restarting the hot water filling operation.

[0140] Furthermore, in STEP 88, control device 31B sets the auxiliary-side water filling set temperature as the auxiliary-side target hot water supply temperature, and controls the amount of heat from first heating section 11 of auxiliary water heater 2B so as to achieve this auxiliary-side target hot water supply temperature. Then, control device 31B executes the process from STEP 89 described above.

[0141] In this embodiment, by controlling the operation of the main water heater 2A and the auxiliary water heater 2B as described above, when water supply to the hot water tap CL is started while both the main water heater 2A and the auxiliary water heater 2B are performing hot water filling operations, hot water is supplied to the hot water tap CL at the temperature set by the user (either the main-side hot water filling set temperature, the auxiliary-side hot water filling set temperature, or the hot water supply set temperature), preventing the user from feeling uncomfortable. Furthermore, while hot water supply to the hot water tap CL continues, both the main-side target hot water temperature and the auxiliary-side target hot water temperature are kept constant at the same temperature, preventing fluctuations in the temperature of the hot water supplied to the hot water tap CL.

[0142] Furthermore, because filling the bathtub BTA with water is performed at the main bath filling set temperature whether it is interrupted and then resumed in response to the start of water flow to the hot water tap CL or continues without interruption, it is possible to prevent the bathtub water temperature from rising above the main bath filling set temperature when filling the bathtub BTA is complete.In addition, because it is possible to prevent the bathtub BTA from being filled with water at a temperature lower than the main target hot water supply temperature, even if reheating is performed after filling the bathtub BTA, energy consumption for the reheating can be reduced.

[0143] Similarly, filling the bathtub BTB with water is performed at the auxiliary-side water filling set temperature whether it is interrupted and then resumed in response to the start of water flow to the hot water tap CL or whether it continues without interruption, so when filling the bathtub BTB with water is complete, the bathtub water temperature can be prevented from rising above the auxiliary-side water filling set temperature.In addition, because it is possible to prevent the bathtub BTB from being filled with water at a temperature lower than the auxiliary-side target hot water supply temperature, even if reheating is performed after filling the bathtub BTB, energy consumption for the reheating can be reduced.

[0144] Therefore, energy consumption in reheating, which is generally less energy efficient than hot water supply, can be reduced, and the energy efficiency of the hot water supply system 1 can be improved.

[0145] [Other embodiments] The present invention is not limited to the above-described embodiment, and other embodiments may be adopted. Some other embodiments are exemplified below.

[0146] In the first embodiment, the bathtub BTA and BTB were connected to the main water heater 2A and the auxiliary water heater 2B, respectively, but the hot water supply system of the present invention does not require, for example, the bathtub BTA to be connected to the main water heater 2A. In this case, the second heating section 13 and circulation water passage 14 of the main water heater 2A are not required. Even in this case, by executing the processing shown in Figures 2 and 3, it is possible to achieve the same effect as when only the auxiliary water heater 2B performs the water filling operation in the first embodiment.

[0147] Furthermore, in the first embodiment, the auxiliary side bath filling set temperature may be set as the main side target hot water supply temperature and the auxiliary side target hot water supply temperature, respectively, in STEP 2 and STEP 12. In this case, if the auxiliary side bath filling set temperature is greater than the hot water supply set temperature, the hot water supply temperature to the hot water tap CL will be higher than the hot water supply set temperature, but because the upper limit of the bath filling set temperature (auxiliary side bath filling set temperature and main side bath filling set temperature) is generally not very high, the hot water supply temperature to the hot water tap CL will not be excessively high.

[0148] For the same reasons as above, in STEP 22 and STEP 42 in the first embodiment, the lower of the main-side bath filling set temperature and the auxiliary-side bath filling temperature may be set as the main-side target hot water supply temperature and the auxiliary-side target hot water supply temperature, respectively. Also, in STEP 31, the main-side bath filling set temperature may be set as the main-side target hot water supply temperature, and in STEP 41, the auxiliary-side bath filling set temperature may be set as the auxiliary-side target hot water supply temperature.

[0149] Furthermore, in the first embodiment, if the main water heater 2A is performing a bath filling operation after the supply of water to the hot water tap CL is stopped (if the judgment result in STEP 24 is negative), the main bath filling set temperature is set as the main target hot water supply temperature in STEP 27. However, if the judgment result in STEP 24 is negative, the processing of STEP 27 may be omitted, and the main target hot water supply temperature may be maintained at the current set value (the temperature set in STEP 22). In this case, although the current set value of the main target hot water supply temperature may be lower than the main bath filling set temperature, the temperature of the bathtub water can be raised to the main bath filling set temperature by reheating water after the bathtub BTA has been filled.

[0150] For the same reason as above, if the determination result of STEP 44 in the first embodiment is negative, the processing of STEP 48 may be omitted, and the auxiliary-side target hot water temperature may be maintained at the current set value. As mentioned above, from the viewpoint of the energy efficiency of the hot water supply system 1, it is preferable to execute the processing of STEPs 27 and 48 when the hot water filling operation (hot water filling operation in the main hot water heater 2A or auxiliary hot water heater 2B) continues after the supply of water to the hot water tap CL is stopped, as in the first embodiment.

[0151] In the first and second embodiments described above, the first hot water supply target portion, the second hot water supply target portion, and the third hot water supply target portion of the present invention are respectively the hot water tap CL, the bathtub BTB, and the bathtub BTA, but the first hot water supply target portion, the second hot water supply target portion, and the third hot water supply target portion of the present invention may be different from those described above. For example, the second hot water supply target portion or the third hot water supply target portion may be a hot water tap other than the hot water tap CL, or a dishwasher, etc.

[0152] In the first and second embodiments, the control devices 31A and 31B correspond to the control devices of the present invention, but for example, a control device that integrates these may be provided in the hot water supply system 1. Also, for example, a higher-level control device than the control devices 31A and 31B may be further provided, and the higher-level control device may execute part of the processing of the control devices 31A and 31B.

[0153] Furthermore, although the first and second embodiments illustrate a hot water supply system 1 having only two water heaters 2A and 2B, the present invention can also be applied to a hot water supply system having three or more water heaters. For example, the same control processing as in the first and second embodiments can be employed for controlling the operation of two of the three or more water heaters. [Explanation of symbols]

[0154] 1...hot water supply system, 2A...main water heater (first water heater), 2B...auxiliary water heater (second water heater), 10...water supply line, 11...first heating section (heating section), 12...hot water supply line, 16...water supply volume adjustment valve (water supply on / off valve), 31A, 31B...control device, CL...hot water tap (first hot water supply target section), BTA...bathtub (third hot water supply target section), BTB...bathtub (second hot water supply target section).

Claims

1. a first water heater and a second water heater, each having a water supply passage, a hot water supply passage, and a heating unit, and each configured to heat hot water supplied via the water supply passage in the heating unit and to dispense the heated hot water via the hot water supply passage; and a control device that controls the operation of the first water heater and the second water heater, wherein the hot water supply passage of the first water heater is connected to a first hot water supply target portion so as to supply the hot water to the first hot water supply target portion, and the hot water supply passage of the second water heater is connected to the first hot water supply target portion and the second hot water supply target portion so as to distribute the hot water to the first hot water supply target portion and the second hot water supply target portion, and further wherein a water supply opening / closing valve capable of opening and closing the water supply passage is mounted to the water supply passage of the second water heater, The hot water supply system is characterized in that when a request for hot water to the first hot water supply target occurs while the control device is controlling the water supply on-off valve to open and operate only the second water heater so that hot water at a second target hot water temperature, which is the target temperature for hot water for the second hot water supply target, is supplied to the second hot water supply target, the control device is configured to use either the first target hot water supply temperature or the second target hot water supply temperature as a common A target hot water temperature for the first hot water supply target and supply hot water at the A target hot water temperature from the first water heater to the first hot water supply target and operate the first water heater and the second water heater so that hot water at the A target hot water temperature is supplied from the second water heater to the first hot water supply target and the second hot water supply target.

2. 2. The hot water supply system according to claim 1, the first hot water supply target portion is a hot water tap, and the second hot water supply target portion is a bathtub, A hot water supply system characterized in that the control device is configured to use the second target hot water supply temperature or the lower of the first target hot water supply temperature and the second target hot water supply temperature as the A target hot water supply temperature.

3. a first water heater and a second water heater, each having a water supply passage, a hot water supply passage, and a heating unit, and each configured to heat hot water supplied via the water supply passage in the heating unit and to dispense the heated hot water via the hot water supply passage; and a control device that controls the operation of the first water heater and the second water heater, wherein the hot water supply passage of the first water heater is connected to a first hot water supply target portion so as to supply the hot water to the first hot water supply target portion, and the hot water supply passage of the second water heater is connected to the first hot water supply target portion and the second hot water supply target portion so as to distribute the hot water to the first hot water supply target portion and the second hot water supply target portion, and further wherein a water supply opening / closing valve capable of opening and closing the water supply passage is mounted to the water supply passage of the second water heater, the control device is configured to, when a request for hot water supply to the first hot water supply target portion occurs while controlling the water supply on-off valve to open and operate only the second water heater so as to supply hot water of a second target hot water temperature, which is a target temperature of the hot water for the second hot water supply target portion, to the second hot water supply target portion, use either the first target hot water temperature, which is the target temperature of the hot water for the first hot water supply target portion, or the second target hot water temperature as a target hot water temperature A common to the first water heater and the second water heater, supply hot water of the target hot water temperature A from the first water heater to the first hot water supply target portion, and operate the first water heater and the second water heater so as to supply hot water of the target hot water temperature A from the second water heater to the first hot water supply target portion and the second hot water supply target portion; The hot water supply passage of the first hot water heater is connected to the first hot water supply target portion and the third hot water supply target portion so as to distribute hot water to the first hot water supply target portion and the third hot water supply target portion, The control device operates the first water heater to supply hot water at a third target hot water supply temperature, which is a target temperature of the hot water for the third hot water supply target portion, to the third hot water supply target portion, and controls the water supply on-off valve to open and operate the second water heater to supply hot water at the second target hot water supply temperature to the second hot water supply target portion, and when a request for hot water supply to the first hot water supply target portion occurs, controls the first target hot water supply temperature, the second target hot water supply temperature, and the third target hot water supply temperature. a target hot water supply temperature B common to the first water heater and the second water heater, and is configured to operate the first water heater and the second water heater so that hot water at the target hot water supply temperature B is supplied from the first water heater to the first hot water supply target portion and the third hot water supply target portion, and so that hot water at the target hot water supply temperature B is supplied from the second water heater to the first hot water supply target portion and the second hot water supply target portion.

4. 4. The hot water supply system according to claim 3, the first hot water supply target portion is a hot water tap, the second hot water supply target portion is a bathtub, and the third hot water supply target portion is a bathtub different from the second hot water supply target portion, A hot water supply system characterized in that the control device is configured to use the lower of the second target hot water supply temperature and the third target hot water supply temperature, or the lowest target hot water supply temperature of the first target hot water supply temperature, the second target hot water supply temperature, and the third target hot water supply temperature as the B target hot water supply temperature.

5. a first water heater and a second water heater, each having a water supply passage, a hot water supply passage, and a heating unit, and each configured to heat hot water supplied via the water supply passage in the heating unit and to dispense the heated hot water via the hot water supply passage; and a control device that controls the operation of the first water heater and the second water heater, wherein the hot water supply passage of the first water heater is connected to a first hot water supply target portion so as to supply the hot water to the first hot water supply target portion, and the hot water supply passage of the second water heater is connected to the first hot water supply target portion and the second hot water supply target portion so as to distribute the hot water to the first hot water supply target portion and the second hot water supply target portion, and further wherein a water supply opening / closing valve capable of opening and closing the water supply passage is mounted to the water supply passage of the second water heater, the control device is configured to, when a request for hot water supply to the first hot water supply target portion occurs while controlling the water supply on-off valve to open and operate only the second water heater so as to supply hot water of a second target hot water temperature, which is a target temperature of the hot water for the second hot water supply target portion, to the second hot water supply target portion, use either the first target hot water temperature, which is the target temperature of the hot water for the first hot water supply target portion, or the second target hot water temperature as a target hot water temperature A common to the first water heater and the second water heater, supply hot water of the target hot water temperature A from the first water heater to the first hot water supply target portion, and operate the first water heater and the second water heater so as to supply hot water of the target hot water temperature A from the second water heater to the first hot water supply target portion and the second hot water supply target portion; the first hot water supply target portion is a hot water tap, the second hot water supply target portion is a bathtub, and the hot water supply path of the first hot water heater is connected to the first hot water supply target portion and the third hot water supply target portion, which is a bathtub different from the second hot water supply target portion, so as to distribute hot water to the first hot water supply target portion and the third hot water supply target portion, The control device operates the first water heater to supply hot water to the third hot water supply target portion at a third target hot water supply temperature, which is a target temperature for the hot water for the third hot water supply target portion, and controls the water supply on-off valve to open and operate the second water heater to supply hot water to the second hot water supply target portion, and when a request for hot water supply to the first hot water supply target portion occurs, the control device performs a first process of interrupting hot water supply to the hot water supply target portion by blocking a flow path of hot water supply water from one of the first and second water heaters, which is a water heater corresponding to the higher target hot water supply temperature of the second target hot water supply temperature and the third target hot water supply temperature, to the hot water supply target portion corresponding to the one of the third hot water supply target portion and the second hot water supply target portion; a second process in which the lower target hot water supply temperature among these is used as a common Cth target hot water supply temperature for the first water heater and the second water heater, and hot water at the Cth target hot water supply temperature is supplied from one of the first water heater and the second water heater to the first hot water supply target portion, and hot water at the Cth target hot water supply temperature is supplied from the other of the first water heater and the second water heater to the hot water supply target portion corresponding to the other of the second hot water supply target portion and the third hot water supply target portion and to the first hot water supply target portion; and a third process in which, after hot water supply to the first hot water supply target portion is completed, hot water is resumed from the one water heater to the hot water supply target portion corresponding to the one of the second hot water supply target portion and the third hot water supply target portion.

6. a first water heater and a second water heater, each having a water supply passage, a hot water supply passage, and a heating unit, and each configured to heat hot water supplied via the water supply passage in the heating unit and to dispense the heated hot water via the hot water supply passage; and a control device that controls the operation of the first water heater and the second water heater, wherein the hot water supply passage of the first water heater is connected to the first hot water supply target portion and the third hot water supply target portion so as to distribute the hot water to the first hot water supply target portion and the third hot water supply target portion, and the hot water supply passage of the second water heater is connected to the first hot water supply target portion and the second hot water supply target portion so as to distribute the hot water to the first hot water supply target portion and the second hot water supply target portion, and further wherein a water supply opening / closing valve capable of opening and closing the water supply passage is mounted to the water supply passage of the second water heater, The control device operates the first water heater to supply hot water at a third target hot water supply temperature, which is a target temperature of the hot water for the third hot water supply target portion, to the third hot water supply target portion, and controls the water supply on-off valve to open and operate the second water heater to supply hot water at a second target hot water supply temperature, which is a target temperature of the hot water for the second hot water supply target portion, when a request for hot water supply to the first hot water supply target portion occurs. A hot water supply system characterized in that one of the hot water temperature, the second target hot water temperature, and the third target hot water temperature is used as a common target hot water temperature B for the first water heater and the second water heater, and the first water heater and the second water heater are operated so that hot water at the target hot water temperature B is supplied from the first water heater to the first hot water supply target portion and the third hot water supply target portion, and hot water at the target hot water temperature B is supplied from the second water heater to the first hot water supply target portion and the second hot water supply target portion.

7. 7. The hot water supply system according to claim 6, the first hot water supply target portion is a hot water tap, the second hot water supply target portion is a bathtub, and the third hot water supply target portion is a bathtub different from the second hot water supply target portion, A hot water supply system characterized in that the control device is configured to use the lower of the second target hot water supply temperature and the third target hot water supply temperature, or the lowest target hot water supply temperature of the first target hot water supply temperature, the second target hot water supply temperature, and the third target hot water supply temperature as the B target hot water supply temperature.

8. a first water heater and a second water heater, each having a water supply passage, a hot water supply passage, and a heating unit, and each configured to heat hot water supplied via the water supply passage in the heating unit and to dispense the heated hot water via the hot water supply passage; and a control device that controls the operation of the first water heater and the second water heater, wherein the hot water supply passage of the first water heater is connected to the first hot water supply target portion and the third hot water supply target portion so as to distribute the hot water to the first hot water supply target portion and the third hot water supply target portion, and the hot water supply passage of the second water heater is connected to the first hot water supply target portion and the second hot water supply target portion so as to distribute the hot water to the first hot water supply target portion and the second hot water supply target portion, and further wherein a water supply opening / closing valve capable of opening and closing the water supply passage is mounted to the water supply passage of the second water heater, The first hot water supply target portion is a hot water tap, the second hot water supply target portion is a bathtub, and the third hot water supply target portion is a bathtub different from the second hot water supply target portion, The control device operates the first water heater to supply hot water to the third hot water supply target portion at a third target hot water supply temperature, which is a target temperature of the hot water for the third hot water supply target portion, and controls the water supply on-off valve to open and operate the second water heater to supply hot water to the second hot water supply target portion at a second target hot water supply temperature, which is a target temperature of the hot water for the second hot water supply target portion, and when a request for hot water supply to the first hot water supply target portion occurs, the control device performs a first process of interrupting hot water supply to the hot water supply target portion by blocking a flow path of hot water supply water from one of the first and second water heaters, which is a water heater corresponding to a higher target hot water supply temperature of the second target hot water supply temperature and the third target hot water supply temperature, to the hot water supply target portion corresponding to the one of the third and second hot water supply target portions; and a third process of using the lower of the first target hot water supply temperature and the third target hot water supply temperature as a common Cth target hot water supply temperature for the first water heater and the second water heater, and supplying hot water at the Cth target hot water supply temperature from one of the first water heater and the second water heater to the first hot water supply target portion and the hot water supply water at the Cth target hot water supply temperature from the other of the first water heater and the second water heater to the hot water supply target portion corresponding to the other of the second hot water supply target portion and the third hot water supply target portion and the first hot water supply target portion; and a third process of resuming hot water supply from the one water heater to the hot water supply target portion corresponding to the one of the second hot water supply target portion and the third hot water supply target portion after hot water supply to the first hot water supply target portion is completed.

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