Hot water system

Abstract

To supply hot water at a proper temperature when supplying hot water to a first hot water supply destination part during supply of hot water to a second hot water supply destination part, in a hot water supply system in which the first hot water supply destination part (a hot water faucet) is connected to both a first hot water supply machine and a second hot water supply machine and the second hot water supply destination part (a bathtub) is connected to the second hot water supply machine.SOLUTION: When supplying hot water to a hot water supply faucet CL while hot water is being supplied to a bathtub BTB from a second hot water supply machine 2B, operation of a flow rate regulation valve 16 of a first hot water supply machine 2A is controlled so that water for hot water supply at a target hot water supply temperature for the hot water supply faucet CL is supplied to the hot water supply faucet CL from the first hot water supply machine 2A with an on / off-valve 26 being closed irrespective of whether a prescribed condition related to necessity of hot water supply to the hot water supply faucet CL from the second hot water supply machine 2B holds or not.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 a plurality of water heaters are connected in parallel between a main water supply channel through which hot water is supplied and a main hot water supply channel from which heated hot water is dispensed, and hot water is supplied from the main water supply channel to one or more water heaters, and the hot water heated by the one or more water heaters is supplied from the main hot water supply channel to a hot water supply target such as a hot water tap (a hot water supply target common to the plurality of water heaters).The system seen in Patent Document 1 has a closable flow control valve provided in a flow channel through which heated hot water flows from each water heater to the main hot water supply channel.

[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 supply targets such as hot water taps. 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 flow control valve provided in the flow path that flows the hot water supply water from the auxiliary water heater to the main hot water supply line is maintained 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 Laid-Open No. 2017-78518 [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 portion (e.g., a hot water tap) so as to supply hot water to the first hot water supply target portion, the hot water supply passage of the second water heater connected to the first hot water supply target portion and the second hot water supply target portion (e.g., a bathtub) so as to distribute hot water to the first hot water supply target portion and the second hot water supply target portion, and further, a hot water supply opening / closing valve that can open and close the hot water supply passage is installed in the hot water supply passage of the second water heater.

[0008] In this case, when the second water heater is not supplying hot water to the second hot water supply target portion, if a specified condition regarding the need for auxiliary hot water supply from the second water heater to the first hot water supply target portion (for example, a hot water tap) is met when hot water is being supplied from the first water heater to the first hot water supply target portion (such as a condition where the first water heater alone does not have enough capacity) then, in addition to the hot water supply from the first water heater to the first hot water supply target portion, it is possible to supply hot water from the second water heater to the first hot water supply target portion as an auxiliary supply.

[0009] However, when hot water is being supplied from the second water heater to a second hot water supply target area (e.g., a bathtub), if, as described above, predetermined conditions regarding the need for supplementary hot water supply from the second water heater to the first hot water supply target area are met, the inventors of the present application have found that if supplementary hot water is supplied from the second water heater to the first hot water supply target area, the following problems arise.

[0010] In other words, when hot water is being supplied from the second water heater to the second hot water supply target portion and hot water is being supplied to the first hot water supply target portion (e.g., hot water tap), if the second water heater is opened to supply hot water to the first hot water supply target portion as an auxiliary supply in addition to supplying hot water from the first water heater to the first hot water supply target portion, a portion of the hot water supply water heated by the second water heater to supply hot water to the second hot water supply target portion is mixed with the hot water supply water heated by the first water heater and supplied to the first hot water supply target portion.

[0011] 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.

[0012] 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 from 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).

[0013] 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.

[0014] 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]

[0015] 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 further, an on-off valve that can open and close the passage is assembled to the passage that distributes hot water from the hot water supply passage of the second water heater to the first hot water supply target portion, a flow rate adjusting valve capable of adjusting the flow rate of hot water supply water flowing from the first hot water heater to the first hot water supply target part; The control device has a function of executing a first control process to control the operation of the first water heater and the flow rate adjustment valve so that hot water at a first target hot water temperature, which is a target temperature for the hot water for the first hot water supply target portion, is supplied from the first water heater to the first hot water supply target portion when a predetermined condition regarding the need for hot water supply from the second water heater to the first hot water supply target portion is met while hot water supply from the second water heater to the second hot water supply target portion is stopped and to control the operation of the on-off valve and the second water heater so that hot water at the first target hot water temperature is supplied from the second water heater to the first hot water supply target portion while the on-off valve is opened; When hot water is supplied to the first hot water supply target portion while the operation of the second hot water heater is being controlled so that the second hot water heater supplies hot water to the second hot water supply target portion, the system is configured to have the function of executing a second control process that controls the operation of the on-off valve and the second hot water heater so that hot water at a second target hot water supply temperature, which is the target temperature of the hot water for the second hot water supply target portion, is supplied from the second hot water heater to the second hot water supply target portion, regardless of whether the specified condition is met, and controls the operation of the first water heater and the flow rate control valve so that hot water at the first target hot water supply temperature is supplied from the first water heater to the first hot water supply target portion (first invention).

[0016] According to the first aspect of the present invention, when hot water is being supplied from the first water heater to the first hot water supply target portion while hot water supply from the second water heater to the second hot water supply target portion is stopped, if a predetermined condition regarding whether hot water supply from the second water heater to the first hot water supply target portion is met, the first control process is executed, so that hot water can be supplied from the second water heater to the first hot water supply target portion in addition to hot water supply from the first water heater to the first hot water supply target portion. In this case, hot water at the first target hot water supply temperature can be supplied from both the first water heater and the second water heater.

[0017] Furthermore, when hot water is supplied to a first hot water supply target portion while the operation of the second hot water heater is controlled so that the second hot water heater supplies hot water to the second hot water supply target portion, the second control process is executed regardless of whether the predetermined condition is satisfied, thereby making it possible to supply hot water to the first hot water supply target portion only from the first hot water heater regardless of whether the predetermined condition is satisfied. In this case, by controlling the operation of the flow rate adjustment valve, the flow rate of hot water supplied from the first hot water heater to the first hot water supply target portion can be reduced, making it possible to supply hot water at the first target hot water supply temperature to the first hot water supply target portion.

[0018] Therefore, according to the first invention, in either case where the specified condition is met when hot water is being supplied from the first water heater to the first hot water supply target portion while hot water supply from the second water heater to the second hot water supply target portion is stopped, or where the specified condition is met when hot water is being supplied to the first hot water supply target portion while the operation of the second water heater is controlled so that hot water is supplied from the second water heater to the second hot water supply target portion, hot water at the first target hot water supply temperature can be supplied to the first hot water supply target portion, thereby preventing the user from feeling uncomfortable with the temperature of the hot water. Therefore, according to the first aspect of the invention, when supplying hot water to the second hot water supply target, hot water can be supplied at an appropriate temperature when supplying hot water to the first hot water supply target.

[0019] In the above first invention, the control device may be configured to execute the second control process when supplying hot water to the first hot water supply target portion while controlling the operation of the second water heater so that the second water heater supplies hot water to the second hot water supply target portion, if the second target hot water supply temperature does not match the first target hot water supply temperature, and if the second target hot water supply temperature matches the first target hot water supply temperature, to control the operation of the on-off valve and the second water heater so that the second water heater supplies hot water at the first target hot water supply temperature or the second target hot water supply temperature to the first hot water supply target portion and the second hot water supply target portion while opening the on-off valve, and to execute a third control process to control the operation of the first water heater and the flow rate adjustment valve so that the first water heater supplies hot water at the first target hot water supply temperature or the second target hot water supply temperature to the first hot water supply target portion (second invention).

[0020] In the present invention, the fact that the second target hot water supply temperature matches the first target hot water supply temperature does not necessarily mean that the second target hot water supply temperature exactly matches the first target hot water supply temperature, but may also mean that the second target hot water supply temperature almost matches (approximately matches) the first target hot water supply temperature.

[0021] According to the second aspect of the present invention, when hot water is supplied to a first hot water supply target portion while controlling the operation of the second hot water heater so that the second hot water heater supplies hot water to the second hot water supply target portion, the second control process is executed if the second target hot water supply temperature does not match the first target hot water supply temperature, while the third control process is executed if the second target hot water supply temperature matches the first target hot water supply temperature. This reduces the number of situations in which the flow control valve reduces the flow rate of hot water to the first hot water supply target portion even when the predetermined condition is met. This makes it possible to improve convenience regarding the hot water supply flow rate for the first hot water supply target portion.

[0022] In the first aspect of the present invention, when the first hot water supply target portion is a hot water tap and the second hot water supply target portion is a bathtub, the control device controls the operation of the second hot water heater so that hot water is supplied from the second hot water heater to the second hot water supply target portion, and when hot water is supplied to the first hot water supply target portion, if the second target hot water supply temperature is lower than the first target hot water supply temperature or is a temperature equal to or lower than the first target hot water supply temperature, the control device executes the second control process; When the temperature is higher than the first target hot water supply temperature, the operation of the on-off valve and the second water heater is controlled so that the second water heater supplies hot water at the first target hot water supply temperature to the first hot water supply target portion and the second hot water supply target portion while the on-off valve is open, and a fourth control process is executed to control the operation of the first water heater and the flow rate control valve so that the first water heater supplies hot water at the first target hot water supply temperature to the first hot water supply target portion (third invention).

[0023] According to this, when hot water is supplied to a first hot water supply target portion (hot water tap) while the operation of the second hot water heater is controlled so that the second hot water heater supplies hot water to a second hot water supply target portion (bathtub), the second control process is executed if the second target hot water supply temperature is lower than the first target hot water supply temperature or is equal to or lower than the first target hot water supply temperature, while the fourth control process is executed if the second target hot water supply temperature is equal to or higher than the first target hot water supply temperature, thereby reducing the number of situations in which the flow control valve reduces the flow rate of hot water to the first hot water supply target portion (hot water tap) even when the predetermined condition is met. This makes it possible to improve the convenience of the hot water supply flow rate to the first hot water supply target portion (hot water tap).

[0024] In addition, in the fourth control process which is executed when the second target hot water supply temperature is equal to or higher than the first target hot water supply temperature, hot water at the first target hot water supply temperature is supplied from the second water heater to the first hot water supply target area (hot water tap) and the second hot water supply target area (bathtub). Therefore, although the hot water supply temperature to the second hot water supply target area (bathtub) will be lower than the second target hot water supply temperature, it is possible to perform so-called reheating after hot water supply (filling) to the second hot water supply target area (bathtub) is completed, and therefore it is possible to raise the temperature of the hot water supply water filled in the second hot water supply target area (bathtub) to the second target hot water supply temperature.

[0025] In the above third invention, the control device can further be configured to execute a third control process in which, when a request for hot water supply to the first hot water supply target unit occurs while controlling the operation of the second water heater so that the second water heater supplies hot water to the second hot water supply target unit, if the second target hot water supply temperature matches the first target hot water supply temperature, the control device controls the operation of the on-off valve and the second water heater so that the second water heater supplies hot water at the first target hot water supply temperature or the second target hot water supply temperature to the first hot water supply target unit and the second hot water supply target unit, while opening the on-off valve, and controls the operation of the first water heater and the flow rate control valve so that the first water heater supplies hot water at the first target hot water supply temperature or the second target hot water supply temperature to the first hot water supply target unit (fourth invention).

[0026] In addition, as in the case of the second invention, the fact that the second target hot water supply temperature matches the first target hot water supply temperature does not necessarily mean that the second target hot water supply temperature exactly matches the first target hot water supply temperature, but may also mean that the second target hot water supply temperature almost matches (approximately matches) the first target hot water supply temperature.

[0027] According to the fourth aspect of the present invention, the third control process is executed when the second target hot water supply temperature is equal to (or substantially equal to) the first target hot water supply temperature, so that even when the predetermined condition is met, the flow rate of hot water to the first hot water supply target (hot water tap) is reduced by the flow control valve, which further reduces the number of situations. This makes it possible to further improve the convenience of the hot water supply flow rate to the first hot water supply target (hot water tap). [Brief explanation of the drawings]

[0028] [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] 4 is a flowchart showing the process of operation control of the main water heater (first water heater) in the first embodiment. [Figure 3] 4 is a flowchart showing the process of controlling the operation of the auxiliary water heater (second water heater) in the first embodiment. [Figure 4] 10 is a flowchart showing the process of operation control of the main water heater (first water heater) in the second embodiment. [Figure 5] 10 is a flowchart showing the process of controlling the operation of an auxiliary water heater (second water heater) in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0029] [First embodiment] A first embodiment of the present invention will be described below with reference to Figs. 1 to 3. Referring to Fig. 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. A bathtub BTB is connected to the water heater 2B as another target for hot water supply. In this embodiment, a bathtub is not connected to the water heater 2A.

[0030] 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 auxiliary supplying hot water to the hot water tap CL 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 and the bathtub BTB correspond to the first hot water supply target and the second hot water supply target, respectively, in the present invention. 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.

[0031] To give a representative explanation of the configuration of the heat source unit 3 of the auxiliary water heater 2B to which the bathtub BTB is connected, the heat source unit 3 comprises 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 bath water which is the hot water supplied to the bathtub BTB, a circulation water passage 14 for circulating the bath water between the second heating section 13 and the bathtub BTB, 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 via the circulation water passage 14 to the bathtub BTB.

[0032] Water supply passage 10 branches off from an upstream water supply passage 4 that is common to water heaters 2A and 2B, and hot water is supplied to each water supply passage 10 from a water supply source (not shown) via the upstream water supply passage 4. The downstream side of hot water supply passage 12 merges with a downstream hot water supply passage 5 (downstream hot water supply passage 5 common to water heaters 2A and 2B) whose downstream end is connected to a hot water tap CL, and hot water is supplied from hot water supply passage 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.

[0033] 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.

[0034] A water supply rate adjustment valve 16 for adjusting 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 BTB downstream, is installed in the hot water supply line 12. The water supply rate adjustment valve 16 of the main hot water heater 2A corresponds to the flow rate adjustment valve in this invention.

[0035] The circulation water passage 14 comprises a return water passage 14a that flows bath water from inside the bathtub BTB 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 BTB, 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 bathwater in the circulation water passage 14. The end of each of the return water passage 14a and the outward water passage 14b on the bathtub BTB side is connected to a pouring spout Ba formed in the side wall near the bottom of the bathtub BTB.

[0036] 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.

[0037] Additionally, each of the first heating section 11 and the second heating section 13 of the heat source unit 3 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 provided with an electric heating device or a heat pump-type heating device instead of or in addition to a combustion-type heating device.

[0038] 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 for detecting the temperature of the bathtub water, a water flow switch 21 for detecting the presence or absence of water flow in the circulation water passage 14, and a water level sensor 22 for detecting the water level of the bathtub water in the bathtub BTB. 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.

[0039] 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 solenoid valve 23 for opening and closing filling water passage 15, and a flow rate sensor 24 for detecting the flow rate of hot water supplied from hot water supply passage 12 through filling water passage 15 to bathtub BTB (the flow rate of hot water supplied to bathtub BTB).

[0040] The heat source unit 3 of the auxiliary water heater 2B is configured as described above. The heat source unit 3 of the main water heater 2A is also configured in the same way as the auxiliary water heater 2B. Therefore, the configuration of the heat source unit 3 of the main water heater 2A will be given the same reference numerals as the heat source unit 3 of the auxiliary water heater 2B, and explanations will be omitted. However, in this embodiment, a bathtub is not connected to the circulation water channel 14 of the heat source unit 3 of the main water heater 2A.

[0041] Furthermore, in the hot water supply system 1 of this embodiment, a hot water supply on-off valve 26 capable of opening and closing the flow path 12a is attached to the hot water supply path 12 of the auxiliary hot water heater 2B in a flow path 12a downstream of the branching point of the hot water filling water path 15 (the flow path 12a that flows hot water from the hot water supply path 12 to the hot water tap CL via the downstream hot water supply path 5). The hot water supply on-off valve 26 corresponds to the on-off valve of the present invention and is constituted by a solenoid valve or the like.

[0042] Additionally, in FIG. 1, hot water supply on / off valve 26 is provided outside heat source unit 3 of auxiliary hot water heater 2B, but it may be mounted on said heat source unit 3. Also, hot water supply on / off valve 26 may have a function of adjusting the flow rate of hot water supply water. Also, in auxiliary hot water heater 2B, water supply amount adjustment valve 16 may be omitted. Also, in main hot water heater 2A, instead of water supply amount adjustment valve 16, a flow rate adjustment valve may be provided in hot water supply path 12, in flow path 12a downstream of the branching point of water filling path 15.

[0043] Each of the 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. The control devices 31A, 31B are mounted on the respective heat source units 3 of the water heaters 2A, 2B. The water heater system 1 also includes, as remote controls for operating the system, a kitchen remote control 32A installed in the kitchen or the like, and a bathroom remote control 33B installed in the bathroom where the bathtub BTB is installed.

[0044] 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 water filling operation that fills the bathtub BTB with 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.

[0045] In addition, although detailed illustrations are omitted, the bathroom remote control 33B is equipped with an operation unit including operation switches for setting the target temperature of the bathtub water in the bathtub BTB, the target water level of the bathtub water, and the target hot water temperature, and operation switches for instructing the execution of a water filling operation corresponding to each bathtub BTB, a display unit that displays various information regarding water filling, etc., and a sound output unit that outputs alarm sounds and audio information.

[0046] 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 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.

[0047] Each of the control devices 31A and 31B has a function to control the operation of the heat source unit 3 of the corresponding water heater 2A or 2B by functions realized by the implemented hardware configuration and program (software configuration). The control device 31B also has a function to control the operation of the on-off valve 26. However, the control device 31A may also have a function to control the operation of the on-off valve 26.

[0048] Next, the operation of the hot water supply system 1 of this embodiment will be described. First, the basic operation of the hot water filling operation, which supplies hot water (fills the bathtub BTB), will be described. The initial state immediately after the hot water supply operation is turned on using the kitchen remote control 32A or the bathroom remote control 33B, is the standby state of the main hot water heater 2A and the auxiliary hot water heater 2B, and in this standby state, the hot water supply opening / closing valve 26 of the auxiliary hot water heater 2B is controlled to be closed by the control device 31B. In addition, the water supply amount adjustment valve 16 of each of the main hot water heater 2A and the auxiliary hot water heater 2B is controlled to be fully open by the control devices 31A and 31B, respectively.

[0049] In the standby state, when an operation to command the execution of the bathtub filling operation for the bathtub BTB is performed using the kitchen remote control 32A or the bathroom remote control 33B, the control device 31B of the auxiliary water heater 2B controls the bathtub filling solenoid valve 23 to open, and also starts the operation of the first heating unit 11 (burner combustion operation), thereby starting the supply of hot water (filling) to the bathtub BTB.

[0050] Then, the control device 31B controls the amount of heating of the first heating unit 11 so that the hot water temperature detected by the temperature sensor 18 of the auxiliary hot water heater 2B matches or nearly matches the target hot water temperature for filling the bathtub BTB. In this case, the target hot water temperature for filling the bathtub is basically the bath filling set temperature, which is the temperature most recently set by the user on the bathroom remote control 33B (or kitchen remote control 32A). As a result, hot water is supplied (filled) to the bathtub BTB at the bath filling set temperature. The bath filling set temperature corresponds to the second target hot water temperature in this invention.

[0051] The control device 31B calculates the amount of hot water required to raise the bathtub water level in the bathtub BTB to the set water level, which is the target value most recently set by the bathroom remote control 33B (or kitchen remote control 32A).The control device 31B then supplies hot water to the bathtub BTB until the amount of hot water supplied to the bathtub BTB (accumulated flow rate) detected based on the output of the flow rate sensor 24 of the bath filling water channel 15 reaches the calculated required amount of hot water.When the required amount of hot water is reached, the control device 31B stops operation of the first heating unit 11 and controls the bath filling solenoid valve 23 to close.This completes filling the bathtub BTB to the set water level.

[0052] 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. In the hot water supply system 1 of this embodiment, the hot water filling operation for filling the bathtub BTB with hot water is carried out as described above with the hot water supply on-off valve 26 of the auxiliary hot water heater 2B in the closed state.

[0053] Next, the operation when supplying hot water to the hot water tap CL will be explained with reference to Figures 2 and 3. In the following explanation, unless otherwise specified, "filling operation" refers to the operation during the process of filling the bathtub BTB with hot water, and does not include the operation during the reheating process that may be performed afterwards.

[0054] The control device 31A of the main water heater 2A executes the control process shown in the flowchart of Fig. 2 regarding the supply of hot water to the hot water tap CL. When the main water heater 2A is in a standby state, the control device 31A executes a determination process in STEP 1 to determine whether or not the supply of water to the hot water tap CL has started, until the determination result becomes affirmative.

[0055] Here, by opening the hot water tap CL, water starts 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 passage 12 of the main hot water heater 2A, and the downstream hot water passage 5. Then, in STEP 1, the control device 31A determines whether water has started to flow to the hot water tap CL based on whether the flow rate detected by the flow rate sensor 17 of the main hot water heater 2A is equal to or greater than a predetermined flow rate.

[0056] When the result of the determination in STEP 1 becomes affirmative due to the start of water supply to the hot water tap CL, the control device 31A starts the hot water supply operation of the main hot water heater 2A in STEP 2. In this case, the operation of the first heating unit 11 of the main hot water heater 2A (combustion operation of the burner) is started, thereby starting the hot water supply operation in which hot water is supplied from the main hot water heater 2A to the hot water tap CL.

[0057] During this hot water supply operation, the control device 31A controls the temperature of the hot water supplied to the hot water tap CL by controlling the amount of heat (the amount of combustion of the burner) of the first heating unit 11 so that the hot water temperature detected by the temperature sensor 18 of the main hot water heater 2A matches or nearly matches the target hot water temperature, which is the target value of the hot water temperature. In this case, the hot water setting temperature, which is the temperature most recently set by the user using the kitchen remote control 32A or the bathroom remote control 33B for hot water supply to the hot water tap CL, is used as the target hot water temperature. As a result, hot water is supplied to the hot water tap CL at the hot water setting temperature. The hot water setting temperature corresponds to the first target hot water temperature in this invention.

[0058] Next, the control device 31A determines whether the supply of water to the hot water tap CL has been stopped (whether the hot water tap CL has been closed) in STEP 3. In this case, the control device 31A determines whether the supply of water to the hot water tap CL has been stopped based on whether the flow rate detected by the flow rate sensor 17 of the main hot water heater 2A has become equal to or lower than a predetermined flow rate.

[0059] If the determination result in STEP 3 is affirmative (if the supply of water to the hot water tap CL is stopped), the control device 31A stops the operation of the first heating unit 11 of the main hot water heater 2A in STEP 10. This stops the hot water supply operation of the main hot water heater 2A.

[0060] If the judgment result in STEP 3 is negative (water continues to flow to the hot water tap CL), the control device 31A judges in STEP 4 whether the hot water heat quantity, which is the amount of heat required to raise the temperature of the hot water water supplied to the hot water tap CL to the hot water set temperature, is greater than the upper limit heat quantity, which is the upper limit of the amount of heat that can be input to the hot water water from the first heating section 11 of the main hot water heater 2A.

[0061] Here, the hot water supply heat quantity is calculated by multiplying the difference between the hot water supply setting temperature and the water supply temperature (the temperature of the hot water supply water flowing through the water supply passage 10 of the main hot water heater 2A) by the hot water supply flow rate to the hot water tap CL. The water supply temperature is detected by a temperature sensor (not shown), or can be estimated from the flow rate detected by the flow rate sensor 17, the hot water supply temperature detected by the temperature sensor 18, and the set value of the heating amount of the first heating unit 11. The flow rate detected by the flow rate sensor 17 of the main hot water heater 2A can be used as the hot water supply flow rate to the hot water tap CL.

[0062] Additionally, in this embodiment, when the judgment result of STEP 4 is positive (the hot water heat quantity is greater than the upper limit heat quantity), this corresponds to the predetermined condition in the present invention (the predetermined condition regarding whether or not hot water is to be supplied from the auxiliary hot water heater 2B to the hot water tap CL) being met.

[0063] If the determination result in STEP 4 is negative (the amount of hot water heat <= the upper limit of the amount of heat), the control device 31A repeats the process from STEP 3. On the other hand, if the hot water supply flow rate to the hot water tap CL is high, for example, the determination result in STEP 4 will be positive (the amount of hot water heat > the upper limit of the amount of heat). In this case, the control device 31A next determines in STEP 5 whether the auxiliary hot water heater 2B is currently in the hot water filling operation. In this case, through communication between the control device 31A and the control device 31B of the auxiliary hot water heater 2B, information indicating whether the auxiliary hot water heater 2B is currently in the hot water filling operation is obtained.

[0064] If the determination result in STEP 5 is negative (the auxiliary water heater 2B is not currently filling the water), the control device 31A requests the control device 31B of the auxiliary water heater 2B to start auxiliary hot water supply from the auxiliary water heater 2B to the hot water tap CL in STEP 6. In response, auxiliary hot water supply from the auxiliary water heater 2B to the hot water tap CL starts as described below. Consequently, by reducing the flow rate of hot water supply water flowing from the upstream water supply passage 4 into the water supply passage 10 of the main water heater 2A, the hot water supply water can be heated to the hot water supply setting temperature in the main water heater 2A.

[0065] Next, in STEP 7, control device 31A determines whether the supply of water to hot water tap CL has been stopped, in the same manner as in STEP 3. If the result of this determination is affirmative (if the supply of water to hot water tap CL has been stopped), control device 31A requests control device 31B of auxiliary hot water heater 2B to stop hot water supply in STEP 12, and further stops operation of first heating unit 11 of main hot water heater 2A in STEP 10 described above.

[0066] If the determination result in STEP 7 is negative (water is still flowing to the hot water tap CL), in STEP 8, the control device 31A determines whether the hot water heat quantity has decreased to a heat quantity equal to or less than a heat quantity (= upper limit heat quantity - α) that is lower than the upper limit heat quantity of the main hot water heater 2A by a predetermined amount α. In this case, the hot water heat quantity is calculated by multiplying the difference between the hot water setting temperature and the water supply temperature by the hot water supply flow rate to the hot water tap CL. The hot water supply flow rate to the hot water tap CL is calculated as the sum of the flow rate detected by flow rate sensor 17 of the main hot water heater 2A and the flow rate detected by flow rate sensor 17 of the auxiliary hot water heater 2B. The control device 31A acquires the flow rate detected by flow rate sensor 17 of the auxiliary hot water heater 2B through communication with the control device 31B.

[0067] If the determination result in STEP 8 is negative (the amount of heat supplied to the hot water > the upper limit of the heat amount - α), control device 31A repeats the process from STEP 7. If the determination result in STEP 8 becomes positive (the amount of heat supplied to the hot water ≦ the upper limit of the heat amount - α), control device 31A requests control device 31B of auxiliary hot water heater 2B to stop hot water supply in STEP 9, and then repeats the process from STEP 3. In this case, the process from STEP 3 is repeated with the supply of hot water from auxiliary hot water heater 2B to hot water tap CL stopped.

[0068] On the other hand, if the judgment result of STEP 5 is positive, i.e., if the hot water heat quantity is greater than the upper limit heat quantity and the auxiliary water heater 2B is currently performing hot water filling operation, the control device 31A adjusts the amount of hot water supplied to the hot water tap CL in STEP 11 by controlling the operation of the water supply volume adjustment valve 16 of the main water heater 2A without requesting the control device 31B of the auxiliary water heater 2B to start hot water supply.

[0069] In this case, control device 31B reduces the amount of hot water supplied to hot water tap CL so that the condition of hot water heat amount≦upper limit heat amount is satisfied. Then, control device 31A repeats the process from STEP 3. This allows hot water to be supplied to hot water tap CL at the hot water supply setting temperature without auxiliary hot water supply from auxiliary hot water heater 2B to hot water tap CL.

[0070] In parallel with the processing being carried out in main water heater 2A as described above, in auxiliary water heater 2B, control device 31B carries out the control processing shown in the flowchart of FIG. When the hot water supply on-off valve 26 of the auxiliary hot water heater 2B is in the closed state, the control device 31B determines in STEP 21 whether or not the auxiliary hot water heater 2B is in the hot water filling operation, and if the result of this determination is affirmative, the control device 31B keeps the hot water supply on-off valve 26 in the closed state in STEP 26 and repeats the determination process of STEP 21. Therefore, when the auxiliary hot water heater 2B is in the hot water filling operation, auxiliary hot water is not supplied from the auxiliary hot water heater 2B to the hot water tap CL.

[0071] If the judgment result of STEP 21 is negative (the hot water filling operation is not in progress), the control device 31B judges in STEP 22 whether or not there has been a request from the control device 31A of the main hot water heater 2A to start hot water supply, and if the judgment result is negative, the process goes through the above-mentioned STEP 26 (while keeping the hot water supply opening / closing valve 26 in a closed state) and repeats the processing from STEP 21.

[0072] If the determination result in STEP 22 is positive (if there is a request to start hot water supply), it means that auxiliary hot water heater 2B is not filling the water with hot water and the determination result in STEP 4 is positive (if the hot water supply heat quantity is greater than the upper limit heat quantity). In this case, in STEP 23, control device 31B controls hot water supply on-off valve 26 to open, and starts hot water supply operation of auxiliary hot water heater 2B.

[0073] In this hot water supply operation, control device 31B controls the temperature of the hot water supplied from auxiliary water heater 2B to hot water tap CL by controlling the amount of heat (amount of combustion of the burner) of first heating unit 11 so that the hot water temperature detected by temperature sensor 18 of auxiliary water heater 2B matches or nearly matches the hot water set temperature as its target value. As a result, hot water is supplied from auxiliary water heater 2B to hot water tap CL at the hot water set temperature in parallel with hot water supply from main water heater 2A to hot water tap CL.

[0074] Furthermore, in STEP 24, control device 31B repeats the process of determining whether or not a request to stop hot water supply has been received from control device 31A of main hot water heater 2A until the result of the determination becomes affirmative. Then, when the result of the determination in STEP 24 becomes affirmative (a request to stop hot water supply has been received from control device 31A), control device 31B closes hot water supply on-off valve 26 of auxiliary hot water heater 2B in STEP 25 and stops operation of first heating unit 11. This stops auxiliary hot water supply from auxiliary hot water heater 2B to hot water tap CL.

[0075] In this embodiment, with regard to the supply of hot water to the hot water tap CL, the operation of the main water heater 2A and the auxiliary water heater 2B is controlled as described above, so that when the hot water filling operation in the auxiliary water heater 2B is stopped, if the condition of hot water supply heat quantity > upper limit heat quantity, which is a predetermined condition regarding whether or not hot water is required to be supplied from the auxiliary water heater 2B to the hot water tap CL, is met, in addition to the supply of hot water from the main water heater 2A to the hot water tap CL, auxiliary hot water supply from the auxiliary water heater 2B to the hot water tap CL is also performed.

[0076] In this case, hot water is supplied from the main water heater 2A to the hot water tap CL and from the auxiliary water heater 2B to the hot water tap CL at the hot water supply set temperature, which prevents the user from feeling uncomfortable with the hot water supply temperature to the hot water tap CL.

[0077] Furthermore, while the auxiliary water heater 2B is performing a hot water filling operation, the hot water supply opening / closing valve 26 of the auxiliary water heater 2B is kept in a closed state, and no auxiliary hot water is supplied from the auxiliary water heater 2B to the hot water tap CL, regardless of whether or not the condition of hot water supply heat quantity > upper limit heat quantity, which is a predetermined condition regarding whether or not hot water is supplied from the auxiliary water heater 2B to the hot water tap CL, is met.

[0078] In this case, the main water heater 2A controls the operation of the water supply amount adjustment valve 16 to reduce the hot water supply flow rate to the hot water tap CL, allowing hot water to be supplied to the hot water tap CL at the hot water supply set temperature. This prevents the user from feeling uncomfortable with the hot water supply temperature to the hot water tap CL. Also, in this case, the auxiliary water heater 2B can continuously supply hot water (fill the bathtub BTB) at the hot water filling set temperature until the bathtub is completely filled. [Second embodiment]

[0079] Next, a second embodiment of the present invention will be described with reference to Figures 4 and 5. Note that this embodiment differs from the first embodiment only in the control processes of the main water heater 2A and the auxiliary water heater 2B related to the supply of hot water to the hot water tap CL, and therefore, a description of the same matters as in the first embodiment will be omitted.

[0080] The control device 31A of the main hot water heater 2A executes control processing for supplying hot water to the hot water tap CL, starting from STEP 31 shown in the flowchart of Fig. 4. In this case, the processing in each of STEPs 31 to 40 and 44 is the same as the processing in each of STEPs 1 to 10 and 12 in the first embodiment.

[0081] In this embodiment, when the judgment result of STEP 34 is positive (when the condition that the hot water heat quantity > the upper limit heat quantity is met), the processing when the judgment result of STEP 35 is positive (when the auxiliary hot water heater 2B is performing a hot water filling operation) differs from that of the first embodiment.

[0082] Specifically, if the determination result in STEP 35 is affirmative, in STEP 41, the control device 31A determines whether the set temperature for filling the bathtub BTB matches the set hot water supply temperature. In this embodiment, "the set temperature for filling the bathtub BTB matches the set hot water supply temperature" does not necessarily mean that the set temperature for filling the bathtub exactly matches the set hot water supply temperature, but also includes cases where the set temperature for filling the bathtub matches the set hot water supply temperature almost exactly. Therefore, in STEP 41, the control device 31A determines whether the set temperature for filling the bathtub matches the set hot water supply temperature based on whether the absolute value of the difference between the set temperature for filling the bathtub BTB and the set hot water supply temperature is a small value equal to or less than a predetermined threshold.

[0083] If the result of the determination in STEP 41 is affirmative (if the set temperature for filling the bath water matches (or almost matches) the set temperature for hot water supply), the control device 31A executes the processing from STEP 36. As a result, in addition to the supply of hot water from the main water heater 2A to the hot water tap CL, auxiliary hot water is supplied from the auxiliary water heater 2B to the hot water tap CL.

[0084] If the determination result in STEP 41 is negative (the absolute value of the difference between the set bath filling temperature and the set hot water supply temperature exceeds a predetermined threshold), control device 31A determines in STEP 42 whether the set bath filling temperature is higher than the set hot water supply temperature. If the determination result in STEP 42 is positive (the set bath filling temperature is greater than the set hot water supply temperature), control device 31A executes the process from STEP 36, just as if the determination result in STEP 41 was positive. As a result, in addition to hot water supplied from main water heater 2A to hot water tap CL, auxiliary hot water is supplied from auxiliary water heater 2B to hot water tap CL.

[0085] If the judgment result of STEP 42 is negative (the absolute value of the difference between the bath filling set temperature and the hot water supply set temperature exceeds a predetermined threshold and the bath filling set temperature is less than the hot water supply set temperature), the control device 31A adjusts the amount of hot water supplied to the hot water tap CL in STEP 43 by controlling the operation of the water supply volume adjustment valve 16 of the main water heater 2A without requesting the control device 31B of the auxiliary water heater 2B to start hot water supply.

[0086] In this case, similar to STEP 11 in the first embodiment, the operation of the water supply amount adjustment valve 16 of the main water heater 2A is controlled to reduce the amount of hot water supplied to the hot water tap CL. Then, the control device 31A repeats the process from STEP 33. This allows hot water to be supplied to the hot water tap CL at the hot water supply setting temperature without auxiliary hot water supply from the auxiliary water heater 2B to the hot water tap CL.

[0087] In parallel with the processing being carried out in main water heater 2A as described above, in auxiliary water heater 2B, control device 31B carries out the control processing shown in the flowchart of FIG. When the hot water supply on-off valve 26 of the auxiliary water heater 2B is in the closed state, the control device 31B determines in STEP 51 whether the auxiliary water heater 2B is currently performing a hot water filling operation, and if the result of this determination is positive (the hot water filling operation is currently being performed), it further determines in STEP 58 whether there has been a request from the control device 31A of the main water heater 2A to start hot water supply.

[0088] If the determination result in STEP 58 is negative (if there is no request to start hot water supply), the control device 31A keeps the hot water supply on-off valve 26 closed in STEP 59, and repeats the process from STEP 51. If the determination result in STEP 58 is positive (if a request to start hot water supply has been received), the control device 31A changes the bath water filling set temperature, which is the target hot water supply temperature for supplying hot water (filling the bath water) to the bathtub BTB, to the hot water supply set temperature in STEP 60, and then executes the process from STEP 53 described below.

[0089] If the judgment result in STEP 51 is negative (if the hot water filling operation is stopped), the control device 31A judges in STEP 52 whether or not there has been a request from the control device 31A of the main hot water heater 2A to start supplying hot water, and if the judgment result is negative (if there has been no request to start supplying hot water), the process goes through the above-mentioned STEP 59 (while keeping the hot water supply opening / closing valve 26 in a closed state) and repeats the processing from STEP 51.

[0090] If the determination result in STEP 52 is positive (if there is a request to start hot water supply), it means that the auxiliary water heater 2B is not filling the water with hot water and the determination result in STEP 34 is positive (if the amount of hot water heat supplied is greater than the upper limit of the amount of heat). Also, the processing in STEP 60 is executed if the auxiliary water heater 2B is filling the water with hot water and the determination result in STEP 34 is positive (if the amount of hot water heat supplied is greater than the upper limit of the amount of heat), and if the determination result in STEP 41 or 42 is positive (if the set temperature for filling the water matches (or is nearly the same as) the set temperature for hot water supply, or if the set temperature for filling the water is higher than the set temperature for hot water supply).

[0091] In these cases, in STEP 53, control device 31A controls hot water supply on-off valve 26 to open and starts hot water supply operation of auxiliary hot water heater 2B. In this hot water supply operation, control device 31B controls the amount of heating (amount of combustion of the burner) of 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 hot water supply set temperature as its target value, thereby controlling the temperature of the hot water water supplied from auxiliary hot water heater 2B to hot water tap CL. As a result, hot water is supplied from auxiliary hot water heater 2B to hot water tap CL at the hot water supply set temperature in parallel with hot water supply from main hot water heater 2A to hot water tap CL.

[0092] Here, when auxiliary water heater 2B performs hot water supply operation after processing in STEP 60, the hot water filling operation (filling bathtub BTB) is also performed in parallel. In this case, hot water supply water whose temperature has been controlled to the same temperature (= hot water supply set temperature) as the hot water supply temperature from auxiliary water heater 2B to hot water tap CL is supplied (filled) to bathtub BTB. Therefore, if the judgment result in STEP 41 is positive, bathtub BTB is filled at a temperature that matches (including a temperature that is almost the same as) the original bath filling set temperature (the temperature set by the user using kitchen remote control 32A or bathroom remote control 33B), and if the judgment result in STEP 42 is positive, bathtub BTB is filled at a temperature lower than the original bath filling set temperature.

[0093] Furthermore, in STEP 54, control device 31B repeats the process of determining whether or not a request to stop hot water supply has been received from control device 31A of main hot water heater 2A until the result of the determination becomes affirmative. Then, when the result of the determination in STEP 54 becomes affirmative (a request to stop hot water supply has been received from control device 31A), control device 31B closes hot water supply on-off valve 26 of auxiliary hot water heater 2B in STEP 55. This stops auxiliary hot water supply from auxiliary hot water heater 2B to hot water tap CL.

[0094] Furthermore, in STEP 56, the control device 31B determines whether the auxiliary water heater 2B is currently performing a water filling operation, and if the determination result is negative (water filling operation is stopped), in STEP 57, it stops the operation of the first heating unit 11.

[0095] If the determination result in STEP 56 is affirmative (if the bath filling operation is in progress), the control device 31B returns the bath filling set temperature to the original temperature (the temperature set by the user using the kitchen remote control 32A or the bathroom remote control 33B) in STEP 61, and then executes the process from STEP 51. In this case, hot water is supplied to the bathtub BTB (filled) at the original bath filling set temperature.

[0096] In this embodiment, with regard to the supply of hot water to the hot water tap CL, the operation of the main water heater 2A and the auxiliary water heater 2B is controlled as described above, so that when the hot water filling operation in the auxiliary water heater 2B is stopped, if the condition of hot water supply heat quantity > upper limit heat quantity, which is a predetermined condition regarding whether or not hot water is required to be supplied from the auxiliary water heater 2B to the hot water tap CL, is met, in addition to the supply of hot water from the main water heater 2A to the hot water tap CL, auxiliary hot water supply from the auxiliary water heater 2B to the hot water tap CL is also performed.

[0097] In this case, hot water is supplied from the main water heater 2A to the hot water tap CL and from the auxiliary water heater 2B to the hot water tap CL at the hot water supply set temperature, which prevents the user from feeling uncomfortable with the hot water supply temperature to the hot water tap CL.

[0098] Furthermore, while the auxiliary water heater 2B is performing the hot water filling operation, unless the judgment result of STEP 41 or 42 is positive, the hot water supply opening / closing valve 26 of the auxiliary water heater 2B is kept in a closed state, and auxiliary hot water supply from the auxiliary water heater 2B to the hot water tap CL is not performed, regardless of whether the condition of hot water supply heat quantity > upper limit heat quantity, which is a specified condition regarding whether hot water is required to be supplied from the auxiliary water heater 2B to the hot water tap CL, is met.

[0099] In this case, the main water heater 2A controls the operation of the water supply amount adjustment valve 16 to reduce the hot water supply flow rate to the hot water tap CL, allowing hot water to be supplied to the hot water tap CL at the hot water supply set temperature. This prevents the user from feeling uncomfortable with the hot water supply temperature to the hot water tap CL. Also, in this case, the auxiliary water heater 2B can continuously supply hot water (fill the bathtub BTB) at the hot water filling set temperature until the bathtub is completely filled.

[0100] Furthermore, even if the auxiliary water heater 2B is performing a hot water filling operation, if the result of the judgment in step 41 or 42 is affirmative and the condition that the hot water supply heat quantity > the upper limit heat quantity is met, in addition to the supply of hot water from the main water heater 2A to the hot water tap CL, auxiliary hot water is supplied from the auxiliary water heater 2B to the hot water tap CL, just as when the hot water filling operation is stopped. Therefore, the processing in step 43 can reduce the number of situations in which the hot water supply flow rate to the hot water tap CL is reduced. Ultimately, the convenience of the hot water supply flow rate to the hot water tap CL can be improved.

[0101] In addition, in this case, hot water is supplied from the main water heater 2A to the hot water tap CL and from the auxiliary water heater 2B to the hot water tap CL at the hot water supply set temperature, which prevents the user from feeling uncomfortable with the hot water supply temperature to the hot water tap CL.

[0102] Furthermore, in this case, if the judgment result of STEP 41 is positive (if the bath filling set temperature matches the hot water supply set temperature), the bathtub BTB can be filled with water at a temperature that matches (including a temperature that is almost the same as) the original bath filling set temperature (the temperature set by the user using the kitchen remote control 32A or the bathroom remote control 33B).

[0103] Furthermore, if the judgment result of STEP 42 is positive (if the 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 original bath filling set temperature, but the bathwater can be heated to the bath filling set temperature by the reheating process after filling.

[0104] [Other embodiments] The present invention is not limited to the above-described embodiment, and other embodiments may be adopted. Some of the other embodiments are exemplified below. In the first and second embodiments, a hot water supply system 1 in which a bathtub is not connected to the main hot water heater 2A has been exemplified, but a bathtub may also be connected to the main hot water heater 2A. Even in this case, when supplying hot water to the hot water tap CL while the hot water filling operation in the main hot water heater 2A is stopped, the same effect as in the first or second embodiment can be achieved by controlling the operation of the main hot water heater 2A and the auxiliary hot water heater 2B in the same way as in the first or second embodiment.

[0105] In the second embodiment, it is also possible to omit one of the processes in steps 41 and 42. For example, when omitting the process in step 41, it is possible to determine in step 42 whether the hot water filling set temperature is equal to or greater than the hot water supply installation temperature, and if the result of the determination is affirmative (including when the hot water filling set temperature = the hot water supply set temperature), to perform hot water supply operation in auxiliary hot water heater 2B, and if the result is negative (when the hot water filling set temperature < the hot water supply set temperature), to not perform hot water supply operation in auxiliary hot water heater 2B (to perform the process in step 43).

[0106] Furthermore, if the judgment result of STEP 41 is positive (if the bath filling set temperature matches (or nearly matches) the hot water supply set temperature), the supply of hot water to the hot water tap CL and the supply of hot water (filling) to the bathtub BTB may be performed with the bath filling set temperature that matches (or nearly matches) the hot water supply set temperature as the target hot water supply temperature.

[0107] Furthermore, in the first embodiment, while the auxiliary water heater 2B is performing a hot water filling operation, the control device 31B of the auxiliary water heater 2B is not requested to start supplying hot water even in a situation where the amount of heat required for hot water supply is greater than the upper limit of the heat quantity, and in the second embodiment, when the auxiliary water heater 2B is performing a hot water filling operation and the judgment results of STEPs 41 and 42 are negative, the control device 31A of the main water heater 2A is not requested to the control device 31B of the auxiliary water heater 2B to start supplying hot water even in a situation where the amount of heat required for hot water supply is greater than the upper limit of the heat quantity. However, in these situations, while the control device 31A of the main water heater 2A requests the control device 31B of the auxiliary water heater 2B to start supplying hot water, the auxiliary water heater 2B may ignore the request (keep the hot water supply on-off valve 26 closed even if the request is received).

[0108] In the first and second embodiments described above, the first and second hot water supply target portions of the present invention are the hot water tap CL and the bathtub BTB, respectively. However, the first and second hot water supply target portions of the present invention may be different from those described above. For example, the second hot water supply target portion may be a hot water tap other than the hot water tap CL, or a dishwasher, etc.

[0109] 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.

[0110] 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]

[0111] 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 (flow rate adjustment valve), 26...hot water on / off valve (on / off valve), 31A, 31B...control device, CL...hot water tap (first hot water supply target part), BTB...bathtub (second hot water supply target part).

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 further wherein an on-off valve is attached to a flow passage that distributes the hot water from the hot water supply passage of the second water heater to the first hot water supply target portion, a flow rate regulating valve capable of regulating the flow rate of hot water supply water flowing from the first hot water heater to the first hot water supply target part; When a target temperature of the hot water supply water for the first hot water supply target part is defined as a first target hot water supply temperature, a hot water supply heat quantity required to raise the temperature of the hot water supply water supplied to the first hot water supply target part to the first target hot water supply temperature, and an upper limit value of the heat quantity that can be input to the hot water supply water from the heating part of the first hot water heater is defined as an upper limit heat quantity, and a predetermined condition is met when a determination result of whether the hot water supply heat quantity is greater than the upper limit heat quantity is affirmative, The control device has a function of executing a first control process to control the operation of the first water heater and the flow rate adjustment valve so that hot water at the first target hot water supply temperature is supplied from the first water heater to the first hot water supply target portion when the predetermined condition is met while hot water supply from the second water heater to the second hot water supply target portion is stopped, and to control the operation of the on-off valve and the second water heater so that hot water at the first target hot water supply temperature is supplied from the second water heater to the first hot water supply target portion while the on-off valve is open; A hot water supply system characterized in that, when hot water is supplied to the first hot water supply target portion while controlling the operation of the second hot water heater to supply hot water from the second hot water supply target portion, the system is configured to have the function of executing a second control process that controls the operation of the on-off valve and the second water heater so that hot water at a second target hot water supply temperature, which is the target temperature of the hot water for the second hot water supply target portion, is supplied from the second hot water heater to the second hot water supply target portion, regardless of whether the specified condition is met, and controls the operation of the first water heater and the flow rate control valve so that hot water at the first target hot water supply temperature is supplied from the first water heater to the first hot water supply target portion.

2. 2. The hot water supply system according to claim 1, The control device is configured to execute the second control process when supplying hot water to the first hot water supply target area while controlling the operation of the second water heater so that the second water heater supplies hot water to the second hot water supply target area, if the second target hot water supply temperature does not match the first target hot water supply temperature, and when the second target hot water supply temperature matches the first target hot water supply temperature, to control the operation of the on-off valve and the second water heater so that the second water heater supplies hot water at the first target hot water supply temperature or the second target hot water supply temperature to the first hot water supply target area and the second hot water supply target area, while keeping the on-off valve open, and to execute a third control process to control the operation of the first water heater and the flow rate control valve so that the first water heater supplies hot water at the first target hot water supply temperature or the second target hot water supply temperature to the first hot water supply target area.

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 further wherein an on-off valve is attached to a flow passage that distributes the hot water from the hot water supply passage of the second water heater to the first hot water supply target portion, a flow rate regulating valve capable of regulating the flow rate of hot water supply water flowing from the first hot water heater to the first hot water supply target part; The control device has a function of executing a first control process to control the operation of the first water heater and the flow rate adjustment valve so that hot water at a first target hot water temperature, which is a target temperature for the hot water for the first hot water supply target portion, is supplied from the first water heater to the first hot water supply target portion when a predetermined condition regarding the need for hot water supply from the second water heater to the first hot water supply target portion is met while hot water supply from the second water heater to the second hot water supply target portion is stopped and the operation of the on-off valve and the second water heater so that hot water at the first target hot water temperature is supplied from the second water heater to the first hot water supply target portion while the on-off valve is open; When hot water is supplied to the first hot water supply target portion while controlling the operation of the second hot water heater to supply hot water from the second hot water heater to the second hot water supply target portion, the control unit is configured to have a function of executing a second control process that controls the operation of the on-off valve and the second hot water heater so that 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, is supplied from the second hot water heater to the second hot water supply target portion, regardless of whether the predetermined condition is met, and controls the operation of the first hot water heater and the flow rate adjustment valve so that hot water of the first target hot water supply temperature is supplied from the first hot water heater to the first hot water supply target portion, the first hot water supply target portion is a hot water tap, and the second hot water supply target portion is a bathtub, The control device is configured to execute the second control process when supplying hot water to the first hot water supply target portion while controlling the operation of the second water heater so that the second water heater supplies hot water to the second hot water supply target portion, if the second target hot water supply temperature is lower than the first target hot water supply temperature or is a temperature below the first target hot water supply temperature, and if the second target hot water supply temperature is a temperature above the first target hot water supply temperature or is higher than the first target hot water supply temperature, to control the operation of the on-off valve and the second water heater so that the second water heater supplies hot water at the first target hot water supply temperature to the first hot water supply target portion and the second hot water supply target portion, while keeping the on-off valve open, and to execute a fourth control process to control the operation of the first water heater and the flow rate control valve so that the first water heater supplies hot water at the first target hot water supply temperature to the first hot water supply target portion.

4. 4. The hot water supply system according to claim 3, The control device is configured to execute a third control process in which, when a request for hot water supply to the first hot water supply target portion occurs while controlling the operation of the second water heater so that the second water heater supplies hot water to the second hot water supply target portion, and when the second target hot water supply temperature matches the first target hot water supply temperature, the control device controls the operation of the on-off valve and the second water heater so that the second water heater supplies hot water at the first target hot water supply temperature or the second target hot water supply temperature to the first hot water supply target portion and the second hot water supply target portion, while opening the on-off valve, and controls the operation of the first water heater and the flow rate control valve so that the first water heater supplies hot water at the first target hot water supply temperature or the second target hot water supply temperature to the first hot water supply target portion.

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