Hot water supply method, system, program, recording medium, hot water supply unit, and control unit

Abstract

To suppress dramatic increase of hot water discharged from a second hot water supply unit when discharged hot water from a first hot water supply unit is discharged through the second hot water supply unit by connecting at least the first hot water supply unit and the second hot water supply unit.SOLUTION: There is provided a hot water supply method or a hot water supply system (2), in which at least a first hot water supply unit (4-1) and a second hot water supply unit (4-2) are connected, hot water discharged from the first hot water supply unit is received by the second hot water supply unit, and then hot water is discharged from the second hot water supply unit. A flow rate sensor (20) detects a water supply flow rate. By using thresholds of a first discharged hot water temperature corresponding to a discharged hot water temperature or less of a minimum discharged hot water amount discharged from the second hot water supply unit, a second discharged hot water temperature exceeding the first discharged hot water temperature, and a water supply flow rate that may realize hot water discharge in a level of at least the minimum discharged hot water amount, a control part (9) sets the first discharged hot water temperature in a case where the flow rate detected by the flow rate sensor is the threshold or less, and sets the second discharged hot water temperature in a case where the flow rate exceeds the threshold.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a hot water supply technology for a hot water supply system that supplies hot water by connecting two or more hot water supply units. [Background technology]

[0002] For example, SOFC (Solid Oxide Fuel C Hot water supply systems that combine a hot water supply unit that uses the exhaust heat of a fuel cell (solid oxide fuel cell) as a heat source with a hot water supply unit that uses, for example, the combustion heat of a fuel gas as a heat source have been put into practical use.

[0003] In a hot water supply system equipped with multiple hot water supply units that use different heat sources, there are two types of control: coordinated control, which coordinates the operation of the multiple hot water supply units, and standalone control, which does not coordinate the operation of the hot water supply units. In standalone control, for example, an arbitrary hot water supply unit is installed on the hot water outlet side of a hot water supply unit that includes an SOFC, allowing for independent hot water supply.

[0004] With regard to such hot water supply systems, in which a heat source supply unit equipped with a fuel cell system is connected to an auxiliary heater and hot water is supplied from the heat source supply unit to the auxiliary heater, it is known that the temperature of the hot water received by the auxiliary heater is controlled on the heat source supply unit side (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2018-4224 A Summary of the Invention [Problem to be solved by the invention]

[0006] Incidentally, when the hot water supply unit is operated in stand-alone mode, i.e. when the upstream and downstream hot water supply units are not controlled in a coordinated manner, the outlet temperature of the upstream hot water supply unit is fixed at, for example, 30° C. In other words, the upstream hot water supply unit outputs hot water at 30° C., and hot water at this outlet temperature is supplied to the downstream hot water supply unit.

[0007] In this case, if the latter stage hot water supply unit is a so-called direct heating type hot water heater that directly heats hot water with combustion heat, the minimum hot water outlet temperature tends to be higher than in the case of a so-called indirect heating type hot water heater that indirectly heats hot water with a heating medium. Therefore, even if the outlet temperature of the former stage hot water supply unit is set to 30°C, the latter stage hot water supply unit may output hot water at a temperature higher than the set temperature depending on the supply flow rate from the former stage hot water supply unit.

[0008] For example, if the outlet temperature of the front hot water supply unit is 30°C and the water supply flow rate is 3 liters / minute, the outlet temperature of the rear hot water supply unit will be 55°C.Also, even if the outlet temperature of the front hot water supply unit is 30°C, if the water supply flow rate is 10 liters / minute, the outlet temperature of the rear hot water supply unit may be 38°C.

[0009] In this case, even if the outlet hot water temperature setting on the remote control of the downstream hot water supply unit is 40 [°C], if the water supply flow rate is 3 [liters / minute], the outlet hot water temperature will be raised to 55 [°C], and there is a problem that the outlet hot water temperature cannot be made below 55 [°C].

[0010] The present disclosure is based on the consideration that the dependence of the outlet hot water temperature in standalone mode on a downstream hot water supply unit reduces the convenience of the hot water supply system, and on the knowledge that even if a direct heating type water heater is used in the downstream hot water supply unit, preventing the outlet hot water temperature from becoming too high by controlling the water supply flow rate enhances the convenience of the hot water supply system.

[0011] Therefore, based on the above problems and findings, the object of the present invention is to connect at least a first hot water supply unit and a second hot water supply unit, and suppress a sudden increase in the hot water temperature from the second hot water supply unit when the hot water from the first hot water supply unit is discharged through the second hot water supply unit. [Means for solving the problem]

[0012] In order to achieve the above object, according to one aspect of the hot water supply method of the present disclosure, at least a first hot water supply unit and a second hot water supply unit are connected, hot water discharged from the first hot water supply unit is received by the second hot water supply unit, and hot water is supplied from the second hot water supply unit, the method comprising: Flowed into the first hot water supply unit A step of detecting a water supply flow rate; , small At least The second hot water supply unit The water supply flow rate at which hot water can be dispensed at the minimum number of dispensed hot water is set as a threshold value, and the flow rate sensor detects water supply If the flow rate is equal to or less than the threshold, The temperature of the hot water outlet of the first hot water supply unit is set to a temperature equal to or lower than the temperature of the hot water outlet of the second hot water supply unit for the lowest hot water outlet number. First outlet temperature To Setting detection If the water supply flow rate exceeds the threshold, The temperature of the hot water outlet of the first hot water supply unit is made to exceed the first hot water outlet temperature. Second outlet temperature To and setting the

[0013] This hot water supply method may further include a step of a timer measuring the elapsed time from the start of hot water supply, and a step of the control unit maintaining the first hot water outlet temperature if the elapsed time is less than a predetermined time.

[0014] In this hot water supply method, the control unit further detection The water supply flow rate is monitored. detection The method may include controlling a transition time from the second hot water outlet temperature to the first hot water outlet temperature to be shorter than a transition time from the first hot water outlet temperature to the second hot water outlet temperature in response to fluctuations in water supply flow rate.

[0015] This hot water supply method may further include a step of setting the first outlet hot water temperature to a temperature equal to or higher than the minimum hot water number at which the second hot water supply unit can dispense hot water and equal to or lower than the temperature at which hot water can be dispensed.

[0016] In order to achieve the above object, according to one aspect of a hot water supply system of the present disclosure, there is provided a hot water supply system including at least a first hot water supply unit and a second hot water supply unit, the first hot water supply unit receiving hot water from the second hot water supply unit, and the second hot water supply unit supplying hot water, Flowed into the first hot water supply unit A flow sensor that detects the water supply flow rate , small At least The second hot water supply unit The water supply flow rate at which hot water can be dispensed at the minimum number of dispensed hot water is set as a threshold value, and the flow rate sensor detects water supply If the flow rate is equal to or less than the threshold, The temperature of the hot water outlet of the first hot water supply unit is set to a temperature equal to or lower than the temperature of the hot water outlet of the second hot water supply unit for the lowest hot water outlet number. First outlet temperature To Setting detection If the water supply flow rate exceeds the threshold, The temperature of the hot water outlet of the first hot water supply unit is made to exceed the first hot water outlet temperature. Second outlet temperature To and a control unit for setting the

[0017] This hot water supply system may further include a timer that measures the elapsed time from the start of hot water supply, and the control unit may maintain the first hot water outlet temperature if the elapsed time is less than a predetermined time.

[0018] In the hot water supply system, the control unit further controls the first hot water supply unit to detection The water supply flow rate is monitored. detection A transition time from the second hot water outlet temperature to the first hot water outlet temperature may be controlled to be shorter than a transition time from the first hot water outlet temperature to the second hot water outlet temperature in response to fluctuations in the water supply flow rate.

[0019] In this hot water supply system, the control unit may further set the first outlet hot water temperature to a temperature equal to or higher than a minimum hot water number at which the second hot water supply unit can dispense hot water and equal to or lower than the temperature at which hot water can be dispensed.

[0020] In order to achieve the above object, according to one aspect of a program of the present disclosure, the program is executed by a computer, and includes: , flowed into the first hot water unit. Ability to obtain water supply information , small At least By the second hot water unit The water supply flow rate at which hot water can be dispensed at the minimum number of dispensed hot water is set as a threshold value, and the flow rate sensor detects water supply If the flow rate is equal to or less than the threshold, The temperature of the hot water outlet of the first hot water supply unit is set to a temperature equal to or lower than the temperature of the hot water outlet of the second hot water supply unit for the lowest hot water outlet number. First outlet temperature To Setting detection If the water supply flow rate exceeds the threshold, The temperature of the hot water outlet of the first hot water supply unit is made to exceed the first hot water outlet temperature. Second outlet temperature To and causing the computer to execute the function of setting.

[0021] This program may further cause the computer to execute a function of acquiring elapsed time information from a timer that measures the elapsed time from the start of hot water dispensing, and a function of maintaining the first hot water dispensing temperature if the elapsed time is less than a predetermined time.

[0022] In this program, the first hot water supply unit detection The water supply flow rate is monitored. detection A time required for transition from the first hot water outlet temperature to the second hot water outlet temperature in response to fluctuations in the water supply flow rate. ,before The transition time from the second heated water outlet temperature to the first heated water outlet temperature may be controlled to be short.

[0023] In order to achieve the above object, one aspect of a recording medium of the present disclosure is a recording medium storing the program.

[0024] In order to achieve the above object, according to one aspect of the hot water supply unit of the present disclosure, the hot water supply unit is connected to at least another hot water supply unit, The hot water produced by heating the inflowing supply water is Hot water unit To serve A hot water supply unit for supplying hot water, Flowed in A flow sensor that detects the water supply flow rate , small At least The other hot water supply unit The water supply flow rate at which hot water can be dispensed at the minimum number of dispensed hot water is set as a threshold value, and the flow rate sensor detects water supply If the flow rate is equal to or less than the threshold, The temperature of the hot water to be supplied to the other hot water supply unit is set to a value lower than the temperature of the hot water to be supplied to the other hot water supply unit for the lowest hot water number. First outlet temperature To Setting detection If the water supply flow rate exceeds the threshold, The temperature of the hot water outlet supplied to the other hot water supply unit is set to exceed the first hot water outlet temperature. Second outlet temperature To and a control unit for setting the

[0025] In order to achieve the above-mentioned object, according to one aspect of a control unit of the present disclosure, the control unit is equipped with either a control unit included in the hot water supply system, the recording medium, or a control unit included in the hot water supply unit. Effect of the Invention

[0026] According to the present disclosure, any of the following effects can be obtained. (1) The flow rate of water entering the first hot water supply unit is monitored, and the temperature of the hot water entering the second hot water supply unit from the first hot water supply unit is reduced, thereby preventing the hot water temperature at the outlet of the second hot water supply unit from becoming too high.

[0027] (2) When the water supply flow rate entering the first hot water supply unit is low, the outlet temperature of the hot water entering the second hot water supply unit from the first hot water supply unit is suppressed to below the outlet temperature of the second hot water supply unit's minimum outlet number. Therefore, even if a direct heating type water heater is used for the second hot water supply unit, the outlet temperature of the second hot water supply unit can be prevented from becoming too high. [Brief description of the drawings]

[0028] [Figure 1] 1 is a diagram showing a hot water supply system according to a first embodiment; [Diagram 2] FIG. 2 is a diagram illustrating an example of a heat source unit. [Diagram 3] FIG. 2 is a diagram illustrating hardware of a control unit and a remote control unit. [Figure 4] FIG. 2 is a diagram showing functional parts of the hot water supply system according to the first embodiment. [Diagram 5] 11 is a flowchart showing a processing procedure for hot water discharge control. [Figure 6] FIG. 4 is a diagram showing an example of hot water discharge control. [Figure 7] FIG. 11 is a diagram showing hardware of a control unit in a hot water supply system according to a second embodiment. [Figure 8] FIG. 11 is a diagram showing functional parts of a hot water supply system according to a second embodiment. [Figure 9] 11 is a flowchart showing a processing procedure for hot water discharge control. [Figure 10] FIG. 4 is a diagram showing an example of hot water discharge control. [Figure 11] FIG. 11 is a diagram showing functional parts of a hot water supply system according to a third embodiment. [Figure 12] 11 is a flowchart showing a processing procedure for hot water discharge control. [Figure 13] FIG. 4 is a diagram showing an example of hot water discharge control. [Figure 14] 13A to 13C are diagrams illustrating the valve opening degree of a mixing valve and its control in a hot water supply system according to a fourth embodiment. [Figure 15] FIG. 4 is a diagram showing an example of hot water discharge control. [Figure 16] FIG. 4 is a diagram showing information presentation of the remote control unit according to the first embodiment. [Figure 17] FIG. 11 is a diagram showing another hot water supply unit in the hot water supply system according to the second embodiment. [Figure 18] FIG. 11 is a diagram showing a hot water supply system according to a third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] First Embodiment FIG. 1 shows a hot water supply system according to a first embodiment. This hot water supply system 2 is an example of the hot water supply system of the present disclosure, and includes a first hot water supply unit 4-1 and a second hot water supply unit 4-2 as an example of at least two hot water supply units, and each of the hot water supply units 4-1 and 4-2 constitutes a stand-alone hot water heater that is operated independently. For example, the hot water supply unit 4-2 is a direct heating type hot water heater that directly heats hot water with combustion heat or exhaust heat. In the present application, an indirect heating type is a heating type that uses a heat medium heated by combustion heat or exhaust heat as a medium.

[0030] In this hot water supply system 2, when supplying hot water, the hot water supply unit 4-1 receives the water supply W, and supplies the hot water HW1, which is the hot water outlet of the hot water supply unit 4-1, to the hot water supply unit 4-2. In the hot water supply unit 4-1, a threshold value Lth is set for the water supply flow rate L, and the water supply flow rate L is monitored. If the water supply flow rate L is equal to or less than the threshold value Lth, the outlet water temperature HWT of the hot water supply unit 4-1 is set to a first outlet water temperature HWT-1, and if the water supply flow rate L exceeds the threshold value Lth, the outlet water temperature HWT is set to a second outlet water temperature HWT-2 that exceeds the outlet water temperature HWT-1. The outlet water temperature HWT-1 is an outlet water temperature that corresponds to a temperature equal to or less than the outlet water temperature of the minimum outlet water number at which the hot water supply unit 4-2 can dispense hot water. A threshold value Lth is set for the water supply flow rate L for switching between the outlet water temperature HWT-1 and the outlet water temperature HWT-2. This threshold value Lth represents the water supply flow rate at which the hot water supply unit 4-2 can dispense hot water at least at the minimum outlet water number. The outlet temperature HWT-1 is a low temperature that is equal to or higher than the minimum outlet number (e.g., No. 3) of the hot water supply unit 4-2 and can be discharged. For example, if hot water HW with a supply water temperature of +25°C can be discharged at 1 liter per minute, the outlet number is defined as No. 1 (see page 87 of the 2018 revised edition of the City Gas Industry Overview (Consumption Equipment Edition) [Japan Gas Association]). Therefore, if the supply water flow rate L is equal to or lower than the threshold value Lth, hot water is discharged at the outlet temperature HWT-1, and if the supply water flow rate L exceeds the threshold value Lth, the outlet temperature HWT-2 is set to be higher than the outlet temperature HWT-1.

[0031] <Hot water supply unit 4-1> This hot water supply unit 4-1 is an example of a hot water supply unit of the present disclosure. This hot water supply unit 4-1 is equipped with a heat storage tank 6, a heat exchanger 8, a control unit 9, and the like. The heat storage tank 6 stores heat using a heat medium HM1 that is heated by a heat source unit 10. As the heat medium HM1, a fluid such as water that can flow and can be heated by the heat source unit 10 is used.

[0032] The heat source unit 10 is equipped with, for example, an SOFC (solid oxide fuel cell) as a heat source, and heats the heat medium HM1 with the exhaust heat generated by the power generation of this SOFC. The heat medium HM1 is stored in a heat storage tank 6, and the heat medium HM1 taken out from the lower layer area is circulated to the heat source unit 10 to exchange heat with the exhaust heat of the SOFC, and after being heated by this heat exchange, is returned to the upper layer area of ​​the heat storage tank 6. Therefore, in the heat storage tank 6, hierarchical heat storage is performed in which the heat storage temperature is raised from the lower layer area to the upper layer area. A temperature sensor 12 detects the heat medium temperature T in the upper layer area of ​​the heat storage tank 6.

[0033] The heat exchanger 8 exchanges heat between the heat medium HM1 and the feed water W, and heats the feed water W with the heat of the heat medium HM1. The heat medium HM1 taken out from the upper region of the heat storage tank 6 flows into the heat medium path 14. By driving the circulation pump 16 installed in this heat medium path 14, the heat medium HM1 taken out from the upper region of the heat storage tank 6 is circulated to the heat exchanger 8, and after heat exchange with the feed water W, is returned to the lower region of the heat storage tank 6.

[0034] When supplying hot water, for example, supply water W flows from water supply passage 18 into heat exchanger 8 due to top water pressure. A flow rate sensor 20 installed in water supply passage 18 detects the flow rate of supply water W flowing into water supply passage 18. This allows the supply water flow rate L entering hot water supply unit 4-1 to be detected.

[0035] The water supply passage 18 is provided with a bypass passage 22 for allowing the water supply W to flow to the hot water outlet side, bypassing the heat exchanger 8. This bypass passage 22 branches off from the water supply passage 18 on the inlet side of the heat exchanger 8, and is connected to the hot water outlet passage 26 via a mixing valve 24 installed on the hot water outlet side of the heat exchanger 8.

[0036] The mixing valve 24 mixes the hot water HW obtained in the heat exchanger 8 with the supply water W to obtain hot water HW1. The hot water HW1, whose outlet temperature has been adjusted according to the mixing ratio of the hot water HW and the supply water W set in the mixing valve 24, is discharged from the outlet hot water passage 26.

[0037] The control unit 9 is composed of, for example, a computer with a communication function. The control unit 9 receives the flow rate detected by the flow rate sensor 20, the temperature detected by the temperature sensor 12, and the like, and performs control including driving the circulation pump 16 and adjusting the mixing ratio of the hot water HW and the feed water W in the mixing valve 24, and switching between the outlet hot water temperatures HWT-1 and HWT-2 of the hot water supply unit 4-1.

[0038] A remote control unit 30 is connected to control unit 9 via a wired or wireless connection. This remote control unit 30 is composed of a computer capable of communicating with control unit 9 and the like, and monitors the water supply flow rate L of hot water supply unit 4-1, sets and switches outlet hot water temperatures HWT-1 and HWT-2, presents information such as the outlet hot water temperature, etc. The control of control unit 9 includes setting a threshold value Lth for the water supply flow rate L described above, monitoring the water supply flow rate L, setting the outlet hot water temperatures HWT-1 and HWT-2, and maintaining or switching them.

[0039] <Hot water supply unit 4-2> In this hot water supply unit 4-2, a direct heating type hot water heater is used which exchanges heat between hot water HW1, which is the hot water discharged from hot water supply unit 4-1, and combustion heat.

[0040] This hot water supply unit 4-2 is connected to the preceding hot water supply unit 4-1 via a connecting passage 32. The hot water outlet passage 26 of the hot water supply unit 4-1 and the water supply passage 34 of the hot water supply unit 4-2 are connected by the connecting passage 32. Therefore, during hot water supply, hot water HW1 generated in the hot water supply unit 4-1 flows through the connecting passage 32 into the water supply passage 34 of the hot water supply unit 4-2.

[0041] This hot water supply unit 4-2 is equipped with a flow sensor 35, a burner 36, a primary heat exchanger 38, a secondary heat exchanger 40, a mixing valve 42, and a control unit 43. The flow sensor 35 detects the supply water flow rate L of hot water HW1 entering the hot water supply unit 4-2 from the hot water supply unit 4-1.

[0042] The burner 36, for example, burns fuel gas G to generate combustion exhaust. The primary heat exchanger 38 is installed upstream of the combustion exhaust and exchanges mainly sensible heat from the combustion exhaust with the medium to be heated. The secondary heat exchanger 40 is installed downstream of the combustion exhaust and exchanges mainly latent heat from the combustion exhaust with the medium to be heated. In other words, the hot water HW1 exchanges heat with the downstream combustion exhaust in the secondary heat exchanger 40, then circulates to the primary heat exchanger 38 and exchanges heat with the upstream combustion exhaust, and hot water HW2 is discharged.

[0043] The water supply passage 34 is provided with a bypass passage 44 for flowing the hot water HW1 to the hot water outlet side, bypassing the primary heat exchanger 38 and the secondary heat exchanger 40. This bypass passage 44 branches off from the water supply passage 34 at the inlet side of the secondary heat exchanger 40, and is connected to the hot water outlet passage 45 via a mixing valve 42 installed on the hot water outlet side of the primary heat exchanger 38. In other words, the hot water HW1 that bypasses the primary heat exchanger 38 and the secondary heat exchanger 40 flows to the mixing valve 42 according to the ratio of the valve opening degree on the bypass passage 44 side of the mixing valve 42 to the valve opening degree on the primary heat exchanger 38 side.

[0044] Control unit 43 is, for example, composed of a computer with a communication function, and when hot water supply unit 4-1 is in stand-alone mode, controls hot water supply unit 4-2 separately from hot water supply unit 4-1. Control unit 43 receives the flow rate detected by flow rate sensor 35, the temperature detected by temperature sensor 47, and the like, and adjusts the combustion of burner 36 and the mixing ratio of hot water HW1 and hot water HW2 in mixing valve 42, and controls the outlet temperature of hot water supply unit 4-2. In other words, control unit 43 outputs hot water HW3 from outlet path 45, which has been adjusted to the outlet temperature set for hot water supply unit 4-2, according to the water supply flow rate L and the outlet temperature HWT of hot water HW1 that hot water supply unit 4-2 receives from hot water supply unit 4-1.

[0045] <Heat source unit 10> As shown in Fig. 2, the heat source unit 10 includes, for example, an SOFC 37, a heat exchanger 39, and a circulation pump 41. Exhaust gas generated by power generation in the SOFC 37 is used to heat the heat medium HM2. During heat exchange, the circulation pump 41 is operated to circulate the heat medium HM1 from the lower layer side of the heat storage tank 6 to the heat exchanger 39. The heat exchanger 39 exchanges heat between the heat mediums HM1 and HM2, and heats the heat medium HM1 with the heat medium HM2. The heated heat medium HM1 is returned to the upper layer side of the heat storage tank 6 and heat is stored therein.

[0046] <Hardware of the control unit 9 and the remote control unit 30> 3 shows an example of hardware of the control unit 9 and the remote control unit 30. In this embodiment, the control unit 9 and the remote control unit 30 are connected by wire, but may be connected wirelessly using Wi-Fi or the like.

[0047] <Control Unit 9> Control unit 9 includes a processor 46, a memory unit 48, an input / output (I / O) unit 50, and a communication unit 52. Processor 46 executes a control program including an OS (Operating System) and hot water outlet control stored in memory unit 48, monitors the water supply flow rate L flowing to hot water supply unit 4-1, and controls the hot water outlet temperature HWT, etc.

[0048] Storage unit 48 includes storage elements such as a ROM (Read-Only Memory) and a RAM (Random-Access Memory). The ROM stores an OS, a hot water supply control program, control data, a database 78 (FIG. 4), etc. The RAM constitutes a work area for information processing.

[0049] Under the control of the processor 46, the I / O 50 acquires detection information from the temperature sensor 12, the flow rate sensor 20, etc., and outputs control signals for controlling the drive of the circulating pump 16, controlling the valve opening degree of the mixing valve 24, etc. The communication unit 52 communicates with the remote control unit 30 under the control of the processor 46.

[0050] <Remote control unit 30> Remote control unit 30 includes a remote control control unit 56, a communication unit 58, an input operation unit 60, and an LCD (Liquid Crystal Display) display unit 62. Like control unit 9, remote control control unit 56 includes a processor, a storage unit, an input / output unit, etc., and links with hot water supply unit 4-1. At this time, communication unit 58 communicates with communication unit 52 of hot water supply unit 4-1 under the control of remote control control unit 56.

[0051] The input operation unit 60 is used for inputting information such as mode settings such as stand-alone mode and outlet hot water temperature settings of the hot water supply unit 4-1 under the control of the remote control control unit 56. This input operation unit 60 may be a touch sensor that covers the screen of the LCD display unit 62.

[0052] The LCD display unit 62 is an example of an information presentation unit in the present disclosure, and is used to present information such as mode information, outlet hot water temperature information, and operating status information.

[0053] <Functional parts of hot water supply unit 4-1> The hot water supply unit 4-1 of this first embodiment sets a threshold value Lth for the hot water supply flow rate L and monitors the hot water supply flow rate L entering the hot water supply unit 4-1, and performs control to set, maintain or switch a first hot water outlet temperature HWT-1 and a second hot water outlet temperature HWT-2 (>HWT-1) as the hot water outlet temperature for the hot water supply unit 4-2, and this control involves multiple functional parts.

[0054] Fig. 4 shows the functional parts included in hot water supply unit 4-1 for realizing the hot water discharge control described above. The configuration shown in Fig. 4 is an example of the functional parts of hot water supply unit 4-1 of the present disclosure, and the present disclosure is not limited to such a configuration.

[0055] As shown in Figure 4, this functional unit includes a mode setting unit 64, an outlet hot water temperature setting unit 66, a mode determination unit 68, a threshold setting unit 70, an outlet hot water determination unit 71, a water supply flow rate determination unit 72, an outlet hot water temperature switching unit 74, a control information acquisition unit 76, a database 78, and a presentation information generation unit 80.

[0056] Mode setting unit 64 cooperates with remote control unit 30 under the control of processor 46, receives a mode setting input from input operation unit 60 of remote control unit 30, and sets, as the operation mode of hot water supply unit 4-1, a stand-alone mode in which hot water supply units 4-1, 4-2 operate independently, or a non-stand-alone mode in which the controls of hot water supply units 4-1, 4-2 are coordinated. In other words, the stand-alone mode is a hot water outlet mode in hot water supply unit 4-1 for changing the outlet hot water temperature in accordance with the water supply flow rate L.

[0057] Outlet hot water temperature setting unit 66 receives outlet hot water temperature setting input from input operation unit 60 of remote control unit 30 as the outlet hot water temperature HWT of hot water supply unit 4-1 under the control of processor 46, and sets outlet hot water temperatures HWT-1 and HWT-2 in control unit 9 of hot water supply unit 4-1. Outlet hot water temperature HWT-1 is a value lower than the outlet hot water temperature of the lowest outlet hot water number in hot water supply unit 4-2, for example.

[0058] For example, during the initial setup of hot water supply system 2, mode determination unit 68 determines the setting mode that is initially set by the control of processor 46. That is, the setting mode is determined to be either stand-alone mode or non-stand-alone mode. If it is non-stand-alone mode, the control of hot water supply units 4-1, 4-2 is coordinated, so that the control of the present disclosure and the setting of the hot water outlet temperature of hot water supply unit 4-1 are released and coordinated control is given priority.

[0059] The threshold setting section 70 is controlled by the processor 46 and sets the above-mentioned threshold Lth for determining the water supply flow rate L in response to operation of the input operation section 60 of the remote control unit 30 .

[0060] Under the control of the processor 46, the hot water discharge determination unit 71 monitors the detected flow rate of the flow sensor 20, and determines that hot water discharge has started when the water supply flow rate L changes from L=0 to L, and determines that hot water discharge has stopped when the water supply flow rate L transitions to L=0.

[0061] The water supply flow rate determination unit 72, under the control of the processor 46, monitors the flow rate detected by the flow rate sensor 20, compares the water supply flow rate L with a threshold value Lth, and determines whether the water supply flow rate L is equal to or less than the threshold value Lth or exceeds the threshold value Lth.

[0062] Under the control of processor 46, outlet hot water temperature switching unit 74 switches the outlet hot water temperature HWT between outlet hot water temperatures HWT-1 and HWT-2 in accordance with the water supply flow rate L. In this case, if the water supply flow rate L is equal to or less than threshold value Lth, the outlet hot water temperature HWT-1 is set, or if the current outlet hot water temperature HWT is HWT-2, it is switched to HWT-1.

[0063] If the water supply flow rate L exceeds the threshold value Lth, the outlet hot water temperature HWT is switched from HWT-1 to HWT-2, or if the current outlet hot water temperature HWT is HWT-2, it is maintained at HWT-2.

[0064] The control information acquisition unit 76, under the control of the processor 46, acquires various types of control information such as setting mode information, threshold information, and outlet hot water temperature information.

[0065] Under the control of processor 46, database 78 stores the above-mentioned mode information, threshold information, outlet hot water temperature information, outlet hot water temperature switching information, control history information, and the like acquired by control information acquisition unit 76 together with date and time information.

[0066] The presentation information generation unit 80 generates presentation information from the above-mentioned mode information, threshold information, outlet hot water temperature information, outlet hot water temperature switching information, control history information, etc. acquired by the control information acquisition unit 76 under the control of the processor 46. Any or all of this information is linked to the remote control unit 30 and presented on the LCD display unit 62.

[0067] <Control of outlet hot water temperature HWT of hot water supply unit 4-1> The control unit 9 receives the flow rate detected by the flow rate sensor 20 from the start of hot water supply, and if the supply water flow rate L is equal to or less than the threshold value Lth, for example, less than 6 [liters / min], sets the outlet hot water temperature HWT to outlet hot water temperature HWT-1. This outlet hot water temperature HWT-1 is set to a value equal to or less than the outlet hot water temperature of the lowest hot water number in the hot water supply unit 4-2, for example, 20 [°C].

[0068] If the water supply flow rate L exceeds the threshold value Lth, for example, 6 liters / min or more, the hot water outlet temperature HWT-2 (for example, 30°C) is changed to a temperature higher than the hot water outlet temperature HWT-1. That is, in this example, the hot water HW1 is changed to the hot water outlet temperature HWT-2, which is 10°C higher than the hot water outlet temperature HWT-1.

[0069] Fig. 5 shows a processing procedure for hot water supply control according to the first embodiment. This hot water supply control is an example of a hot water supply control method, program, etc. of the present disclosure. In Fig. 5, S indicates a process, and the numbers attached to S indicate the order of the processes.

[0070] The processing procedure for this hot water discharge control includes determining the setting mode (S101), setting the hot water discharge temperature (S102), determining whether to start discharging hot water (S103), measuring the water supply flow rate L (S104), determining the water supply flow rate L (S105), setting the hot water discharge temperature (S106, S107), presenting information (S108), and determining whether to stop discharging hot water (S109).

[0071] Determining the set mode (S101): Whether the hot water supply system 2 performs the hot water supply operation in a stand-alone mode or a non-stand-alone mode is set in the initial setting of the hot water supply unit 4-1. In this set mode determination (S101), the initially set mode is determined under the control of the processor 46.

[0072] Setting the outlet hot water temperature (S102): In the case of stand-alone mode, the outlet hot water temperature is set by the outlet hot water temperature setting unit 66 before hot water supply starts. In this case, outlet hot water temperatures HWT-1 and HWT-2 are set as the outlet hot water temperatures. As described above, the outlet hot water temperature HWT-1 is equal to or lower than the outlet hot water temperature of the lowest outlet hot water number in the hot water supply unit 4-2, for example, HWT-1=20°C. The outlet hot water temperature HWT-2 is a higher temperature that exceeds HWT-1.

[0073] Determining whether to start dispensing hot water (S103): This determination of whether to start dispensing hot water (S103) is made by the hot water dispense determination unit 71 under the control of the processor 46 when a demand for hot water is generated. For example, when a demand for hot water is generated, the flow rate is detected by the flow rate sensor 20. The control unit 9 may determine whether to start dispensing hot water based on the occurrence of a flow rate detected by the flow rate sensor 20.

[0074] Measurement of water supply flow rate L (S104): This measurement of the water supply flow rate L (S104) is performed by the flow rate sensor 20. The control unit 9, under the control of the processor 46, acquires water supply flow rate information from the detection output of the flow rate sensor 20 and records it in the memory unit 48.

[0075] Determination of water supply flow rate L (S105): The control unit 9 determines the water supply flow rate L under the control of the processor 46. It is determined whether the water supply flow rate L is equal to or less than a threshold value Lth or exceeds the threshold value Lth. The threshold value Lth is set to, for example, 6 [liters / minute].

[0076] Setting the outlet hot water temperature (S106, S107): If the water supply flow rate L is equal to or less than the threshold value Lth (YES in S105), the outlet hot water temperature is set to HWT-1 (S106); if it exceeds the threshold value Lth (NO in S105), the outlet hot water temperature is set to HWT-2 (S107).

[0077] Presentation of information (S108): The control unit 9 provides control information to the remote control unit 30 under the control of the processor 46. As a result, information such as a mode display, hot water dispense start information display, water supply flow rate information display, and hot water dispense stop information display is presented on the remote control unit 30.

[0078] Determining whether hot water is to be stopped (S109): Under the control of the processor 46, the control unit 9 determines whether hot water is to be stopped or not from the water supply flow rate L (S109). In other words, if hot water is not to be stopped (NO in S109), the process transitions to S104 to continue hot water supply, and if hot water is to be stopped (YES in S109), the process transitions to S101.

[0079] <An example of pouring control> FIG. 6 shows an example of hot water outlet control according to the first embodiment, where A shows the changes in water supply flow rates L1 and L2, B shows the switching between hot water outlet temperatures HWT-1 and HWT-2, and C shows the changes in the hot water outlet temperature HWT of hot water HW3.

[0080] In response to a demand for hot water, water supply is started to the hot water supply unit 4-1 at time t0. Figure 6A shows two water supply flow rates L1 and L2 with different increasing trends. Lth is a threshold for switching between the outlet hot water temperatures HWT-1 and HWT-2 with the water supply flow rate L as a parameter.

[0081] As shown in B of Figure 6, when the water supply flow rate L1 is equal to or less than the threshold value Lth, the outlet hot water temperature HWT-1 is set. The outlet hot water temperature HWT-1 starts to rise from time t1 when it exceeds threshold Lth, and is switched to outlet hot water temperature HWT-2 at time t2. In contrast, the water supply flow rate L2 increases more slowly than the water supply flow rate L1, so the outlet hot water temperature HWT-1 starts to rise from time t3 when it exceeds threshold Lth (in this case, t3>t2), and is switched to outlet hot water temperature HWT-2 at time t4. Ut is the time required to transition from outlet hot water temperature HWT-1 to outlet hot water temperature HWT-2 (= transition time).

[0082] Eventually, the water supply flow rate L1 or L2 decreases, passes the threshold value Lth at time t5, and then disappears at time t7. In this case, the outlet hot water temperature HWT-2 starts to decrease from time t5 when the water supply flow rate L1 falls below the threshold value Lth, and is switched to the outlet hot water temperature HWT-1 at time t6 before reaching time t7. Dt is the time required to transition from the outlet hot water temperature HWT-2 to the outlet hot water temperature HWT-1 (=transition time).

[0083] In response to switching between the outlet hot water temperatures HWT-1 and HWT-2 of the hot water supply unit 4-1, the outlet hot water temperature HWT of the hot water HW3 of the hot water supply unit 4-2 remains constant as shown in C of Fig. 6. ts is the time when the hot water supply unit 4-2 starts to discharge hot water, and HWTO is the target temperature.

[0084] <Transition time Ut, Dt> When the feed water flow rate L1 increases, the transition time Ut is the elapsed time between time points t1 and t2, and similarly, the elapsed time between time points t3 and t4. This transition time Ut may be varied according to the increasing tendencies of the feed water flow rates L1 and L2.

[0085] When the feed water flow rate L1 decreases, the transition time Dt is the elapsed time between time points t5 and t6. The magnitude relationship between the transition time Dt and the transition time Ut is set to Dt < Ut.

[0086] When the feed water flow rate L increases, the hot water outlet temperature is gently increased from the hot water outlet temperature HWT-1 to the hot water outlet temperature HWT-2, and when the feed water flow rate L decreases, it is quickly changed from the hot water outlet temperature HWT-2 to the hot water outlet temperature HWT-1. Thereby, a rapid temperature rise such as an overshoot of the hot water outlet temperature HW3 of the hot water supply unit 4-2 that receives the hot water HW1 from the hot water supply unit 4-1 and discharges hot water can be suppressed.

[0087] <Suppression of overshoot of the hot water outlet temperature of the hot water supply unit 4-2> At the time of hot water discharge, the primary heat exchanger 38 and the secondary heat exchanger 40 of the hot water supply unit 4-2 are supplied with heat from the burner 36 in an amount corresponding to the hot water outlet temperature HWT-2 from the hot water supply unit 4-1 and the feed water flow rate L. The combustion amount of the burner 36 and the valve opening degree of the mixing valve 42 of the hot water supply unit 4-2 are adjusted according to the feed water flow rate L.

[0088] When the feed water flow rate L decreases, the hot water supply unit 4-2 decreases the combustion amount of the burner 36 according to the feed water flow rate L, adjusts the mixing valve 42, and the hot water outlet temperature of the hot water HW3 is controlled to the set temperature. When the feed water flow rate L becomes equal to or less than the threshold value Lth, only the temperature control of the hot water supply unit 4-2 responds to the flow rate decrease, and the hot water HW1 from the hot water supply unit 4-1 can be quickly switched from the hot water outlet temperature HWT-2 to the hot water outlet temperature HWT-1. Thereby, the occurrence of a rapid temperature rise such as an overshoot of the hot water outlet temperature of the hot water HW3 of the hot water supply unit 4-2 is suppressed.

[0089] <Effects of the first embodiment> According to such a configuration, any of the following effects can be obtained. (1) The outlet hot water temperature HWT of the hot water supply unit 4-1 is restricted to the outlet hot water temperature HWT-1, and a sudden rise, such as an overshoot, in the outlet hot water temperature of the hot water supply unit 4-2 can be restricted.

[0090] (2) The water supply flow rate L to the hot water supply unit 4-1 is monitored, and if the water supply flow rate L is below a threshold value Lth, the outlet water temperature HWT-1 is maintained. If the water supply flow rate L exceeds the threshold value Lth, the outlet water temperature HWT-1 is switched to the outlet water temperature HWT-2, thereby utilizing the stored thermal energy.

[0091] (3) The transition time Dt is made shorter and quicker than the transition time Ut, so that a sudden increase in the outlet hot water temperature of the hot water supply unit 4-2 in response to a decrease in the water supply flow rate L can be prevented.

[0092] (4) The hot water supply unit 4-1 can be newly installed or modified regardless of the hot water supply specifications of the existing hot water supply unit 4-2, for example, an indirect heating type water heater using a plate heat exchanger, or a direct heating type water heater having a higher minimum hot water output number than an indirect heating type water heater, thereby realizing a highly convenient hot water supply system 2.

[0093] (5) Even if the hot water supply unit 4-1 of the present disclosure is an existing hot water supply unit, a hot water supply unit of any specification can be selected for the hot water supply unit 4-2 without being affected by the specifications of the existing hot water supply unit, thereby increasing user convenience.

[0094] (6) Feedback (FB) control or feedforward (FF) control is used for the hot water supply unit 4-2. Regardless of which control method is used, the transition time Ut can be made long so that the hot water outlet temperature rise of the hot water supply unit 4-1 can be accommodated, i.e., the rise in the hot water outlet temperature can be controlled to a gradual state.

[0095] Second Embodiment In addition to the control of the first embodiment, the second embodiment includes control for switching the outlet hot water temperature after a predetermined time has elapsed since the start of hot water outlet.

[0096] Fig. 7 shows a control unit 9 of a hot water supply unit 4-1 according to the second embodiment. In Fig. 7, the same parts as in Fig. 3 are given the same reference numerals.

[0097] The control unit 9 according to the second embodiment is provided with a timer 51. The timer 51 measures the hot water discharge time Ht, which is the time elapsed from the start of hot water discharge, under the control of the processor 46. A threshold value Hth is set for this hot water discharge time Ht, and this threshold value Hth is, for example, Hth=5 seconds.

[0098] <Functional parts of hot water supply unit 4-1> Fig. 8 shows the functional parts of a hot water supply unit 4-1 according to the second embodiment. In Fig. 8, the same parts as in Fig. 4 are given the same reference numerals. The functional parts of a hot water supply unit 4-1 according to the second embodiment include a hot water tapping time information acquisition part 82 and a hot water tapping time determination part 84 in addition to the functional parts shown in the first embodiment.

[0099] The mode setting unit 64, outlet hot water temperature setting unit 66, mode determination unit 68, threshold setting unit 70, outlet hot water determination unit 71, supply water flow rate determination unit 72, outlet hot water temperature switching unit 74, control information acquisition unit 76, database 78, and presentation information generation unit 80 are the same as in the first embodiment, so their explanation will be omitted.

[0100] Under the control of processor 46, hot water outlet time information acquisition unit 82 acquires from timer 51 hot water outlet time Ht, which is the elapsed time from the start of hot water supply (=start of water supply).

[0101] Under the control of the processor 46, the hot water outlet time determination unit 84 determines whether the hot water outlet time Ht is equal to or greater than a threshold value Hth, and provides the result of this determination as switching information for the hot water outlet temperature HWT.

[0102] The other functional parts are similar to those in the first embodiment, so they are given the same reference numerals and their explanations are omitted. The control information acquisition unit 76 acquires various types of control information such as setting mode information, threshold information, hot water outlet temperature information, hot water outlet time information, and threshold information related to the hot water outlet time under the control of the processor 46. This control information and other information is then provided to the database 78 and the presentation information generation unit 80, where it is stored in the database 78 and presented on the LCD display unit 62.

[0103] <Water discharge control> Fig. 9 shows a processing procedure for hot water supply control according to the second embodiment. This hot water supply control is an example of a hot water supply control method, program, etc. of the present disclosure. In Fig. 9, S indicates a process, and the numbers attached to S indicate the order of the processes.

[0104] The processing procedure for this hot water discharge control includes determining the setting mode (S201), setting the hot water discharge temperature (S202), determining whether to start discharging hot water (S203), measuring the hot water discharge time Ht (S204), measuring the water supply flow rate L (S205), determining the water supply flow rate L (S206), setting the hot water discharge temperature (S207), determining the hot water discharge time Ht (S208), setting the hot water discharge temperature (S209), presenting information (S210), and determining whether to stop discharging hot water (S211).

[0105] The determination of the setting mode (S201) is the same as the determination of the setting mode (S101) described above, the setting of the outlet water temperature (S202) is the same as the setting of the outlet water temperature (S102) described above, the determination of the start of outlet water discharge (S203) is the same as the determination of the start of outlet water discharge (S103) described above, the measurement of the water supply flow rate L (S205) is the same as the measurement of the water supply flow rate L (S104) described above, the determination of the water supply flow rate L (S206) is the same as the determination of the water supply flow rate L described above (S105), the setting of the outlet water temperature (S207) is the same as the setting of the outlet water temperature (S106) described above, and the setting of the outlet water temperature (S209) is the same as the setting of the outlet water temperature (S107) described above, so explanations thereof will be omitted.

[0106] Measuring hot water outlet time Ht (S204): Under the control of processor 46, timer 51 measures hot water outlet time Ht, which is the elapsed time from the start of hot water supply (start of water supply), and under the control of processor 46, hot water outlet time information acquisition unit 82 acquires the hot water outlet time information.

[0107] Determining hot water outlet time Ht (S208): Under the control of the processor 46, the hot water outlet time determination unit 84 determines whether the hot water outlet time Ht is equal to or greater than the threshold value Hth after determining the water supply flow rate L (S206). In other words, if the water supply flow rate L is not equal to or less than the threshold value Lth (NO in S206), the process waits until the hot water outlet time Ht becomes equal to or greater than the threshold value Hth. In this case, in determining the water supply flow rate L (S206), it is determined that the water supply flow rate L exceeds the threshold value Lth (NO in S206), so the water outlet temperature HWT-2 is set when the water outlet time Ht becomes equal to or greater than the threshold value Hth.

[0108] Presentation of information (S210): The control unit 9 provides control information to the remote control unit 30 under the control of the processor 46. As a result, information such as a mode display, hot water dispense start information display, water supply flow rate information display, hot water dispense time display, and hot water dispense stop information display is presented on the remote control unit 30.

[0109] Determining whether hot water is being dispensed (S211): Under the control of the processor 46, the control unit 9 determines whether hot water is being dispensed from the water supply flow rate L (S211). In other words, if hot water is not being dispensed (NO in S211), the process transitions to S204 to continue dispensing hot water, and if hot water is being dispensed (YES in S211), the process transitions to S201.

[0110] <An example of pouring control> Fig. 10 shows an example of hot water outlet control according to the second embodiment, where A shows the transition of the water supply flow rates L1 and L2, B shows the switching of the hot water outlet temperatures HWT-1 and HWT-2, and C shows the transition of the hot water outlet temperature HWT of the hot water HW3. In Fig. 10, the same parts as in Fig. 6 are given the same reference numerals.

[0111] In the second embodiment, the process of switching between outlet heated water temperatures HWT-1, HWT-2 using the water supply flow rate L as a parameter is similar to that in the first embodiment (FIG. 6), and therefore a description thereof will be omitted.

[0112] In the second embodiment, as shown in A of Fig. 10, the time from time t10 when water supply starts to time t12 is set as a threshold value Hth. The hot water discharge time Ht is determined by this threshold value Hth.

[0113] As shown in B of Figure 10, at water supply flow rate L1, the threshold value Lth is already exceeded at time t11, and the outlet hot water temperature HWT-1 begins to rise from time t12 when the hot water discharge time Ht exceeds the threshold value Hth. At time t14, the outlet hot water temperature HWT-1 is switched to the outlet hot water temperature HWT-2. In contrast, at water supply flow rate L2, after the hot water discharge time Ht has exceeded the threshold value Hth, the outlet hot water temperature HWT begins to rise from time t13 when the water supply flow rate L2 exceeds the threshold value Lth, and is switched to the outlet hot water temperature HWT-2 at time t15.

[0114] Eventually, the feed water flow rate L1 or the feed water flow rate L2 decreases, passes the threshold value Lth at time t16, and then disappears at time t18. In this case, the feed water flow rate L1 decreases from time t16 when it becomes equal to or less than the threshold value Lth, and is switched to the outlet hot water temperature HWT-1 at time t17.

[0115] Then, as shown in C of Fig. 10, the hot water supply unit 4-2 starts supplying hot water from time ts, and the outlet temperature HWT of the hot water HW3 supplied from the hot water supply unit 4-2 remains constant as the outlet temperatures HWT-1 and HWT-2 of the hot water supply unit 4-1 are switched. HWTO is the target temperature.

[0116] <Setting the threshold Hth and its function> The water supply flow rate L is determined from the point when the threshold value Hth has elapsed since the start of hot water supply. Before the threshold value Hth has elapsed, the hot water outlet temperature HWT-1 is maintained. Then, after the threshold value Hth has elapsed, when the water supply flow rate L exceeds the threshold value Lth, the hot water outlet temperature HWT-1 can be shifted to the hot water outlet temperature HWT-2.

[0117] The threshold value Hth is, for example, 5 seconds. That is, the outlet hot water temperature HWT-1 of the hot water supply unit 4-1 is maintained for 5 seconds.

[0118] Therefore, time is secured for the water supply flow rate L to stabilize, that is, for the detection output of the flow sensor 20 to stabilize, and when the water supply flow rate L exceeds the threshold value Lth, the outlet water temperature HWT-1 can be changed to the outlet water temperature HWT-2, thereby improving the reliability of operation.

[0119] <Advantages of the Second Embodiment> According to this configuration, any one of the following effects can be obtained. (1) In addition to obtaining the same effects as the first embodiment, after stabilizing the water supply flow rate L, it is possible to compare it with the threshold value Lth, thereby improving the reliability of the transition operation from the hot water outlet temperature HWT-1 to the hot water outlet temperature HWT-2.

[0120] Third embodiment This third embodiment includes control that monitors fluctuations in the water supply flow rate L when hot water is dispensed, switches the hot water outlet temperatures HWT-1, HWT-2 in response to those fluctuations, and inhibits switching between the hot water outlet temperatures HWT-1, HWT-2 in the event that the fluctuations in the water supply flow rate L are slight.

[0121] <Functional parts of hot water supply unit 4-1> Fig. 11 shows the functional parts of a hot water supply unit 4-1 according to a third embodiment. In Fig. 11, the same parts as those in Fig. 4 or 8 are given the same reference numerals.

[0122] The functional parts of the hot water supply unit 4-1 in this third embodiment include a mode setting part 64, an outlet hot water temperature setting part 66, a mode determination part 68, a threshold setting part 70, an outlet hot water determination part 71, a water supply flow rate determination part 72, an outlet hot water temperature switching part 74, a control information acquisition part 76, a database 78, and a presentation information generation part 80, which are similar to those in the first embodiment, as well as a standby time information acquisition part 83, a standby time determination part 85, and a flow rate fluctuation determination part 86.

[0123] In this embodiment, the determination of the water supply flow rate L performed by the water supply flow rate determination unit 72 includes both a flow rate determination that triggers measurement of the standby time Jt, and a flow rate determination that triggers switching between the outlet water temperatures HWT-1 and HWT-2, under the control of the processor 46.

[0124] Under the control of the processor 46, the standby time information acquisition unit 83 acquires from the timer 51 the standby time Jt, which is the elapsed time from the point in time when the water supply flow rate L exceeded the threshold value Lth.

[0125] Under the control of processor 46, standby time determination unit 85 determines whether or not standby time Jt has elapsed, and provides the result of this determination as switching information for outlet hot water temperature HWT.

[0126] Flow rate fluctuation determination unit 86 obtains detection information about the water supply flow rate L when the outlet hot water temperature is set to HWT-1, and determines the flow rate fluctuation.

[0127] The control information acquisition unit 76 acquires various types of control information such as setting mode information, threshold information, outlet hot water temperature information, standby time information, etc. This control information is then provided to the database 78 and the presentation information generation unit 80, and is stored in the database 78 or presented on the LCD display unit 62.

[0128] In addition, the mode setting unit 64, the outlet hot water temperature setting unit 66, the mode determination unit 68, the threshold setting unit 70, the outlet hot water determination unit 71, the water supply flow rate determination unit 72, the outlet hot water temperature switching unit 74, the control information acquisition unit 76, the database 78, and the presentation information generation unit 80 are the same as in the first and second embodiments, and therefore their explanations will be omitted.

[0129] <Water discharge control> 12 shows a process procedure for hot water supply control according to the third embodiment. This hot water supply control is an example of the hot water supply control method, program, etc. of the present disclosure.

[0130] The processing procedures for hot water discharge control include determining the setting mode (S301), setting the hot water discharge temperature (S302), determining whether to start dispensing hot water (S303), measuring the water supply flow rate L (S304), determining the water supply flow rate L (S305), setting the water outlet temperature (S306), determining the standby time Jt (S307), setting the water outlet temperature (S308), presenting information (S309), determining whether to stop dispensing hot water (S310), monitoring fluctuations in the water supply flow rate L (S311), determining the water supply flow rate L (S312), and determining the standby time Jt (S313).

[0131] The setting mode determination (S301) corresponds to the setting mode determination (S101) described above, the outlet water temperature setting (S302) corresponds to the outlet water temperature setting (S102) described above, the water outlet start determination (S303) corresponds to the water outlet start determination (S103) described above, the measurement of the water supply flow rate L (S304) corresponds to the measurement of the water supply flow rate L (S104) described above, the determination of the water supply flow rate L (S305) corresponds to the determination of the water supply flow rate L (S105) described above, the outlet water temperature setting (S306) corresponds to the outlet water temperature setting (S106) described above, and the outlet water temperature setting (S308) corresponds to the outlet water temperature setting (S107) described above, so explanations of these will be omitted.

[0132] Determination of standby time Jt (S307): If the water supply flow rate L is not equal to or less than the threshold value Lth (NO in S305), the standby time information acquisition unit 83, under the control of the processor 46, acquires standby time information from the time measured by the timer 51, and the standby time determination unit 85, under the control of the processor 46, determines whether the standby time Jt has elapsed. In other words, if the standby time Jt has not elapsed (NO in S307), the device remains in standby mode until the standby time Jt has elapsed.

[0133] In this case, when the water supply flow rate L is determined to be greater than the threshold value Lth (NO in S305), the outlet hot water temperature HWT-2 is set when the standby time Jt has elapsed (S308).

[0134] Presentation of information (S309) and determination of stopping of hot water discharge (S310): These are the same as in the second embodiment, and therefore the explanation thereof will be omitted.

[0135] Monitoring Fluctuations in Feedwater Flow Rate L (S311): The flow rate fluctuation determination unit 86, under the control of the processor 46, acquires the determination result of the feedwater flow rate L by the feedwater flow rate determination unit 72 and monitors fluctuations in the feedwater flow rate L.

[0136] Determination of the water supply flow rate L (S312): The water supply flow rate determination unit 72, under the control of the processor 46, determines whether the water supply flow rate L is equal to or less than the threshold value Lth or exceeds the threshold value Lth.

[0137] Determination of standby time Jt (S313): If the water supply flow rate L is not equal to or less than the threshold value Lth (NO in S312), the standby time information acquisition unit 83, under the control of the processor 46, acquires standby time information from the time measured by the timer 51, and the standby time determination unit 85, under the control of the processor 46, determines whether the standby time Jt has elapsed. In other words, if the standby time Jt has not elapsed (NO in S313), the device remains in standby mode until the standby time Jt has elapsed.

[0138] In this case, when the water supply flow rate L is determined to exceed the threshold value Lth (NO in S312), the outlet hot water temperature HWT-2 is set when the standby time Jt has elapsed (S308).

[0139] <An example of pouring control> Fig. 13 shows an example of hot water outlet control according to the third embodiment, where A shows the change in the water supply flow rate L, B shows the switching between the hot water outlet temperatures HWT-1 and HWT-2, and C shows the change in the hot water outlet temperature HWT of the hot water HW3. In Fig. 13, the same parts as in Fig. 10 are given the same reference numerals.

[0140] In the third embodiment, the process of switching between outlet heated water temperatures HWT-1, HWT-2 using the water supply flow rate L as a parameter is the same as in the second embodiment (FIG. 10), so a description thereof will be omitted.

[0141] In the third embodiment, as shown in A of Figure 13, water supply is started at time t20, and a waiting time Jt is set from time t21 when the water supply flow rate L1 exceeds the threshold Lth to time t22, and similarly from time t26 to time t27.

[0142] This waiting time Jt is the interval time from the point when the water supply flow rate L exceeds the threshold value Lth to the point when the hot water outlet temperature HWT-1 begins to increase, and is a dead band time during which the hot water outlet temperature HWT-1 is not increased even if the water supply flow rate L exceeds the threshold value Lth.In this case, it is the time during which the hot water outlet temperature HWT-1 is maintained.

[0143] As shown in B of Figure 13, when the water supply flow rate L exceeds the threshold value Lth, the outlet hot water temperature HWT-1 begins to rise at time t22, which is the waiting time Jt after time t21, and is switched to the outlet hot water temperature HWT-2 at time t23 during the transition time Ut.

[0144] Eventually, the water supply flow rate L decreases, and at time t24 when it falls below the threshold value Lth, the outlet hot water temperature HWT-2 immediately begins to decrease, and at time t25 it is switched to the outlet hot water temperature HWT-1.

[0145] After reaching the outlet hot water temperature HWT-1, the feed water flow rate L fluctuates drastically from time t25, reaching time t26. Period Jm represents the period during which the feed water flow rate L fluctuates. During this period of fluctuation, standby time determination unit 85 determines whether the period during which the feed water flow rate L exceeds threshold value Lth is equal to or longer than the standby time Jt. In this case, during period Jm from time t25 to time t26, the period during which the feed water flow rate L exceeds threshold value Lth does not exceed the standby time Jt. As a result, the outlet hot water temperature HWT-1 is maintained.

[0146] Between time t26 and time t27, the water supply flow rate L continuously exceeds the threshold value Lth. In other words, the period during which the water supply flow rate L exceeds the threshold value Lth is equal to or longer than the standby time Jt.

[0147] When the water supply flow rate L exceeds the threshold value Lth, the outlet hot water temperature HWT-1 starts to rise at time t27, which is the elapsed standby time Jt from time t26, and switches to the outlet hot water temperature HWT-2 at time t28 during the transition time Ut.

[0148] As soon as the water supply flow rate L decreases and falls below the threshold value Lth at time t29, the outlet hot water temperature HWT-2 immediately begins to decrease, and at time t30 it switches to the outlet hot water temperature HWT-1.

[0149] Then, as shown in FIG. 13C, hot water supply unit 4-2 starts supplying hot water from time ts, and despite switching between outlet hot water temperatures HWT-1, HWT-2 of hot water supply unit 4-1, outlet hot water temperature HWT of hot water HW3 remains constant.

[0150] In this case, even if the water supply flow rate L fluctuates drastically from time t25 to time t26 after the hot water outlet temperature HWT-1 is reached, the hot water outlet temperature HWT of the hot water HW3 of the hot water supply unit 4-2 remains stable because the hot water supply unit 4-1 is maintained at the hot water outlet temperature HWT-1. HWTO is the target temperature.

[0151] <Waiting time Jt setting and its function> When the water supply flow rate L exceeds the threshold value Lth, the outlet hot water temperature HWT-1 can be increased after the standby time Jt has elapsed, and the outlet hot water temperature HWT-1 can be transitioned to the outlet hot water temperature HWT-2 after the transition time Ut has elapsed.

[0152] Furthermore, even if the water supply flow rate L fluctuates, the outlet heated water temperature HWT-1 can be maintained as long as the period during which the water supply flow rate L exceeds the threshold value Lth does not exceed the standby time Jt.

[0153] <Advantages of the Third Embodiment> According to this configuration, any one of the following effects can be obtained. (1) The same effects as those of the first and second embodiments can be obtained, and the outlet hot water temperatures HWT-1 and HWT-2 can be changed in response to fluctuations in the water supply flow rate L.

[0154] (2) When the water supply flow rate L exceeds the threshold value Lth, the hot water outlet temperature is changed from HWT-1 to HWT-2 starting from the point at which the standby time Jt is exceeded. This prevents a change in the hot water outlet temperature from HWT-1 to HWT-2 due to slight fluctuations in the water supply flow rate L, thereby stabilizing operation.

[0155] [Fourth embodiment] This fourth embodiment includes a control for changing the outlet hot water temperatures HWT-1, HWT-2 by the valve opening degree θ of the mixing valve 24.

[0156] FIG. 14 shows valve opening control of the mixing valve 24, where A shows the state of valve opening θ1, B shows the state of valve opening θ2, and C shows the relationship between valve opening θ1, θ2, outlet hot water temperatures HWT-1, HWT-2, and transition time Δt.

[0157] The mixing valve 24 is provided with a valve body 92 in a chamber 90 of a valve body 88. Ports 94-1, 94-2, and 94-3 are formed in the chamber 90. The port 94-1 is connected to the bypass path 22 and receives the supply water W. The port 94-2 is connected to the hot water outlet path of the heat exchanger 8 and receives the hot water HW. The port 94-3 outputs the hot water HW1 obtained by mixing the supply water W and the hot water HW in the chamber 90.

[0158] The valve element 92 is rotatable about a central axis O within the chamber 90. This valve element 92 rotates by receiving a rotational force from a stepping motor 96, and is controlled to valve openings θ1, θ2. A driving output is applied to the stepping motor 96 from a valve driving unit 98, and this driving output is controlled by the control unit 9 described above. This control includes control of the setting of the valve openings θ1, θ2, the transition time Δtθ12 from the valve opening θ1 to the valve opening θ2, and the transition time Δtθ21 from the valve opening θ2 to the valve opening θ1.

[0159] As shown in A of FIG. 14, when the valve opening degree θ1 (<θ2) of the valve element 92 of the mixing valve 24, the outlet temperature HWT-1 of the hot water HW1 is obtained.

[0160] As shown in FIG. 14B, when the valve opening degree θ2 of the valve element 92 of the mixing valve 24 is set, the outlet temperature HWT-2 of the hot water HW1 is obtained.

[0161] As shown in C of Fig. 14, the aforementioned transition time Ut is set by the valve opening θ1 = outlet hot water temperature HWT-1, valve opening θ2 = outlet hot water temperature HWT-2, and the transition time Δtθ12 from valve opening θ1 to valve opening θ2. Also, the aforementioned transition time Dt is set by the transition time Δtθ21 (<Δtθ12) from valve opening θ2 to valve opening θ1.

[0162] <An example of pouring control> FIG. 15 shows an example of hot water outlet control according to the fourth embodiment, where A shows the transition of the water supply flow rate L, and B shows the switching of the hot water outlet temperatures HWT-1, HWT-2 according to the valve openings θ1, θ2.

[0163] When the water supply flow rate L is equal to or less than the threshold value Lth, a valve opening θ1 (hot water outlet temperature HWT-1) is set in the mixing valve 24. The water supply flow rate L increases from time t30 when the water supply W starts. From time t31 when the water supply flow rate L exceeds the threshold value Lth, the valve opening θ1 is increased, and at time t32, the valve opening θ2 (hot water outlet temperature HWT-2) is reached.

[0164] The water supply flow rate L decreases, passes the threshold value Lth at time t33, and then disappears at time t35. In this case, the valve opening θ2 decreases from time t33 when the water supply flow rate L becomes equal to or less than the threshold value Lth, and is switched to the valve opening θ1 (hot water outlet temperature HWT-1) at time t34 before time t35 is reached.

[0165] The transition time Δtθ12 from the valve opening θ1 to the valve opening θ2 is set to be longer than the transition time Δtθ21 from the valve opening θ2 to the valve opening θ1. As a result, the transition from the outlet hot water temperature HWT-1 to the outlet hot water temperature HWT-2 is gradual, and the transition from the outlet hot water temperature HWT-2 to the outlet hot water temperature HWT-1 is instantaneous.

[0166] Therefore, the outlet hot water temperature HWT of hot water supply unit 4-2 follows the switching of the outlet hot water temperatures HWT-1, HWT-2 of hot water supply unit 4-1, and the outlet hot water temperature HWT of hot water HW3 can be changed. EXAMPLES

[0167] 16 shows information presentation of the remote control unit 30. In the information presentation mode of this remote control unit 30, various screens such as a hot water tapping information presentation screen 100 are displayed on the LCD display section 62.

[0168] An example of a hot water outlet information display screen 100 has a mode display section 102, a hot water outlet temperature display section 104, a water supply information display section 106, and the like.

[0169] The mode display section 102 displays "Setting Mode" in the title section, and the display window 108 displays mode setting information such as the stand-alone mode described above.

[0170] The outlet hot water temperature display unit 104 has “Outlet Hot Water Temperature” displayed in the title section, and its display window 110 displays the aforementioned outlet hot water temperatures HWT-1 and HWT-2, which are the current outlet hot water temperatures, as well as other presented information such as setting information and operating information.

[0171] The water supply information display section 106 displays "Water Supply Information" in the title section, and its display window section 112 displays operational information such as the presence or absence of water supply, the water supply flow rate, etc.

[0172] <Effects of Example 1> According to the first embodiment, any one of the following effects can be obtained. (1) When hot water is dispensed, the processor 46 can automatically or manually control the LCD display 62 to display information such as current operating information. (2) The operating information when the hot water is dispensed can be easily recognized from the information displayed on the LCD display unit 62, and can be used for maintenance, etc. EXAMPLES

[0173] The hot water supply unit 4-2 is not limited to a direct heating type hot water heater, and may be an indirect heating type hot water heater that receives hot water HW1 from the hot water supply unit 4-1 and indirectly heats this hot water HW1 with the heat of the heat medium HM3.

[0174] Fig. 17 shows a hot water supply system 2 according to Example 2. In Fig. 17, the same parts as in Fig. 1 are given the same reference numerals.

[0175] In this hot water supply system 2, an indirect heating type water heater is used for the hot water supply unit 4-2. Therefore, in this hot water supply unit 4-2, hot water HW1 from hot water supply unit 4-1 is heat exchanged with heat medium HM3 in heat exchanger 116, and hot water HW1 is heated by the heat of heat medium HM3.

[0176] Heat medium circulation path 114, which circulates heat medium HM3, is equipped with heat medium tank 118, circulation pump 120, and heat exchanger 122. Heat medium tank 118 is a tank for storing heat medium HM3. Circulation pump 120 is controlled by control unit 43 when hot water is discharged, and circulates heat medium HM3 through heat exchangers 116 and 122 via heat medium circulation path 114. Heat exchanger 122 exchanges heat between the circulating heat medium HM3 and heat of the combustion exhaust gas from burner 124, heating the heat medium HM3.

[0177] <Effects of Example 2> According to the second embodiment, any one of the following effects can be obtained. (1) Even if the indirect heating water heater according to the second embodiment is used for the hot water supply unit 4-2, the system or method disclosed herein can similarly suppress a sudden increase in the outlet hot water temperature HWT of the hot water HW3. (2) An existing indirect heating water heater can be used for the hot water supply unit 4-2. EXAMPLES

[0178] Fig. 18 shows a hot water supply system according to Example 3. In Fig. 18, the same parts as in Fig. 1 are given the same reference numerals.

[0179] In the hot water supply system 2 according to the third embodiment, two or more hot water supply units 4-2, 4-21, 4-22, 4-23, ... are installed for the hot water supply unit 4-1, as shown in Fig. 18. A connecting passage 32 is connected to each water supply passage 34 of each of the hot water supply units 4-21, 4-22, 4-23, ..., and hot water HW1 is supplied from the hot water supply unit 4-1.

[0180] Each of the hot water supply units 4-21, 4-22, 4-23, ... is an independent hot water supply source for the hot water supply unit 4-1, and operates in a stand-alone mode, similar to the first embodiment. Also, each of the hot water supply units 4-21, 4-22, 4-23, ... may be a hot water supply device of the same specification or may be a hot water supply device of different specifications, and any hot water supply device may be used.

[0181] The hot water HW1 dispensed by the hot water supply unit 4-1 is received, and the hot water is individually dispensed from each hot water supply unit 4-21, 4-22, 4-23, ... so that hot water HW31 can be dispensed from the hot water supply unit 4-21, hot water HW32 from the hot water supply unit 4-22, and hot water HW33 from the hot water supply unit 4-23.

[0182] <Effects of Example 3> According to the third embodiment, any one of the following effects can be obtained. (1) As mentioned above, the hot water supply unit 4-1 can supply hot water HW at the outlet temperature HWT-1 or HWT-2 depending on the water supply flow rate L, the hot water supply time t, or the water supply flow rate fluctuation to multiple hot water supply units, such as the hot water supply units 4-21, 4-22, and 4-23.

[0183] (2) When the water supply flow rate L from hot water supply unit 4-1 is equal to or lower than threshold value Lth, the temperature of hot water supply unit 4-1 can be lowered to outlet hot water temperature HWT-1, thereby preventing a sudden rise in the outlet hot water temperature of each hot water supply unit 4-21, 4-22, 4-23, etc.

[0184] (3) The hot water supply unit 4-1 can be newly installed or modified regardless of the hot water supply specifications of each existing hot water supply unit 4-21, 4-22, 4-23, etc., for example, an indirect heating type water heater using a plate heat exchanger, or a direct heating type water heater having a higher minimum hot water output number than an indirect heating type water heater, thereby realizing a highly convenient hot water supply system 2.

[0185] (4) Even if the hot water supply unit 4-1 disclosed herein is an existing hot water supply unit, any specification of hot water supply unit can be selected for each hot water supply unit 4-21, 4-22, 4-23, etc., without being affected by the specifications of the existing hot water supply unit, thereby increasing user convenience.

[0186] Other Embodiments The present disclosure includes the following embodiments. (1) Although the heat source unit 10 uses the exhaust heat of the SOFC as a heat source, an exhaust heat source other than the SOFC may be used as the heat source.

[0187] (2) The heat source installed in the hot water supply units 4-2, 4-21, 4-22, 4-23, etc. uses the heat of combustion of fuel gas as a heat source, but other heat sources such as heat of combustion of liquid fuel, electric heat, etc. may also be used.

[0188] As described above, the most preferred embodiment of the present invention has been described. The present invention is not limited to the above description. Various modifications and changes are possible for those skilled in the art based on the gist of the invention described in the claims or disclosed in the description for carrying out the invention. It goes without saying that such modifications and changes are included in the scope of the present invention. [Industrial Applicability]

[0189] According to the present disclosure, the outlet hot water temperature on the first hot water supply unit is changed according to the water supply flow rate, so that even when the water supply flow rate from the first hot water supply unit to the second hot water supply unit is low, the increase in the outlet hot water temperature on the second hot water supply unit can be suppressed, thereby realizing a highly convenient hot water supply system. [Explanation of symbols]

[0190] L Water supply flow rate L Lth Threshold HWT, HWT-1, HWT-2 outlet water temperature HM1, HM2, HM3 heating medium W Water Supply T heating medium temperature HW1, HW2, HW3 Hot water 2. Hot water system 4-1, 4-2, 4-21, 4-22, 4-23 Hot water unit 6. Heat storage tank 8 Heat exchanger 9. Control Unit 10 Heat source unit 12, 41 Temperature sensor 14 Heat transfer path 16 Circulation pump 18 Water supply channel 20 Flow Sensor 22 Bypass Road 24 Mixing valve 26 Hot water outlet 30 Remote control unit 32 Connecting road 34 Water supply channel 35 Flow Sensor 36 Burner 37 SOFC 38 Primary heat exchanger 39 Heat exchanger 40 Secondary heat exchanger 41 Circulation Pump 42 Mixing valve 43 Control Unit 44 Bypass Road 45 Hot water outlet 46 processors 47 Temperature Sensor 48 Memory section 50 Input / output section (I / O) 51 Timer 52 Communications Department 56 Remote control unit 58 Communications Department 60 Input operation section 62 LCD display section 64 Mode setting section 66 Hot water outlet temperature setting section 68 Mode determination section 70 Threshold setting unit 71 Hot water supply determination unit 72 Water supply flow rate determination section 74 Hot water temperature switching unit 76 Control information acquisition unit 78 Databases 80 Presentation information generation section 82 Hot water discharge time information acquisition unit 83 Waiting time information acquisition unit 84 Water outlet time determination unit 85 Waiting time determination unit 86 Flow rate fluctuation determination unit 88 Valve body 90 Chamber 92 Valve body 94-1, 94-2, 94-3 ports 96 Stepping Motor 98 Valve drive unit 100 Hot water information display screen 102 Mode display section 104 Hot water temperature display unit 106 Water supply information display section 108, 110, 112 Display window 114 Heat medium circulation path 116, 122 heat exchanger 118 Heat Transfer Tank 120 Circulation Pump 124 Burner

Claims

1. A hot water supply method comprising: connecting at least a first hot water supply unit and a second hot water supply unit; receiving hot water from the first hot water supply unit in the second hot water supply unit; and supplying hot water from the second hot water supply unit, A flow rate sensor detects a flow rate of water flowing into the first hot water supply unit; a control unit sets a threshold value to a water supply flow rate at which hot water can be dispensed at a minimum hot water supply number by at least the second hot water supply unit, and if the detected water supply flow rate of the flow sensor is equal to or lower than the threshold value, sets the temperature of the hot water outlet of the first hot water supply unit to a first outlet temperature corresponding to or lower than the outlet temperature of the minimum hot water supply number by the second hot water supply unit, and if the detected water supply flow rate exceeds the threshold value, sets the temperature of the hot water outlet of the first hot water supply unit to a second outlet temperature higher than the first outlet temperature; A hot water supply method comprising:

2. Furthermore, a step of measuring an elapsed time from the start of hot water dispensing by a timer; If the elapsed time is less than a predetermined time, the control unit maintains the first outlet heated water temperature. The process and The hot water supply method according to claim 1, comprising:

3. The hot water supply method of claim 1 or claim 2 further includes a step in which the control unit monitors the detected water supply flow rate of the first hot water supply unit and controls the transition time from the second hot water outlet temperature to the first hot water outlet temperature to be shorter than the transition time from the first hot water outlet temperature to the second hot water outlet temperature in accordance with fluctuations in the detected water supply flow rate.

4. A hot water supply method as described in any one of claims 1 to 3, further comprising a step of setting the first hot water outlet temperature to a temperature equal to or higher than the minimum hot water outlet number at which the second hot water supply unit can dispense hot water, but lower than the temperature at which hot water can be dispensed.

5. A hot water supply system including at least a first hot water supply unit and a second hot water supply unit, the first hot water supply unit receiving hot water from the second hot water supply unit, and the second hot water supply unit supplying hot water, a flow rate sensor that detects a flow rate of water flowing into the first hot water supply unit; a control unit which sets a threshold value to a water supply flow rate at which hot water can be dispensed at a minimum hot water supply number by at least the second hot water supply unit, and if the detected water supply flow rate of the flow sensor is equal to or lower than the threshold value, sets the temperature of the hot water outlet of the first hot water supply unit to a first outlet temperature which corresponds to or lower than the outlet temperature of the minimum hot water supply number by the second hot water supply unit, and if the detected water supply flow rate exceeds the threshold value, sets the temperature of the hot water outlet of the first hot water supply unit to a second outlet temperature which exceeds the first outlet temperature; A hot water system including:

6. The hot water supply system according to claim 5 , further comprising a timer that measures an elapsed time from a start of hot water supply, wherein the control unit maintains the first hot water outlet temperature if the elapsed time is less than a predetermined time.

7. The hot water supply system of claim 5 or claim 6, further comprising: the control unit monitoring the detected water supply flow rate of the first hot water supply unit; and controlling the transition time from the second hot water outlet temperature to the first hot water outlet temperature to be shorter than the transition time from the first hot water outlet temperature to the second hot water outlet temperature in accordance with fluctuations in the detected water supply flow rate.

8. A hot water supply system as described in any one of claims 5 to 7, further comprising: the control unit setting the first hot water outlet temperature to a temperature equal to or higher than the minimum hot water outlet number at which the second hot water supply unit can dispense hot water, but lower than the temperature at which hot water can be dispensed.

9. A program executed by a computer, A function of acquiring information on water supply flowing into the first hot water supply unit from a flow rate sensor that detects a water supply flow rate; a function of setting a threshold value to a water supply flow rate at which hot water can be dispensed at the minimum hot water supply number by at least a second hot water supply unit, and if the detected water supply flow rate of the flow sensor is equal to or lower than the threshold value, setting the temperature of the hot water outlet of the first hot water supply unit to a first outlet temperature corresponding to or lower than the outlet temperature of the minimum hot water supply number by the second hot water supply unit, and if the detected water supply flow rate exceeds the threshold value, setting the temperature of the hot water outlet of the first hot water supply unit to a second outlet temperature exceeding the first outlet temperature; A program for causing the computer to execute the above.

10. In addition, there is a function to obtain elapsed time information from a timer that measures the time elapsed since the start of hot water dispensing, a function of maintaining the first outlet heated water temperature if the elapsed time is less than a predetermined time; The program according to claim 9, which causes the computer to execute the steps of:

11. The program described in claim 9 or claim 10 further causes the computer to execute a function of monitoring the detected water supply flow rate of the first hot water supply unit, and controlling the transition time from the second hot water outlet temperature to the first hot water outlet temperature to be shorter relative to the transition time from the first hot water outlet temperature to the second hot water outlet temperature in accordance with fluctuations in the detected water supply flow rate.

12. A recording medium storing the program according to any one of claims 9 to 11.

13. A hot water supply unit that is connected to at least another hot water supply unit and supplies hot water generated by heating incoming supply water to the other hot water supply unit, A flow rate sensor that detects the flow rate of the incoming water supply; a control unit which sets a threshold value to a water supply flow rate at which hot water can be dispensed at least by the other hot water supply unit at a minimum hot water supply number, and if the water supply flow rate detected by the flow rate sensor is equal to or lower than the threshold value, sets the temperature of the hot water supply to the other hot water supply unit to a first outlet temperature which corresponds to or lower than the outlet temperature of the minimum hot water supply number by the other hot water supply unit, and if the detected water supply flow rate exceeds the threshold value, sets the temperature of the hot water supply to the other hot water supply unit to a second outlet temperature which exceeds the first outlet temperature; A hot water unit including:

14. A control unit incorporating any one of a control unit included in the hot water supply system according to claim 5, a recording medium according to claim 12, or a control unit included in the hot water supply unit according to claim 13.

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