Linked hot water system

Abstract

To provide a connection type hot water supply system capable of achieving both of improvement of responsiveness and suppression of deterioration progress of a hot water supply device.SOLUTION: In a connection type hot water supply system (10) including; a plurality of combustion type hot water supply devices (11-14) arranged in parallel between water supply piping (1) and hot water supply piping (2); and control means (15) for changing the number of hot water supply devices (11-14) operated according to a use amount of supplied hot water, one main hot water supply device operated in starting hot water supply and a sub-hot water supply device additionally operated besides the main hot water supply device are determined to the plurality of hot water supply devices (11-14). The control means (15) additionally operates one non-operated sub-hot water supply device to supply hot water when the use amount of supplied hot water of the hot water supply device finally starting operation, among the hot water supply devices in operation becomes a specified value or more. Hot water supply operation states by the plurality of hot water supply devices are learned and stored to determine a high load time zone when the use amount of supplied hot water is increased, and the specified value for additionally operating the sub-hot water supply device is lowered at this high load time zone.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a linked hot water supply system that includes multiple hot water supply devices and a system control device that controls the number of operating hot water supply devices, and that changes the number of operating devices to supply hot water in order to adjust the heating capacity according to the amount of hot water used. [Background technology]

[0002] Conventionally, hot water supply systems for general households have been used that store hot water heated by a heat pump heat source with high operating efficiency in a hot water storage tank and use the stored hot water for hot water supply. In such hot water supply systems, a technology is known that determines the optimal operating mode based on usage records, as described in Patent Document 1, for example, to store hot water according to the actual usage of the user.

[0003] On the other hand, in dormitories, lodging facilities, sports gyms, and the like, hot water usage can increase rapidly in a short period of time due to the concentration of hot water usage caused by multiple users taking showers, etc., and hot water usage can also decrease temporarily and then suddenly increase again. Furthermore, the time and number of users using hot water vary greatly from day to day, making it difficult to store hot water appropriately based on usage history, as in Patent Document 1. Therefore, in such facilities, linked hot water supply systems are used that supply hot water by changing the number of operating combustion-type hot water supply devices to adjust the heating capacity according to hot water usage. Linked hot water supply systems supply hot water at a set target temperature to hot water supply pipes, and hot water users can use hot water at the desired temperature from a hot water tap with a temperature adjustment function.

[0004] A linked hot water supply system adjusts the heating capacity of an operating hot water supply device according to the amount of hot water used (the amount of hot water discharged at a target temperature) and changes the number of operating hot water supply devices, so it can handle not only large amounts of hot water but also small amounts of hot water with only one operating device. Patent Document 2, for example, describes a linked hot water supply system that is configured to change the number of operating devices based on the amount of hot water used (the amount of water supplied from the water supply pipe and the amount of heat supplied by each hot water supply device). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-89208 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-292383 Summary of the Invention [Problem to be solved by the invention]

[0006] In conventional linked hot water supply systems, when the heating capacity of the currently operating hot water supply device is insufficient to supply hot water at the target temperature, an additional hot water supply device is activated. At this time, the currently operating hot water supply device is often already at its maximum heating capacity, and the additional hot water supply device takes some time from ignition to increasing its heating capacity and stabilizing the hot water supply, which creates an issue with its responsiveness to sudden increases in hot water usage.

[0007] The linked hot water supply system of Patent Document 2 increases the number of operating units when the hot water supply volume of an operating water heater becomes high, and decreases the number of operating units when the hot water supply volume of an operating water heater becomes low, based on the three levels of hot water supply volume preset for each water heater: high, medium, and low. Therefore, in response to a sudden increase in hot water usage, the hot water supply volume of the operating water heater can be increased while the next water heater is additionally driven, improving responsiveness.

[0008] On the other hand, each water heater in the linked hot water supply system of Patent Document 2 is controlled so that the amount of hot water supplied is medium for the majority of hot water supply operations, and the number of operating units tends to increase even when the amount of hot water consumption is such that hot water can be supplied without increasing the number of operating units. As a result, the cumulative operating time of each water heater increases and the deterioration progresses more quickly, which may lead to an earlier maintenance or replacement period for the linked hot water supply system.

[0009] An object of the present invention is to provide a linked hot water supply system that can achieve both improved responsiveness and suppression of the progression of deterioration of the hot water supply device. [Means for solving the problem]

[0010] The linked hot water supply system of the invention of claim 1 is a linked hot water supply system comprising a plurality of combustion-type hot water supply devices installed in parallel between a water supply pipe and a hot water supply pipe, and a control means for changing the number of the hot water supply devices to be operated depending on the amount of hot water used, and for the plurality of hot water supply devices, one main hot water supply device is set to be operated when hot water supply starts, and a sub-hot water supply device for operating additional hot water supply devices other than the main hot water supply device, and the control means is characterized in that when the heating capacity of the hot water supply device that was last started to operate among the operating hot water supply devices reaches or exceeds a specified value, it operates one of the inactive sub-hot water supply devices to supply hot water, learns and memorizes the hot water supply operation status of the plurality of hot water supply devices, sets a high-load time period when hot water use increases, and lowers the specified value for operating additional sub-hot water supply devices during this high-load time period.

[0011] According to the above configuration, the linked hot water supply system operates the main hot water supply device to supply hot water when hot water supply starts. When the heating capacity of the last operating hot water supply device reaches or exceeds a specified value, the number of operating devices is increased by one. The control device of this linked hot water supply system sets a time period during which hot water usage increases based on the learned hot water supply operation status as a high-load time period, and during this high-load time period, the specified value that serves as the criterion for increasing the number of operating devices is lowered from the specified value during other high-load time periods. This allows the sub-hot water supply device to be operated while increasing the heating capacity of the last operating hot water supply device during high-load time periods. Therefore, the timing of starting operation of the sub-hot water supply device can be advanced during high-load time periods, allowing for a quick response to increases in hot water usage and improving responsiveness. Furthermore, because the specified value is higher during other than high-load time periods than during high-load time periods, the increase in the number of operating devices can be suppressed, thereby suppressing the progression of deterioration of the hot water supply devices.

[0012] The linked hot water supply system of the invention of claim 2 is characterized in that, in the invention of claim 1, the high load time period is set based on a maximum water flow rate that flows through the plurality of hot water supply devices. With the above configuration, among the learned and stored hot water supply operation statuses, time periods during which the number of operating units needs to be increased based on the maximum water flow rate are set as high-load time periods. Therefore, the high-load time periods can be set more appropriately based on the hot water supply operation status in which the number of operating units is likely to increase due to the earlier timing of the start of operation of the sub-hot water supply units during the high-load time period.

[0013] The linked hot water supply system of the invention of claim 3 is characterized in that, in the invention of claim 1, the high load time period is set based on the rate of increase in the amount of water flowing through the multiple hot water supply devices. With the above configuration, among the learned and stored hot water supply operation conditions, time periods in which it is preferable to rapidly increase the number of operating units are set as high-load time periods based on the rate of increase in water flow. Therefore, the high-load time periods can be set more appropriately based on the hot water supply operation conditions in which the number of operating units is likely to increase because the timing of the start of operation of the sub-hot water supply units is advanced during the high-load time periods. [Effects of the Invention]

[0014] According to the linked hot water supply system of the present invention, it is possible to improve responsiveness and suppress the progression of deterioration of the hot water supply device. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a diagram showing a linked hot water supply system according to an embodiment of the present invention; [Figure 2] 1 is an explanatory diagram of a hot water supply device constituting a linked hot water supply system according to an embodiment. [Figure 3] FIG. 10 is a diagram showing an example of setting a high-load time period based on the learned and stored hot water usage record. [Figure 4] 10 is a flowchart of the control of the number of operating units. [Figure 5] FIG. 10 is an explanatory diagram of the increase and decrease in heating capacity during normal hours. [Figure 6] FIG. 10 is an explanatory diagram of the increase in heating capacity during a high-load time period. [Figure 7] FIG. 10 is an explanatory diagram of the transition of a decrease in heating capacity during a high-load time period. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, the mode for carrying out the present invention will be described based on examples. [Example]

[0017] As shown in FIG. 1, tap water is supplied to water supply pipe 1 as indicated by arrow W. A linked hot water supply system 10 is installed so that the tap water introduced from water supply pipe 1 is heated to a target temperature and supplied to hot water supply pipe 2, which is equipped with multiple hot water taps F1-Fm. This linked hot water supply system 10 includes multiple (four in this example) hot water heaters 11-14 and a system controller 15 as control means communicatively connected to these hot water heaters 11-14 to control the number of operating units. System controller 15 includes an operation remote control 15a for setting, for example, the outlet hot water temperature of the linked hot water supply system 10. The multiple hot water heaters 11-14 are connected in parallel between water supply pipe 1 and hot water supply pipe 2, and any of the hot water heaters 11-14 can supply hot water to the multiple hot water taps F1-Fm. The multiple hot water taps F1-Fm have the function of adjusting the temperature, for example, by mixing the hot water with tap water, so that hot water users can adjust the temperature to their desired level. The number of water heating devices constituting linked hot water system 10 is not limited to four, but may be two or more.

[0018] Next, hot water supply devices 11-14 will be described, but since these hot water supply devices 11-14 have the same configuration, the description will be given of hot water supply device 11 and the description of hot water supply devices 12-14 will be omitted. As shown in Fig. 2, water heater 11 is a combustion-type water heater configured to use the heat of combustion of fuel gas in combustion section 21 to heat hot water flowing through heat exchange section 22. This water heater 11 has water supply section 23 that supplies clean water to heat exchange section 22, and hot water outlet section 24 that adjusts the temperature of the hot water heated in heat exchange section 22 and outputs the hot water.

[0019] Combustion section 21 has burner 25 having multiple combustion compartments, fuel regulating valve 26 that adjusts the flow rate of fuel gas supplied to burner 25, combustion fan 27 that supplies combustion air, and ignition device 28 that ignites burner 25 using electric discharge. Burner 25 is equipped with on-off valves 25a to 25d corresponding to the multiple combustion compartments.

[0020] The water supply section 23 has a water supply passage 29 connecting the water supply piping 1 and the heat exchange section 22, a water supply valve 30 that opens and closes the water supply passage 29, a water supply temperature sensor 31 that detects the temperature of the clean water (water supply temperature), and a water supply flow rate sensor 32 that detects the flow rate of the clean water (water supply flow rate) supplied to the heat exchange section 22.

[0021] The hot water outlet section 24 has a hot water outlet passage 34 connecting the heat exchange section 22 and the hot water supply pipe 2, a bypass passage 35 branching off from the water supply passage 29 downstream of the water supply valve 30 and connected to the hot water outlet passage 34, and a bypass flow rate adjustment valve 36. The bypass flow rate adjustment valve 36 adjusts the flow rate of clean water flowing from the water supply passage 29 into the bypass passage 35. The hot water outlet passage 34 is equipped with a first hot water outlet temperature sensor 37 that detects the temperature of the hot water heated in the heat exchange section 22, a second hot water outlet temperature sensor 38 that detects the temperature of the hot water (outlet hot water temperature) adjusted by mixing the heated hot water with clean water from the bypass passage 35, and a hot water outlet flow rate adjustment valve 39. The hot water outlet flow rate adjustment valve 39 adjusts the flow rate of clean water introduced from the water supply pipe 1 by adjusting the hot water outlet flow rate of the hot water supplied to the hot water supply pipe 2, i.e., is a water rate adjustment means that adjusts the water flow rate of the hot water heater 11.

[0022] Water heater 11 has a control unit 40 that controls the hot water supply operation of water heater 11 in cooperation with system control device 15. Control unit 40 acquires the flow rate detected by water supply flow rate sensor 32 and the temperatures detected by water supply temperature sensor 31 and first and second hot water outlet temperature sensors 37, 38. Based on these detected flow rates and temperatures, control unit 40 changes and adjusts the heating capacity by controlling the rotation speed of combustion fan 27, the opening degree of fuel adjustment valve 26, and the opening and closing of on-off valves 25a to 25d, and also adjusts the opening degree of bypass flow rate adjustment valve 36. This performs a hot water supply operation in which hot water at a set target temperature is supplied to hot water supply pipe 2.

[0023] For example, if hot water at the target temperature cannot be supplied because the amount of hot water used is large, control unit 40 adjusts the opening of hot water outlet flow rate adjustment valve 39 to reduce the amount of water passing through, thereby enabling hot water at the target temperature to be supplied. The amount of water passing through hot water heater 11 is calculated by control unit 40 based on the flow rate detected by water supply flow rate sensor 32, the opening of bypass flow rate adjustment valve 36, and the opening of hot water outlet flow rate adjustment valve 39.

[0024] System control device 15 sets one of multiple water heating devices 11-14 (for example, water heating device 11) that are candidates for operation in hot water supply operation as a main water heating device, and sets the water heating devices other than the main water heating device (for example, water heating devices 12-14) as sub-water heating devices. The main water heating device is the water heating device that is operated first when hot water supply starts. The sub-water heating devices are water heating devices that are not operated when hot water supply starts, but are operated additionally while hot water is being supplied. Since there is one main water heating device, the number N of sub-water heating devices is N=3.

[0025] When setting up the sub-water heating devices, the operation priority (order of additional operation) of the sub-water heating devices other than the main water heating device with the highest operation priority is set, for example, the first sub-water heating device, the second sub-water heating device, and the third sub-water heating device. Furthermore, in order to reduce the difference in accumulated operation time or operation load among multiple water heating devices 11-14, system control device 15 performs a rotation setting to switch the main water heating device and the sub-water heating devices, for example, periodically or according to the accumulated operation time.

[0026] Control unit 40 of the main hot water supply device opens water supply valve 30 and opens hot water outlet flow rate adjustment valve 39, for example, fully. Control unit 40 of the sub-hot water supply device closes water supply valve 30 and opens hot water outlet flow rate adjustment valve 39, for example, halfway, which is less than fully open. When any of hot water taps F1 to Fm is opened and the water supply flow rate of the main hot water supply device reaches or exceeds a predetermined operation start flow rate, hot water supply operation begins using only the main hot water supply device.

[0027] When the heating capacity of the main hot water supply apparatus, for example, exceeds a specified value, the additional operation condition is met, and there are inactive sub-hot water supply apparatuses among the operation candidates, system control device 15 additionally operates one of the inactive sub-hot water supply apparatuses with the highest operation priority. Because the incoming clean water is distributed among multiple operating hot water supply apparatuses, system control device 15 adjusts the opening of hot water outlet flow rate adjustment valve 39 of the hot water supply apparatus that was last to start operating, for example, so that the heating capacity of the hot water supply apparatus that started operating first is maintained.

[0028] During hot water supply operation, system control device 15 learns and stores the hot water supply operation status of multiple hot water supply devices 11-14, for example, as shown in Fig. 3. The hot water supply operation status that is learned and stored includes, for example, the number of operating units, water flow rate, heating capacity, time of day, etc. Then, based on the learned and stored hot water supply operation status, for example, a time period when hot water usage is high is set as a high-load time period. In this case, because hot water usage is high, for example, a time period when three or more operating units are set as a high-load time period.

[0029] System control device 15 turns on the high-load time period mode during high-load time periods and turns off the high-load time period mode during normal time periods (time periods other than high-load time periods). Note that, for example, when linked hot water supply system 10 is on its first day of operation or the learned and stored hot water supply operation status is initialized, system control device 15 performs hot water supply operation as a normal time period until at least one day's worth of hot water supply operation status is learned and stored.

[0030] System control device 15 relaxes the additional operation conditions of the sub-water heater during high-load time periods (when high-load time period mode is ON) compared to the additional operation conditions during normal time periods (when high-load time period mode is OFF). The specified value is set to the normal time period specified value (e.g., maximum heating capacity) during normal time periods, and to a high-load time period specified value lower than the normal time period specified value (e.g., 50% of maximum heating capacity) during high-load time periods, thereby relaxing the additional operation conditions.

[0031] Instead of the number of operating units, a time period with a predetermined standard water flow rate F0 or more can be set as a high-load time period based on the maximum value of the total water flow rate (maximum water flow rate) of multiple water heating devices 11-14. Also, a time period in which the water flow rate increase rate calculated from the total water flow rate of multiple water heating devices 11-14 (for example, the maximum increase in the total water flow rate within a unit time) is a predetermined standard increase rate I0 or more can be set as a high-load time period. Because the number of operating units is likely to increase when the high-load time period mode is ON, setting the high-load time period based on the maximum water flow rate or the water flow rate increase rate allows for more appropriate setting of the high-load time period.

[0032] For example, when the hot water tap F1 is opened and the water supply flow rate sensor 32 of the main hot water supply device detects a flow rate equal to or greater than a predetermined start flow rate, the main hot water supply device starts operation to supply hot water, and the system control device 15 starts controlling the number of operating units. This control of the number of operating units will be explained based on the flowchart in Figure 4. In the figure, Si (i = 1, 2, ...) represents a step.

[0033] When control of the number of operating units is started, the number N of sub-water heating devices is obtained in S1 and the process proceeds to S2. Then, in S2, since only the main water heating device has started operating immediately after the start of hot water supply operation, the number n of operating sub-water heating devices is set to zero and the process proceeds to S3.

[0034] In S3, it is determined whether the high-load time period setting is OFF. If the determination in S3 is Yes, the process proceeds to S4, where the normal time period specified value is set as the specified value, and the process proceeds to S6. This sets the specified value to, for example, the maximum heating capacity of the water heater. Note that the normal time period specified value may be lower than the maximum heating capacity.

[0035] On the other hand, if the determination in S3 is No, the process proceeds to S5, where the high-load time period specified value is set as the specified value, and the process proceeds to S6. This sets the specified value to a value lower than the normal time period specified value, for example, 50% of the maximum heating capacity of the water heater. Note that the high-load time period specified value may be any value as long as it is lower than the normal time period specified value and higher than the heating capacity at the start flow rate.

[0036] In S6, it is determined whether the heating capacity of the water heater that last started operating has reached or exceeded a specified value. This is the step for determining the additional operating conditions of the sub-water heater. System control device 15 determines whether the heating capacity of water heaters 11-14 has reached or exceeded a specified value based on various data related to water heater operation that is acquired for learning and storing the water heater operation status. The water heater that last started operating is the main water heater if only the main water heater is operating, and if a sub-water heater is also operating, it is the sub-water heater that last started operating among the operating sub-water heaters.

[0037] If the determination in S6 is Yes, the process proceeds to S7. Then, in S7, it is determined whether the number n of operating sub-water heating devices is smaller than the number N of sub-water heating devices. This is the step to determine whether there are any inactive sub-water heating devices that can be additionally operated. If the determination in S7 is Yes, the process proceeds to S8, where one of the inactive sub-water heating devices is additionally operated in S8, and the process proceeds to S9. Then, in S9, the number n of operating sub-water heating devices is incremented by 1, and the process proceeds to S10. At this time, the control unit 40 of the sub-water heating device that received the additional operation command begins operation by opening the water supply valve 30 of that sub-water heating device.

[0038] On the other hand, if the determination in S6 is No, the sub-water heating device is not additionally operated and the process proceeds to S10. Also, if the determination in S7 is No, there is no sub-water heating device that is not yet in operation and can be additionally operated, so the process proceeds to S10 without additionally operating the sub-water heating device.

[0039] In S10, it is determined whether the water supply flow rate of the water heater that was last activated among the currently operating water heaters has fallen below the activation flow rate. If the amount of hot water usage decreases, the water flow rate of the currently operating water heaters will also decrease, so to compensate for this decrease, the opening of the hot water outlet flow rate adjustment valve 39 of the water heater that was last activated is preferentially adjusted, thereby reducing the heating capacity. If the water supply flow rate falls below the activation flow rate, stable hot water operation will become difficult, so this is the step where the operation stop conditions are determined to stop the water heater that was last activated.

[0040] If the determination in S10 is No, the process returns to S3. If the determination in S10 is Yes, the process proceeds to S11, where the operation of the water heater that last started operation is stopped in S11, and the process proceeds to S12. Control unit 40 of the water heater that has been instructed by system control device 15 to stop operation closes water supply valve 30 of that water heater to stop operation.

[0041] In S12, it is determined whether the number n of operating sub-water heating devices is zero. If the determination in S12 is No (n>0), the process proceeds to S13, where the number n of operating sub-water heating devices is decremented by 1, and since at least the main water heating device is operating, the process returns to S3. On the other hand, if the determination in S12 is Yes (n=0), the operation of the main water heating device was stopped in S11, so the process proceeds to S14. Then, in S14, hot water supply operation is terminated and control of the number of operating devices is terminated.

[0042] Next, an example of the transition of heating capacity during hot water supply operation in normal hours will be described with reference to FIG. During normal hours, hot water supply operation begins in state (a) with only the main water heater operating, and then the heating capacity is increased until the main water heater reaches the normal hourly specified value U0 (additional operation condition is met), at which point one sub-water heater (first sub-water heater) is additionally operated, transitioning to state (b).Furthermore, upon satisfaction of the additional operation condition, the second sub-water heater is additionally operated, transitioning to state (c), and then the third sub-water heater is additionally operated, allowing the heating capacity to be increased to state (d) where all of the multiple water heaters 11-14 are operating at maximum heating capacity.

[0043] On the other hand, if the hot water supply flow rate decreases from state (d), for example, the heating capacity is preferentially reduced by reducing the opening of the hot water outlet flow rate adjustment valve 39 of the hot water supply device (third sub-hot water supply device) that was last activated among the operating hot water supply devices. Then, when the water supply flow rate of this third sub-hot water supply device falls below the operation start flow rate (when the operation stop condition is met), operation is stopped. By further reducing the heating capacity and reducing the heating capacity in the reverse order of the operation start order to reduce the number of operating units, the system transitions to state (a) via states (c) and (b), and then to state (a). When the water supply flow rate of the main hot water supply device falls below the operation start flow rate, hot water supply operation is terminated. Furthermore, even if the amount of hot water usage increases or decreases during hot water supply, the heating capacity of the hot water supply device that was last activated among the operating hot water supply devices is adjusted, and the number of operating units is changed according to the additional operation condition and operation stop condition.

[0044] Next, an example of the increase in heating capacity during hot water supply operation during a high load time period will be described with reference to FIG. During high-load periods, hot water supply operation begins in state (a) with only the main water heater operating, and then the heating capacity is increased until the heating capacity of the main water heater exceeds the high-load period specified value H0 (additional operation conditions are met), at which point one sub-water heater (first sub-water heater) is additionally operated, transitioning to state (b).Furthermore, upon satisfaction of additional operation conditions, a second sub-water heater is additionally operated, transitioning to state (c), and then a third sub-water heater is additionally operated, allowing the heating capacity to be increased to state (d) where all of the multiple water heaters 11-14 are operating at maximum heating capacity.

[0045] In this way, during high-load periods, the next sub-water heater starts operating while the last operating water heater increases its heating capacity. Therefore, during high-load periods, the heating capacity of linked hot water supply system 10 increases more quickly than during normal periods, improving responsiveness.

[0046] Next, an example of the transition of the decrease in heating capacity during hot water supply operation during a high load time period will be described with reference to FIG. For example, if the hot water supply flow rate decreases from state (a), the opening of the hot water outlet flow rate control valve 39 of the last operating hot water supply device (third sub-hot water supply device) is reduced, thereby preferentially reducing the heating capacity and transitioning to state (b). At this time, the reduction is performed so that the water supply flow rate does not fall below the operation start flow rate (so that the operation stop condition is not met). If the heating capacity is further reduced, the heating capacity is reduced in the reverse order of operation start so that the operation stop condition is not met, maintaining the number of operating units, and transitioning to state (c), for example. Maintaining the number of operating units allows the heating capacity of operating hot water supply devices to be increased quickly in the event of a sudden increase in hot water usage, resulting in improved responsiveness compared to normal times. This allows for a quick increase in heating capacity, particularly when the majority of multiple hot water users are replaced and hot water usage fluctuates dramatically.

[0047] To further reduce the heating capacity from state (c), the last operating water heater (third sub-water heater) is stopped, and the heating capacity of the other operating water heaters is adjusted to transition to state (d). In this way, the number of operating units is reduced one by one in the reverse order of their start-up, and the heating capacity of the operating water heaters is adjusted to reduce the heating capacity of the linked hot water supply system 10. Although not shown, when the flow rate detected by the water supply flow sensor 32 of the main water heater falls below the start-up flow rate, the hot water supply operation is terminated. The heating capacity of the operating water heaters can also be increased or decreased so that they maintain the same heating capacity.

[0048] The operation and effects of the linked hot water supply system 10 will now be described. In the linked hot water supply system 10, the main hot water supply unit operates to supply hot water when hot water supply begins. When the heating capacity of the last operating hot water supply unit reaches or exceeds a specified value, the number of operating units is increased by one. The system control device 15 of this linked hot water supply system 10 sets a time period during which hot water usage increases as a high-load time period based on the learned hot water supply operation status. During this high-load time period, the specified value that serves as the criterion for increasing the number of operating units is lowered from the specified value during other high-load time periods. This allows the sub-hot water supply unit to be activated while increasing the heating capacity of the last operating hot water supply unit. This allows the timing of the sub-hot water supply unit's activation to be advanced, allowing for a quick response to increased hot water usage and improving responsiveness. Furthermore, because the specified value is higher during other than high-load time periods than during high-load time periods, the increase in the number of operating units is suppressed, thereby suppressing the progression of deterioration of the hot water supply units.

[0049] When a high-load time period is set based on the maximum water flow rate through multiple water heaters, the timing at which the sub-water heater starts operating is advanced when the high-load time period mode is on, allowing the high-load time period to be set more appropriately even in hot water operation situations where the number of operating units is likely to increase.Furthermore, when a high-load time period is set based on the rate of increase in the water flow rate through multiple water heaters, the high-load time period can be set more appropriately even in hot water operation situations where the number of operating units is likely to increase when the high-load time period mode is on.

[0050] System control device 15 may control the hot water supply operation of multiple hot water supply devices 11-14. Also, an external control device connected to linked hot water supply system 10 via an internet line may set high-load time periods. In addition, those skilled in the art may implement the above-described embodiments in various modified forms without departing from the spirit of the present invention, and the present invention includes such modified forms. [Explanation of symbols]

[0051] 1: Water supply piping 2: Hot water supply piping 10: Connected hot water system 11-14: Hot water supply equipment 15: System control device (control means) 15a: Operation remote control 21: Combustion section 22:Heat exchange section 23: Water supply section 24: Tap area 25: Burner 25a to 25d: 1st to 4th combustion sections 25e~25h: On-off valve 26: Fuel adjustment valve 27: Combustion fan 28:Ignition device 29:Water supply passage 30: Water supply valve 31: Water supply temperature sensor 32: Water supply flow sensor 34: Hot water passage 35: Bypass passage 36: Bypass flow control valve 37: First hot water outlet temperature sensor 38: Second hot water outlet temperature sensor 39: Flow rate control valve 40: Control section F1~Fm: Hot water tap

Claims

1. A linked hot water supply system includes a plurality of combustion-type hot water supply devices installed in parallel between a water supply pipe and a hot water supply pipe, and a control means for changing the number of the hot water supply devices to be operated according to the amount of hot water used. For the plurality of water heaters, one main water heater is set to be operated when hot water supply starts, and a sub-water heater is set to be operated in addition to the main water heater, The control means is a linked hot water supply system characterized in that when the heating capacity of the hot water supply device that was last started among the operating hot water supply devices reaches or exceeds a specified value, it operates one of the inactive sub-hot water supply devices to supply hot water, learns and memorizes the hot water supply operation status of the multiple hot water supply devices, sets a high-load time period during which hot water usage increases, and lowers the specified value for operating the additional sub-hot water supply device during this high-load time period.

2. The linked hot water supply system according to claim 1 , wherein the high-load time period is set based on a maximum water flow rate through the plurality of hot water supply devices.

3. 2. The linked hot water supply system according to claim 1, wherein the high-load time period is set based on an increase rate of water flow through the plurality of hot water supply devices.

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