Hot water supply system and water heater

Abstract

To provide a technique capable of appropriately increasing / decreasing the number of operating water heaters.SOLUTION: A water heating system includes a plurality of water heaters connected in parallel with each other and a connection control device which controls the plurality of water heaters. The connection control device is configured to select at least one of the plurality of water heaters as a water heater to be activated, select the rest of the plurality of water heaters as a water heater to be deactivated, transmit an activation instruction to the controller of the water heater to be activated, and transmit a deactivation instruction to the controller of the water heater to be deactivated. The connection control device may increase or decrease the number of operation target water heaters based on the maximum flow rate of the valve and the detected flow rate detected by the flow rate sensor in each of the operation target water heaters, and when increasing the number of operation target water heaters, the connection control device may select a water heater to be the next operation target water heater from the water heaters not transmitting the abnormality signal among the water heaters included in the stop target water heaters.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a hot water supply system including a plurality of hot water heaters connected in parallel with each other, and to a hot water heater that can constitute the hot water supply system. [Background technology]

[0002] In the hot water supply system of Patent Document 1, multiple water heaters connected in parallel are connected to a connection unit. The connection unit sets the flow rate range of the water heaters to three levels: "low," "medium," and "high." When the flow rate of any of the operating water heaters increases to "high," the connection unit activates one of the multiple water heaters that is not operating. Furthermore, when the flow rate of any of the operating water heaters decreases to "low," the connection unit stops that water heater. In other words, the connection unit increases or decreases the number of operating water heaters depending on the flow rate of the operating water heaters. Furthermore, operating water heaters adjust the heating power for heating hot water based on the outlet water temperature detected by a temperature sensor installed in the hot water outlet pipe. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2002-357361 Summary of the Invention [Problem to be solved by the invention]

[0004] The hot water supply system of Patent Document 1 is based on the assumption that all water heaters have the same maximum flow rate, and therefore the number of operating water heaters can be appropriately increased or decreased based on the flow rate of the operating water heaters. However, in this type of water heater, if an abnormality occurs in the heating unit, the heating capacity of the heating unit may be reduced by reducing the maximum flow rate of the water heater. In a hot water supply system equipped with such a water heater, the maximum flow rates of the multiple water heaters may differ from one another. In this case, the above assumption is broken, and the above hot water supply system may not be able to appropriately increase or decrease the number of operating water heaters. This specification provides a technology that can appropriately increase or decrease the number of operating water heaters in a hot water supply system including a water heater that reduces the maximum flow rate when an abnormality occurs in the heating unit. [Means for solving the problem]

[0005] In a first aspect of the present technology, a hot water supply system may include a plurality of water heaters connected in parallel with each other and a linkage control device that controls the plurality of water heaters. In this case, each of the plurality of water heaters may include a heating unit that heats hot water, a flow sensor that detects the flow rate of hot water flowing into the water heater, a valve that limits the flow rate of hot water flowing into the water heater to a limit flow rate or less, and a control unit that can communicate with the linkage control device. Furthermore, the control unit may be configured to start heating hot water by the heating unit when the detected flow rate detected by the flow sensor becomes equal to or greater than an ignition flow rate while the heating unit is not heating hot water, adjust the heating capacity of the heating unit while the heating unit is heating hot water so that the temperature of the hot water heated by the heating unit approaches a hot water supply setting temperature while the heating unit is heating hot water, and stop heating hot water by the heating unit when the detected flow rate becomes equal to or less than an extinguishing flow rate while the heating unit is heating hot water. The connection control device may be configured to select some of the multiple water heaters as water heaters to be operated and the remaining of the multiple water heaters as water heaters to be stopped, send an operation instruction to the control unit of the water heater to be operated, and send a stop instruction to the control unit of the water heater to be stopped. The control unit may be configured to control the valve so that the restricted flow rate becomes the maximum flow rate when receiving an operation instruction from the connection control device, and to control the valve so that the restricted flow rate becomes zero when receiving a stop instruction from the connection control device, and to reduce the heating capacity of the heating unit by reducing the maximum flow rate when an abnormality related to the heating unit occurs, and to send an abnormality signal indicating the occurrence of the abnormality to the connection control device. The connection control device may increase or decrease the water heaters to be operated based on the maximum flow rate of the valve and the detected flow rate in each of the water heaters to be operated, and when increasing the number of water heaters to be operated, select a water heater to be the next water heater to be operated from among the water heaters included in the water heaters to be stopped that have not transmitted an abnormality signal.

[0006] According to the above configuration, if there is a water heater transmitting an abnormality signal among the water heaters to be stopped, the connection control device does not select that water heater as a water heater to be operated. In other words, with the above configuration, among the water heaters to be stopped, a water heater that has experienced an abnormality and reduced its maximum flow rate is excluded from the selection targets for water heaters to be operated. Therefore, in a water heating system including a water heater that reduces its maximum flow rate when an abnormality related to the heating unit occurs, the number of water heaters to be operated can be appropriately increased or decreased. Note that in this specification, the term "water heater that has not transmitted an abnormality signal" includes both a water heater that has not transmitted an abnormality signal in the past and a water heater that has transmitted an abnormality signal in the past but is not currently transmitting an abnormality signal.

[0007] In a second aspect of the present technology, in the first aspect, each of the plurality of water heaters may further include a water supply temperature sensor that detects the temperature of hot water flowing into the water heater. In this case, the control unit may be configured to adjust the heating capacity of the heating unit based on the hot water supply setting temperature, the detected flow rate, and the detected temperature detected by the water supply temperature sensor when the heating unit is heating the hot water.

[0008] According to the above configuration, the amount of heat to be provided to the hot water at the flow rate flowing into the water heater can be calculated based on the difference between the hot water setting temperature and the detected temperature and the detected flow rate. Therefore, the heating capacity of the heating unit can be adjusted based on the calculated amount of heat.

[0009] According to a third aspect of the present technology, in the first or second aspect, the heating unit may include a gas burner.

[0010] According to the above configuration, for example, when an abnormality occurs in the gas burner, the maximum flow rate can be reduced, thereby reducing the heating power of the gas burner.

[0011] In a fourth aspect of the present technology, in any one of the first to third aspects, the abnormality related to the heating unit may include a temperature of a predetermined part of the water heater in which the heating unit is arranged exceeding a threshold temperature. In this case, when an abnormality occurs, the control unit may gradually reduce the maximum flow rate without sending an abnormality signal to the connection control device, and may be configured to send an abnormality signal to the connection control device when the maximum flow rate is equal to or less than the threshold flow rate.

[0012] If the heat generated by the heating unit causes the temperature of a specific part in the water heater to exceed a threshold temperature, there is a risk of damage to the specific part. According to the above configuration, even if the temperature of the specific part exceeds the threshold temperature, an abnormality signal is not sent to the connection control device until the maximum flow rate of the water heater falls below the threshold flow rate, and the maximum flow rate is gradually reduced. Therefore, by gradually lowering the temperature of the specific part of the water heater to be operated while leaving the water heater whose temperature of the specific part exceeds the threshold temperature as a selection target water heater to be operated, damage to the specific part can be suppressed.

[0013] In a fifth aspect of the present technology, in any one of the first to fourth aspects, each of the plurality of water heaters may include a first memory that stores abnormality information indicating that an abnormality has occurred. In this case, the control unit may be configured to continuously send an abnormality signal to the connection control device while the abnormality information is stored in the first memory. Furthermore, when increasing the number of water heaters to be operated, the connection control device may select a water heater to be the next water heater to be operated from among the water heaters included in the water heaters to be stopped that are not currently sending an abnormality signal.

[0014] According to the above configuration, the connection control device can select a water heater that is not currently transmitting an abnormality signal as the water heater to be operated.

[0015] According to a sixth aspect of the present technology, in the fifth aspect, the control unit may delete the abnormality information stored in the first memory when the abnormality is resolved.

[0016] According to the above configuration, when the abnormality is resolved, the water heater stops transmitting the abnormality signal. Therefore, the connection control device can select the water heater in which the abnormality has been resolved as the water heater to be operated.

[0017] In a seventh aspect of the present technology, in any one of the first to sixth aspects above, the control unit may be configured to further transmit identification information for identifying the water heater to the connection control device along with the abnormality signal. In this case, the connection control device may include a second memory that stores the identification information received from the control unit in association with abnormality occurrence information indicating that an abnormality has occurred in the water heater, and when increasing the number of water heaters to be operated, the connection control device may select a water heater to be the next water heater to be operated from among the water heaters included in the water heaters to be stopped and whose identification information is not stored in the second memory in association with the abnormality occurrence information.

[0018] According to the above configuration, the connection control device can select the water heater to be operated based on the identification information stored in the second memory in association with the abnormality occurrence information.

[0019] In an eighth aspect of the present technology, in the seventh aspect, when the abnormality is resolved, the control unit may be configured to further transmit an abnormality resolution signal indicating that the abnormality has been resolved together with the identification information to the coupling control device. In this case, when the coupling control device receives the abnormality resolution signal and the identification information, the coupling control device may delete at least one of the abnormality occurrence information stored in the second memory and the identification information stored in association with the abnormality occurrence information.

[0020] According to the above configuration, when the abnormality in the water heater is resolved, at least one of the abnormality occurrence information and the identification information stored in association with the abnormality occurrence information is deleted from the second memory. Therefore, the connection control device can select the water heater in which the abnormality has been resolved as the water heater to be operated.

[0021] In a ninth aspect of the present technology, in any one of the first to eighth aspects above, when the connection control device receives an abnormality signal from the water heater to be operated, it may send a stop instruction to the water heater to be operated, and may select a water heater to be the new water heater to be operated from among the water heaters to be stopped.

[0022] According to the above configuration, when an abnormality occurs in the water heater to be operated, the water heater to be operated can be stopped and a new water heater to be operated can be selected.

[0023] According to a tenth aspect of the present technology, in any one of the first to ninth aspects, the hot water supply system may further include a notification unit that notifies a user that an abnormality has occurred.

[0024] According to the above configuration, the user can be made aware that an abnormality has occurred in the water heater.

[0025] In an eleventh aspect of the present technology, in any one of the first to tenth aspects above, the connection control device may be configured to determine one of multiple flow rate levels set for the detected flow rate of the water heater to be operated, and increase or decrease the number of water heaters to be operated based on the number of water heaters to be operated for each determined flow rate level.

[0026] When an abnormality occurs in the heating section of a water heater to be operated and the maximum flow rate of the water heater to be operated is reduced, the detected flow rate of the water heater to be operated also decreases. Therefore, the flow rate level of the detected flow rate of a water heater to be operated when an abnormality occurs in the heating section and the maximum flow rate is reduced cannot be properly determined. Therefore, when an abnormality occurs in the heating section and the maximum flow rate of a water heater to be operated is reduced, the number of water heaters to be operated for each flow rate level cannot be properly calculated. According to the hot water supply system disclosed in this specification, a water heater that has an abnormality in the heating section and the maximum flow rate is reduced is not selected as a water heater to be operated, so the number of water heaters to be operated for each flow rate level can be properly calculated. This makes it possible to properly increase or decrease the number of water heaters to be operated based on the number of water heaters to be operated for each flow rate level.

[0027] According to a twelfth aspect of the present technology, in any one of the first to eleventh aspects, the connection control device may be configured by a control unit of a water heater included in the plurality of water heaters.

[0028] According to the above configuration, the configuration of the hot water supply system can be simplified compared to a configuration in which, for example, a connection control device separate from the hot water heater is provided.

[0029] This specification also discloses a water heater that can constitute the hot water supply system. The water heater may include a heating unit that heats hot water, a flow sensor that detects the flow rate of hot water flowing into the water heater, a valve that limits the flow rate of hot water flowing into the water heater to a limit flow rate or less, and a control unit that can communicate with other water heaters. In this case, the control unit may be capable of selectively executing a master unit process and a slave unit process that is subordinate to the master unit process. Furthermore, the slave unit process may include a process for starting heating of hot water by the heating unit when the detected flow rate detected by the flow sensor is equal to or greater than the ignition flow rate while the heating unit is not heating hot water; a process for adjusting the heating capacity of the heating unit when the heating unit is heating hot water so that the temperature of the hot water heated by the heating unit approaches the hot water supply setting temperature while the heating unit is heating hot water; and a process for terminating heating of hot water by the heating unit when the detected flow rate is equal to or less than the extinguishing flow rate while the heating unit is heating hot water. The parent unit processing may also include a process of selecting some of the multiple water heaters as water heaters to be operated, selecting the remaining of the multiple water heaters as water heaters to be stopped, sending an operation instruction to the control unit of the water heater to be operated, and sending a stop instruction to the control unit of the water heater to be stopped. Furthermore, the child unit processing may include a process of controlling the valve so that the restricted flow rate becomes the maximum flow rate when an operation instruction is received from the water heater executing the parent unit processing, and controlling the valve so that the restricted flow rate becomes zero when a stop instruction is received from the water heater executing the parent unit processing, and a process of reducing the heating capacity of the heating unit by reducing the maximum flow rate when an abnormality related to the heating unit occurs, and sending an abnormality signal indicating the occurrence of the abnormality to the water heater executing the parent unit processing. The parent unit processing may include a process for increasing or decreasing the number of water heaters to be operated based on the maximum valve flow rate and the detected flow rate for each of the water heaters to be operated, and a process for selecting, when increasing the number of water heaters to be operated, a water heater to be the next water heater to be operated from among the water heaters included in the water heaters to be stopped that are not transmitting an abnormality signal.

[0030] The connection control device constituting the hot water supply system, the computer program for the connection control device, and the control method for the connection control device are also novel and useful. [Brief explanation of the drawings]

[0031] [Figure 1] 1 shows a schematic diagram of a hot water supply system 100 according to an embodiment. [Figure 2] 1 shows a schematic diagram of a water heater 10A. [Figure 3] 1 shows a configuration diagram of a hot water supply system 100. FIG. [Figure 4] 1 shows a flowchart of a heating process. [Figure 5] 10 shows a flowchart of an abnormality resolution process. [Figure 6] 10 shows a flowchart of a process for selecting a water heater to be operated. [Figure 7] 10 shows a flowchart of an abnormality notification process. [Figure 8] 10 shows a flowchart of an abnormality notification stop process. DETAILED DESCRIPTION OF THE INVENTION

[0032] (Example) (Configuration of hot water supply system 100) As shown in FIG. 1, the hot water supply system 100 of this embodiment includes a plurality of water heaters 10A-10D, a plurality of faucets 2, a hot water pipe 4, a water supply pipe 6, and a remote control 50. The plurality of water heaters 10A-10D are connected in parallel to the water supply pipe 6 and the hot water pipe 4. In the hot water supply system 100, hot water is supplied to the plurality of water heaters 10A-10D via the water supply pipe 6. The plurality of water heaters 10A-10D heat the supplied hot water to generate hot water. The hot water generated by the plurality of water heaters 10A-10D is supplied to users via the hot water pipe 4 and the plurality of faucets 2.

[0033] (Configuration of water heater 10A) Of the plurality of water heaters 10A to 10D, the structure of water heater 10A will be described with reference to Figure 2. Note that each of water heaters 10A to 10D has the same configuration. Water heater 10A includes a water pipe 12, a heat medium pipe 14, a heat exchanger 15, an air supply duct 17, an exhaust duct 18, a heating unit 20, and a control unit 40.

[0034] The upstream end of the water supply pipe 12 is connected to the water supply pipe 6 (see Figure 1). Hot water is supplied to the water supply pipe 12 from the water supply pipe 6. The water supply pipe 12 is equipped with a water supply temperature sensor 30, a flow rate sensor 32, a water volume servo 34, a bypass waterway 35, an outlet hot water temperature sensor 36, and a bypass servo 38. The water supply temperature sensor 30, the flow rate sensor 32, and the water volume servo 34 are arranged upstream of the heat exchanger 15, and the outlet hot water temperature sensor 36 and the bypass servo 38 are arranged downstream of the heat exchanger 15. The downstream end of the water supply pipe 12 is connected to the hot water supply pipe 4 (see Figure 1).

[0035] The supply water temperature sensor 30 detects the temperature of hot water flowing from the supply water pipe 6 into the water supply pipe 12. The flow rate sensor 32 detects the flow rate of hot water flowing from the supply water pipe 6 into the water supply pipe 12. The water volume servo 34 is a so-called servo valve that limits the flow rate of hot water into the water supply pipe 12. The water volume servo 34 can be switched between an open state, which allows hot water to flow from the supply water pipe 6 into the water supply pipe 12, and a closed state, which blocks the flow of hot water from the supply water pipe 6 into the water supply pipe 12. The limited flow rate, which is the flow rate of hot water flowing from the supply water pipe 6 into the water supply pipe 12, changes depending on the opening of the water volume servo 34. The bypass water passage 35 causes hot water in the water supply pipe 12 to bypass the heat exchanger 15. The bypass servo 38 controls the amount of hot water flowing into the bypass water passage 35. The outlet hot water temperature sensor 36 detects the temperature of hot water flowing from the water supply pipe 12 to the hot water supply pipe 4.

[0036] The heat medium pipe 14 is a closed circuit within the water heater 10A that circulates a heat medium between the heat exchanger 15 and the heating unit 20. The heat medium pipe 14 is equipped with a pump 16. The pump 16 circulates the heat medium within the heat medium pipe 14. In this embodiment, the heat medium is water or antifreeze. In a modified example, the heat medium pipe 14 may be connected to the heat medium pipes 14 of other water heaters 10B to 10D, for example. The heat exchanger 15 exchanges heat between the heat medium and hot water. The high-temperature heat medium from the heating unit 20 is radiated by the heat exchanger 15 to lower its temperature, and the hot water in the water pipe 12 is heated to raise its temperature, producing hot water.

[0037] The heating unit 20 includes a gas burner 22, a sensible heat exchanger 24, and a latent heat exchanger 26. The gas burner 22 combusts fuel gas (e.g., city gas) supplied from a fuel supply source (not shown). The sensible heat exchanger 24 exchanges heat between the combustion gas burned by the gas burner 22 and the heat medium passing through the heat medium pipe 14. The latent heat exchanger 26 recovers latent heat from the combustion gas to heat the heat medium after heat exchange with the heat medium in the sensible heat exchanger 24. Heating the heat medium in the heat medium pipe 14 by both the sensible heat exchanger 24 and the latent heat exchanger 26 can improve energy efficiency compared to, for example, a configuration in which the heat medium is heated only by the sensible heat exchanger 24. Furthermore, by recovering heat from the combustion gas by both the sensible heat exchanger 24 and the latent heat exchanger 26, the temperature inside the exhaust duct 18, which will be described later, can be reduced compared to, for example, a configuration in which heat is recovered from the combustion gas only by the sensible heat exchanger 24. In a modified example, the heating unit 20 may heat the heat medium inside the heat medium pipe 14 by an electric heater instead of the gas burner 22. Furthermore, the heating unit 20 may not include the latent heat exchanger 26, and may heat the heat medium only by the sensible heat exchanger 24. Alternatively, the water heater 10A may not include the heat medium pipe 14, the heat exchanger 15, and the pump 16, and the water pipe 12 may pass through the heating unit 20, and the hot water inside the water pipe 12 may be directly heated by the gas burner 22.

[0038] Air intake duct 17 is provided on top of water heater 10A and connects the inside and outside of water heater 10A. Air intake duct 17 draws air S1 from the outside into the inside of water heater 10A using a fan (not shown). This causes gas burner 22 in heating section 20 to burn fuel gas. Exhaust duct 18 is located adjacent to air intake duct 17 and connects the inside and outside of water heater 10A. Exhaust duct 18 is connected to heating section 20. Combustion gas generated by gas burner 22 in heating section 20 passes through latent heat exchanger 26 and sensible heat exchanger 24 to become exhaust gas E1, which is then discharged to the outside of water heater 10A via exhaust duct 18. Exhaust duct 18 is equipped with an exhaust temperature sensor 19 that detects the temperature of exhaust gas E1 in exhaust duct 18.

[0039] (Configuration of remote control 50) Remote control 50 shown in FIG. 1 is placed in a user's home (not shown). Remote control 50 is operated by a user to operate multiple water heaters 10A to 10D. As shown in FIG. 3, remote control 50 includes an operation unit 51, a display unit 52, a communication I / F 53, and a control unit 54. Operation unit 51 accepts various inputs from the user. Operation unit 51 accepts an operation from the user to turn on the power to hot water supply system 100. Operation unit 51 also accepts an input from the user of a hot water supply temperature setting, which is the temperature of hot water to be supplied by faucet 2. Display unit 52 displays various information related to multiple water heaters 10A to 10D. Communication I / F (abbreviation for interface) 53 is an I / F for communicating with each of water heaters 10A to 10D. Control unit 54 is a computer equipped with a CPU and memory.

[0040] As shown in Fig. 3, the water heater 10A further includes a communication I / F 13. The communication I / F 13 is an I / F for communication between the communication I / Fs (not shown) of the other water heaters 10B to 10D and the communication I / F 53 of the remote control 50. In this embodiment, the water heaters 10A to 10D and the remote control 50 are connected to each other so that they can communicate with each other via wired communication. In a modified example, the water heaters 10A to 10D and the remote control 50 may be connected to each other so that they can communicate with each other wirelessly.

[0041] Water heater 10A is assigned ID "01". Similarly, water heater 10B is assigned ID "02", water heater 10C is assigned ID "03", and water heater 10D is assigned ID "04". Each ID "01" to "04" is information for identifying the water heater. Each ID "01" to "04" is assigned by a parent unit, which will be described later, when each water heater 10A to 10D is connected.

[0042] In this embodiment, water heaters 10A-10D are used in a linked configuration. In other words, the multiple water heaters 10A-10D cooperate with one another while each operating as an individual water heater and supplying hot water to the multiple faucets 2. When the power to hot water supply system 100 is turned on using remote control 50, the power to all of the multiple linked water heaters 10A-10D is turned on. In hot water supply system 100, when a hot water supply setting temperature is input using remote control 50 and hot water supply pipe 4 is opened by faucet 2, hot water heated to the hot water supply setting temperature is supplied from faucet 2.

[0043] For example, when the amount of hot water supplied from faucet 2 is relatively small, the water volume servo 34 of one water heater (e.g., 10A) is opened, and the water volume servos 34 of the other water heaters 10B-10D are closed. This allows only water heater 10A to heat water and supply it to faucet 2. Also, when the flow rate of hot water supplied to faucet 2 is relatively large, the number of operating water heaters increases. For example, the water volume servos 34 of two water heaters (e.g., 10A and 10B) are opened, and the water volume servos 34 of the other water heaters 10C and 10D are closed. This allows hot water to be supplied to faucet 2 at a relatively large flow rate using two water heaters 10A and 10B.

[0044] In this way, when water heaters 10A-10D are connected and used, energy consumption can be reduced, for example, when a relatively small flow rate of hot water is supplied to faucet 2, compared to a system including a single water heater with a large heating capacity obtained by adding together the heating capacities of water heaters 10A-10D. Furthermore, by connecting water heaters 10A-10D of the same type, a variety of heating capacities can be achieved, thereby improving the versatility of water heaters 10A-10D.

[0045] When multiple water heaters 10A-10D are connected and used, a water heater selected from the multiple water heaters 10A-10D operates as a "master unit." Furthermore, the multiple water heaters 10A-10D also operate as "slave units." Here, the "master unit" is a water heater that primarily manages the entire hot water supply system 100. In contrast, the "slave units" are water heaters that operate subordinately to the master unit. Water heater 10A operates as both a "master unit" and a "slave unit." That is, in this embodiment, water heater 10A can selectively perform master unit processing based on its operation as a master unit and slave unit processing based on its operation as a slave unit. Therefore, the configuration of hot water supply system 100 can be simplified compared to, for example, a system that includes a linkage control device that manages the entire hot water supply system 100 separately from each of water heaters 10A-10D.

[0046] As a master unit process, water heater 10A executes, for example, an operation target water heater selection process (see FIG. 6) that selects a water heater to be operated from among water heaters 10A to 10D. In response to receiving an operation instruction from the master unit, water heaters 10A to 10D execute, as a slave unit process, for example, a heating process (see FIG. 4) that heats hot water. Hereinafter, the water heater selected as the master unit may be simply referred to as the "master unit," and the water heater selected as the slave unit may be simply referred to as the "slave unit."

[0047] For example, water heater 10A may be selected as the master unit by the user when connecting water heaters 10A to 10D. Alternatively, water heater 10A may be automatically selected as the master unit based on information such as a unique serial number assigned to each of water heaters 10A to 10D. In other words, water heater 10A is not set as the master unit at the time of manufacture, and may be selected as the master unit afterwards when connected to other water heaters 10B to 10D.

[0048] (Configuration of control unit 40) 3, the control unit 40 of the water heater 10A is a computer including a CPU 42 and a memory 44. The control unit 40 is electrically connected to each part of the water heater 10A. The control unit 40 receives values ​​detected from, for example, each of the sensors 30, 32, 36, 19, etc. The control unit 40 also controls the operation of the pump 16, the gas burner 22, the water volume servo 34, the bypass servo 38, etc.

[0049] Memory 44 includes volatile memory and nonvolatile memory. Memory 44 stores program 46, master unit flag F1, ignition flow rate L1, correction value L2, extinguishing flow rate L3, threshold temperature Tth1, threshold flow rate Lth1, water heater table Ta1, discriminant table Ta2, and condition table Ta3. Each piece of information is pre-stored in memory 44 when water heater 10A is manufactured. In a modified example, each piece of information may be subsequently downloaded via the Internet from a server provided by the vendor of water heater 10A, or may be subsequently installed via media.

[0050] The control unit 40 executes various processes in accordance with a program 46 stored in the memory 44. For example, the control unit 40 executes a heat power adjustment process (see S22 in FIG. 4) that adjusts the heat power of the gas burner 22 of the heating unit 20. In the heat power adjustment process, the control unit 40 calculates the required heat quantity by multiplying the difference between the hot water supply setting temperature received from the remote control 50 and the temperature detected by the water supply temperature sensor 30 by the flow rate detected by the flow rate sensor 32, and adjusts the heat power of the gas burner 22 according to the calculated required heat quantity. As a result, the temperature of the hot water heated by the heating unit 20 approaches the hot water supply setting temperature. Furthermore, the control unit 40 executes the processes shown in FIGS. 4 to 8.

[0051] Master unit flag F1 is information indicating that water heater 10A has been selected as a master unit in hot water supply system 100. Master unit flag F1 is stored in memory 44, for example, in response to water heater 10A being selected by a user or an installer. When master unit flag F1 is stored in memory 44, control unit 40 recognizes that it has been selected as the master unit, and executes the master unit processing shown in FIGS. 6 to 8, for example. When master unit flag F1 is not stored in memory 44, control unit 40 recognizes that it has been selected as a slave unit, and executes the slave unit processing shown in FIGS. 4 and 5, for example. Note that control unit 40 can execute the slave unit processing even if master unit flag F1 is stored in memory 44, i.e., even if it has been selected as the master unit.

[0052] Ignition flow rate L1 is a flow rate used to determine whether to ignite gas burner 22 of heating unit 20. For example, even if water volume servo 34 is fully open, if faucet 2 is closed, hot water will stagnate in water pipe 12. If gas burner 22 is ignited in this state, the temperature of the hot water stagnating in water pipe 12 may rise excessively. For this reason, when faucet 2 is opened and flow rate sensor 32 detects a flow rate equal to or greater than ignition flow rate L1, gas burner 22 is ignited.

[0053] The correction value L2 is a value for calculating a minimum flow rate L4, which will be described later, based on the ignition flow rate L1.

[0054] The extinction flow rate L3 is a flow rate used to determine whether the gas burner 22 of the heating unit 20 is extinguished. When the faucet 2 is closed, the flow rate of hot and cold water in the water pipe 12 decreases to or below the extinguishing flow rate L3. Therefore, when the faucet 2 is closed and a flow rate below the extinguishing flow rate L3 is detected, the gas burner 22 is extinguished. The extinguishing flow rate L3 has a value smaller than the ignition flow rate L1. This prevents the gas burner 22 from repeatedly igniting and extinguishing. However, the extinguishing flow rate L3 may have the same value as the ignition flow rate L1.

[0055] The threshold temperature Tth1 corresponds to the exhaust temperature detected by the exhaust temperature sensor 19. The threshold temperature Tth1 is a temperature for determining whether a temperature rise of the exhaust gas E1 in the exhaust duct 18 may cause damage to the exhaust duct 18, for example. The threshold temperature Tth1 is set according to the materials of the exhaust duct 18 and the components surrounding the exhaust duct 18. For example, if the components surrounding the exhaust duct 18 contain resin, the threshold temperature Tth1 is set relatively low. This prevents the resin in the components from melting. In this way, the temperature of the exhaust gas E1 generated by the combustion of the gas burner 22 (i.e., the exhaust temperature) is required to be kept below the threshold temperature Tth1. As described above, the heating power of the gas burner 22 is adjusted according to the required heat amount calculated by multiplying the difference between the hot water supply setting temperature and the detected temperature by the detected flow rate. Furthermore, when the maximum flow rate decreases, i.e., when the aperture of water volume servo 34 decreases, the detected flow rate, which is the flow rate of hot and cold water flowing from water supply pipe 6 into water supply pipe 12, also decreases. Therefore, for example, the heating power of gas burner 22 at a first maximum flow rate is smaller than the heating power of gas burner 22 at a second maximum flow rate that is greater than the first maximum flow rate. In water heater 10A, when the exhaust temperature is equal to or greater than threshold temperature Tth1, a process is executed to reduce the aperture of water volume servo 34 and decrease the maximum flow rate. This reduces the heating power of gas burner 22, thereby lowering the exhaust temperature.

[0056] The threshold flow rate Lth1 corresponds to the detected flow rate detected by the flow rate sensor 32. The threshold flow rate Lth1 is a value used in the heating process described below, and indicates the lower limit of the maximum flow rate.

[0057] Water heater table Ta1 is information used by the master unit to manage each of the water heaters 10A-10D. For this reason, water heater table Ta1 is stored in memory 44 of the master unit (i.e., water heater 10A), and is not stored in memory 44 of the other water heaters 10B-10D. When the master unit is connected to the other water heaters 10B-10D, it acquires various information from each of the water heaters 10B-10D and stores the information in water heater table Ta1. Water heater table Ta1 stores the valve status, maximum flow rate, detected flow rate, and status information for not only water heater 10A, but also the other connected water heaters 10B-10D. Valve status includes "open," which indicates that the water volume servo 34 is fully open, and "closed," which indicates that the water volume servo 34 is fully closed. Valve status may further include, for example, "50%," which indicates that the water volume servo 34 is only half open. The maximum flow rate indicates the flow rate of hot water or cold water that can currently be supplied to water heaters 10A-10D. The detected flow rate indicates the flow rate currently detected by flow sensor 32. The status information includes "abnormal," which indicates that an abnormality has occurred in the water heater, and "normal," which indicates that no abnormality has occurred. In this embodiment, an abnormality includes, for example, the exhaust temperature detected by exhaust temperature sensor 19 arranged in exhaust duct 18 being equal to or higher than the above-mentioned threshold temperature Tth1. In a modified example, the abnormality may be a blockage of exhaust duct 18, or overheating of heating unit 20 or the housing (symbol omitted) of water heater 10A. Furthermore, water heater table Ta1 may store, for example, only the valve status of each water heater 10A-10D.

[0058] The discriminant table Ta2 stores discriminants for discriminating the flow rate level of the detected flow rate. The flow rate levels include "small," "medium," and "large." In this embodiment, if the detected flow rate is equal to or less than the minimum flow rate L4, the flow rate level is determined to be "small." The minimum flow rate L4 is the flow rate obtained by adding the correction value L2 to the ignition flow rate L1 described above. Furthermore, if the detected flow rate is greater than the minimum flow rate L4 and equal to or less than the upper limit flow rate L5, the flow rate level is determined to be "medium." The upper limit flow rate L5 is a predetermined value set based on the maximum flow rate. In this embodiment, the upper limit flow rate L5 is a flow rate that is 90% of the maximum flow rate. In other words, the upper limit flow rate L5 is a value set based on the maximum flow rate. If the detected flow rate is greater than the upper limit flow rate L5, the flow rate level is determined to be "large."

[0059] Condition table Ta3 stores an increase condition for selecting a water heater from among the water heaters to be stopped and increasing the number of water heaters to be operated, and a decrease condition for decreasing the number by stopping the operation of the water heaters to be operated. In this specification, a "water heater to be stopped" refers to a water heater that is not operating among the multiple water heaters 10A-10D. More specifically, it refers to a water heater whose valve state indicates "closed." In contrast, a "water heater to be operated" refers to a water heater that is operating among the multiple water heaters 10A-10D. More specifically, it refers to a water heater whose valve state indicates "open." In this embodiment, the increase condition is met when the number of water heaters with a "large" flow rate level exceeds the number of water heaters with a "small" flow rate level among the water heaters to be operated. In this case, a water heater to be operated is selected from the water heaters to be stopped, and the water volume servo 34 of that water heater is opened. This increases the number of water heaters to be operated. Furthermore, if the number of water heaters with a flow rate level of "small" among the water heaters to be operated exceeds the number with a flow rate level of "large," the reduction condition is met. In this case, a water heater to be stopped is selected from the water heaters to be operated, and the water volume servo 34 of that water heater is closed. This reduces the number of water heaters to be operated. Although not shown in the figure, if the number of water heaters with a flow rate level of "small" is equal to the number of water heaters with a flow rate level of "large," the number of water heaters to be operated is maintained. In this way, in this embodiment, the number of water heaters to be operated is increased or decreased based on condition table Ta3, which is based on the number of water heaters to be operated for each flow rate level of "small," "medium," and "large."

[0060] Here, specific examples of the increase and decrease conditions will be described. First, case C1 will be described, in which no abnormality has occurred in the water heater. As an example, a case will be described in which, for example, only water heater 10A with ID "01" is selected as the water heater to be operated, and the maximum flow rate Lm1 of water heater 10A is 10 L / min, the detected flow rate Ld1 is 9.6 L / min, and the minimum flow rate L4 is 3.0 L / min. The detected flow rate of 9.6 L / min exceeds the upper limit flow rate L5 (9.0 L / min, i.e., 90% of the maximum flow rate of 10 L / min). Therefore, based on discriminant table Ta2, the detected flow rate Ld1 of water heater 10A is determined to be a "large" flow rate level. In this case, the number of units with a "large" flow rate level (i.e., 1 unit) is greater than the number of units with a "small" flow rate level (i.e., 0 units), and the increase condition is satisfied.

[0061] This selects the next water heater (e.g., 10B) to be operated, and the water volume servo 34 of that water heater 10B is opened. As a result, the 9.6 L / min of hot and cold water that had been flowing only to water heater 10A is now distributed to both water heaters 10A and 10B. Therefore, the detected flow rates of each water heater 10A and 10B decrease to approximately 4.8 L / min, half of 9.6 L / min. In this case, the detected flow rates of each water heater 10A and 10B to be operated are greater than the minimum flow rate L4 (3.0 L / min) and less than the upper limit flow rate L5 (9.0 L / min), so both detected flow rates are determined to be at a "medium" flow level. Therefore, the number of units with a "low" flow rate (i.e., 0 units) is equal to the number with a "high" flow rate (i.e., 0 units), and neither the increase nor decrease condition is satisfied. Therefore, the operation of each water heater 10A and 10B continues.

[0062] Next, we will explain case C2 in which an abnormality has occurred in water heater 10A. In this case, for example, only water heater 10A with ID "01" is selected as the water heater to be operated, and an abnormality has occurred in water heater 10A. Therefore, in this case, instead of the information surrounded by the dashed line in case C1, the information surrounded by the dashed line in case C2 shown to the right of water heater table Ta1 is stored in water heater table Ta1. Details will be described later with reference to Figure 4, but for example, when the exhaust temperature of exhaust gas E1 detected by exhaust temperature sensor 19 becomes equal to or higher than threshold temperature Tth1, the maximum flow rate Lm1 (10 L / min) of water heater 10A is reduced to maximum flow rate Lm2 (6 L / min), for example.

[0063] When the maximum flow rate Lm2 is set to 6 L / min, for example, if the detected flow rate Ld2 of water heater 10A becomes 5.6 L / min, the detected flow rate Ld2 exceeds the upper limit flow rate L5 (5.4 L / min, i.e., 90% of the maximum flow rate Lm2), and the detected flow rate Ld2 is determined to be a "large" flow rate level. In this case, as in the example described above, the number of units with a "large" flow rate level (i.e., 1 unit) becomes greater than the number with a "small" flow rate level (i.e., 0 units), and water heater 10B is selected as the next water heater to be operated. In case C2, the detected flow rate of water heater 10B decreases to approximately 2.8 L / min, half of 5.6 L / min. This is below the minimum flow rate L4 (3.0 L / min) described above. Therefore, the detected flow rates of both water heaters 10A and 10B are determined to be "small" flow rates. As a result, the number of units with a "low" flow rate level (i.e., 2 units) becomes greater than the number of units with a "high" flow rate level (i.e., 0 units). In this case, the reduction condition is met, so one of the water heaters 10A, 10B (e.g., 10B) is selected as the water heater to be stopped, and operation of that water heater is stopped. That is, in this case, the water volume servo 34 of the water heater 10B selected as the water heater to be stopped is closed.

[0064] When the water volume servo 34 of water heater 10B is closed, the flow rate of hot water flowing into water heater 10B becomes zero. The hot water that had been flowing into water heater 10B flows back into water heater 10A, whose water volume servo 34 remains open. As a result, the detected flow rate Ld2 of water heater 10A rises again to 5.6 L / min. In this case, as described above, the detected flow rate Ld2 of water heater 10A is determined to be a "large" flow rate level, the increase condition is met, and 10B, for example, is again selected as the next water heater to be operated, and the water volume servo 34 of that water heater is opened. However, as described above, when the hot water that had been flowing into water heater 10A is dispersed, the detected flow rates of each water heater 10A, 10B fall below the minimum flow rate L4, the decrease condition is met, and the water volume servo 34 of one of water heaters 10A, 10B (for example, 10B) is closed. In this way, in a configuration in which the maximum flow rate is reduced when an abnormality occurs, if the maximum flow rate becomes less than twice the minimum flow rate L4, the number of water heaters to be operated increases, and if hot and cold water is dispersed, the detected flow rate may become less than the minimum flow rate L4, and there is a risk that the number of water heaters to be operated will frequently increase and decrease. Below, we will explain the processing executed in hot water supply system 100 of this embodiment to appropriately calculate and appropriately increase or decrease the number of water heaters to be operated in a configuration in which the maximum flow rate is reduced when an abnormality occurs.

[0065] (heat treatment) The heating process executed by the control unit 40 (i.e., CPU 42) of the water heaters 10A to 10D will be described with reference to Figure 4. The heating process is a process in which each of the water heaters 10A to 10D heats hot water supplied from the water supply pipe 6 (see Figure 1), and is a slave unit process executed in common by each of the water heaters 10A to 10D. The control unit 40 of each of the water heaters 10A to 10D executes the process of Figure 4 in response to receiving the above-mentioned operation instruction from the master unit (for example, 10A).

[0066] In S2, the control unit 40 fully opens the water volume servo 34. This allows hot water to flow from the water supply pipe 6 into the water flow pipe 12 when the user operates the faucet 2 to open the hot water supply pipe 4.

[0067] In S10, the control unit 40 monitors whether the detected flow rate of the flow sensor 32 is equal to or greater than the ignition flow rate L1 stored in the memory 44. If the detected flow rate is equal to or greater than the ignition flow rate L1 (YES in S10), the control unit 40 advances the process to S20.

[0068] In S20, the control unit 40 ignites the gas burner 22. This causes the heating of the hot water in the water pipe 12 to begin.

[0069] In S22, the control unit 40 executes the heating power adjustment process. As described above, in the heating power adjustment process, the heating power of the gas burner 22 is adjusted according to the required heat amount calculated by multiplying the difference between the hot water supply setting temperature and the detected temperature by the detected flow rate. As a result, the temperature of the hot water heated by the gas burner 22 approaches the hot water supply setting temperature input into the remote control 50 by the user.

[0070] In S30, the control unit 40 monitors whether the detected flow rate is equal to or less than the fire extinguishing flow rate L3 stored in the memory 44. If the detected flow rate is equal to or less than the fire extinguishing flow rate L3 (YES in S30), the control unit 40 proceeds to S60. If the detected flow rate exceeds the fire extinguishing flow rate L3 (NO in S30), the control unit 40 proceeds to S40.

[0071] In S40, the control unit 40 determines whether the exhaust temperature detected by the exhaust temperature sensor 19 is equal to or greater than the threshold temperature Tth1 stored in the memory 44. If the exhaust temperature is below the threshold temperature Tth1 (NO in S40), the control unit 40 returns the process to S22 and executes the heating power adjustment process again in S22. If the exhaust temperature is equal to or greater than the threshold temperature Tth1 (YES in S40), the control unit 40 advances the process to S42.

[0072] In S42, the control unit 40 reduces the maximum flow rate by decreasing the opening of the water volume servo 34. Here, the control unit 40 gradually decreases the maximum flow rate according to the difference between the exhaust temperature and the threshold temperature Tth1. Specifically, when the difference between the exhaust temperature and the threshold temperature Tth1 exceeds a predetermined value, the control unit 40 decreases the maximum flow rate by a first flow rate width. Furthermore, when the difference between the exhaust temperature and the threshold temperature Tth1 does not exceed the predetermined value, the control unit 40 decreases the maximum flow rate by a second flow rate width smaller than the first flow rate. In a modified example, the control unit 40 may decrease the maximum flow rate by a flow rate width proportional to the difference between the exhaust temperature and the threshold temperature Tth1, or may decrease the maximum flow rate by a predetermined flow rate width regardless of the difference between the exhaust temperature and the threshold temperature Tth1.

[0073] In S50, the control unit 40 determines whether the maximum flow rate is equal to or less than the threshold flow rate Lth1 stored in the memory 44. If the maximum flow rate exceeds the threshold flow rate Lth1 (NO in S50), the control unit 40 returns to S22 and executes the heating power adjustment process again. If the maximum flow rate is reduced by the process of S42, that is, if the opening of the water volume servo 34 is reduced, the flow rate of hot and cold water flowing into the water pipe 12 (i.e., the detected flow rate) decreases. As described above, if the detected flow rate decreases, the heating power of the gas burner 22 is reduced, and the exhaust temperature decreases. If the exhaust temperature is higher than the threshold temperature Tth1 (YES in S40), the control unit 40 repeats the processes of S22 to S42 until the maximum flow rate becomes equal to or less than the threshold flow rate Lth1. As a result, the control unit 40 can gradually reduce the maximum flow rate and gradually lower the exhaust temperature until the maximum flow rate becomes equal to or less than the threshold flow rate Lth1. This prevents the exhaust temperature from continuing to exceed the threshold temperature Tth1. Here, the smaller the threshold flow rate Lth1, the lower the exhaust temperature can be. However, for example, if the threshold flow rate Lth1 becomes too small, the number of target water heaters to be operated will increase or decrease frequently, as in the specific example described above. For this reason, in this embodiment, a value obtained by adding a predetermined correction value to a flow rate obtained by doubling the minimum flow rate L4 is used as the threshold flow rate Lth1. Therefore, as in the specific example described above, since the maximum flow rate Lm2 does not become less than twice the minimum flow rate L4, even if the number of target water heaters to be operated increases and hot and cold water is distributed, frequent increases or decreases in the number of target water heaters to be operated can be suppressed. If the maximum flow rate is less than or equal to the threshold flow rate Lth1 (YES in S50), the control unit 40 proceeds to S52.

[0074] In S52, the control unit 40 stores the abnormality information in the memory 44. The abnormality information is information indicating that an abnormality has occurred in the water heater (for example, 10A) in which the control unit 40 is arranged.

[0075] In S54, the control unit 40 continuously transmits an abnormality signal to the parent unit. This allows the parent unit to be notified that an abnormality has occurred in the water heater in which the control unit 40 is located. If an abnormality occurs in the water heater 10A selected as the parent unit, the control unit 40 of that water heater 10A transmits an abnormality signal to itself. That is, in this case, the abnormality signal is transmitted and received within the control board of the control unit 40 of the water heater 10A. This allows the control unit 40 of the water heater 10A to know that an abnormality has occurred in itself.

[0076] In S56, the control unit 40 receives a stop signal from the parent unit that has received the abnormality signal.

[0077] In S60, the control unit 40 extinguishes the gas burner 22. As a result, heating of the hot water in the water pipe 12 is stopped.

[0078] In S62, control unit 40 fully closes water volume servo 34. As a result, the flow rate of hot and cold water flowing into water heater 10A becomes zero. After S62, the processing in FIG. 4 ends.

[0079] (Abnormality resolution process) The abnormality resolution process executed by the control unit 40 will be described with reference to FIG. 5. The abnormality resolution process is a process executed when an abnormality has been resolved in a water heater in which an abnormality has occurred. Hereinafter, the water heater in which an abnormality has occurred may be referred to as the "abnormal water heater." The control unit 40 of the abnormal water heater executes the process of FIG. 5 in response to receiving a resolution operation acceptance signal from the remote control 50. The resolution operation acceptance signal is transmitted to the abnormal water heater by the remote control 50, for example, when a repair person cleans the inside of the exhaust duct 18 of the water heater in which an abnormality has occurred and then uses the operation unit 51 of the remote control 50 to perform an abnormality resolution operation indicating that the abnormality has been resolved. In the initial stage of FIG. 5, the control unit 40 continues to transmit the abnormality signal (see S54 in FIG. 4). Note that the method of transmitting the resolution operation acceptance signal is not limited to transmission from the remote control 50, and various methods may be used.

[0080] In S70, the control unit 40 deletes the abnormality information stored in the memory 44 in S52 of FIG.

[0081] In S72, the control unit 40 stops the transmission of the abnormality signal to the parent unit, which began in S54 of Fig. 4. That is, the control unit 40 continues to transmit the abnormality signal to the parent unit until the abnormality information is deleted in S70.

[0082] In S80, the control unit 40 transmits the ID and an abnormality resolution signal to the parent unit. This notifies the parent unit that the abnormality has been resolved. After S80, the processing in FIG. 5 ends.

[0083] (Process for selecting the water heater to be operated) The process for selecting a water heater to be operated, which is executed by the control unit 40, will be described with reference to Figure 6. The process for selecting a water heater to be operated is a process for selecting a water heater to be operated, and is one of the parent unit processes described above. The control unit 40 executes the process of Figure 6, for example, in response to the hot water supply system 100 being powered on by the remote control 50. Note that if the parent unit flag F1 (see Figure 3) is stored in the control unit 40's memory 44, the control unit 40 continues the process of Figure 6 while the hot water supply system 100 is powered on.

[0084] In S90, the control unit 40 selects a water heater to be set as the target water heater to be operated. The control unit 40 selects the water heater from among the multiple water heaters 10A to 10D in a predetermined order (for example, in the order of IDs "01" to "04"). Below, the water heater selected in S90 may be referred to as the "target water heater," and the ID of the target water heater may be referred to as the "target ID."

[0085] In S100, the control unit 40 determines whether the status information stored in the water heater table Ta1 in association with the target ID of the target water heater selected in S90 is "abnormal," or whether an abnormality signal (see S70 in FIG. 5) is currently being received from the target water heater along with the target ID. If at least one of the conditions of whether the status information of the target water heater is "abnormal" and whether an abnormality signal is being received from the target water heater is met (YES in S100), the control unit 40 determines that an abnormality has occurred in the target water heater, returns the process to S90, and selects another water heater as the target water heater. In this way, the control unit 40 determines whether an abnormality has occurred in the target water heater based on both the condition that the status information is "abnormal" and the condition that an abnormality signal is currently being received from the target water heater. Therefore, for example, even if communication between the parent unit and the child unit is poor and an abnormality signal is not properly received from the child unit, it is possible to determine that an abnormality has occurred in the target water heater based on the status information in memory 44. In a modified example, in S100, the control unit 40 may determine that an abnormality has occurred in the target water heater based on either whether the status information of the target water heater is "abnormal" or whether an abnormality signal has been received from the target water heater. The control unit 40 repeats the processes of S90 and S100 until a target water heater that is not experiencing an abnormality is selected. If the status information of the target water heater is "normal" and no abnormality signal has been received from the target water heater (NO in S100), the control unit 40 determines that the target water heater is normal and proceeds to S102.

[0086] In S102, the control unit 40 transmits an operation instruction to the target water heater. That is, the target water heater is selected as the water heater to be operated. As a result, the water heater to be operated executes the heating process shown in FIG.

[0087] In S104, the control unit 40 acquires the detected flow rate from the water heater to be operated to which the operation instruction was transmitted in S102.

[0088] In S106, the control unit 40 uses the discriminant table Ta2 in the memory 44 to identify the flow rate level of the detected flow rate of the water heater to be operated, acquired in S104.

[0089] In S110, the control unit 40 determines whether the increase condition is met based on the flow rate level identified in S106 and the condition table Ta3 in memory 44. If the increase condition is met (YES in S110), the control unit 40 returns the process to S90 and selects a new target water heater. This executes the process of S100 described above for the target water heater, and by identifying a new, normal target water heater, the number of water heaters to be operated can be increased. If the increase condition is not met (NO in S110), the control unit 40 advances the process to S120.

[0090] In S120, the control unit 40 determines whether there are two or more water heaters to be operated, based on the water heater table Ta1 in the memory 44. Specifically, the control unit 40 determines whether there are two or more water heaters whose valve status in the water heater table Ta1 indicates "open." If there is one water heater to be operated (NO in S120), the control unit 40 returns the process to S104 and again acquires the detected flow rate from the water heater to be operated. In other words, if there is one water heater to be operated, the control unit 40 repeats the processes of S104 to S110 until the increase condition is met. If there are two or more water heaters to be operated (YES in S120), the control unit 40 proceeds to S130.

[0091] In S130, the control unit 40 determines whether the reduction condition is met based on the flow rate level identified in S106 and the condition table Ta3 in the memory 44. If the reduction condition is not met (NO in S130), the control unit 40 returns the process to S104 and again acquires the detected flow rate of the water heater to be operated. If the reduction condition is met (YES in S130), the control unit 40 proceeds to S132.

[0092] In S132, the control unit 40 identifies the target water heater to send a stop command to from among the multiple target water heaters to be operated, based on a pre-stored order (for example, in order of longest actual operating time), and sends the stop command to the target water heater to be operated. As a result, the target water heater to be operated extinguishes the gas burner 22 (S60 in FIG. 4) and fully closes the water volume servo 34 (S62). This reduces the number of target water heaters to be operated.

[0093] (Abnormality notification processing) The abnormality notification process executed by the control unit 40 will be described with reference to Figure 7. The abnormality notification process is a parent unit process executed in parallel with the process of selecting the water heater to be operated in Figure 6 described above. The abnormality notification process is a process for notifying the occurrence of an abnormality when an abnormality occurs in the water heater to be operated and for stopping the operation of the water heater to be operated. The control unit 40 executes the process of Figure 7 in response to receiving an abnormality signal (S54 in Figure 4) from the abnormal water heater described above.

[0094] In S140, control unit 40 transmits a notification instruction to remote control 50. The notification instruction is an instruction to remote control 50 to display an abnormality occurrence screen on display unit 52 of remote control 50 and output an alarm sound. The abnormality occurrence screen includes an error code indicating that the exhaust temperature of the abnormal water heater exceeds threshold temperature Tth1, and the ID of the abnormal water heater. This not only notifies the user that an abnormality has occurred in the water heater, but also allows the user to recognize which of the multiple water heaters 10A to 10D is the abnormal water heater.

[0095] In S150, control unit 40 sends a stop signal to the abnormal water heater (S56 in FIG. 4). This causes control unit 40 of the abnormal water heater to extinguish gas burner 22 (S60 in FIG. 4) and fully close water volume servo 34 (S62 in FIG. 4). This stops operation of the abnormal water heater, and in the process of FIG. 6 described above, the next water heater to be operated is selected from the water heaters to be stopped.

[0096] (Abnormality notification stop processing)

[0097] The abnormality notification stop processing executed by the control unit 40 will be described with reference to Figure 8. Like the abnormality notification processing of Figure 7, the abnormality notification stop processing is a parent unit processing executed in parallel with the operation target water heater selection processing of Figure 6. The abnormality notification stop processing is processing for changing an abnormal water heater so that it can be selected as an operation target water heater when the abnormality in the abnormal water heater is resolved. The control unit 40 executes the processing of Figure 8 in response to receiving an ID and an abnormality resolution signal from the abnormal water heater (S80 of Figure 5).

[0098] In S160, the control unit 40 changes the status information stored in association with the ID of the received abnormal water heater from "abnormal" to "normal" based on the water heater table Ta1. In other words, the control unit 40 deletes the status information indicating the abnormality stored in association with the ID of the abnormal water heater. This allows the control unit 40 to recognize that the abnormality in the abnormal water heater has been resolved (S100 in Figure 6). Therefore, the control unit 40 can select the abnormal water heater as the next water heater to be operated in the subsequent water heater to be operated selection process (see Figure 6).

[0099] In S170, the control unit 40 transmits a notification stop instruction to the remote control 50. The notification stop instruction instructs the remote control 50 to stop displaying the abnormality occurrence screen and outputting the alarm sound. This allows the user to recognize that the abnormality in the abnormal water heater has been resolved. After S170, the processing in FIG. 8 ends.

[0100] (Effects of this embodiment) Thus, in the hot water supply system 100 of this embodiment, if the target water heater is transmitting an abnormality signal, i.e., if an abnormality has occurred in the target water heater (YES in S100 of FIG. 6), the target water heater is not selected as a water heater to be operated. As a result, a water heater whose maximum flow rate has been reduced is not selected as a water heater to be operated. In other words, among the water heaters to be stopped, a water heater whose maximum flow rate has been reduced is excluded from the selection targets as a water heater to be operated, so the hot water supply system 100 can appropriately calculate the number of water heaters to be operated for each flow rate level, even though the maximum flow rates for each water heater may differ from one another, and can appropriately increase or decrease the number of water heaters to be operated.

[0101] Furthermore, in the hot water supply system 100 of this embodiment, even if the exhaust temperature becomes equal to or higher than the threshold temperature Tth1 (YES in S40 in FIG. 4), the water heater 10A can continue to operate while reducing the maximum flow rate (S42) and reducing the thermal power (S22). However, if the maximum flow rate of the water heater 10A becomes equal to or lower than the threshold flow rate Lth1 (YES in S50 in FIG. 4), the master unit does not select the water heater 10A as the water heater to be operated (S100 in FIG. 6). In this way, even if an abnormality occurs, the hot water supply system 100 can appropriately increase or decrease the number of water heaters to be operated by excluding the water heater 10A from the selection of water heaters to be operated while enabling the individual operation of the water heater 10A.

[0102] (Correspondence) The control unit 40 that executes the processes of Figures 6, 7, and 8, i.e., the control unit 40 that executes the parent unit process, is an example of a "coupling control device," and the control unit 40 that executes the processes of Figures 4 and 5, i.e., the control unit 40 that executes the child unit process, is an example of a "control unit." The exhaust duct 18 is an example of a "predetermined unit." The "abnormal" status information is an example of "abnormality occurrence information."

[0103] (Variation 1) The hot water supply system 100 may further include a connection control device that manages the entire hot water supply system 100, separate from the plurality of hot water heaters 10A-10D. In this case, the control unit 40 of each of the hot water heaters 10A-10D may execute only the slave unit processing of Figures 4 and 5, and the connection control device may execute the master unit processing of Figures 6-8.

[0104] (Variation 2) The discriminant for a "large" flow level may include, for example, the difference between the maximum flow rate and the detected flow rate being smaller than a predetermined threshold, instead of the detected flow rate exceeding the upper limit flow rate L5 (90% of the maximum flow rate).

[0105] (Variation 3) 4, instead of calculating the required heat quantity by multiplying the difference between the set hot water temperature and the detected temperature by the detected flow rate and adjusting the heat power of gas burner 22 so that the temperature of the heated water approaches the set hot water temperature, control unit 40 may, for example, calculate the additional heat quantity required by multiplying the difference between the set hot water temperature and the outlet hot water temperature detected by outlet hot water temperature sensor 36 by the detected flow rate and adjust the heat power of gas burner 22 so that the outlet hot water temperature approaches the set hot water temperature.In a further variation, control unit 40 may use both the difference between the set hot water temperature and the detected temperature and the difference between the set hot water temperature and the outlet hot water temperature to adjust the heat power of gas burner 22 so that the outlet hot water temperature approaches the set hot water temperature.

[0106] (Variation 4) Each of the plurality of water heaters 10A-10D may be provided with, for example, a heat exchanger temperature sensor that detects the temperature around sensible heat exchanger 24, instead of or in addition to exhaust gas temperature sensor 19. In this case, control unit 40 may compare the detected temperature of the heat exchanger temperature sensor with a threshold temperature in S40 of FIG. 4, and proceed to S42 if the detected temperature of the heat exchanger temperature sensor is equal to or higher than the threshold temperature (YES in S40). This makes it possible to prevent the temperature around sensible heat exchanger 24 from rising above the threshold temperature. In this modification, the periphery of sensible heat exchanger 24 is an example of a "predetermined portion." In a further modification, each of the plurality of water heaters 10A-10D may be provided with a heat exchanger temperature sensor that detects the temperature around latent heat exchanger 26. In this modification, the periphery of latent heat exchanger 26 is an example of a "predetermined portion."

[0107] The technical elements described in this specification or drawings exhibit technical utility either alone or in various combinations, and are not limited to the combinations set forth in the claims at the time of filing. Furthermore, the technologies illustrated in this specification or drawings can achieve multiple objectives simultaneously, and achieving one of those objectives is itself technically useful. [Explanation of symbols]

[0108] 2: Karan 4: Hot water pipe 6: Water supply pipe 10: Hot water system 10A~10D: Water heater 12: Water pipe 13,53: Communication I / F 14: Heat medium tube 15: Heat exchanger 16: Pump 17: Air supply duct 18: Exhaust duct 19: Exhaust temperature sensor 20: Heating section 22: Gas burner 24: Sensible heat exchanger 26:Latent heat exchanger 30: Water supply temperature sensor 32: Flow sensor 34: Valve 36: Outlet water temperature sensor 40,54: Control section 42: CPU 44: Memory 46: Program 50: Remote control 51:Operation unit 52: Display section 100: Hot water system L1: Ignition flow rate L2: Correction value L3: Extinguishing flow rate L4: Minimum flow rate L5: Upper limit flow rate

Claims

1. 1. A hot water system, comprising: A plurality of water heaters connected in parallel with each other; A connection control device that controls the plurality of water heaters; Equipped with Each of the plurality of water heaters A heating unit that heats hot water; a flow rate sensor for detecting the flow rate of the hot water flowing into the water heater; a valve that limits the flow rate of the hot water flowing into the water heater to a limit flow rate or less; a control unit capable of communicating with the connection control device; Equipped with The control unit When the flow rate detected by the flow rate sensor becomes equal to or greater than an ignition flow rate while the heating unit is not heating the hot water, the heating unit starts heating the hot water. When the heating unit is heating the hot water, the heating capacity of the heating unit is adjusted so that the temperature of the hot water heated by the heating unit approaches a hot water supply setting temperature; When the detected flow rate becomes equal to or less than the extinguishing flow rate while the heating unit is heating the hot water, the heating unit stops heating the hot water. It is structured as follows: The connection control device is configured to select some of the plurality of water heaters as water heaters to be operated, select the remaining of the plurality of water heaters as water heaters to be stopped, send an operation instruction to the control unit of the water heater to be operated, and send a stop instruction to the control unit of the water heater to be stopped, The control unit When the operation instruction is received from the connection control device, the valve is controlled so that the restricted flow rate becomes a maximum flow rate, and when the stop instruction is received from the connection control device, the valve is controlled so that the restricted flow rate becomes zero; When an abnormality occurs in the heating unit, the maximum flow rate is reduced to reduce the heating capacity of the heating unit, and an abnormality signal indicating the occurrence of the abnormality is transmitted to the connection control device. It is structured as follows: The connection control device The number of water heaters to be operated is increased or decreased based on the maximum flow rate of the valve and the detected flow rate in each of the water heaters to be operated; When increasing the number of water heaters to be operated, a water heater to be the next water heater to be operated is selected from among the water heaters included in the water heaters to be stopped and which have not transmitted the abnormality signal. It is configured as follows: Hot water system.

2. Each of the plurality of water heaters further includes a water supply temperature sensor that detects the temperature of the hot water flowing into the water heater; The hot water supply system of claim 1, wherein the control unit is configured to adjust the heating capacity of the heating unit based on the hot water setting temperature, the detected flow rate, and the detected temperature detected by the water supply temperature sensor when the heating unit is heating the hot water.

3. The hot water supply system according to claim 1 , wherein the heating section comprises a gas burner.

4. The abnormality related to the heating unit includes a temperature of a predetermined part of the water heater in which the heating unit is disposed exceeding a threshold temperature, The control unit When the abnormality occurs, the maximum flow rate is gradually reduced without transmitting the abnormality signal to the connection control device, configured to transmit the abnormality signal to the linkage control device when the maximum flow rate is below a threshold flow rate; The hot water system according to claim 1 .

5. Each of the plurality of water heaters includes a first memory that stores abnormality information indicating that the abnormality has occurred, the control unit is configured to continuously transmit the abnormality signal to the connection control device while the abnormality information is stored in the first memory; When the number of water heaters to be operated is increased, the connection control device selects a water heater to be the next water heater to be operated from among the water heaters included in the water heaters to be stopped that are not currently transmitting the abnormality signal. The hot water system according to claim 1 .

6. The hot water supply system according to claim 5 , wherein the control unit deletes the abnormality information stored in the first memory when the abnormality is resolved.

7. The control unit is configured to further transmit, together with the abnormality signal, identification information for identifying the water heater to the connection control device; The connection control device a second memory that stores the identification information received from the control unit in association with abnormality occurrence information indicating that the abnormality has occurred in the water heater; When increasing the number of water heaters to be operated, a water heater to be the next water heater to be operated is selected from among the water heaters included in the water heaters to be stopped, the identification information of which is not stored in the second memory in association with the abnormality occurrence information. The hot water system according to claim 1 .

8. The control unit is configured to, when the abnormality is resolved, further transmit an abnormality resolution signal indicating that the abnormality has been resolved to the connection control device together with the identification information; When the connection control device receives the abnormality resolution signal and the identification information, the connection control device deletes at least one of the abnormality occurrence information stored in the second memory and the identification information stored in association with the abnormality occurrence information. The hot water supply system according to claim 7.

9. When the connection control device receives the abnormality signal from the water heater to be operated, it transmits the stop instruction to the water heater to be operated, and selects a water heater to be a new water heater to be operated from the water heaters included in the water heaters to be stopped. The hot water system according to claim 1 .

10. The hot water supply system according to claim 1 , further comprising a notification unit that notifies a user that the abnormality has occurred.

11. The connection control device The detected flow rate of the target water heater is determined to be one of multiple flow rate levels; increasing or decreasing the number of water heaters to be operated based on the determined number of water heaters to be operated for each flow rate level; It is configured as follows: The hot water system according to claim 1 .

12. The hot water supply system according to claim 1 , wherein the connection control device is configured by the control unit of a hot water heater included in the plurality of hot water heaters.

13. A water heater, A heating unit that heats hot water; a flow rate sensor for detecting the flow rate of the hot water flowing into the water heater; a valve that limits the flow rate of the hot water flowing into the water heater to a limit flow rate or less; a control unit capable of communicating with other water heaters; Equipped with the control unit is capable of selectively executing a master unit process and a slave unit process that is subordinate to the master unit process, The slave device process includes: A process of starting heating of the hot water by the heating unit when the flow rate detected by the flow rate sensor becomes equal to or greater than an ignition flow rate while the heating unit is not heating the hot water; When the heating unit is heating the hot water, a process of adjusting the heating capacity of the heating unit so that the temperature of the hot water heated by the heating unit approaches a hot water supply setting temperature; a process of terminating the heating of the hot water by the heating unit when the detected flow rate becomes equal to or less than the extinguishing flow rate while the heating unit is heating the hot water; Equipped with The master unit processing includes a process of selecting some of the plurality of water heaters as water heaters to be operated, selecting the remaining of the plurality of water heaters as water heaters to be stopped, transmitting an operation instruction to the control unit of the water heater to be operated, and transmitting a stop instruction to the control unit of the water heater to be stopped, The slave device process includes: a process of controlling the valve so that the restricted flow rate becomes a maximum flow rate when the operation instruction is received from the water heater executing the parent unit processing, and controlling the valve so that the restricted flow rate becomes zero when the stop instruction is received from the water heater executing the parent unit processing; When an abnormality occurs in the heating unit, a process of reducing the heating capacity of the heating unit by reducing the maximum flow rate and transmitting an abnormality signal indicating the occurrence of the abnormality to the water heater that executes the parent unit process; Equipped with The parent device process includes: A process of increasing or decreasing the number of water heaters to be operated based on the maximum flow rate of the valve and the detected flow rate in each of the water heaters to be operated; When increasing the number of water heaters to be operated, a process of selecting a water heater to be the next water heater to be operated from among the water heaters included in the water heaters to be stopped and which have not transmitted the abnormality signal; Equipped with Water heater.

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