WATER HEATER CONNECTION SYSTEM

Description

REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No. 2024-026366 filed on Feb. 26, 2024. The entire content of the priority application is incorporated herein by reference.

TECHNICAL FIELD

The present teachings relate to a water heater connection system.

BACKGROUND ART

A water heater connection system is described in Japanese Patent Application Publication No. H06-288624. This water heater connection system includes: a plurality of water heaters disposed in parallel to each other between a water supply pipe and a hot water discharge pipe; and a connection controller configured to control operation of the plurality of water heaters. Each of the plurality of water heaters includes: a burner configured to heat water flowing from the water supply pipe to the water heater as required; a flow rate regulation valve configured to regulate a flow rate of water flowing from the water supply pipe to the water heater; a flow rate sensor configured to detect the flow rate of water flowing from the water supply pipe to the water heater; and an individual controller configured to communicate with the connection controller. The individual controller is configured to operate in a disconnected operation mode when the individual controller cannot communicate with the connection controller. When the flow rate sensor does not detect water flow in the disconnected operation mode, the individual controller stands by with the flow rate regulation valve set to fully closed.

SUMMARY

In the above-mentioned water heater connection system, since the water stops flowing from the water supply pipe into the water heater(s) operating in the disconnected operation mode, these water heater(s) cannot further be used to supply hot water. Due to this, when a part of the water heaters cannot communicate with the connection controller, performance in supplying hot water as a whole may be deteriorated in the water heater connection system. The present teachings provide an art configured to suppress deterioration in performance of a water heater connection system in supplying hot water as a whole even when some of water heaters cannot communicate with a connection controller in the water heater connection system.

In a first aspect, a water heater connection system may comprise: a plurality of water heaters connected in parallel to each other and between a water supply pipe and a hot water discharge pipe; and a connection controller configured to control operation of the plurality of water heaters. wherein each of the plurality of water heaters may include: a burner configured to heat water flowing from the water supply pipe to the water heater as required; a flow rate regulation valve configured to regulate a flow rate of the water flowing from the water supply pipe to the water heater; a flow rate sensor configured to detect the flow rate of the water flowing from the water supply pipe to the water heater; and an individual controller configured to communicate with the connection controller. the individual controller may be configured to operate in a disconnected operation mode when the individual controller cannot communicate with the connection controller. When the flow rate sensor does not detect water flow in the disconnected operation mode, the individual controller may stand by with the flow rate regulation valve set to a first opening degree which is smaller than being fully open and larger than being fully closed.

Because in the above-described water heater connection system the water heater(s) operating in the disconnected operation mode each stands by with the opening degree of the flow rate regulation valve set to the first opening degree, which is larger than being fully closed, water continues to flow from the water supply pipe into that water heater even after the water heater has entered into the disconnected operation mode. As a result, the water heater can still be used for supplying hot water. Due to this, the performance in supplying hot water of the water heater connection system as a whole can be suppressed from deteriorating when some of the water heaters cannot communicate with the connection controller.

In a general water heater connection system, a water heater configured to operate in accordance with an instruction from a connection controller stands by with a flow rate regulation valve being fully open or fully closed. Specifically, in the water heater connection system, a water heater which the connection controller intends to operate next among water heaters that have not started operating (e.g., if none of the plurality of water heaters are operating, a water heater that is intended to be operated first) stands by with the flow rate regulation valve being fully open, and the other water heater(s) among the water heaters that have not started operating stand by with the flow rate regulation valve being fully closed. This aims to flow water concentratedly through the water heater which is intended to be operated next (e.g., the water heater that is intended to be operated first) such that that water heater can start supplying hot water immediately when the entire flow rate of the water heater connection system increases. If the water heater operating in the disconnected operation mode stands by with the opening degree of the flow rate regulation valve set to fully open, there would be less increase in the flow rate of water flowing in the water heater that is intended to be operated next (e.g., water heater that is intended to be operated first) when the entire flow rate of the water heater connection system 100 increases, as a result of which the water heater cannot start supplying hot water immediately. According to the above configuration, since the water heater operating in the disconnected operation mode stands by with the opening degree of the flow rate regulation valve set to the first opening degree that is smaller than being fully open, the flow rate of the water flowing in the water heater that is intended to be operated next (e.g., water heater that is intended to be operated first) can be significantly increased when the entire flow rate in the water heater connection system increases, as a result of which that water heater can start supplying hot water immediately.

In a second aspect, according to the first aspect, the individual controller may be configured to ignite the burner when the flow rate detected by the flow rate sensor becomes equal to or greater than a predetermined ignition flow rate. The first opening degree may be smaller than an opening degree corresponding to the ignition flow rate.

According to the above configuration, since the water heater operating in the disconnected operation mode stands by with the opening degree of the flow rate regulation valve set to an opening degree sufficiently small, the flow rate of water flowing in the water heater which the connection controller intends to operate next (e.g., water heater that is intended to be operated first) can be significantly increased when the entire flow rate in the water heater connection system increases, by which that water heater can immediately start supplying hot water.

In a third aspect, according to the second aspect, when the flow rate sensor detects water flow while the individual controller stands by with the flow rate regulation valve set to the first opening degree, the individual controller may increase an opening degree of the flow rate regulation valve from the first opening degree to a second opening degree which is larger than the opening degree corresponding to the ignition flow rate.

According to the above configuration, when the entire flow rate in the water heater connection system increases, the flow rate of the water heater operating in the disconnected operation mode can be increased, by which that water heater operating in the disconnected operation mode can immediately start supplying hot water.

In a fourth aspect, according to the third aspect, when the individual controller increases the opening degree of the flow rate regulation value to the second opening degree and the flow rate detected by the flow rate sensor increases accordingly, the individual controller may further increase the opening degree of the flow rate regulation valve. When the individual controller increases the opening degree of the flow rate regulation value to the second opening degree and the flow rate detected by the flow rate sensor does not increase accordingly, the individual controller may maintain the opening degree of the flow rate regulation valve.

When the flow rate that can be supplied by the water heater connection system is smaller than the flow rate that can be supplied at the hot water supply outlet(s) (i.e., when the water heater connection system is bottlenecked), by increasing the opening degree of the flow rate regulation valve, the flow rate detected by the flow rate sensor increases. Contrary to this, when the flow rate that can be supplied by the water heater connection system is greater than the flow rate that can be supplied at the hot water supply outlet(s) (i.e., when the water heater connection system is not bottlenecked), even when the opening degree of the flow rate regulation valve is increased, the flow rate detected by the flow rate sensor does not increase. According to the above configuration, the opening degree of the flow rate regulation valve can be increased to an opening degree at which the water heater connection system is not bottlenecked.

In a fifth aspect, according to the fourth aspect, when the flow rate detected by the flow rate sensor increases while the individual controller maintains the opening degree of the flow rate regulation value at the second opening degree, the individual controller may increase the opening degree of the flow rate regulation valve.

The situation where the flow rate detected by the flow rate sensor increases despite the opening degree of the flow rate regulation valve is maintained happens when the flow rate that can be supplied by the water heater connection system is greater than the flow rate that can be supplied at the hot water supply outlet(s) (i.e., the water heater connection system is not bottlenecked) and also the flow rate that can be supplied at the hot water supply outlet(s) increases. According to the above configuration, because the opening degree of the flow rate regulation valve is increased in such cases, the opening degree of the flow rate regulation valve can be increased in accordance with the increase in the flow rate that can be supplied at the hot water supply outlet(s).

In a sixth aspect, according to the fourth or fifth aspect, when the flow rate detected by the flow rate sensor decreases while the individual controller maintains the opening degree of the flow rate regulation valve at the second opening degree, the individual controller may decrease the opening degree of the flow rate regulation valve.

The situation where the flow rate detected by the flow rate sensor decreases despite the opening degree of the flow rate regulation valve is maintained happens when the flow rate that can be supplied by the water heater connection system is greater than the flow rate that can be supplied at the hot water supply outlet(s) (i.e., the water heater connection system is not bottlenecked) and also the flow rate that can be supplied at the hot water supply outlet(s) decreases. According to the above configuration, because the opening degree of the flow rate regulation valve is decreased in such cases, the opening degree of the flow rate regulation valve can be decreased in accordance with the decrease in the flow rate that can be supplied at the hot water supply outlet(s).

In a seventh aspect, according to any one of the first to sixth aspects, each of the plurality of water heaters may further comprise a notifier. When the individual controller cannot communicate with the connection controller, the individual controller may notify via the notifier that the individual controller is operating in the disconnected operation mode.

According the above configuration, when it is impossible to communicate with the connection controller and the water heater(s) are operating in the disconnected operation mode, the user can be immediately notified of that situation.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a configuration of a water heater connection system 100 according to an embodiment.

FIG. 2 illustrates a water heater 1 according to the embodiment.

FIG. 3 illustrates a flowchart of a mode determination process according to the embodiment.

FIG. 4 illustrates a flowchart of a disconnected operation process of the water heater 1 according to the embodiment.

DETAILED DESCRIPTION

Representative, non-limiting examples of the present disclosure will now be described in further detail with reference to the attached drawings. This detailed description is merely intended to teach a person of skill in the art further details for practicing preferred aspects of the present teachings and is not intended to limit the scope of the disclosure. Furthermore, each of the additional features and teachings disclosed below may be utilized separately or in conjunction with other features and teachings to provide improved water heater connection systems, as well as methods for using and manufacturing the same.

Moreover, combinations of features and steps disclosed in the following detailed description may not be necessary to practice the disclosure in the broadest sense, and are instead taught merely to particularly describe representative examples of the disclosure. Furthermore, various features of the above-described and below-described representative examples, as well as the various independent and dependent claims, may be combined in ways that are not specifically and explicitly enumerated in order to provide additional useful embodiments of the present teachings.

All features disclosed in the description and/or the claims are intended to be disclosed separately and independently from each other for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter, independent of the compositions of the features in the embodiments and/or the claims. In addition, all value ranges or indications of groups of entities are intended to disclose every possible intermediate value or intermediate entity for the purpose of original written disclosure, as well as for the purpose of restricting the claimed subject matter.

Embodiments

As illustrated in FIG. 1, a water heater connection system 100 according to the present embodiment comprises a plurality of water heaters 1. The plurality of water heaters 1 is disposed in parallel to each other between a water supply pipe 110 and a hot water discharge pipe 120 such that water is supplied from the water supply pipe 110 and hot water is delivered to the hot water discharge pipe 120. Each of the water heaters 1 is coupled via a corresponding water supply coupling pipe 112 to the water supply pipe 110. Water such as tap water from an unillustrated water source is supplied to the water supply pipe 110. Each of the water heaters 1 is coupled via a corresponding hot water discharge coupling pipe 122 to the hot water discharge pipe 120. The hot water discharge pipe 120 supplies hot water to a hot water supply outlet such as a bathroom and/or a kitchen. The hot water discharge pipe 120 comprises a faucet 124 such as a tap for increasing/decreasing flow rate of hot water supplied to the supply outlet and/or shower (in FIG. 1, described as a single faucet 124 for easier illustration). Further, each of the plurality of water heaters 1 is coupled via a corresponding gas supply coupling pipe 132 to a gas supply pipe 130. Fuel gas such as city gas is supplied from an unillustrated gas supply source to the gas supply pipe 130. Due to this, the plurality of water heaters 1 is supplied with fuel gas from the gas supply pipe 130. The plurality of water heaters 1 is configured to communicate with each other via a communication cable 140.

(Configuration of Water Heaters 1)

As illustrated in FIG. 2, each of the water heaters 1 comprises a burner 3, a fan 4, a vapor heat exchanger 6, an inlet pipe 7, an outlet pipe 8, a can body 10, a controller 30, an input device 32, and an indicator 34. The burner 3 and the vapor heat exchanger 6 are accommodated within the can body 10. The vapor heat exchanger 6 is disposed above the burner 3. The fan 4 supplies air for combustion from below the can body 10. Combustion gas of the burner 3 flows within the can body 10 from bottom to top, thereby heating the vapor heat exchanger 6. Combustion exhaust gas after heating the vapor heat exchanger 6 is discharged from an exhaust vent 10a arranged at a top of the can body 10.

The vapor heat exchanger 6 is coupled to the inlet pipe 7 and the outlet pipe 8. An end of the inlet pipe 7 on an upstream side is coupled to the water supply coupling pipe 112. An end of the outlet pipe 8 on a downstream side is coupled to the hot water discharge coupling pipe 122. The water heater 1 further comprises a bypass pipe 9 which bypasses the vapor heat exchanger 6 and connects the inlet pipe 7 and the outlet pipe 8, and a bypass servo 24 configured to regulate an opening degree of the bypass pipe 9 to change a bypass ratio (ratio of the flow rate of water supplied toward the bypass pipe 9 to the flow rate of water supplied to the vapor heat exchanger 6). Water supplied from the water supply coupling pipe 112 is supplied from the inlet pipe 7 to the vapor heat exchanger 6, and is heated by the vapor heat exchanger 6 and becomes hot water of a high temperature. Thereafter, the hot water of high temperature flowing from the vapor heat exchanger 6 is mixed with water of a low temperature flowing from the inlet pipe 7 to the bypass pipe 9, and the temperature of the water is adjusted, and then is delivered from the outlet pipe 8 to the hot water discharge coupling pipe 122.

The burner 3 comprises a first burner 3a, a second burner 3b, and a third burner 3c. The burner 3 is supplied by a gas pipe 11 with the fuel gas. An upstream end of the gas pipe 11 is coupled to the gas supply coupling pipe 132. The gas pipe 11 comprises a main gas electromagnetic valve 12, a gas proportional valve 13, and switch gas electromagnetic valves 14a, 14b, 14c in this order from the upstream side. When the main gas electromagnetic valve 12 is in the open state, the fuel gas is supplied to the burner 3, whereas when the main gas electromagnetic valve 12 is in the closed state, the fuel gas supply to the burner 3 is stopped. The gas proportional valve 13 is configured to regulate a volume of the fuel gas supplied to the burner 3. The switch gas electromagnetic valves 14a, 14b, 14c are disposed corresponding to the first burner 3a, the second burner 3b, and the third burner 3c, respectively. When each of the switch gas electromagnetic valves 14a, 14b, 14c is in the open state, the fuel gas is supplied to the corresponding one of the first burner 3a, the second burner 3b, and the third burner 3c, whereas when each of the switch gas electromagnetic valves 14a, 14b, 14c is in the closed state, the fuel gas stops being supplied to the corresponding one of the first burner 3a, the second burner 3b, and the third burner 3c. By switching each of the switch gas electromagnetic valves 14a, 14b, 14c between the open state and the closed state, a range of combustion (combustion range) of the burner 3 can be switched.

In each water heater 1, the combustion range of the burner 3 can be switched among three levels. A first combustion range being at the lowest level corresponds to a state in which the first burner 3a operates and the second and third burners 3b, 3c are not operated. A second combustion range being at a higher level than the first combustion range corresponds to a state in which the first and second burners 3a, 3b operate and the third burner 3c is not operated. A third combustion range being at a higher level than the second combustion range and being at the highest level corresponds to a state in which all the first burner 3a, the second burner 3b, and the third burner 3c operate. In the water heater 1, a rotation speed of the fan 4 is predetermined according to a current combustion range of the burner 3 and the combustion level within that combustion range, and thus the fan 4 rotates at the predetermined rotation speed.

In proximity to the burner 3, an ignition plug 16 for igniting the burner 3 and a flame rod 17 configured to detect combustion flame of the burner 3 are disposed. Further, an igniter 15 configured to apply high voltage on the ignition plug 16 to generate spark discharge is disposed.

The inlet pipe 7 comprises a flow rate sensor 18 configured to detect a flow rate of water supplied to the inlet pipe 7 (which is equal to a flow rate of hot water discharged from the outlet pipe 8), a flow rate regulation valve 19 configured to regulate the flow rate of the water supplied to the inlet pipe 7, and a supplied water temperature sensor 25 configured to detect a temperature of the water supplied to the inlet pipe 7. The outlet pipe 8 comprises a heat exchanger outlet temperature sensor 21 configured to detect the temperature of the water flowing from the vapor heat exchanger 6 and a discharged hot water temperature sensor 23 configured to detect the temperature of the water flowing from the outlet pipe 8.

The controller 30 is configured to control operation of the water heater 1. The controller 30 is an electrical unit composed of a microcomputer, a memory, etc. The controller 30 operates in accordance with a program stored in the memory. The controller 30 is inputted with detected signals of the flame rod 17, the flow rate sensor 18, the supplied water temperature sensor 25, the heat exchanger outlet temperature sensor 21, and the discharged hot water temperature sensor 23. Further, operations of the fan 4, the main gas electromagnetic valve 12, the gas proportional valve 13, the switch gas electromagnetic valves 14a, 14b, 14c, the igniter 15, the flow rate regulation valve 19, and the bypass servo 24 are controlled by control signals outputted from the controller 30. The controller 30 is coupled with the input device 32 and the indicator 34. The input device 32 comprises for example a plurality of input switches. A user of the water heater 1 is able to input various settings for the operation of the water heater 1 via the input device 32. The indicator 34 comprises for example a liquid crystal display. The indicator 34 is configured to notify the user of the water heater 1 of various information related to the operation of the water heater 1. The controller 30 is further coupled with the communication cable 140. The controller 30 is configured to communicate bidirectionally with the controllers 30 of the other water heaters 1 via the communication cable 140.

(Ignition Process and Extinguish Process)

The controller 30 constantly monitors the flow rate detected by the flow rate sensor 18. When the flow rate detected by the flow rate sensor 18 becomes equal to or more than a predetermined ignition flow rate (e.g., 2.7 L/min) with the burner 3 not operating, the controller 30 executes the ignition process of the burner 3. That is, the controller 30 activates the fan 4, sets the main gas electromagnetic valve 12 and the switch gas electromagnetic valve 14a in the open state, activates the igniter 15, and ignites the first burner 3a to start the combustion of the burner 3.

While the burner 3 is operating, the controller 30 regulates opening/closing of the switch gas electromagnetic valves 14a, 14b, 14c, an opening degree of the gas proportional valve 13, the rotation speed of the fan 4, and an opening degree of the bypass servo 24 such that the temperature detected by the heat exchanger outlet temperature sensor 21 becomes a predetermined target temperature (e.g., 60° C.) and the temperature detected by the discharged hot water temperature sensor 23 becomes a supplied hot water designated temperature designated by the user.

When the flow rate detected by the flow rate sensor 18 becomes less than a predetermined extinguish flow rate (e.g., 2.0 L/min) while the burner 3 is operating, the controller 30 executes an extinguish process of the burner 3. That is, the controller 30 stops driving the fan 4, sets the main gas electromagnetic valve 12 and the switch gas electromagnetic valves 14a, 14b, 14c in the closed state, and extinguishes the burner 3 to finish the combustion of the burner 3.

(Solo Operation Mode and Connected Operation Mode)

The water heater 1 is configured to select either a solo operation mode or a connected operation mode as its operation mode. In the solo operation mode, the water heater 1 operates without communicating with other water heater(s) 1. In the connected operation mode, the water heater 1 operates by utilizing communication with the other water heaters 1. When the connected operation mode is selected as the operation mode, the water heater 1 is configured to select either a parent machine operation mode or a child machine operation mode as its operation mode. In the parent machine operation mode, the water heater 1 operates dominantly relative to the other water heaters 1. In the child machine operation mode, the water heater 1 operates subjectively relative to the other water heater(s) 1. Specifically, the water heater 1 selected to be in the parent machine operation mode (may be referred to as simply water heater 1 being a parent machine) sends an operation instruction to another water heater 1 selected to operate in the child machine operation mode (may be referred to as simply water heater 1 being a child machine). The water heater 1 being the child machine (hereafter, child water heater 1) operates in accordance with the operation instruction received from the water heater 1 being the parent machine (hereafter, parent water heater 1). That is, when the water heater 1 is selected to operate in the parent machine operation mode, the controller 30 of that water heater 1 functions as a connection controller configured to control respective operations of the plural water heaters 1 and also as an individual controller configured to control an operation of the water heater 1 itself. Further if the water heater 1 is selected to operate in the child machine operation mode, the controller 30 of that water heater 1 does not function as the connection controller configured to control the respective operations of the plural water heaters 1, but can function only as the individual controller configured to control the operation of that water heater 1 itself. Whether the operation mode of the water heater 1 is to operate in the solo operation mode or in the connected operation mode can be inputted in advance via the input device 32. Further, if the connected operation mode is selected as the operation mode, whether the operation mode of the water heater 1 is the parent machine operation mode or the child machine operation mode can be inputted in advance via the input device 32.

(Mode Determination Process)

When power of the water heater 1 is turned on, the controller 30 executes a mode determination process shown in FIG. 3.

In S2, the controller 30 determines whether the operation mode of the water heater 1 is the connected operation mode or not. If the operation mode of the water heater 1 is the solo operation mode (in case of NO), the process proceeds to S4.

In S4, the controller 30 executes processes in the solo operation mode. In the solo operation mode, the controller 30 stands by with the flow rate regulation valve 19 set to fully open.

If a mode setting of the water heater 1 is the connected operation mode in S2 (in case of YES), the process proceeds to S6. In S6, the controller 30 determines whether the operation mode of the water heater 1 is the parent machine operation mode or not. If the operation mode is the parent machine operation mode (in case of YES), the process proceeds to S8.

In S8, the controller 30 executes a parent machine operation process in order to cause the water heater 1 to operate in the parent machine operation mode. That is, the controller 30 utilizes the communication with other child water heater(s) 1 to determine whether the flow rate regulation valve 19 of each water heater 1 is to be fully open or fully closed, and instructs the child water heater(s) 1 to stand by with the flow rate regulation valve 19 being fully open or fully closed.

When the operation mode is the child machine operation mode in S6 (in case of NO), the process proceeds to S10. In S10, the controller 30 determines whether it is possible to communicate with the parent water heater 1. If it is possible to communicate with the parent water heater 1 (in case of YES), the process proceeds to S12. In S12, the controller 30 executes a child machine operation process in order to cause the water heater 1 to operate in the child machine operation mode. That is, the controller 30 utilizes the communication with the parent water heater 1 to stand by with the flow rate regulation valve 19 being fully open or fully closed in accordance with an instruction from the parent water heater 1.

When it is impossible to communicate with the parent water heater 1 in S10 (in case of NO), the process proceeds to S14. In S14, the controller 30 executes a disconnected operation process (FIG. 4) in order to cause the water heater 1 to operate in the disconnected operation mode.

(Disconnected Operation Process)

As illustrated in FIG. 4, in S20, the controller 30 notifies the user of being operating in the disconnected operation mode via the indicator 34.

In S22, the controller 30 stands by with an opening degree of the flow rate regulation valve 19 set to a first opening degree. The first opening degree is larger than 0% and smaller than 100% when the opening degree of being fully closed is deemed 0% and the opening degree of being fully open is deemed 100%. Further, the first opening degree is smaller than an opening degree corresponding to the ignition flow rate (e.g., 2.7 L/min) (that is, opening degree of the flow rate regulation valve 19 at which the flow rate of water flowing in the flow rate regulation valve 19 becomes the ignition flow rate when the water is supplied to the flow rate regulation valve 19 with a sufficiently great supplying pressure).

In S24, the controller 30 stands by until water flow starts in the water heater 1. The controller 30 determines that the water flow has started when the flow rate detected by the flow rate sensor 18 remains equal to or more than a predetermined water flow detection flow rate (e.g., 1.0 L/min) over a predetermined time period (e.g., one minute) or longer. Alternatively, the controller 30 may determine that the water flow has started when an accumulated flow rate since when the water flow started to be detected by the flow rate sensor 18 becomes equal to or more than a water flow accumulated flow rate (e.g., 1.0 L). When it is determined that the water flow has started in S24 (in case of YES), the process proceeds to S26.

In S26, the controller 30 increases the opening degree of the flow rate regulation valve 19 by a predetermined opening degree increase amount (e.g., 5%).

In S28, the controller 30 determines whether the flow rate detected by the flow rate sensor 18 increases by a predetermined flow rate (e.g. 0.2 L/min) or more. When it is detected that the detected flow rate increases by the predetermined flow rate (e.g., 0.2 L/min) or more (in case of YES), the process returns to S26, and the controller 30 further increases the opening degree of the flow rate regulation valve 19. When it is not detected that the detected flow rate increases by the predetermined flow rate (e.g., 0.2 L/min) or more in S28 (in case of NO), the process proceeds to S30.

If, at the time the process of S26 is performed, the flow rate that can be supplied by the water heater connection system 100 is smaller than the flow rate that can be supplied by a faucet 124 of the hot water discharge pipe 120 (i.e., when the water heater connection system 100 is bottlenecked), the flow rate detected by the flow rate sensor 18 in S28 increases by increasing the opening degree of the flow rate regulation valve 19 in S26. Contrary to this, if, at the time the process of S26 is performed, the flow rate that can be supplied by the water heater connection system 100 is greater than the flow rate that can be supplied by the faucet 124 of the hot water discharge pipe 120 (i.e., when the water heater connection system 100 is not bottlenecked), even when the opening degree of the flow rate regulation valve 19 is increased in S26, the flow rate detected by the flow rate sensor 18 in S28 does not increase. Due to this, by conducting the processes of S26 and S28 repeatedly, the controller 30 can increase the opening degree of the flow rate regulation valve 19 to an opening degree at which the water heater connection system 100 would not be bottlenecked.

In S30, the controller 30 stands by until a predetermined time (e.g., one minute) elapses.

In S32, the controller 30 determines whether the flow rate detected by the flow rate sensor 18 increases by the predetermined flow rate (e.g., 0.2 L/min) or more. When it is detected that the detected flow rate increases by the predetermined flow rate (e.g., 0.2 L/min) or more (in case of YES), the process proceeds to S34. In S34, the controller 30 increases the opening degree of the flow rate regulation valve 19 by the predetermined opening degree increase amount (e.g., 5%). After S34, the process returns to S30. When it is not detected that the detected flow rate increases by the predetermined flow rate (e.g., 0.2 L/min) or more in S32 (in case of NO), the process proceeds to S36.

Since the process of S32 is performed after the process of S30, at the time the process of S32 is executed, the opening degree of the flow rate regulation valve 19 was not increased or decreased immediately before then. Due to this, the situation where the flow rate detected by the flow rate sensor 18 increases in S32 happens when the flow rate that can be supplied by the water heater connection system 100 is greater than the flow rate that can be supplied by the faucet 124 of the hot water discharge pipe 120 (that is, the water heater connection system 100 is not bottlenecked) and also the flow rate that can be supplied by the faucet 124 of the hot water discharge pipe 120 increases. Due to this, by executing the processes of S32 and S34, the controller 30 can increase the opening degree of the flow rate regulation valve 19 in accordance with the increase in the flow rate that can be supplied by the faucet 124 of the hot water discharge pipe 120.

In S36, the controller 30 determines whether the flow rate detected by the flow rate sensor 18 has decreased by the predetermined flow rate (e.g., 0.2 L/min) or more. When it is detected that the detected flow rate has decreased by the predetermined flow rate (e.g., 0.2 L/min) or more (in case of YES), the process proceeds to S38. In S38, the controller 30 decreases the opening degree of the flow rate regulation valve 19 by a predetermined opening degree decrease amount (e.g., 5%). After S38, the process returns to S30. When it is not detected that the detected flow rate has decreased by the predetermined flow rate (e.g., 0.2 L/min) or more in S36 (in case of NO), the process proceeds to S40.

Since the process of S36 is performed after the processes of S30 and S32, at the time the process of S36 is executed, the flow rate regulation valve 19 has not gone through any increase nor decrease of its opening degree immediately before S36. Due to this, the situation where the flow rate detected by the flow rate sensor 18 decreases in S36 happens when the flow rate that can be supplied by the water heater connection system 100 is greater than the flow rate that can be supplied by the faucet 124 of the hot water discharge pipe 120 (that is, the water heater connection system 100 is not bottlenecked) and the flow rate that can be supplied by the faucet 124 of the hot water discharge pipe 120 has decreased. Due to this, by executing the processes of S36 and S38, the controller 30 can decrease the opening degree of the flow rate regulation valve 19 in accordance with the decrease in the flow rate that can be supplied by the faucet 124 of the hot water discharge pipe 120.

In S40, the controller 30 determines whether the water flow has finished in the water heater 1. The controller 30 determines that the water flow has finished when the flow rate detected by the flow rate sensor 18 is less than the predetermined water flow detection flow rate (e.g., 1.0 L/min) over a predetermined time period (e.g., one minute) or longer. When the water flow has not finished in S40 (in case of NO), the process proceeds to S32. When the water flow has finished in S40 (in case of YES), the process proceeds to S22.

Modifications

In the above embodiments, a configuration where one of the plurality of water heaters 1 operates as the parent machine and the other water heaters 1 operate as the child machines was described. Differently from the above embodiment, an unillustrated controller dedicated for connection control may be coupled to the communication cable 140, by which all the water heaters 1 of the plurality of water heaters 1 may operate in accordance with an instruction from the controller dedicated for connection control. In this case, each water heater 1 of the plurality of water heaters 1 may be configured to select only the child machine operation mode as an operation mode when the connected operation mode is selected.

Features of Embodiment

As described above, in one or more embodiments, the water heater connection system 100 comprises the plurality of water heaters 1 connected in parallel to each other and between the water supply pipe 110 and the hot water discharge pipe 120; and the controller 30 of the parent water heater 1 (example for a connection controller) configured to control operation of the plurality of water heaters 1. Each of the plurality of water heaters 1 includes: the burner 3 configured to heat water flowing from the water supply pipe 110 to the water heater 1 as required; the flow rate regulation valve 19 configured to regulate the flow rate of water flowing from the water supply pipe 110 to the water heater 1; the flow rate sensor 18 configured to detect the flow rate of water flowing from the water supply pipe 110 to the water heater 1; and the controller 30 (example for an individual controller) configured to communicate with the controller 30 of the water heater 1 being the parent machine. The controller 30 is configured to operate in the disconnected operation mode when the controller 30 cannot communicate with the controller 30 of the water heater 1 being the parent machine. When the flow rate sensor 18 does not detect water flow in the disconnected operation mode, the controller 30 stands by with the opening degree of the flow rate regulation valve 19 set to the first opening degree which is smaller than being fully open and larger than being fully closed.

Because in the above-described water heater connection system 100 the water heater(s) 1 operating in the disconnected operation mode each stands by with the opening degree of the flow rate regulation valve 19 set to the first opening degree which is larger than being fully closed, water continues to flow from the water supply pipe 110 into that water heater 1 even after the water heater 1 has entered into the disconnected operation mode. As a result of this, the water heater 1 can still be used for supplying hot water. Due to this, the performance in supplying hot water of the water heater connection system 100 as a whole can be suppressed from deteriorating when one or more of the water heaters 1 cannot communicate with the controller 30 of the parent water heater 1.

In the general water heater connection system 100, the water heater 1 configured to operate in accordance with an instruction from the controller 30 of the parent water heater 1 stands by with the flow rate regulation valve 19 set to fully open or fully closed. Specifically, in the water heater connection system 100, the water heater 1 which the controller 30 of the parent water heater 1 intends to operate next among the water heaters 1 that have not started operating (e.g., if none of the plurality of water heaters 1 are operating, the water heater 1 that is intended to be operated first) stands by with the flow rate regulation valve 19 set to fully open, and the other water heaters 1 among the water heaters 1 that have not started operating stand by with the flow rate regulation valves 19 being fully closed. This aims to flow water concentratedly through the water heater 1 which is intended to be operated next (e.g., the water heater 1 that is intended to be operated first) such that that water heater 1 can start supplying hot water immediately when the entire flow rate of the water heater connection system 100 increases. If the water heater 1 operating in the disconnected operation mode stands by with the opening degree of the flow rate regulation valve 19 set to fully open, there would be less increase in the flow rate of water flowing in the water heater 1 that is intended to be operated next (e.g., water heater 1 that is intended to be operated first) when the entire flow rate of the water heater connection system 100 increases, as a result of which the water heater 1 cannot start supplying hot water immediately. According to the above configuration, since the water heater 1 operating in the disconnected operation mode stands by with the opening degree of the flow rate regulation valve 19 set to the first opening degree that is smaller than being fully open, the flow rate of the water flowing in the water heater 1 that is intended to be operated next (e.g., water heater 1 that is intended to be operated first) can be significantly increased when the entire flow rate in the water heater connection system 100 increases, as a result of which that water heater 1 can start supplying hot water immediately.

In one or more embodiments, the controller 30 is configured to ignite the burner 3 when the flow rate detected by the flow rate sensor 18 is equal to or greater than the predetermined ignition flow rate. The first opening degree is smaller than an opening degree corresponding to the ignition flow rate.

According to the above configuration, since the water heater 1 operating in the disconnected operation mode stands by with the opening degree of the flow rate regulation valve 19 set to an opening degree sufficiently small, the flow rate of water flowing in the water heater 1 that is intended to be operated next (e.g., water heater 1 that is intended to be operated first) can be significantly increased when the entire flow rate in the water heater connection system 100 increases, by which that water heater 1 can immediately start supplying hot water.

In one or more embodiments, when the flow rate sensor 18 detects water flow while the controller 30 stands by with the flow rate regulation valve 19 set to the first opening degree, the controller 30 increases the opening degree of the flow rate regulation valve 19 from the first opening degree to the second opening degree which is larger than the opening degree corresponding to the ignition flow rate.

According to the above configuration, when the entire flow rate in the water heater connection system 100 increases, the flow rate of the water heater 1 operating in the disconnected operation mode can be immediately increased, by which that water heater 1 operating in the disconnected operation mode can immediately start supplying hot water.

In one or more embodiments, when the controller 30 increases the opening degree of the flow rate regulation value 19 to the second opening degree and the flow rate detected by the flow rate sensor 18 increases accordingly, the controller 30 further increases the opening degree of the flow rate regulation valve 19. When the controller 30 increases the opening degree of the flow rate regulation value 19 to the second opening degree and the flow rate detected by the flow rate sensor 18 does not increase accordingly, the controller 30 maintains the opening degree of the flow rate regulation valve 19.

When the flow rate that can be supplied by the water heater connection system 100 is smaller than the flow rate that can be supplied at the hot water supply outlet(s) (i.e., when the water heater connection system 100 is bottlenecked), by increasing the opening degree of the flow rate regulation valve 19, the flow rate detected by the flow rate sensor 18 increases. Contrary to this, when the flow rate that can be supplied by the water heater connection system 100 is greater than the flow rate that can be supplied at the hot water supply outlet(s) (i.e., when the water heater connection system 100 is not bottlenecked), even when the opening degree of the flow rate regulation valve 19 is increased, the flow rate detected by the flow rate sensor 18 does not increase. According to the above configuration, the opening degree of the flow rate regulation valve 19 can be increased to an opening degree at which the water heater connection system 100 is not bottlenecked.

In one or more embodiments, when the flow rate detected by the flow rate sensor 18 increases while the controller 30 maintains the opening degree of the flow rate regulation value 19 at the second opening degree, the controller 30 increases the opening degree of the flow rate regulation valve 19.

The situation where the flow rate detected by the flow rate sensor 18 increases despite the opening degree of the flow rate regulation valve 19 is maintained happens when the flow rate that can be supplied by the water heater connection system 100 is greater than the flow rate that can be supplied at the hot water supply outlet(s) (i.e., the water heater connection system 100 is not bottlenecked) and also the flow rate that can be supplied at the hot water supply outlet(s) increases. According to the above configuration, because the opening degree of the flow rate regulation valve 19 is increased in such cases, the opening degree of the flow rate regulation valve 19 can be increased in accordance with the increase in the flow rate that can be supplied at the hot water supply outlet(s).

In one or more embodiments, when the flow rate detected by the flow rate sensor 18 decreases while the controller 30 maintains the opening degree of the flow rate regulation valve 19 at the second opening degree, the controller 30 decreases the opening degree of the flow rate regulation valve 19.

The situation where the flow rate detected by the flow rate sensor 18 decreases despite the opening degree of the flow rate regulation valve 19 is maintained happens when the flow rate that can be supplied by the water heater connection system 100 is greater than the flow rate that can be supplied at the hot water supply outlet(s) (i.e., the water heater connection system 100 is not bottlenecked) and also the flow rate that can be supplied at the hot water supply outlet(s) decreases. According to the above configuration, because the opening degree of the flow rate regulation valve 19 is decreased in such cases, the opening degree of the flow rate regulation valve 19 can be decreased in accordance with the decrease in the flow rate that can be supplied at the hot water supply outlet(s).

In one or more embodiments, each of the plurality of water heaters 1 further comprises the indicator 34 (example for a notifier). When the controller 30 cannot communicate with the controller 30 of the parent water heater 1, the controller 30 notifies via the indicator 34 that the controller 30 is operating in the disconnected operation mode.

According the above configuration, when it is impossible to communicate with the controller 30 of the parent water heater 1 and the water heater(s) 1 are operating in the disconnected operation mode, the user can be immediately notified of that situation.