JP7637594B2 - Instant hot water system - Google Patents

Description

The present invention relates to an instant hot water system that quickly dispenses hot water when the hot water tap is opened.

In an instant hot water system, an instant hot water circulation path in which an instant hot water circulation pump is installed is connected to a hot water outlet path that supplies hot water to a hot water tap such as a faucet, and instant hot water operation is performed in which the hot water is heated by a heating device while the instant hot water circulation pump is driven to circulate the hot water in the instant hot water circulation path, thereby enabling hot water to be dispensed promptly when the hot water tap is opened. In conventional instant hot water systems, when a combustion signal is received from the heat source unit during instant hot water operation, hot water is assumed to have been supplied to the hot water tap, and the instant hot water circulation pump is stopped and the instant hot water operation is interrupted, so that the hot water tap side is not depressurized by the instant hot water circulation pump, and a sufficient amount of hot water can be dispensed from the hot water tap (for example, Patent Document 1).

JP 2000-18625 A

However, in conventional instant hot water systems, if a hot water filling path is provided that branches off from the hot water outlet path and connects to the bathtub, when the heat source unit is combusted by the hot water filling operation and a combustion signal is output, the instant hot water operation is stopped regardless of the supply of hot water to the hot water tap. When only the hot water filling operation is in progress, there is no hot water supply to the hot water tap, so there is no need to interrupt the instant hot water operation and stop the instant hot water circulation pump so that a sufficient amount of hot water can be dispensed from the hot water tap. In other words, there is a problem in that the instant hot water operation is stopped even when only the hot water filling operation is in progress, which should not be stopped, thereby compromising the convenience of the user, who can immediately dispense hot water by the instant hot water operation when the hot water tap is opened. Note that even if a hot water supply flow rate sensor is provided in the water supply path or hot water outlet path and the operation of the instant hot water operation is determined based on the flow rate detection value of the hot water flowing through the hot water outlet path by this hot water supply flow rate sensor, as long as the hot water supply flow rate sensor detects a flow rate during the hot water filling operation, the same problem as when the combustion signal is used will occur.

The present invention was made in consideration of the above circumstances, and aims to provide an instant hot water system that prevents the instant hot water operation from being stopped unnecessarily due to the water filling operation, thereby improving the convenience of the instant hot water operation for the user.

The instant hot water system according to the present invention comprises:
An instant hot water system including a first heating device and a second heating device for heating water to generate hot water, a water supply passage for supplying water from a water supply source to the first heating device, a hot water outlet passage for supplying the hot water generated by the first heating device to a hot water outlet valve, an instant hot water circulation passage connected to the hot water outlet passage, and a control device for enabling instant hot water operation in which hot water is circulated in the instant hot water circulation passage while being heated by the second heating device,
A hot water filling path is provided which branches off from the hot water outlet path upstream of the connection position of the immediate hot water circulation path and is connected to the bathtub, and a hot water filling operation can be performed to supply hot water from the hot water outlet path to the bathtub through the hot water filling path,
The control device is provided with a control configuration that determines whether, during instant hot water operation, the water filling operation and hot water supply to the hot water tap are being used simultaneously, or the water filling operation is being used alone, and prohibits instant hot water operation when the water filling operation and hot water supply to the hot water tap are being used simultaneously, and continues the instant hot water operation when the water filling operation is being used alone.

According to the above configuration, when the water filling operation is used alone, the instant hot water operation continues without being stopped. As a result, the instant hot water operation is not stopped due to the use of only the water filling operation, which should not be stopped, even if hot water is not being supplied to the hot water tap. Therefore, unnecessary stopping of the instant hot water operation due to the water filling operation can be suppressed, so hot water can be dispensed immediately when the hot water tap is used even during the water filling operation. This improves the convenience for users with the instant hot water operation.

In the instant hot water system,
a hot water supply flow rate sensor provided in the hot water outlet passage upstream of a branch point to the water supply passage or the hot water filling passage, for detecting the flow rate of hot water flowing through the hot water outlet passage;
a water filling flow rate sensor provided in the water filling path for detecting the flow rate of water flowing through the water filling path;
When the flow rate difference between the detected values of the hot water filling flow sensor and the hot water supply flow sensor during instant hot water operation is equal to or greater than a predetermined flow rate, the control device determines that the hot water filling operation and the hot water supply to the hot water tap are being used simultaneously, and prohibits instant hot water operation, and when the flow rate difference is less than the predetermined flow rate, it determines that the hot water filling operation is being used alone, and continues instant hot water operation.

According to the above configuration, the flow rate of hot water detected by the hot water supply flow sensor is the total flow rate of the hot water outlet flow rate from the hot water tap and the hot water filling flow rate through the hot water filling passage. Therefore, not only the hot water supply flow rate sensor but also the flow rate difference between the hot water filling flow rate sensor and the hot water supply flow rate sensor is used to determine whether hot water has been discharged from the hot water tap, and the operation of the instant hot water operation is determined according to the result of the determination. In other words, if the flow rate difference between the detection values of the hot water filling flow rate sensor and the hot water supply flow rate sensor is less than a predetermined flow rate, it can be assumed that the detection value of the hot water supply flow rate sensor is the detection value of the flow rate due to the hot water filling operation only, and it is determined that the hot water filling operation is being used alone, and the instant hot water operation is continued. Therefore, if the operation of the instant hot water operation is determined by the combustion signal of the heat source machine as in the conventional case or if the operation of the instant hot water operation is determined only by the detection value of the hot water supply flow rate sensor, the instant hot water operation will be stopped even if the bathtub is only filled with hot water. However, with this configuration, it is possible to suppress unnecessary stopping of the instant hot water operation due to the hot water filling operation only, improving the convenience of the user by the instant hot water operation.

FIG. 1 is a schematic diagram showing the overall configuration of an instant hot water system according to an embodiment. 11 is a flowchart for explaining the basic processing operation of the instant hot water operation. 11 is a flowchart for explaining the processing operation for restarting instant hot water operation. 11 is a flowchart for explaining the processing operation of the instant hot water operation during the hot water filling operation. 11 is a flowchart for explaining the processing operations after restarting instant hot water operation during hot water filling operation.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
As shown in Fig. 1, the instant hot water system 1 according to the embodiment has an instant hot water function that can supply hot water immediately when the hot water tap P1 is opened, and mainly comprises a hot water supply circuit A1, a heating circuit A2, an instant hot water circuit A3, and a control device 2. In addition, a remote control (e.g., a kitchen remote control, a bath remote control, etc.) 8 is provided for remotely operating the instant hot water system 1. The remote control 8 is provided with various switches such as an operation switch that enables hot water supply to the hot water tap P1, a bath fill switch that causes the bathtub 23 to be filled with hot water, a reheat switch that causes the bathtub water in the bathtub 23 to be reheated, and an instant hot water switch that causes the instant hot water circuit A3 to operate in an instant hot water mode.

The hot water supply circuit A1 has a hot water supply side heating means 30 which serves as a first heating device, and a hot water supply side fluid flow path.
The hot water supply side heating means 30 includes, in order from the bottom, a hot water supply side burner unit 33, a hot water supply side first heat exchanger 31, and a hot water supply side second heat exchanger 32. In addition, below the hot water supply side burner unit 33, a blower fan 70 is provided which is also used by the heating side heating means 40 of the heating circuit A2.

The hot water supply side fluid flow paths include a water supply path 90 that is connected to the water supply source and is connected to the upstream end of the hot water supply side second heat exchanger 32, a connection path 95 that connects the downstream end of the hot water supply side second heat exchanger 32 and the upstream end of the hot water supply side first heat exchanger 31, a hot water outlet path 100 that is connected to a hot water tap P1 such as a faucet and is connected to the downstream end of the hot water supply side first heat exchanger 31, a hot water supply bypass path 105 that bypasses the water supply path 90 and the hot water outlet path 100, and a hot water filling path 250 that fills the bathtub 23 with hot water. In addition, a water pipe 96 that leads water from the water supply is branched off from the water supply path 90 and connected to the hot water outlet path 100, and a hot water pipe 97 that leads hot water from the hot water outlet path 100 is branched off from the hot water outlet path 100.

The water supply passage 90 is provided with, in order from the upstream side, a hot water supply flow rate sensor 91 that detects the flow rate of water flowing through the water supply passage 90 to detect the flow rate of hot water flowing through the hot water outlet passage 100, a water supply temperature sensor 92 that detects the temperature of the water flowing through the water supply passage 90, a water volume servo 93 that changes the opening degree of the water supply passage 90 (including full closure), and a bypass servo 94 that changes the opening degree of the hot water supply bypass passage 105 that connects the water supply passage 90 and the hot water outlet passage 100 (including full closure). Note that the hot water supply flow rate sensor 91 provided in the water supply passage 90 detects the flow rate of hot water flowing through the hot water outlet passage 100, but a flow rate sensor may be provided in the hot water outlet passage 100 upstream of the branch with the hot water filling passage 250 to detect the flow rate of hot water flowing through the hot water outlet passage 100.

In the hot water outlet path 100, from the upstream side, there are provided a heat exchanger temperature sensor 101 that detects the temperature of the hot water discharged from the hot water supply side first heat exchanger 31, and an outlet hot water temperature sensor 103 that detects the temperature of the hot water supplied downstream of the junction with the hot water supply bypass path 105.

With the above-described configuration of the hot water supply circuit A1, when the hot water tap P1 is opened and the hot water supply flow rate detected by the hot water supply flow rate sensor 91 is equal to or greater than the ignition water volume, the hot water supply side burner unit 33 ignites and burns, and the water supplied to the water supply passage 90 from the water supply is heated by heat exchange in the hot water supply side second heat exchanger 32 and the hot water supply side first heat exchanger 31 using the combustion exhaust gas discharged from the hot water supply side burner unit 33, and the heated hot water is supplied to the hot water tap P1 through the hot water outlet passage 100, and the hot water is discharged from the hot water tap P1.

The water filling path 250 is connected to a bath return path 251 that is pulled out from the water outlet path 100 and connected to the bathtub 23. In the water filling path 250, from the upstream side, there are interposed a water filling solenoid valve 261 that opens and closes the water filling path 250, a check valve 263 that prevents backflow of hot water from the water filling path 250 to the water outlet path 100, and a water filling flow rate sensor 262 that detects the flow rate of hot water supplied from the water outlet path 100 to the water filling path 250.

When the hot water filling operation is started by turning on the hot water filling switch on the remote control 8, the hot water filling solenoid valve 261 is opened. Then, hot water flows from the hot water outlet path 100 into the hot water filling path 250, causing the hot water supply flow sensor 91 to detect a flow rate greater than the ignition water amount, igniting and burning the hot water supply side burner unit 33, and the hot water from the hot water outlet path 100 is supplied to the bathtub 23 from the bath return path 251 through the hot water filling path 250. Then, when the accumulated hot water filling flow rate detected by the hot water filling flow sensor 262 reaches the set hot water amount, the hot water filling solenoid valve 261 is closed and the supply of hot water from the hot water filling path 250 is stopped. Also, the flow rate detected by the hot water supply flow sensor 91 becomes less than the extinguishing water amount, and the hot water supply side burner unit 33 is extinguished. Next, the bath circulation pump 224 is driven, and the bath water in the bathtub 23 is circulated through the bath return path 251 and the bath supply path 252 and heated by the bath liquid heat exchanger 221 of the heating circuit A2. When the temperature of the bath water reaches the set bath temperature, the bath filling operation is completed.

The instant hot water circuit A3 is mainly composed of an instant hot water circulation path 300, an instant hot water circulation pump 311, and an instant hot water liquid heat exchanger 313 which serves as the second heating device. The instant hot water circulation path 300 is connected between the hot water outlet terminal of the hot water outlet path 100 where the hot water tap P1 is arranged, and a position downstream of the hot water filling path 250 in the hot water outlet path 100. The instant hot water circulation path 300 takes in hot water from the connection part on the hot water outlet terminal side at a downstream position of the hot water outlet path 100, and flows hot water into the connection part at a downstream position of the hot water filling path 250 to form a circulation circuit that circulates hot water. In the instant hot water circulation path 300, an instant hot water amount sensor 310, an instant hot water circulation pump 311, an instant hot water temperature sensor 312, and an instant hot water liquid heat exchanger 313 are disposed, and further, upstream of the instant hot water amount sensor 310, a check valve 317, an overpressure relief valve 316, an air-water separator 314, and an expansion tank 315 are disposed. By driving the instant hot water circulation pump 311, hot water is circulated in the instant hot water circulation path 300. Even if hot water is circulated in the instant hot water circulation path 300, no water flow is generated in the entire water supply path 90 and the hot water outlet path 100, so the hot water supply flow rate sensor 91 installed in the water supply path 90 does not detect the water flow.

The instant hot water liquid-liquid heat exchanger 313 is composed of a plate-type heat exchanger in which a planar flow path through which hot water in the instant hot water circulation path 300 flows and a planar flow path through which hot water in the heating branch circulation path 270, which is part of the heating circuit A2, flows are stacked. In the instant hot water liquid-liquid heat exchanger 313, heat exchange (liquid-liquid heat exchange) is carried out between the hot water circulating in the instant hot water circulation path 300 and the hot water flowing in the heating branch circulation path 270, and the hot water circulating in the instant hot water circulation path 300 is heated.

With the above-described configuration of the instant hot water circuit A3, when instant hot water operation is performed, the instant hot water circulation pump 311 circulates hot water in the instant hot water circulation path 300, while the hot water heated by the instant hot water liquid-liquid heat exchanger 313 is retained in the instant hot water circulation path 300. Therefore, when the hot water tap P1 is opened, hot water is dispensed from the instant hot water circulation path 300, and hot water can be dispensed immediately.

In the embodiment, the instant hot water circuit A3 is configured to form an instant hot water circulation path 300 downstream of the hot water outlet path 100, provide an instant hot water circulation pump 311, and heat the hot water in the instant hot water circulation path 300 with an instant hot water liquid-liquid heat exchanger (heating device) 313 connected to the heating circuit A2 side to provide instant hot water, but it may also be configured to provide instant hot water by heating the hot water in the instant hot water circulation path 300 with an independent heating device such as a heater.

The heating circuit A2 has a heater-side heating means 40 and a heater-side fluid flow path.
As the heater-side heating means 40, a heater-side burner unit 43, a heater-side first heat exchanger 41, and a heater-side second heat exchanger 42 are arranged in this order from the bottom.

The heating side fluid flow paths include a heating return path 200 connected to the upstream end of the heating side second heat exchanger 42, a heating forward path 210 connected to the downstream end of the heating side first heat exchanger 41, a communication forward path 205 and a communication return path 206 connecting the downstream end of the heating side second heat exchanger 42 and the upstream end of the heating side first heat exchanger 41 across a cistern 201, a bath branch path 240 branching off from the heating forward path 210 and connected to the heating return path 200, and a heating branch circulation path 270 branching off from the communication return path 206 and connected to the bath branch path 240.

The heating forward path 210 is connected to the high-temperature heating terminal (such as a hot air heater) P2. The connection return path 206 is provided with a heating circulation pump 211 for circulating hot water between the high-temperature heating terminal P2 and the heating side heating means 40. A low-temperature branch path 216 branches off from the connection return path 206 from the middle downstream of the heating circulation pump 211, and is connected to a thermal valve header 212 for connecting the low-temperature heating terminal (such as a floor heater) P3. A heating branch circulation path 270 branches off from the connection return path 206 downstream of the low-temperature branch path 216, and the heating branch circulation path 270 is provided with an instant hot water flow control valve 271 that changes the opening degree of the heating branch circulation path 270 (including full closure), and an instant hot water liquid-liquid heat exchanger 313.

The heating return path 200 is connected to a heating return path 217 that returns hot water from the low-temperature heating terminal P3. The heating outward path 210 is provided with a heating high temperature sensor 213 that detects the temperature of the hot water discharged from the heating side first heat exchanger 41, and the connecting outward path 205 is provided with a heating low temperature sensor 215 that detects the temperature of the hot water supplied from the cistern 201 to the low-temperature branch path 216. A bath liquid heat exchanger 221 is provided midway on the bath branch path 240 that branches off from the heating outward path 210 and connects to the heating return path 200.

With the above-described configuration of the heating circuit A2, the heating circulation pump 211 is operated and the heating side burner unit 43 is ignited and combusted, whereby the hot and cold water flowing through the heating return path 200 is heat-exchanged and heated in the heating side second heat exchanger 42 and the heating side first heat exchanger 41 by the combustion exhaust gas discharged from the heating side burner unit 43, and the heated hot water (heat medium) is circulated and supplied from the heating forward path 210 to each heating terminal P2, P3, the bath liquid-liquid heat exchanger 221, and the immediate hot water liquid-liquid heat exchanger 313. Note that the heat medium for heating is not limited to hot and cold water, and antifreeze may also be used.

The bath return path 251, together with the bath supply path 252, constitutes a bath circulation path between the bathtub 23 and the bath liquid heat exchanger 221. The bath return path 251 is provided with a bath return temperature sensor 225 that detects the temperature of the bath water flowing from the bathtub 23 into the bath return path 251, a bath circulation pump 224 for circulating the bath water in the bathtub 23 through the bath supply path 252 and the bath return path 251, a water level sensor 223 that detects the water level of the bath water in the bathtub 23, and a bath water flow switch 222 that detects whether the bath water is flowing in the bath return path 251 at a rate greater than a predetermined flow rate.

A bath outflow temperature sensor 226 is installed in the bath outflow path 252 to detect the temperature of the bath water flowing from the bath liquid heat exchanger 221 to the bathtub 23. By operating the bath circulation pump 224, bath water circulates in the bath circulation path connecting the bathtub 23 and the bath liquid heat exchanger 221. The bath liquid heat exchanger 221 is a plate-type heat exchanger in which a planar flow path through which bath water from the bath return path 251 flows and a planar flow path through which hot water from the bath branch path 240 flows are stacked. In the bath liquid heat exchanger 221, heat exchange (liquid-liquid heat exchange) is performed between the bath water flowing in the bath outflow path 252 and the hot water flowing in the bath branch path 240, and the bath water flowing in the bath outflow path 252 is heated. The bath branch path 240 is provided with a reheating flow control valve 220 that changes the opening degree of the bath branch path 240 (including full closure).

The control device 2 is composed of an electronic circuit board, software, etc., and includes a control function unit that controls each operation in the instant hot water system 1, a timer unit that measures time, a memory unit that stores data and programs, etc., and a communication unit that communicates with each sensor, each pump, each valve, and other components to be controlled. A remote control 8 that remotely controls each operation of the instant hot water system 1 and temperature settings is connected to the control device 2 so that it can communicate with the control device 2. The instant hot water operation in the instant hot water system 1 is performed by turning on the instant hot water switch of the remote control 8. The control device 2 has a control configuration that stops the instant hot water operation when it detects that the hot water tap P1 is opened and hot water is being dispensed from the hot water tap P1 (i.e., the hot water tap P1 is being used and hot water is being supplied to the hot water tap P1) during the instant hot water operation, and continues the execution of the instant hot water operation when it detects that the hot water tap P1 is not opened and hot water is not being dispensed from the hot water tap P1 (i.e., the hot water tap P1 is not being used and hot water is not being supplied to the hot water tap P1). The state in which the hot water tap P1 is opened and hot water is dispensed from the hot water tap P1 is also referred to as "hot water supply in use" (hot water supply use at the hot water tap P1), and the state in which hot water supply use at the hot water tap P1 is not in use is also referred to as "hot water supply not in use." In addition, in this embodiment, when a hot water filling operation is performed during an instant hot water operation, the control device 2 is configured to stop the instant hot water operation when the hot water filling operation and the hot water supply use at the hot water tap P1 are performed simultaneously, and to continue the instant hot water operation without stopping it when only the hot water filling operation is being performed.

Next, a description will be given of the basic processing of the instant hot water operation by the instant hot water system 1 of the embodiment. Note that the basic processing of the instant hot water operation (FIG. 2) described below shows the relationship between the hot water supply and the presence or absence of hot water supply at the hot water tap P1.
2, when the instant hot water operation is started by turning on the instant hot water switch in step S1, the control device 2 judges whether or not the hot water supply is unused at the hot water tap P1 in step S2. In step S2, if the hot water supply flow rate (flow rate of water flowing through the water supply passage 90) detected by the hot water supply flow rate sensor 91 is less than the judgment flow rate Q1 (for example, 1.0 L/min), it is judged that the hot water tap P1 is closed and the hot water supply is unused, and in step S3, the control device 2 drives the instant hot water circulation pump 311 of the instant hot water circulation passage 300. Hot water is circulated in the instant hot water circulation passage 300 by driving the instant hot water circulation pump 311.

Next, in step S4, the control device 2 judges whether hot water is circulating normally in the instant hot water circulation path 300. In step S4, if the instant hot water flow rate (flow rate of hot water flowing through the instant hot water circulation path 300) detected by the instant hot water amount sensor 310 is not at or above a predetermined flow rate (e.g., 2.0 L/min) and is not continued for a predetermined time (e.g., 10 seconds), it is judged that hot water is not circulating normally in the instant hot water circulation path 300, and in step S5, the control device 2 controls the instant hot water circulation pump 311 to stop driving, and causes an error stop of the instant hot water operation. When an error stop is performed, an error notification may be given.

On the other hand, in step S4, if the hot water flow rate detected by the hot water flow sensor 310 is equal to or greater than the predetermined flow rate and continues for a predetermined time or more, it is determined that the circulation of hot water in the hot water circulation path 300 is normal, and in step S6, the control device 2 drives the heating circulation pump 211 of the heating circuit A2 to start heating combustion in the heating side heating means 40.

From the start of heating combustion until the heating temperature (the temperature of the hot water discharged from the heating side first heat exchanger 41) detected by the heating high temperature sensor 213 reaches the instant hot water setting temperature (e.g., 60°C) (if "NO" in step S7), in step S8, the control device 2 determines whether hot water has been used at the hot water tap P1. That is, if the hot water supply flow rate sensor 91 detects in step S8 that the hot water supply flow rate (the flow rate of water flowing through the water supply passage 90) is equal to or greater than the judgment flow rate Q1, it is determined that the hot water tap P1 has been opened and hot water has been used at the hot water tap P1, and in step S9, the control device 2 stops the heating combustion of the heating side heating means 40, stops driving the instant hot water circulation pump 311, and interrupts the instant hot water operation. Then, in step S10, when the hot water flow rate sensor 91 detects that the hot water flow rate is less than the judgment flow rate Q1, the hot water tap P1 is closed to stop the hot water supply, it is determined that the hot water tap P1 is no longer being used to supply hot water, and the control device 2 proceeds to the process of restarting the instant hot water operation (Figure 3).

On the other hand, in step S7, if the heating temperature (the temperature of the hot water discharged from the heating side first heat exchanger 41) detected by the heating high temperature sensor 213 reaches the instant hot water set temperature due to heating combustion, in step S11, the control device 2 opens the instant hot water flow control valve 271. As a result, the heat medium is circulated in the heating branch circulation path 270, the instant hot water liquid-liquid heat exchanger 313 is heated, and the hot water in the instant hot water circulation path 300 is heated via the instant hot water liquid-liquid heat exchanger 313.

Until the instant hot water temperature, which is the temperature of the hot water in the instant hot water circulation path 300 detected by the instant hot water temperature sensor 312, reaches the instant hot water setting temperature (if "NO" in step S12), in step S13, the control device 2 judges whether hot water has been used at the hot water tap P1. If the hot water supply flow rate sensor 91 detects in step S13 that the hot water supply flow rate is equal to or greater than the judgment flow rate Q1, it is judged that the hot water tap P1 has been opened and hot water has been used at the hot water tap P1, and in step S14, the control device 2 stops the heating combustion of the heating side heating means 40, stops the operation of the instant hot water circulation pump 311, closes the instant hot water flow rate control valve 271, and interrupts the instant hot water operation. After that, in step S15, when the hot water supply flow rate sensor 91 detects that the hot water supply flow rate is less than the judgment flow rate Q1, it is judged that the hot water tap P1 has been closed and hot water supply has been stopped, and the control device 2 proceeds to the process of restarting the instant hot water operation (Figure 3).

In addition, in step S12, if the instant hot water temperature detected by the instant hot water temperature sensor 312 reaches the instant hot water set temperature, in order to suppress the rise in the hot water temperature in the instant hot water circulation path 300 and maintain it at a constant temperature (e.g., about 60°C), in step S16, the control device 2 stops the heating combustion of the heating side heating means 40, stops driving the instant hot water circulation pump 311, closes the instant hot water flow control valve 271, and interrupts instant hot water operation. After that, the process proceeds to restart instant hot water operation (Figure 3).

Next, the operation of the instant hot water operation restart process will be described.
Referring to FIG. 3, in the process of restarting the instant hot water operation, when the process shifts to this instant hot water operation restart process, in step S21, the control device 2 starts counting the standby time.

In step S22, if the instant hot water temperature, which is the temperature of the hot water in the instant hot water circulation path 300 detected by the instant hot water temperature sensor 312, has fallen below the instant hot water start temperature (e.g., 55°C) or the standby time has elapsed beyond a predetermined standby time (e.g., 10 minutes), in step S23, the control device 2 drives the instant hot water circulation pump 311 to circulate the hot water in the instant hot water circulation path 300.

Next, in step S24, similar to the processing of step S4 in FIG. 2, the control device 2 judges whether hot water is circulating normally in the instant hot water circulation path 300. If it is judged in step S24 that hot water is not circulating normally in the instant hot water circulation path 300, the control device 2 controls the instant hot water circulation pump 311 to stop driving in step S25, and stops the instant hot water operation due to an error. If it is judged in step S24 that the circulation of hot water in the instant hot water circulation path 300 is normal, in step S26, hot water is circulated in the instant hot water circulation path 300 for a predetermined circulation time (e.g., 1 minute) after the instant hot water circulation pump 311 is started to be driven in step S23.

After circulating the hot water in the instant hot water circulation path 300 for a predetermined circulation time, if the instant hot water temperature, which is the temperature of the hot water in the instant hot water circulation path 300 detected by the instant hot water temperature sensor 312, is equal to or higher than the instant hot water start temperature in step S27, the control device 2 stops driving the instant hot water circulation pump 311 in step S28, waits for the instant hot water operation to resume, and transitions the process to step S21. If the instant hot water temperature detected by the instant hot water temperature sensor 312 has fallen below the instant hot water start temperature in step S27, the control device 2 transitions the process to step S6 in FIG. 2 and resumes the instant hot water operation.

According to the above instantaneous hot water operation control, when the hot water tap P1 is opened, hot water can be immediately dispensed from the hot water tap P1. In addition, when the hot water tap P1 is opened and hot water supply use is detected, the instantaneous hot water operation is interrupted and the instantaneous hot water circulation pump 311 is stopped, so that the hot water tap P1 side is not depressurized by the instantaneous hot water circulation pump 311, and a sufficient amount of hot water can be dispensed from the hot water tap P1. Furthermore, if the instantaneous hot water circulation pump 311 is driven to circulate hot water in the instantaneous hot water circulation path 300 while hot water supply is being used from the hot water tap P1, a pressure difference occurs between the hot water outlet path 100 and the instantaneous hot water circulation path 300, which generates air bubbles and causes the air bubbles to enter the instantaneous hot water circulation path 300 and eventually corrode the piping of the instantaneous hot water circulation path 300. However, by stopping the instantaneous hot water circulation pump 311 when hot water supply is being used, the problem of air bubbles entering the instantaneous hot water circulation path 300 and corroding the piping can be prevented.

Next, the operation of the instant hot water operation during the hot water filling operation will be described.
4, when the control device 2 detects that the hot water filling operation switch has been turned ON (step S31) using the remote control 8 while the instant hot water operation is being performed, the control device 2 opens the hot water filling solenoid valve 261 in step S32 and starts the hot water supply/hot water filling determination process. Note that the hot water supply/hot water filling determination process is performed until the hot water filling operation is completed.

Next, in step S33, the control device 2 determines whether the flow rate difference ΔQ (absolute value) between the hot water supply flow rate detected by the hot water supply flow rate sensor 91 and the hot water filling flow rate detected by the hot water filling flow rate sensor 262 is less than the judgment flow rate Q2 (e.g., 2.0 L/min). Here, the detection value of the hot water supply flow rate detected by the hot water supply flow rate sensor 91 includes the hot water outlet flow rate from the hot water outlet tap P1 and the hot water filling flow rate of the hot water flowing through the hot water filling path 250. Therefore, the flow rate difference ΔQ (absolute value) between the hot water supply flow rate detected by the hot water supply flow rate sensor 91 and the hot water filling flow rate detected by the hot water filling flow rate sensor 262 can be assumed to be the hot water outlet flow rate due to hot water supply use at the hot water outlet tap P1. In addition, the flow rate judgment value (judgment flow rate Q2) for judging whether hot water supply is being used or stopped at the hot water tap P1 during the hot water filling operation is set to a value larger than the flow rate judgment value (judgment flow rate Q1) when hot water supply use and hot water supply stop are judged only by the detection value of the hot water flow rate sensor 91 when the hot water filling operation is not being performed, taking into account fluctuations in the detection values of the two sensors, the hot water supply flow rate sensor 91 and the hot water filling flow rate sensor 262, due to the opening of the hot water filling solenoid valve 261 and the hot water tap P1.

In step S33, if the flow rate difference ΔQ is equal to or greater than the judgment flow rate Q2, in step S34, the control device 2 determines that the hot water tap P1 has been opened and hot water has been supplied from the hot water tap P1, i.e., the hot water filling operation and the hot water supply from the hot water tap P1 have been used simultaneously, and in step S35, prohibits the instant hot water operation. By prohibiting the instant hot water operation, in step S36, the control device 2 stops the instant hot water circulation pump 311 of the instant hot water circulation path 300, stops the heating combustion of the heating side heating means 40, and controls the instant hot water flow control valve 271 of the heating branch circulation path 270 to close. This stops the instant hot water operation in which hot water is circulated and heated by the instant hot water circuit A3. Therefore, by stopping the drive of the instant hot water circulation pump 311, sufficient hot water can be supplied from the hot water tap P1, and the problem of air bubbles being mixed into the instant hot water circulation path 300 can also be prevented.

When instant hot water operation is prohibited, if the flow rate difference ΔQ becomes less than the judgment flow rate Q2 in step S37, the control device 2 determines in step S38 that the hot water tap P1 is closed, hot water supply is stopped, and only the water filling operation is being performed. In this case, the control device 2 cancels the prohibition of instant hot water operation in step S39, allows instant hot water operation, and proceeds to operation "A" (Figure 3) of the instant hot water operation restart process.

As shown in Figure 3, in the instant hot water operation restart process for restarting instant hot water operation after it has been stopped during a water filling operation, if the instant hot water temperature, which is the temperature of the hot water in the instant hot water circulation path 300 detected by the instant hot water temperature sensor 312, falls below the instant hot water start temperature in step S27, the process transitions to "C" shown in Figure 5. Note that the process procedure from "C" onwards is as shown in Figure 5, and follows the process procedure from "B" onwards (steps S6 to S16) in the basic instant hot water operation process shown in Figure 2. Therefore, the explanation of the basic instant hot water operation process described above should be referred to, and will not be repeated here. However, in the process of restarting instant hot water operation during hot water filling operation shown in FIG. 5, instead of the process of determining whether hot water has been used in the basic process of instant hot water operation in FIG. 2 (steps S8 and S13 in FIG. 2), it is determined that hot water has been used at the hot water tap P1 if the flow rate difference ΔQ (absolute value) between the hot water flow rate detected by the hot water flow rate sensor 91 and the hot water filling flow rate detected by the hot water filling flow rate sensor 262 is equal to or greater than the determination flow rate Q2 (steps S8c and S13c in FIG. 5). Also, instead of the process of determining whether hot water has been stopped in the basic process of instant hot water operation in FIG. 2 (steps S10 and S15 in FIG. 2), it is determined that hot water has been stopped at the hot water tap P1 if the flow rate difference ΔQ (absolute value) is less than the determination flow rate Q2 (steps S10c and S15c).

Referring again to FIG. 4, during the water filling operation, if step S33 determines that the flow rate difference ΔQ (absolute value) between the water supply flow rate detected by the water supply flow rate sensor 91 and the water filling flow rate detected by the water filling flow rate sensor 262 is less than the judgment flow rate Q2, then in step S40 the control device 2 determines that only water filling operation is being used, i.e., the water outlet tap P1 is closed and hot water is not being used to supply hot water from the water outlet tap P1. If only water filling operation is being used, then in step S41 the control device 2 continues the instant hot water operation without stopping it.

As described above, according to this embodiment, when the hot water filling operation is used alone, the instant hot water operation continues without being stopped, so that the instant hot water operation is not stopped due to the use of only the hot water filling operation, which should not be stopped, even if hot water is not being supplied from the hot water tap P1. Therefore, unnecessary stopping of the instant hot water operation due to the hot water filling operation can be suppressed, so hot water can be supplied immediately when hot water is used even during the hot water filling operation. This improves the convenience of the user with the instant hot water operation. In addition, the durability of the instant hot water circulation pump 311 is improved because the repeated stopping and starting of the instant hot water circulation pump 311, in which the instant hot water circulation pump 311 is stopped when the hot water filling operation is performed and started when the hot water filling operation is completed, can be suppressed.

The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims.
For example, in the embodiment, the hot water supply/filling judgment process is executed from the time the ON operation of the hot water filling operation switch is detected until the hot water filling operation is completed, but it may also be executed while the hot water filling solenoid valve 261 is open (i.e., from the time the open signal of the hot water filling solenoid valve 261 is output to the time the close signal of the hot water filling solenoid valve 261 is output), etc.
In addition, in the embodiment, as the flow rate judgment value for hot water supply use and hot water supply stop, the judgment flow rate Q2 (Figures 4 and 5) during water filling operation is set to a value greater than the judgment flow rate Q1 (Figure 2) when there is no water filling operation, but the judgment flow rate Q2 may be set to the same value as the judgment flow rate Q1, or may be set to a value smaller than the judgment flow rate Q1.
In the embodiment, in the basic processing operation of the instant hot water operation (FIG. 2), the same value of the judgment flow rate Q1 is used as the judgment value for judging whether hot water supply is in use or not, but different values may be used for each judgment value for hot water supply in use and not in use. For example, the judgment value for hot water supply in use and not in use may be the ignition water amount and the extinguishing water amount, which are the amounts of water used by the hot water supply side burner unit 33 for ignition and extinguishing. In this case, in FIG. 2, the ignition water amount is used as the judgment value for whether hot water supply is in use or not in steps S2, S8, and S13, and the extinguishing water amount is used as the judgment value for whether hot water supply has been stopped from the hot water supply in use state in steps S10 and S15. The extinguishing water amount can be set to a value smaller than the ignition water amount.

1 Instant hot water system 2 Control device 8 Remote control 30 Hot water supply side heating means (first heating device)
31 Hot water supply side first heat exchanger 32 Hot water supply side second heat exchanger 33 Hot water supply side burner unit 40 Heating side heating means 41 Heating side first heat exchanger 42 Heating side second heat exchanger 43 Heating side burner unit 90 Water supply path 91 Hot water supply flow rate sensor 100 Hot water outlet path 200 Heating return path 205 Communication outward path 206 Communication return path 210 Heating outward path 211 Heating circulation pump 261 Hot water filling solenoid valve 262 Hot water filling flow rate sensor 270 Heating branch circulation path 271 Instant hot water flow rate control valve 300 Instant hot water circulation path 310 Instant hot water water volume sensor 311 Instant hot water circulation pump 312 Instant hot water temperature sensor 313 Instant hot water liquid-liquid heat exchanger (second heating device)
P1 Hot water tap P2 High temperature heating terminal P3 Low temperature heating terminal A1 Hot water circuit A2 Heating circuit A3 Instant hot water circuit

Claims (2)

An instant hot water system including a first heating device and a second heating device for heating water to generate hot water, a water supply passage for supplying water from a water supply source to the first heating device, a hot water outlet passage for supplying the hot water generated by the first heating device to a hot water outlet valve, an instant hot water circulation passage connected to the hot water outlet passage, and a control device for enabling instant hot water operation in which hot water is circulated in the instant hot water circulation passage while being heated by the second heating device,
A hot water filling path is provided which branches off from the hot water outlet path upstream of the connection position of the immediate hot water circulation path and is connected to the bathtub, and a hot water filling operation can be performed to supply hot water from the hot water outlet path to the bathtub through the hot water filling path,
The control device is an instant hot water system having a control configuration that determines whether the instant hot water operation and hot water supply to the hot water tap are being used simultaneously or the instant hot water operation is being used alone during instant hot water operation, and prohibits instant hot water operation when the instant hot water operation and hot water supply to the hot water tap are being used simultaneously, and continues instant hot water operation when the instant hot water operation is being used alone. In the instant hot water system according to claim 1,
a hot water supply flow rate sensor provided in the hot water outlet passage upstream of a branch point to the water supply passage or the hot water filling passage, for detecting the flow rate of hot water flowing through the hot water outlet passage;
a water filling flow rate sensor provided in the water filling path for detecting the flow rate of water flowing through the water filling path;
This instant hot water system has a control device that, when the flow rate difference between the detected values of the hot water filling flow sensor and the hot water supply flow sensor during instant hot water operation is equal to or greater than a predetermined flow rate, determines that the hot water filling operation and the hot water supply to the hot water tap are being used simultaneously, and prohibits instant hot water operation, and, when the flow rate difference is less than the predetermined flow rate, determines that the hot water filling operation is being used alone, and continues the instant hot water operation.