JP7315201B2 - Hot water system and water heater - Google Patents

Description

The present invention relates to a hot water supply system that heats hot water by circulating it between a heat exchanger of the water heater and an external pipe to heat the hot water and enables immediate hot water supply from the hot water tap of the external pipe, and a water heater used in the hot water supply system.

2. Description of the Related Art A known water heater has an instant hot water function by connecting a return pipe with a circulation pump to a water supply pipe connected to a heat exchanger (see Patent Document 1, for example). In this water heater with instant hot water function, a hot water supply pipe and a return pipe are connected by an external pipe to form a circulation path with the hot water supply pipe, the external pipe, the return pipe, and the water supply pipe. Therefore, when the hot water supply valve provided in the external pipe is opened, hot water can be supplied immediately.

JP 2004-286397 A

In this hot water supply system, even if the water heater is installed outdoors, or even if it is installed indoors, outside air is sucked in through the exhaust stack due to the negative pressure generated in the combustion chamber due to the operation of the ventilation fan, and the water in the pipes such as the heat exchanger may freeze in winter or in cold regions.
Therefore, in order to prevent freezing, countermeasures are taken such as using a heater to heat the pipes, operating a circulation pump to circulate the water, and raising the water temperature with the residual heat of the circulation pump, but adding a heater will increase the cost. In addition, the use of a circulation pump requires long-term operation, which also leads to an increase in cost, and there is a possibility that the operation noise may make the user feel uncomfortable.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a hot water supply system and a water heater that are energy-saving, low-cost, and that can prevent freezing by reducing the discomfort caused by the operation noise of the circulation pump.

In order to achieve the above object, the invention according to claim 1 provides a water heater having a burner, a heat exchanger, a water supply pipe connected to the heat exchanger, a hot water discharge pipe connected to the heat exchanger, and a control means for controlling the burner,
an external pipe connected between the hot water outlet pipe and the water supply pipe, forming a circulation path in which the hot water discharged from the hot water outlet pipe returns to the water supply pipe and reaches the heat exchanger, and to which a plurality of hot water supply valves including a hot water supply valve for supplying hot water to the bathtub are connected;
a circulation pump provided in the circulation path and controlled by the control means;
a water flow detection means for detecting water flow accompanying the opening of the hot water tap;
and a water stop means for stopping the flow of water through the circulation path,
The control means is capable of controlling the water stop means, and is capable of executing hot water supply control to stop water supply to the circulation path by the water stop means when supply of a predetermined amount of hot water to the bathtub by opening the hot water supply tap is confirmed by the water supply detection means,
having preventive condition detection means for detecting the presence or absence of a necessary condition for freeze prevention at a predetermined location in the circulation route;
The control means is characterized in that, when the preventive condition detection means detects that the necessary conditions for antifreeze are satisfied after supplying a predetermined amount of hot water to the bathtub , the control means cancels the stoppage of water supply to the circulation path by the water cutoff means and executes antifreeze control to operate the circulation pump until the water in the predetermined location is replaced.
According to a second aspect of the invention, in the structure of the first aspect, the operation of the circulating pump associated with detection by the preventive condition detection means is set in advance, and is performed for a period of time necessary to complete replacement of water at a predetermined location.
In order to achieve the above object, the invention according to claim 3 is a water heater having a burner, a heat exchanger, a water supply pipe connected to the heat exchanger, a hot water discharge pipe connected to the heat exchanger, and a control means for controlling the burner,
The control means is capable of executing anti-freezing control when installed in the hot water supply system according to claim 1 or 2.
The invention according to claim 4 is the structure according to claim 3, wherein a return pipe having one end connected to the water supply pipe and the other end connectable to an external pipe is provided in the housing of the water heater, and the circulation pump is provided in the return pipe.

According to the present invention, when the prevention condition detection means detects that the necessary condition for freezing prevention is satisfied after supplying a predetermined amount of hot water to the bathtub , the control means cancels the stoppage of the water flow through the circulation path by the water shutoff means and operates the circulation pump until the water in the predetermined location is replaced. Therefore, it is possible to prevent freezing by saving energy, reducing costs, and reducing the discomfort caused by the operation noise of the circulation pump.
According to the second aspect of the invention, in addition to the above effects, the operation of the circulating pump accompanying the detection of the preventive condition detection means is set in advance and is performed only for the time necessary for completing water replacement at a predetermined location.
According to the fourth aspect of the invention, in addition to the above effects, the return pipe and the circulation pump are provided in the housing of the water heater, so that the hot water supply system can be easily constructed.

1 is a schematic diagram of a hot water supply system; FIG. 4 is a flow chart of hot water filling control and anti-freezing control; FIG. 10 is an explanatory diagram of the monitor display of the portable terminal in the hot water filling control; FIG. 4 is a schematic diagram showing a modification of the hot water supply system;

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below with reference to the drawings.
(Configuration of hot water supply system)
FIG. 1 is a schematic diagram showing an example of a hot water supply system S. As shown in FIG. The hot water supply system S is an instant hot water system including a water heater 1 and an external pipe 30 for circulation connected to the water heater 1 .
First, in the water heater 1, a combustion chamber 3 having three burner units 4, 4 . . . The bottom surface of the housing 2 is provided with a gas connection port 7 to which an external gas pipe is connected, a water supply connection port 8 to which an external water supply pipe is connected, and a hot water supply connection port 9 and a return connection port 10 to which an external hot water supply pipe is connected.
The burner units 4, 4, . A fan 16 for supplying combustion air to the burner unit 4 and an outside air temperature sensor 17 such as a thermistor for detecting the temperature of the outside air sucked into the fan 16 are provided in the lower part of the combustion chamber 3 .

The heat exchanger 5 is of a fin-tube type having a heat transfer tube passing through a plurality of fins arranged at predetermined intervals in the thickness direction in a meandering manner. A water supply pipe 18 connected to the water supply connection port 8 is connected to the inlet end of the heat transfer pipe, and a hot water supply pipe 19 connected to the hot water supply connection 9 is connected to the outlet end of the heat transfer pipe. A bypass pipe 20 that bypasses the heat exchanger 5 is connected between the water supply pipe 18 and the hot water discharge pipe 19 .
Further, on the upstream side of the connecting portion of the bypass pipe 20 in the water supply pipe 18, a water side on-off valve 21, an incoming water temperature sensor 22 such as a thermistor for detecting the incoming water temperature, and a water quantity sensor 23 for detecting the quantity of water are provided. Furthermore, an outlet temperature sensor 24 such as a thermistor for detecting the temperature of the outlet from the heat exchanger 5 is provided upstream from the connecting portion of the bypass pipe 20 in the hot water outlet pipe 19, and an outlet hot water temperature sensor 25 such as a thermistor for detecting the outlet hot water temperature is provided downstream from the connecting portion.

A return pipe 26 having a circulation pump 27 and a check valve 28 positioned on the discharge side is connected between the return connection port 10 and the water supply pipe 18 on the upstream side of the water quantity sensor 23 .
The external pipe 30 is connected between the hot water supply connection port 9 and the return connection port 10, and has a plurality of hot water taps 31, 31, . One of the hot water taps 31 is for supplying hot water to the bathtub 32 (hereinafter referred to as "hot water tap 31A" when distinguished from the other hot water taps 31).
As a result, hot water discharged from the hot water pipe 19 returns to the return pipe 26 through the external pipe 30, reaches the heat exchanger 5 through the water supply pipe 18, and forms a circulation path in which hot water is discharged from the hot water pipe 19 again.

In the hot water supply system S configured as described above, when the operation switch provided on the controller 35 or the remote controller 36 is pressed, the controller 35 operates the circulation pump 27 to circulate hot water in the circulation path. At the same time, the main solenoid valve 12 and the on-off valve 15 are opened to supply fuel gas to the burner unit 4, and the fan 16 is driven to perform ignition control and burn the burner unit 4. Then, the controller 35 controls the opening degree of the proportional control valve 13 and the rotational speed of the fan 16 so that the set temperature set by the controller 35 or the remote control 36 is obtained, thereby performing the heat retention operation. Therefore, when any one of the hot water taps 31 is opened, hot water can be immediately supplied at the set temperature.

On the other hand, when the controller 35 pushes a hot water supply switch provided on the controller 35 and the remote controller 36 to open the hot water supply tap 31A, the burner unit 4 is burned to supply hot water of a set temperature to the bathtub 32 until the amount of water detected by the water amount sensor 23 reaches the set amount of hot water.
In addition, when the controller 35 monitors the temperature detected by the outside air temperature sensor 17 and determines that the cold air flowing from the exhaust hood 6 may cause the water in the heat transfer tubes of the heat exchanger 5 to freeze, the controller 35 can perform freeze prevention control to operate the circulation pump 27 so that the replacement amount of water equivalent to the amount of water stored in the heat transfer tubes circulates through the circulation path. The automatic hot water filling control and anti-freezing control will be described below with reference to the flow chart of FIG.

(Description of automatic hot water filling control)
In step (hereinafter simply referred to as "S") 1, when the pressing operation (ON operation) of the hot water filling switch is confirmed, in S2, it is determined whether or not the water flow sensor 23 detects the water flow due to the opening of the hot water tap 31A. When the water supply is detected here, the controller 35 ignites the burner unit 4 to start supplying hot water of the set temperature from the hot water tap 31A to the bathtub 32 in S3.
When reaching the set amount of hot water is confirmed in S4, the water side opening/closing valve 21 is closed in S5 to finish filling hot water, the hot water filling switch is blinked, and the pressing operation (OFF operation) of the hot water filling switch is determined in S6. If the hot water filling switch is pushed here, the water side on-off valve 21 is opened in S7, and the presence or absence of water flow is confirmed by the water quantity sensor 23 in S8. If the user turns off the hot water supply switch and closes the hot water supply faucet 31A, water flow is not confirmed (NO in S8), so the automatic hot water supply control is terminated while the water side on-off valve 21 is opened (END).
After that, the presence or absence of water supply is confirmed again in S10, and if the water supply is not confirmed here, the automatic hot water filling control is terminated, but when it is confirmed that a predetermined time (for example, 90 seconds) has passed in S11 while the water supply state is still maintained, the water side on-off valve 21 is closed and the hot water supply switch is notified to prompt the OFF operation in S12. When the hot water filling switch is turned off in S13, the automatic hot water filling control ends.

(Explanation of display screen of mobile terminal)
In this hot water supply system S, by installing application software capable of Wi-Fi communication in the mobile terminal 40 such as a smart phone via the remote control 36, the mobile terminal 40 is capable of confirming control and performing predetermined remote operations. The operation of the portable terminal 40 and the display screen on the monitor 41 in the automatic hot water filling control will be described below.
FIG. 3A shows a home screen of the application software displayed on the monitor 41, and an icon 42 for automatic hot water filling is displayed at the bottom. When this icon 42 is touch-operated, the screen is switched to that shown in FIG. Since the "start" displayed here has the same function as the hot water filling switch, when the "start" is touched, S1 in FIG. 2 becomes YES, and the subsequent processing is executed. In S2, a display prompting opening of the faucet (hot water tap 31A in this case) is displayed as shown in FIG.

During filling, based on information from the controller 35 via the remote controller 36, the current situation (hot water amount) is displayed with a scale 43 and percentage values as shown in FIG. If "OK" is touched here, filling of hot water is completed in S5, and a display for confirming closing of the faucet is displayed as shown in (F) of the figure (S6). If the hot water tap 31A is closed and "yes" is touched, the hot water filling completion screen shown in FIG.
If water flow is not detected here, the screen returns to the home screen, but if water flow is detected, a screen prompting closing of the faucet is displayed in S9 as shown in FIG. When the hot water tap 31A is closed and "OK" is touched, the hot water filling completion screen shown in FIG.

On the other hand, when "OK" is not touched and a predetermined period of time has elapsed while water flow is detected (S11), the water side on-off valve 21 is closed (S12) and the display of (H) in the figure continues (S13). Therefore, the home screen does not return until the hot water supply valve 31A is closed and water supply is not detected.
When "stop" is touched on the screen shown in FIG. 4D during hot water filling, a screen for confirming that hot water filling is interrupted and the hot water tap 31A is closed is displayed as shown in FIG. If water flow is not detected here, the home screen is returned to, but if water flow is detected, a screen prompting closing of the faucet is displayed as shown in FIG.

(Description of antifreeze control)
The antifreeze control is first executed in S1 in a state where the hot water supply switch is not turned on. If the temperature detected by the outside air temperature sensor 17 drops to a predetermined temperature in the determination of S21, it is assumed that anti-freezing is necessary, and the circulation pump 27 is operated in S22. Next, when it is confirmed in S23 that the water in the heat transfer tubes has been replaced, the operation of the circulation pump 27 is stopped in S24, and the process returns to S1. Completion of this replacement is confirmed by the elapse of the calculated time, which is calculated in advance from the performance of the circulation pump 27 and the amount of water in the heat transfer tubes.
In this way, water at other locations in the circulation path is transferred into the heat transfer tubes, thus preventing freezing.

Further, this anti-freezing control is executed even in a standby state in which, in the automatic hot water filling control, the hot water filling is stopped in S5 and the hot water filling switch is turned off in S6. That is, if the temperature detected by the outside air temperature sensor 17 drops to a predetermined temperature in the determination of S25 while in the standby state, the water side on-off valve 21 is opened in S26, assuming that anti-freezing is required. The presence or absence of water flow is confirmed in S27, and if water flow is not confirmed here, the circulation pump 27 is operated in S28, and when it is confirmed in S29 that the water in the heat transfer tubes has been replaced, the operation of the circulation pump 27 is stopped in S30 and the process returns to S1.

On the other hand, if the determination in S27 is YES, that is, if water flow is confirmed, the circulation pump 27 is not operated, and the process proceeds to S9 to give notification and perform the processes from S10 to S13. As a result of these processes, the hot water supply valve 31A remains open for some time, so the water in the heat transfer tube is transferred to the circulation path, and the water in other places is transferred to the heat transfer tube, so that substantial replacement is performed. If the determination in S13 is NO, that is, if the hot water supply switch is not turned off, the process proceeds to S25.

(Effects of the invention related to anti-freezing control)
According to the hot water supply system S and the water heater 1 of the above-described embodiments, the controller 35 (control means) operates the circulation pump 27 until the water in the heat transfer tubes (predetermined locations) of the heat exchanger 5 is replaced when the outside air temperature sensor 17 (preventive condition detection means) detects that the temperature has decreased to a predetermined temperature (satisfaction of the necessary conditions for freezing prevention). Therefore, it is possible to save energy, reduce costs, and prevent freezing by reducing the discomfort caused by the operating noise of the circulation pump 27 .
Especially here, the operation of the circulation pump 27 accompanying the detection of the outside air temperature sensor 17 is set in advance, and is performed only for the time required to complete the replacement of water in the heat transfer tubes of the heat exchanger 5, so the water replacement can be reliably performed in the minimum required operation time.
Further, since the water heater 1 includes the return pipe 26 and the circulation pump 27 in the housing 2, the hot water supply system S can be easily constructed.

In the above embodiment, the outside air temperature sensor is provided on the fan, but the outside air temperature sensor may be provided at another location or may be provided at a plurality of locations. Of course, instead of the outside air temperature, if possible, the temperature can be detected by providing a sensor directly at the location where freezing prevention is required.
In addition, the circulation pump may be operated each time a necessary condition such as a temperature drop is satisfied, or may be performed periodically by detecting the water temperature at a predetermined location after water replacement and calculating the time required for the next replacement.
Furthermore, in the above embodiment, it is assumed that the entire system is installed indoors and cold air is sucked in from the exhaust hood, so the water is replaced with the heat transfer pipes of the heat exchanger.

(Effect of the invention related to freeze prevention control after completion of hot water filling)
According to the hot water supply system S of the above embodiment, the outside air temperature sensor 17 is further provided to detect the presence or absence of a necessary condition for freezing prevention in the heat transfer tubes of the heat exchanger 5 in the circulation path. When the outside air temperature sensor 17 detects a drop in the temperature to a predetermined temperature while the water supply to the circulation path is stopped by the water side on-off valve 21 (water stop means) in the hot water supply control, the controller 35 can execute the freeze prevention control to operate the circulation pump 27 until the water in the heat transfer tubes is replaced. , the water side on-off valve 21 is opened to confirm the water flow state of the circulation path by the water quantity sensor 23 (water flow detection means), and if the water flow is not confirmed, the circulation pump 27 is operated, and if the water flow is confirmed, the water side on-off valve 21 is closed without operating the circulation pump 27, and the antifreeze control is completed.
Thus, when the hot water tap 31A is closed, the water can be replaced by running the circulation pump 27, and when the hot water tap 31A is not closed, the water can be replaced by flowing water instead of the operation of the circulation pump 27, and freezing can be prevented in either case. Therefore, even when freezing prevention becomes necessary after hot water filling is completed in the hot water filling control, the freezing prevention control can be reliably performed.

An on-off valve provided on the hot water outlet pipe may be used as the water stop means.
Further, the predetermined time in S11 from the detection of water flow in S10 in the flowchart of FIG. 2 to the closing of the water side on-off valve again may be lengthened in accordance with the time at which water replacement is completed in the case of transition from the time when freeze prevention is determined to be necessary.

(Effect of the invention related to forgetting to close notification)
According to the hot water supply system S and the water heater 1 of the above embodiment, after the hot water supply control is executed, the controller 35 cancels the stoppage of water flow in the circulation path by the water side on-off valve 21 (water stop means) (S7), checks the water flow state of the circulation path by the water amount sensor 23 (water flow detection means) (S8), and if water flow is not confirmed, maintains the water stoppage cancellation state (END). Since the user is informed (S9), it is possible to reliably inform the user that the hot water supply valve 31A has been forgotten to close the valve, thereby allowing the user to perform the closing operation. Therefore, the usability is improved when hot water is automatically filled.
In particular, here, the controller 35 notifies that the hot water tap 31A has been left unclosed and also stops the water flow through the circulation path by means of the water side on-off valve 21, thereby preventing wasteful use of water due to the closed closed error.

The mobile terminal 40 further includes a remote controller 36 having a wireless communication function and a mobile terminal 40 having application software capable of wireless communication. When the controller 35 detects water flow through the water flow sensor 23 after the hot water supply control is executed, the controller 35 notifies the mobile terminal 40 of the forgetting to close the hot water tap 31A via the application software ((H) in FIG. 3). (G)), it is possible to reliably inform the user via the portable terminal 40 that the hot water supply tap 31A has been left unclosed so that the user can perform the closing operation.

Informing the mobile terminal that the hot water tap has been left unclosed may be performed by electronic sound, synthetic voice, or the like, in addition to the screen display.
In addition, the notification of forgetting to close the hot water supply valve may be made by push notification even when the application software is not running. By performing such a push notification, it is possible to reliably notify the user using the mobile terminal.
Furthermore, in the above embodiment, the remote controller has the function of wireless communication with the portable terminal, but the controller may have the wireless communication function regardless of the presence or absence of the remote controller. Even if there are multiple mobile terminals, the same application software can be used to automatically fill the hot water and notify that the door has been forgotten to be closed.

In addition, common to each invention, the configuration of the water heater is not limited to the above form, the number of burner units can be increased or decreased, and each invention can be applied to a latent heat recovery type equipped with a sub heat exchanger.
Further, in the above embodiment, the return pipe and the circulation pump are provided in the housing and connected to the external pipe, but as shown in FIG. In this case, the circulation pump 27 may be provided in the water pipe 33 or may be provided in the water supply pipe 18 on the upstream side of the water quantity sensor 23 .

1 Water heater 2 Housing 3 Combustion chamber 4 Burner unit 5 Heat exchanger 6 Exhaust hood 7 Gas connection port 8 Water supply connection port 9 Hot water supply connection port 10 Return connection port 11 Gas pipe 16 Fan 17 Outside air temperature sensor 18 Water supply pipe 19 Hot water outlet pipe 21 Water side opening/closing valve 22 Inlet water temperature sensor 23 Water amount sensor 24 Outlet temperature sensor 25 Hot water temperature sensor 26 Return pipe 27 Circulation pump 30 External pipe 31 (31A) Hot water tap 32 Bathtub 35 Controller 36 Remote control 40 Portable terminal 41 Monitor S Hot water supply system.

Claims (4)

a water heater having a burner, a heat exchanger, a water supply pipe connected to the heat exchanger, a hot water discharge pipe connected to the heat exchanger, and a control means for controlling the burner;
an external pipe connected between the hot water outlet pipe and the water supply pipe, forming a circulation path in which hot water discharged from the hot water outlet pipe returns to the water supply pipe and reaches the heat exchanger, and to which a plurality of hot water supply valves including a hot water supply valve for supplying hot water to a bathtub are connected;
a circulation pump provided in the circulation path and controlled by the control means;
water flow detection means for detecting water flow accompanying opening of each hot water tap;
and a water stop means for stopping water flow through the circulation path,
The control means is capable of controlling the water stop means, and is capable of executing hot water filling control to stop water flow through the circulation path by means of the water stop means when supply of a predetermined amount of hot water to the bathtub by opening the hot water supply tap is confirmed by the water flow detection means,
a prevention condition detecting means for detecting whether or not there is a necessary condition for freezing prevention at a predetermined location in the circulation route;
The hot water supply system is characterized in that, when the control means detects that the necessary conditions for freezing prevention are satisfied by the prevention condition detection means after supplying a predetermined amount of hot water to the bathtub , the control means cancels the stoppage of the water flow through the circulation path by the water stop means, and executes antifreeze control to operate the circulation pump until the water in the predetermined location is replaced. 2. The hot water supply system according to claim 1, wherein the operation of the circulation pump associated with the detection by the preventive condition detection means is set in advance and is performed for a period of time necessary to complete replacement of water at the predetermined location. A water heater having a burner, a heat exchanger, a water supply pipe connected to the heat exchanger, a hot water discharge pipe connected to the heat exchanger, and a control means for controlling the burner,
3. A water heater, wherein said control means is capable of executing said anti-freezing control when incorporated in the hot water supply system according to claim 1 or 2. 4. The water heater according to claim 3, wherein a return pipe having one end connected to the water supply pipe and the other end connectable to the external pipe is provided in the housing of the water heater, and the circulation pump is provided in the return pipe.

Images