JP7576838B2 - Water heater - Google Patents

Description

This disclosure relates to a water heater that heats water passing through a heat exchanger with the combustion exhaust from a burner to provide hot water.

When the controller detects water flowing through the water heater, the burner is ignited and the water passing through the heat exchanger is heated by the exhaust gas from the burner to dispense hot water. An external remote control is connected to the controller, and various operations such as turning the device on and off and setting the temperature of the hot water dispensed can be performed using the operation unit on the remote control (see, for example, Patent Document 1). In some cases, these various operations can also be performed using the operation unit on the controller.
Meanwhile, there is a water heater equipped with an instant hot water function, which is provided by connecting a return pipe equipped with a circulation pump to a water supply pipe connected to a heat exchanger (see, for example, Patent Document 2). In this water heater with instant hot water function, an external pipe is connected between the hot water outlet pipe and the return pipe, forming a circulation path between the hot water outlet pipe, the external pipe, the return pipe, and the water supply pipe, and a hot water system capable of keeping the temperature by circulating hot water through this circulation path with a circulation pump and heating it with a heat exchanger is constructed. Therefore, when the hot water tap on the external pipe is opened, hot water can be supplied immediately.

JP 2020-204440 A JP 2004-286397 A

In such a water heater, if a power outage occurs while hot water is being dispensed (while the burner is burning), and water continues to flow when the power is restored, the burner combustion control will continue. In this case, if the user is not aware that the power outage has been restored, hot water will suddenly come out while they are using it, surprising them.
On the other hand, in a water heater in which the operation switch can be turned on and off using an operation unit such as a remote control, if a power outage occurs while the operation switch is in the ON state, the setting may be such that the operation switch will be turned OFF when the power is restored. In this case, when a user recognizes that the power has returned from the power outage, in addition to temporarily stopping the flow of water by closing the hot water tap, they must also turn the operation switch ON again, which is troublesome.

Therefore, the purpose of this disclosure is to provide a water heater that does not suddenly start dispensing hot water without the user's knowledge when power is restored after a power outage.

In order to achieve the above object, the present disclosure provides a water heater having a burner, a heat exchanger, a water supply pipe connected to the heat exchanger, a hot water outlet pipe connected to the heat exchanger, a water flow detection means for detecting the flow of water in the appliance, a control means for controlling the burner, and an operation means for switching the operating state of the appliance between ON and OFF ,
The control means is characterized in that, when power is turned on, it prohibits the burner from burning until the water flow detection means confirms that the water is stopped inside the appliance, and when it confirms that the operating state has been switched to ON by the operating means before the water flow detection means confirms that the water is stopped inside the appliance, it lifts the prohibition on the burner from burning .
Another aspect of the present disclosure is characterized in that, in the above configuration, the device further includes a notification means for notifying that combustion by the burner is prohibited.

According to the present disclosure, when the power is turned on, the control means prohibits the burner from burning until the water flow detection means confirms that the water in the appliance is stopped, so even if a power outage occurs while hot water is being dispensed and the water flow continues when the power is restored, hot water will not suddenly come out while the water is being used. Therefore, the user can recognize that the power has been restored and can stop the water flow before resuming use of hot water.
In particular , when the control means confirms that the operation state has been switched to ON by the operation means before the water flow detection means has confirmed the water stop state in the appliance, the control means cancels the prohibition on burner combustion, so that the prohibition on burner combustion can be cancelled by simply turning the operation switch ON without having to temporarily stop the water flow, thus reducing the user's effort and improving usability.
According to another aspect of the present disclosure, in addition to the above effects, an alarm means notifies the user that burner combustion is prohibited, so that the user can quickly recognize that combustion is prohibited when power is restored and can stop the water flow.

FIG. 1 is a schematic diagram of a hot water supply system. 13 is a flowchart of hot water discharge control after power is turned on. 13 is a flowchart of a modified example of hot water discharge control after power is turned on.

Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings.
Fig. 1 is a schematic diagram showing an example of a water heater. This water heater 1 has an instantaneous hot water supply function provided with a return pipe 26 having a circulation pump 27, and by connecting an external piping 30 for circulation, a hot water supply system S capable of instantaneous hot water supply is constructed.
First, in water heater 1, a combustion chamber 3 is installed in a housing 2. In combustion chamber 3, from below, three burner units 4, 4..., a heat exchanger 5, and an exhaust hood 6 are provided. On the bottom surface of housing 2, 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, a hot water supply connection port 9 to which an external hot water supply pipe is connected, and a return connection port 10 are provided.
The burner units 4, 4... are composed of a plurality of burners, the number of which differs from one another. A gas pipe 11 equipped with a main solenoid valve 12 and a proportional control valve 13 is connected to the gas connection port 7. The gas pipe 11 branches into three branch pipes 14, 14..., and the burner units 4 are connected to each branch pipe 14 via an on-off valve 15. A fan 16 is provided at the bottom of the combustion chamber 3 to supply combustion air to the burner units 4.

The heat exchanger 5 is of a fin-tube type having a heat transfer tube that penetrates a plurality of fins arranged in parallel at a predetermined interval in the thickness direction in a serpentine manner. A water supply pipe 18 that is connected to the water supply connection port 8 is connected to the inlet end of the heat transfer tube. A hot water outlet pipe 19 that is connected to the hot water supply connection port 9 is connected to the outlet end of the heat transfer tube. A bypass pipe 20 that bypasses the heat exchanger 5 is connected between the water supply pipe 18 and the hot water outlet pipe 19.
Further, upstream of the connection of the bypass pipe 20 to the water supply pipe 18, there are provided a water-side opening/closing valve 21, an inlet water temperature sensor 22 such as a thermistor for detecting the inlet water temperature, and a water volume sensor 23 for detecting the water volume. Furthermore, upstream of the connection of the bypass pipe 20 to the hot water outlet pipe 19, there is provided an outlet temperature sensor 24 such as a thermistor for detecting the outlet temperature from the heat exchanger 5, and downstream of the connection, there is provided an outlet hot water temperature sensor 25 such as a thermistor for detecting the outlet hot water temperature.

A return pipe 26 equipped with a circulation pump 27 and a check valve 28 located on the discharge side is connected between the return connection port 10 and the water supply pipe 18 upstream of the water volume sensor 23.
The external piping 30 is connected between the hot water supply connection port 9 and the return connection port 10 and is provided with a plurality of hot water taps 31, 31.... One of the hot water taps 31 is for supplying hot water to a bathtub 32 (hereinafter, when distinguishing it from the other hot water taps 31, it will be referred to as "hot water tap 31A").
This creates a circulation path in which hot water discharged from the hot water outlet pipe 19 returns to the return pipe 26 through the external piping 30, reaches the heat exchanger 5 via the water supply pipe 18, and is discharged again from the hot water outlet pipe 19.
Reference numeral 35 denotes a controller that controls the operation of the water heater 1 and the water heating system S. A remote control 36 is connected to the controller 35. The remote control 36 is provided with an operation unit, such as an operation switch, a water filling switch, and a button for changing the set temperature, and a display unit for displaying the operation status. The operation unit and display unit may also be provided in the controller 35.

In the hot water supply system S configured as described above, when the operation switch provided on the controller 35 or remote control 36 is turned on, the controller 35 operates the circulation pump 27 to open the water side opening/closing valve 21, and circulates hot water in the circulation path. At the same time, the main solenoid valve 12 and the opening/closing 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. The controller 35 then performs a heat retention operation by controlling the opening degree of the proportional control valve 13 and the rotation speed of the fan 16 so that the temperature detected by the outlet hot water temperature sensor 25 becomes the set temperature set by the controller 35 or remote control 36. Therefore, when any of the hot water taps 31 is opened, hot water can be instantly supplied at the set temperature.
On the other hand, when the hot water tap 31A is opened by pressing the hot water filling switch provided on the controller 35 or the remote control 36, the controller 35 detects the flow of water through the appliance using the water volume sensor 23, and then combusts the burner unit 4, enabling automatic hot water filling control to supply hot water at the set temperature to the bathtub 32 until the water volume detected by the water volume sensor 23 reaches the set hot water volume.

If a power outage occurs while the hot water supply system S is in operation, the heat retention operation of the hot water supply system S stops and the combustion in the burner unit 4 stops.
However, if the controller 35 is set to return to the ON operating state (keep warm operation ON) when the power is restored after a power outage, or if the hot water tap 31 is open, the controller 35 will detect water flowing through the circulation path and startle the burner unit 4, causing hot water to suddenly come out while the user is using water, surprising the user.
Therefore, when power is restored from a power outage, the controller 35 prohibits combustion in the burner unit 4 until the water level sensor 23 confirms that the water supply to the circulation path is stopped.
The hot water discharge control after power is turned on will be described below with reference to the flow chart of FIG.

First, when the power is restored from a power outage in S1 and the power is turned on, the controller 35 prohibits, in S2, combustion in the burner unit 4. This prohibition of combustion is performed by turning off the operation switch, or by prohibiting combustion in the burner unit 4 by internal control regardless of whether the operation switch is on.
At the same time, the fact that combustion is prohibited is notified via the remote control 36. This notification is made by displaying the fact that combustion is prohibited on the display section of the remote control 36 with characters or figures, or by emitting a buzzer or a synthesized voice.
Next, in S3, it is determined whether water is stopped in the circulation path. If the result is NO, that is, if the water flow sensor 23 detects water flow caused by the opening of the hot water tap 31, combustion in the burner unit 4 is not permitted, and the prohibition of combustion continues.
On the other hand, if water flow through the circulation path is not confirmed in S3 due to the water being stopped when the power is turned on or the user closing the hot water tap 31 in response to a notification from the remote control 36, the controller 35 permits combustion of the burner unit 4 in S4. Therefore, when the hot water tap 31 is opened again in S5 and water flow is confirmed by the water volume sensor 23, the controller 35 executes hot water output control by combusting the burner unit 4 in S6.

In this way, in the water heater 1 and water heating system S of the above-mentioned form, when the power is turned on, the controller 35 (control means) prohibits combustion of the burner unit 4 (burner) until the water flow sensor 23 (water flow detection means) confirms that the water is stopped within the appliance.
With this configuration, even if a power outage occurs while hot water is being dispensed and the water continues to flow when the power is restored, hot water will not suddenly come out while the user is using the water. Therefore, the user can recognize that the power outage has been restored and can temporarily stop the water flow before resuming use of the hot water.
In particular, since the remote control 36 (notification means) notifies the user that combustion in the burner unit 4 is prohibited, the user can quickly recognize that combustion is prohibited when the power is restored and can stop the water supply.

In the above embodiment, the controller 35 is set to return to the ON operating state when the unit is restored from a power outage, but if the controller 35 is set to return to the OFF operating state (keep warm operation OFF) when the unit is restored from a power outage, the user must once again turn the operation switch ON using the remote control 36, which is troublesome. Therefore, a modified example that can reduce this hassle will be described with reference to the flowchart in FIG.
When power is restored from a power outage and the power is turned on in S11, the controller 35 prohibits combustion in the burner unit 4 in S12 and notifies the user via the remote control 36 that combustion is currently prohibited.
Next, in S13, it is determined whether water is stopped in the circulation path. If the answer is YES, i.e., if water is not passing through the circulation path, then in S14, combustion of the burner unit 4 is permitted. Therefore, when the hot water tap 31 is opened in S15 and water flow is confirmed by the water volume sensor 23, the controller 35 performs hot water discharge control by combusting the burner unit 4 in S16. Up to this point, it is the same as in FIG. 2.

However, if the determination in S13 detects that water is flowing through the circulation path due to the opening of the hot water tap 31, the controller 35 determines in S17 whether the operation switch has been turned ON. If the ON operation is not confirmed here, combustion in the burner unit 4 is not permitted, and the prohibition of combustion continues.
On the other hand, when it is confirmed in S17 that the operation switch is turned ON, the controller 35 permits combustion in the burner unit 4 in S14. Therefore, the burner unit 4 starts combustion together with the operation of the circulation pump 27, and the heat retention operation is resumed, making it possible to supply hot water immediately.
The reason why confirmation that the operation switch has been turned ON is set as a condition for allowing combustion is that when the user turns the operation switch ON, it can be assumed that the user is aware that the power has been restored, and the user will not be surprised when hot water is dispensed.

Even in this modified example, if a power outage occurs while hot water is being dispensed and water continues to flow when the power is restored, the user will not be surprised by hot water suddenly coming out while they are using it.
However, if the controller 35 confirms that the operation state has been switched to ON by the controller 35 or the remote control 36 (operation means) before the water level sensor 23 confirms that the water inside the appliance is stopped, the controller 35 releases the inhibition of combustion in the burner unit 4 even if water is flowing, so that the inhibition of combustion in the burner unit 4 can be released by simply turning the operation switch ON without having to stop the water flow once. This reduces the user's effort and improves usability.

In the above embodiment, the return pipe and the circulation pump are provided inside the housing and connected to the external piping, but the return pipe may be eliminated and the external piping may be connected to the water pipe connected to the water supply pipe to form a circulation path, and the circulation pump and the check valve may be provided in the external piping. In this case, the circulation pump may be provided in the water pipe, or may be provided in the water supply pipe upstream of the water volume sensor.
However, the present invention can also be applied to water heaters that do not have external piping and do not have an instant hot water supply function (no circulation pump). The ON operating state of this water heater refers to a state in which the control means is capable of controlling the hot water supply by igniting the burner when it detects the flow of water in the appliance, and is capable of accepting and executing various operations such as filling the water tank with hot water, reheating the water, and changing the set temperature using an operation unit such as a remote control.
In addition, the configuration of the water heater is not limited to the above-mentioned form, and the number of burner units can be increased or decreased, and the present invention is also applicable to a latent heat recovery type water heater equipped with a secondary heat exchanger.

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

Claims (2)

A water heater having a burner, a heat exchanger, a water supply pipe connected to the heat exchanger, a hot water outlet pipe connected to the heat exchanger, a water flow detection means for detecting the flow of water in the appliance, a control means for controlling the burner , and an operation means for switching the operating state of the appliance between ON and OFF ,
This water heater is characterized in that, when the power is turned on, the control means prohibits the burner from burning until the water flow detection means confirms that the water is stopped inside the appliance, and when it confirms that the operating state has been switched to ON by the operating means before the water flow detection means confirms that the water is stopped inside the appliance, it lifts the prohibition on the burner from burning . 2. The water heater according to claim 1 , further comprising a notification means for notifying that combustion of the burner is prohibited.

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