JP6667365B2 - Water heater - Google Patents

Description

  The present invention includes a heat exchanger to which a water inlet pipe and a hot water pipe are connected, and a burner for heating water flowing through the heat exchanger, and a bypass for bypassing the heat exchanger between the water inlet pipe and the hot water pipe. The present invention relates to a water heater provided with a pipe.

As disclosed in Patent Literature 1, the water heater includes a heat exchanger whose internal water is heated by a burner, a water supply pipe connected to an upstream side of the heat exchanger, and a tap water connected to a downstream side. 2. Description of the Related Art There is known a pipe having a pipe and a bypass pipe connected between a water supply pipe and a tapping pipe to bypass a heat exchanger.
In such a water heater, an outlet temperature thermistor for detecting an outlet temperature from the heat exchanger is provided near a connection portion of the tapping pipe with the heat exchanger, and a controller monitors the outlet temperature, and When the temperature becomes higher than the predetermined temperature, the controller decreases the opening of the bypass valve that adjusts the amount of water flowing to the bypass pipe, thereby relatively increasing the amount of water flowing to the heat exchanger, and thereby performing heat exchange. To prevent the vessel from overheating.

  On the other hand, some large-sized water heaters have a high-temperature hot-water tapping function of tapping at a high temperature (for example, 85 ° C). In such a water heater, when the high-temperature hot water supply function is selected by the user, the controller closes the bypass valve, closes the bypass pipe, and controls so that all of the small amount of water is heated by the heat exchanger.

JP 2014-25664 A

  By the way, in the above-mentioned water heater, when the outlet temperature thermistor fails, hot water having a temperature higher than the detected temperature flows into the tapping pipe, giving a heat load to a sealing member such as an O-ring provided at a pipe connection portion, thereby accelerating the deterioration. There is a risk. Further, in a water heater with a high-temperature hot water supply function, hot water is supplied at a higher temperature than intended by the user due to a failure of the outlet temperature thermistor.

On the other hand, depending on the type of water heater, a bimetal operating at a predetermined temperature may be provided downstream of the water passage of the heat exchanger in consideration of a case in which there is no water in the pipe of the heat exchanger. There is a type provided with a boiling prevention device including a heat-sensitive switch such as a switch, and an electric circuit for mechanically stopping the combustion of the burner by cutting off a part of the circuit when the heat-sensitive switch is operated.
Therefore, it is conceivable to use this boiling prevention device to stop high-temperature hot water when the outlet temperature thermistor breaks down by operating the boiling prevention device.

However, since the heat-sensitive switch is fixed to the pipe, which is the water passage of the heat exchanger, via a metal mounting member, it is easily affected by heat from the heat exchanger and the burner. A deviation may occur between the temperature and the temperature at the mounting portion of the thermal switch. For this reason, in order to prevent the water heater from stopping unexpectedly due to a malfunction, it is necessary to set a temperature higher than the boiling temperature with a sufficient margin as the operating temperature of the thermal switch.
Then, if an attempt is made to cope with the failure of the outlet temperature thermistor with the boiling prevention device, it takes time from when the hot water of an unusually high temperature is discharged to when the heat-sensitive switch is activated and the combustion of the burner is stopped. Therefore, the high-temperature hot water is discharged for a relatively long time without reducing the heat load applied to the hot water. On the other hand, if the operating temperature of the thermal switch is set to be low, when the hot water tapping function is selected, combustion is stopped by the operation of the thermal switch even though the tapping is performed at a normal temperature within the function, It will impair usability.

  Accordingly, the present invention addresses the failure of the outlet temperature thermistor with a boiling prevention device using a heat-sensitive switch such as a bimetal switch, and in that case, an early operation is performed only when abnormally high-temperature hot water is discharged from the heat exchanger. It is an object of the present invention to provide a water heater in which combustion of a burner is stopped to reduce a heat load on a seal member and the like and maintain usability.

In order to achieve the above object, the invention according to claim 1 has a heat exchanger having a water passage section and heated by a burner, and a water inlet pipe connected to an upstream end of the water passage section, A hot water pipe connected to the downstream end of the water passage section, a bypass pipe connected between the water inlet pipe and the hot water pipe to bypass the heat exchanger, and a bypass amount adjusting means for adjusting the amount of water to the bypass pipe An outlet temperature thermistor provided upstream of the connection of the bypass pipe in the tapping pipe to detect an outlet temperature from the water passage portion, and monitoring the detected temperature of the outlet temperature thermistor to determine an abnormality of the outlet temperature thermistor. In addition, a controller that controls the bypass amount adjusting means, a thermal stop switch provided in the water passage section and operated at a predetermined temperature, and a combustion stopping means for stopping combustion of the burner when the thermal switch is operated, A hot water heater When the controller determines that the outlet temperature thermistor is abnormal, the amount of water to the bypass pipe is increased by the bypass amount adjusting means, the amount of water to the heat exchanger is reduced, and the temperature of the water passing section is increased until the heat-sensitive switch is activated. It is characterized by making it.
According to a second aspect of the present invention, in the configuration of the first aspect, a tapping thermistor for detecting a tapping temperature after mixing with water from the bypass pipe is provided downstream of a connection portion of the tapping pipe in the tapping pipe. The controller also monitors the detected temperature of the tapping thermistor, and the controller determines that both the detected temperature of the outlet temperature thermistor and the detected temperature of the tapping thermistor do not reach the predetermined determination temperature or more before the predetermined time of the burner ignition confirmation. In this case, it is determined that the outlet temperature thermistor and the hot water thermistor are abnormal.

According to the first aspect of the present invention, when the controller determines that the outlet temperature thermistor is abnormal, the controller increases the amount of water to the bypass pipe by the bypass amount adjusting means, decreases the amount of water to the heat exchanger, and sets the Temperature is raised until the heat-sensitive switch is activated, so that abnormally high-temperature hot water is discharged from the heat exchanger even if the failure of the outlet temperature thermistor is dealt with by the combustion stop means using the heat-sensitive switch. Only when this occurs, the burner combustion can be stopped early. Therefore, it is possible to reduce the heat load applied to the sealing member by shortening the time of tapping at an abnormally high temperature, and in the case where there is a hot tapping function, the burner combustion does not stop unexpectedly, and the usability can be maintained. it can. Furthermore, since an existing thermistor and combustion stopping means can be used, cost increase can be suppressed.
According to the second aspect of the invention, in addition to the effect of the first aspect, the abnormality determination can be strictly performed using the tapping thermistor. Therefore, there is no possibility that the abnormality determination is performed at an early timing and the usability is impaired.

It is the schematic of a water heater. 9 is a flowchart of thermistor abnormality determination control.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram showing an example of a water heater. In the water heater 1, a combustion chamber 2 provided with an air supply fan 3 is formed in an appliance body, and fuel gas and a supply gas are supplied inside the combustion chamber 2. A plurality of (here, three units) burners 4, 4,... For burning the mixed gas with the primary air from the air fan 3 are provided, and the burners 4, 4,. The water exchanger is provided with a water supply pipe 6 connected to an upstream end of the water pipe and a tapping pipe 7 connected to a downstream end of the water pipe. This heat exchanger 5 is connected to a tapping pipe 7 to recover sensible heat from the combustion exhaust gas of the burners 4, 4,..., And is connected to a water supply pipe 6 to recover latent heat from the combustion exhaust gas. And a secondary heat exchanger 5B. The drain generated in the secondary heat exchanger 5B is neutralized in the neutralizer 8 and discharged outside the device.

  The gas pipe 9 for supplying the fuel gas to each burner 4 is provided with an original solenoid valve 10 and a gas proportional valve 11, and the branch pipes 9a, 9a,. , Switching electromagnetic valves 12 are provided, and each of the valves can be controlled by the controller 13. Reference numeral 14 denotes an ignition electrode connected to an igniter (not shown), and reference numeral 15 denotes a flame rod for detecting a flame.

Further, a bypass pipe 16 that bypasses the heat exchanger 5 is connected between the water supply pipe 6 and the tapping pipe 7, and a water supply pipe is provided upstream of a connection position of the water supply pipe 6 with the bypass pipe 16. A water amount sensor 17 for detecting the amount of water flowing through the water supply 6, a water amount servo 18 for controlling the amount of water in the water supply pipe 6, and an incoming water thermistor 19 for detecting the incoming water temperature are provided. The bypass pipe 16 is provided with a bypass servo 20 as bypass amount adjusting means for controlling the amount of water to the bypass pipe 16, and is electrically connected to the controller 13.
On the other hand, the outlet pipe 7 has an outlet temperature thermistor 21 for detecting an outlet temperature from the heat exchanger 5 near the connection with the heat exchanger 5, and water at a downstream side of the connection point with the bypass pipe 16. A tapping thermistor 22 for detecting the temperature after mixing is provided. Reference numeral 23 denotes an outside air temperature thermistor for detecting an outside air temperature, which is electrically connected to the controller 13.

  Reference numeral 24 denotes a boiling prevention device as a combustion stopping means, which is fixed to a water pipe of the heat exchanger 5 via a mounting member outside the can body of the heat exchanger 5 and serves as a heat-sensitive switch which operates at a predetermined temperature. It is formed by a bimetal switch 25 and a circuit board 26 on which an electric circuit for mechanically stopping the combustion of the burner 4 by cutting off a part of the circuit when the bimetal switch 25 is activated is formed. Accordingly, when the water pipe is heated to a high temperature (for example, 90 ° C.), the bimetal switch 25 is activated and the electric circuit on the circuit board 26 activates the burner 4 when the water pipe becomes hot (eg, 90 ° C.). Combustion is forcibly stopped. Reference numeral 27 denotes a remote controller connected to the controller 13 for setting a hot water temperature and the like.

The abnormality determination control of the thermistor by the controller 13 in the water heater 1 configured as described above will be described with reference to the flowchart of FIG.
First, when a hot water tap (not shown) provided at the downstream end of the tapping pipe 7 is opened to allow water to flow through the appliance, in S1, a signal obtained from the water amount sensor 17 determines whether the amount of water flowing through the appliance exceeds the amount of ignition water. Check if. Here, when it is confirmed that the ignition water amount has been exceeded, in S2, the controller 13 rotates the air supply fan 3 to perform pre-purge, and also switches the original electromagnetic valve 10, the switching electromagnetic valve 12, and the gas proportional valve 11 to each other. Each is opened to supply gas to the burner 4 and to operate the igniter to control the ignition of the burner 4.

Next, in S3, the flame of the burner 4 is detected by the frame rod 15. If the flame cannot be detected here, the controller 13 closes each valve in S4 and stops the operation. On the other hand, if a flame is detected in S3, the controller 13 starts a 30-second timer in S5.
Next, in S6, it is determined whether the outlet temperature detected from the outlet temperature thermistor 21 is lower than the determination temperature of 35 ° C, and whether the tapping temperature detected from the tapping thermistor 22 is lower than the determination temperature of 35 ° C. Is determined. Here, if NO, that is, if the detected temperature of at least one of the outlet temperature thermistor 21 and the tap water thermistor 22 is equal to or higher than 35 ° C., the normal operation is performed in S7. This is because the opening of the gas proportional valve 11 is controlled in accordance with the difference between the tapping temperature detected by the tapping thermistor 22 and the set temperature set by the remote controller 27 to continuously change the gas amount, The controller 13 controls the tap water temperature to make the temperature equal to the set temperature. The controller 13 changes the number of revolutions of the air supply fan 3 in accordance with the change in the gas amount under the control of the gas proportional valve 11, thereby controlling the gas amount and the air amount. And control the ratio.

On the other hand, if it is determined in S6 that the detected temperatures of both thermistors 21 and 22 are lower than 35 ° C., it is checked in S8 whether 30 seconds have elapsed since the timer was started after the flame detection. If 30 seconds have not elapsed, the process returns to S6 to confirm the detected temperatures of both thermistors 21 and 22. If either or both detected temperatures are 35 ° C. or higher, normal operation is performed in S7.
Then, if S8 is YES, that is, if 30 seconds have elapsed while both of the detected temperatures of both thermistors 21 and 22 are less than 35 ° C., the controller 13 determines that an abnormality has occurred in both thermistors 21 and 22. In S9, the bypass servo 20 is controlled to increase the bypass ratio (for example, 45%). As a result, the amount of water to the heat exchanger 5 decreases and the temperature of the water pipe increases, so that the bimetal switch 25 reaches the operating temperature and operates, the boiling prevention device 24 operates and the combustion of the burner 4 is forcibly performed. Will be stopped. Although not shown, the condition for canceling the abnormality determination control is not limited to the confirmation of the temperature exceeding the determination temperature between the outlet temperature and the tapping temperature, but also the use of the user by turning off the power by operating the remote controller 27 or closing the hot water tap. Suspension is included.

  As described above, according to the water heater 1 of the above-described embodiment, when the controller 13 determines that the outlet temperature thermistor 21 is abnormal, the controller 13 increases the amount of water to the bypass pipe 16 by the bypass servo 20 and reduces the amount of water to the heat exchanger 5. By reducing the temperature of the water pipe and increasing the temperature of the water pipe until the bimetal switch 25 operates, even if the failure of the outlet temperature thermistor 21 is dealt with by the boiling prevention device 24 using the bimetal switch 25, the heat exchanger The combustion of the burner 4 can be stopped at an early stage only when abnormally high-temperature water is discharged from 5. Therefore, it is possible to reduce the heat load applied to the sealing member by shortening the time of tapping at an abnormally high temperature, and to maintain the usability without abruptly stopping the combustion of the burner 4 when the hot tapping function is provided. Can be. Furthermore, since the existing thermistors 21 and 22 and the boiling prevention device 24 can be used, cost increase can be suppressed.

  In particular, here, the controller 13 sets that the detected temperature of the outlet temperature thermistor 21 and the detected temperature of the tapping thermistor 22 both reach a predetermined judgment temperature (here, 35 ° C.) or more before a predetermined time period for confirming ignition of the burner 4 has elapsed. If not, it is determined that the outlet temperature thermistor 21 and the tapping thermistor 22 are abnormal. Therefore, the tapping thermistor 22 can be used to make a strict error determination. Therefore, there is no possibility that the abnormality determination is performed at an early timing and the usability is impaired.

The temperature for determining the thermistor abnormality is not limited to 35 ° C., and may be changed as appropriate. However, if the temperature is too low, the abnormality cannot be detected.
However, the abnormality determination of the thermistor is not limited to the determination in S6. For example, it is determined whether or not the detected temperature of the tapping thermistor is higher than the detected temperature of the outlet temperature thermistor by a predetermined temperature (for example, 10 ° C.) or more. The determination may be made under different conditions, such as when it is determined that the thermistor is abnormal.
On the other hand, the timer related to the abnormality determination can also be increased or decreased in other than 30 seconds.
Further, the bypass ratio when the abnormality of the thermistor is determined is not limited to 45% but may be higher.

Further, in the above-described embodiment, the abnormality determination of the thermistor is performed within a predetermined time after the confirmation of the burner ignition. May continuously determine the abnormality.
In the above embodiment, the abnormality is determined by monitoring the detected temperatures of both the outlet temperature thermistor and the tap water thermistor. However, the abnormality can be determined by monitoring only the detected temperature of the outlet temperature thermistor. .

In addition, in the above-described embodiment, a description is given of a water heater having a secondary heat exchanger for recovering latent heat. However, there is no secondary heat exchanger, and only a primary heat exchanger (main heat exchanger) for recovering sensible heat is used. The present invention is applicable even to a water heater having a water heater.
Further, the application of the present invention is not hindered even in the case of a water heater with a bath in which a tapping pipe is branched and connected to a bathtub to form a circulation circuit of hot water between the bath heat exchanger and the bathtub.

  1, hot water heater, 2, combustion chamber, 3, air supply fan, 4, burner, 5, heat exchanger, 6, water supply pipe, 7, hot water pipe, 9, gas pipe, 10 ··· Original solenoid valve, 11 ·· Gas proportional valve, 12 ··· Switching solenoid valve, 13 ··· Controller, 14 ··· Ignition electrode, 15 ··· Frame rod, 16 ··· Bypass pipe, 20 ··· Bypass servo, 21 ··· Outlet temperature thermistor, 22 ·· Hot water thermistor, 24 ··· Boiling prevention device, 25 ·· Bimetal switch.

Claims (2)

A heat exchanger having a water passage section and heated by a burner,
An inlet pipe connected to the upstream end of the water passage section,
A tapping pipe connected to the downstream end of the water passage section,
A bypass pipe connected between the inlet pipe and the tapping pipe to bypass the heat exchanger;
Bypass amount adjusting means for adjusting the amount of water to the bypass pipe,
An outlet temperature thermistor that is provided upstream of the connection part of the bypass pipe in the tapping pipe and detects an outlet temperature from the water passage part;
A controller that monitors the detected temperature of the outlet temperature thermistor to determine the abnormality of the outlet temperature thermistor, and controls the bypass amount adjusting unit,
A water heater comprising: a heat-sensitive switch provided at the water passage section and operating at a predetermined temperature; and combustion stopping means for stopping combustion of the burner when the heat-sensitive switch is operated.
When the controller determines that the outlet temperature thermistor is abnormal, the controller adjusts the amount of water to the bypass pipe by the bypass amount adjusting means, decreases the amount of water to the heat exchanger, and adjusts the temperature of the water passage section to the heat-sensitive value. A water heater characterized by being raised until a switch is activated. Downstream from the connection of the bypass pipe in the tapping pipe, a tapping thermistor for detecting tapping temperature after mixing with water from the bypass pipe is provided, and the controller also monitors the detected temperature of the tapping thermistor. ,
The controller is configured such that, if a detected temperature of the outlet temperature thermistor and a detected temperature of the tapping thermistor both do not reach a predetermined determination temperature or more before a predetermined time of confirming ignition of the burner, the outlet temperature thermistor and The water heater according to claim 1, wherein the hot water thermistor is determined to be abnormal.

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