JP3538945B2 - Water heater with fin clogging detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water heater provided with a fin clogging detecting device for detecting a fin clogging of a heat exchanger.

[0002]

2. Description of the Related Art In a water heater that transfers heat of combustion of a burner to feed water by a fin tube type heat exchanger to convert the heat to high-temperature hot water, when the temperature of the fin is low, the combustion gas contains corrosive components such as sulfur in the combustion gas. Moisture adheres to the heat exchanger and oxidizes and corrodes the fins, depositing oxides on the fin walls. In addition, during combustion when the temperature of the fins of the water heater becomes high, a reaction between the combustion gas and the fins generates high-temperature oxides on the fin walls. And, by long-term use of water heater,
The deposition of these metal oxides on the fins becomes remarkable, and a fin blockage condition occurs in which the flow of combustion gas between the fins is obstructed. As a result, there is a risk that the passage of the exhaust gas is hindered, resulting in an oxygen-deficient combustion state, and furthermore, the nonflammable gas is after-fired and the flame leaks out of the hood.

[0003] Conventionally, as a heat exchanger abnormality detecting device for a water heater of this type, for example, as disclosed in Japanese Patent Application Laid-Open No. 63-123951, a water flow sensor mounted on a hot water supply pipe provided with a heat exchanger is known. Output, and the heat transfer amount of the heat exchanger is calculated based on the output of the inlet-side temperature sensor provided on the inlet-side hot water supply pipe of the heat exchanger and the outlet-side temperature sensor provided on the outlet-side hot water supply pipe, The heating amount set by the ability switching knob or the like was compared. Then, when the heat transfer amount becomes abnormally lower than the heating amount, that is, when the heat transfer efficiency of the heat exchanger becomes low, the fin blockage of the heat exchanger is determined.

[0004]

However, the heat exchanger abnormality detecting device requires a water amount sensor, an inlet temperature sensor, and an outlet temperature sensor for judging the fin blockage, and has a complicated structure and a high detection cost. There is a problem that it becomes expensive. An object of the present invention is to solve the above-mentioned problem, and an object of the present invention is to provide a heat exchanger abnormality detection device for a water heater that can detect a fin blockage abnormality of a heat exchanger at a low cost with a simple configuration.

[0005]

In order to achieve the above object, the structural features of the invention according to the first aspect include a fin tube type heat exchanger provided with a water supply pipe and a hot water supply pipe, and this heat exchanger. A water heater provided with a gas burner for heating the heat exchanger, and the outer wall temperature of the heat exchanger attached to the wall of the heat exchanger.
Temperature sensor for detecting the temperature, reference temperature setting means for setting a predetermined reference temperature, and comparing the detected value of the temperature sensor with the reference temperature set value, and warning when the detected value becomes larger than the reference temperature set value. A comparison means for outputting a signal and a warning display means for receiving and displaying a warning signal are provided.

According to a second aspect of the present invention, there is provided a fin clogging detecting device according to the first aspect.
In the water heater equipped with the two-stage warning signal by the comparison means
Output to the floor and receive the second stage warning signal to burner
Combustion stop control means for stopping the combustion operation
And there .

[0007]

According to the first aspect of the present invention, the temperature sensor provided on the wall surface of the heat exchanger is provided.
Of the heat exchanger whose temperature has risen due to fin blockage
The outer wall temperature can be directly detected. And this inspection
The output value is compared with a predetermined reference temperature set value, and when the detected value is larger than the reference temperature set value, a warning is displayed on the warning display means as a heat exchanger abnormality, so that the abnormality is surely detected. You can know. Further, this heat exchanger abnormality detecting device uses only one temperature sensor, and has a very simple configuration as compared with the related art. Therefore, the heat exchanger abnormality can be detected at low cost.

Further, according to the second aspect of the present invention, a heat exchanger is provided by a first-stage warning signal.
Warning of abnormal fin clogging and further fin clogging
The second stage warning signal is output in the state where
The combustion operation by the burner was stopped . The result
As a result, in addition to the effects of the invention according to claim 1, the heat exchanger
Oxygen deficiency due to fin blockage, leakage of flame out of container, etc.
Can be prevented beforehand .

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a water heater according to a reference example . Water heater 10 has a cylindrical combustion chamber 11. The combustion chamber 11 has an upper end opened and a lower end closed, and a part of the lower end is connected to a blower 17 described later. A heat exchanger 12 having a large number of metal fins 12a around it is provided in an upper part in the combustion chamber 11.
A water supply pipe P1 is connected to the inlet side of the heat exchanger 12, and a water supply pipe P2 is connected to the outlet side. Water pipe P
As shown in FIG. 1, the water supply pipe 1 and the hot water supply pipe P2 are guided downward through the combustion chamber 11, and the water supply pipe P1 is connected to a water supply source (not shown) such as tap water. Hot water tap 21 is connected. A water flow switch 22 for detecting the presence or absence of water flow is provided in the water supply pipe P1.

Below the heat exchanger 12 in the combustion chamber 11,
A burner 13 having a gas nozzle 13a is provided. The gas nozzle 13a is provided with a proportional control valve 1 for adjusting a gas amount.
4a and a gas supply pipe PG provided with an electromagnetic valve 14b for opening and closing the gas flow path are connected to supply gas to the burner 13 from a gas supply source (not shown). In the vicinity of the upper part of the burner 13, there is provided a spark electrode 13c connected to the high-voltage side terminal of the igniter 13b for igniting the supply gas. And burner 13
The heat exchanger 12 is heated by the combustion of the gas due to the ignition of this heat, and this heat is transmitted to the water passing through the heat exchanger 12,
The hot water is discharged to the hot water supply pipe P2.

An exhaust hood 15 for discharging exhaust gas to the outside is provided downstream of the heat exchanger 12 in the combustion chamber 11. A thermistor 16 for temperature detection is arranged in an exhaust space in the hood 15. Note that a temperature sensor other than the thermistor 16, such as a thermocouple, may be used. Blower 17 provided at the bottom in combustion chamber 11
Has a sirocco fan (hereinafter simply referred to as a fan) 17a rotatably supported in a fan case, and an electric motor 17b connected to a rotating shaft thereof.

Next, an electric control device 30 for electrically controlling the operation of the water heater configured as described above will be described with reference to the drawings. This electric control device 30 has a
As shown in the figure, a control circuit 31 is provided. Control circuit 3
Reference numeral 1 denotes a microcomputer including a CPU, a ROM, a RAM, an I / O, and the like, and executes a "water heater control program" corresponding to the flowchart shown in FIG. Further, the control circuit 31 includes a temperature determination circuit for comparing the reference temperature TB with a temperature detection value input T from the thermistor 16.

The reference temperature TB is determined in advance in consideration of a combustion gas amount, a calorific value of the gas, and the like. Further, the temperature of the exhaust space at the time of initial use of the water heater when the water heater is actually operated in the area where the water heater is actually installed at the initial stage of mounting the appliance is measured, and the reference temperature TB is calculated and determined based on the result. Is more accurate. In this reference example ,
The reference temperature is set in two stages: a first reference temperature TB1 that warns of a fin clogging abnormality, and a second reference temperature TB2 that stops the combustion operation by a burner that is higher than the first reference temperature TB1.

The thermistor 16 and the water flow switch 22 are connected to the input side of the control circuit 31. The igniter 13b, the proportional control valve 14a, the solenoid valve 14b, and the electric motor 17b for driving the fan 17a are connected to the output side of the control circuit 31 via drive circuits 32a to 32d. On the output side of the control circuit 31, there is provided a heat exchanger abnormality indicator lamp 19 (not shown) provided on the front of the water heater 10 for lighting when the output of the thermistor 16 becomes higher than the reference temperature TB. 32e. The drive circuits 32a to 32e receive signals from the control circuit 31, and receive signals from the igniter 13b, the proportional control valve 14a,
The power supply to the solenoid valve 14b, the electric motor 17b, and the heat exchanger abnormality display lamp 19 is controlled.

Next, the operation of the reference example configured as described above will be described. When a power supply (not shown) is turned on, the control circuit 31 starts execution of a “water heating control program” shown in FIG. 3 in step 40, and in step 41 it is determined whether or not water is passed. When water is started to flow into the water supply pipe P1 by opening the hot water tap 21, the water flow switch 22 is turned on. In response to this, the control circuit 31 shifts the program to step 42 based on the determination of “YES” in step 41, energizes the electric motor 17b to rotate the fan 17a, and supplies the combustion air to the burner 13. Supply. At the same time, in step 43, the solenoid valve 14b is turned on to supply gas to the burner 13, and the igniter 13
Activate b to ignite the gas and start the combustion control.
As a result, the heat exchanger 12 is heated, the heat is transmitted to the water flowing in from the water supply pipe P1, and the water is heated and supplied to the water supply pipe P2.

The control circuit 31 reads the first and second temperature reference values TB1 and TB2 at step 44, and inputs the detected value T of the thermistor 16 at step 45. Next, in step 46, the detected value T is compared with the first and second temperature reference values TB1, TB2. When the heat exchanger is normal, the detected value T is lower than any of the first and second temperature reference values TB1 and TB2.
Based on the determination of "O", the program proceeds to step 49, where it is determined whether or not the water flow switch 22 is turned off, that is, whether or not the water is stopped. When hot water is being supplied, the program returns to step 47 based on the determination of "NO", and the processing of steps 47 to 49 is repeated thereafter. Then, when the hot water tap 21 is closed and the water supply is stopped, the program proceeds to step 50 based on the determination of "YES" in step 49, and the "combustion control" is stopped, and
At 1, post-purging is performed to reduce the temperature of the heat exchanger 12 to a certain value or less, and further, at step 52, the execution of the program ends.

As the water heater 10 is used for a long time, the fins 12a are gradually oxidized and corroded, and
When the metal oxide accumulates in a, a so-called fin blockage state occurs in which the fin interval is reduced. When the fin is clogged, the heat exchange amount of the heat exchanger 12 is reduced, and as a result, the temperature of the exhaust gas is higher than when the heat exchanger is normal. As described above, when the fins are closed and the temperature T of the exhaust gas becomes higher than the predetermined first temperature reference value TB1, the program proceeds to step 53 based on the determination of "YES" in step 47. Then, the heat exchanger abnormality display signal 1 is output. In response, the driving circuit 32e
Causes the heat exchanger abnormality display lamp 19 to light up and display the heat exchanger abnormality.

Then, the fin blockage further progresses,
The temperature T of the exhaust gas is a predetermined second temperature reference value TB2
If it becomes higher, the program proceeds to step 54 based on the determination of “YES” in step 48, the “combustion control” is stopped, and the fan 17
The rotation of a is stopped. Then, at step 56, the heat exchanger abnormality display signal 2 is output. In response to this, the drive circuit 32e causes the heat exchanger abnormality display lamp 19 to perform blinking display of the stop of combustion control due to the heat exchanger abnormality. And
In step 52, the execution of the program ends.

As described above, according to the above reference example , the use of one thermistor makes it possible to detect a fin clogging abnormality in a heat exchanger of a water heater simply and inexpensively as compared with the prior art. . Further, by stopping the combustion of the water heater in response to the detection of the heat exchanger abnormality, it is possible to prevent defects such as oxygen deficiency due to fin blockage and leakage of the flame out of the container. In addition, the effectiveness by detecting a heat exchanger abnormality can be further enhanced.

Next, an embodiment will be described with reference to the drawings. In the water heater according to the present embodiment, the thermistor 33 is directly mounted on the wall surface of the heat exchanger 12, as schematically shown in FIG. That is, an attempt is made to detect that the transfer of heat to the supplied water is hindered by the clogging of the fins of the heat exchanger 12, and as a result, the outer wall temperature of the heat exchanger becomes higher than normal. Other configurations are the same as those of the above-described reference example . In the embodiment configured as described above, the fin clogging abnormality of the heat exchanger of the water heater can be detected simply and at low cost as compared with the related art, similarly to the above-described reference example .

In the above embodiment , the abnormality detection by the heat exchanger abnormality detecting device is performed in two stages, an abnormality is displayed first, and the combustion state of the water heater is stopped at the second stage where the detected temperature is high. However, the abnormality display and the combustion stop may be performed at the same time. Further, without stopping the combustion state, for example, the maximum capacity can be limited (for example, No. 20 to No. 16) to enable safe use. Furthermore, although the abnormal display reference temperature is set to two values, three or more reference temperatures may be provided and displayed according to the degree of fin clogging of the heat exchanger. Also,
For the display mode of the heat exchanger abnormality display lamp,
The present invention is not limited to those shown in the embodiments, but can be implemented with various changes. Furthermore, as an abnormality display means of the heat exchanger,
Sound display means such as a buzzer can be used instead of the lamp. The heat exchanger abnormality detecting device for a water heater shown in the above embodiment is used for a water heater in a kitchen or a lavatory, but can also be used for a water heater for a bathtub or the like.

[Brief description of the drawings]

FIG. 1 is a schematic view schematically showing a water heater according to a reference example of the present invention.

FIG. 2 is a block diagram showing an electric control device of the water heater.

FIG. 3 is a flowchart of a “water heater control program” executed by the control circuit of FIG. 2;

FIG. 4 is a schematic view showing a part of the water heater according to the embodiment .

[Explanation of symbols]

10 hot water heater, 11 combustion chamber, 12 heat exchanger, 12a
... Fin, 13 ... Burner, 15 ... Exhaust hood, 16 ... Thermistor, 17 ... Blower, 17a ... Fan, 17b ... Electric motor, 18 ... Reference temperature setting switch, 19 ... Heat exchanger abnormality display lamp, 21 ... Hot water tap , 22 ... water flow switch, 30 ... electric control device, 31 ... control circuit, 33 ... thermistor, P1 ... water supply pipe, P2 ... hot water supply pipe.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-5-322160 (JP, A) JP-A-5-196229 (JP, A) JP-A-5-164323 (JP, A) JP-A-59-1984 52129 (JP, A) JP-A 4-41946 (JP, U) JP-A 61-63547 (JP, U) JP-A 60-21657 (JP, U) (58) Fields surveyed (Int. Cl. ⁷ , DB name) F23N 5/24 104 F23N 5/02 345

Claims (2)

(57) [Claims] 1. A water heater comprising a fin tube type heat exchanger having a water supply pipe and a hot water supply pipe, and a gas burner for heating the heat exchanger, wherein the heat exchanger is mounted on a wall surface of the heat exchanger. Outer wall of the vessel
A temperature sensor for detecting a temperature, reference temperature setting means for setting a predetermined reference temperature, and comparing the detected value of the temperature sensor with the reference temperature set value, wherein the detected value is larger than the reference temperature set value. A water heater provided with a fin clogging detection device, comprising: comparison means for outputting a warning signal when the warning signal is output; and warning display means for receiving and displaying the warning signal. 2. The fin clogging detection according to claim 1,
In the water heater provided with the device, the warning signal by the comparing means is output in two stages,
In response to the second-stage warning signal, the burner starts burning.
Characterized in that a combustion stop control means for stopping is provided.
Heat exchanger abnormality detector for water heater .