JPH08233259A - Hot water supply apparatus equipped with fin clogging-detecting device - Google Patents

Abstract

PURPOSE: To detect the clogging of the fin of a heat-exchanger at a low cost by a method wherein a detected value of a temperature sensor which is provided in a heat-exchanger and a reference temperature set value are compared, and when the detected value becomes larger than the reference temperature set value, an alarm indication is provided. CONSTITUTION: A detected value of a temperature sensor 16 which is provided at an upper part of a heat-exchanger 12 in a combustion chamber 11, and a reference temperature set value which is determined in advance are compared, and when the detected value becomes higher than the reference temperature set value, it is displayed on an alarm display means (e.g., a heat-exchanger abnormality indication lamp) as an abnormality of the heat-exchanger 12. The reference temperature is determined in advance while taking the quantity of a combustion gas and the calorific power of the gas, etc., under consideration. Also, the temperature of an air discharging space at an initial usage of a hot water supply apparatus 10 when the hot water supply apparatus 10 is operated in an area where the hot water supply apparatus 10 is actually installed, at an initial stage such as the attaching of the apparatus, etc., is actually measured, and if the reference temperature is operated by the result and determined, the reference temperature becomes more accurate. By this method, a clogged abnormality of a fin 12a of the heat-exchanger 12 can be detected at a low cost.

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 detection device for detecting fin clogging of a heat exchanger.

[0002]

2. Description of the Related Art In a water heater for transferring combustion heat of a burner to a hot water by a fin tube type heat exchanger to turn it into high temperature hot water, when a fin temperature is low, a corrosive component such as sulfur in a combustion gas is contained. Moisture adheres to the heat exchanger and oxidizes and corrodes the fins, depositing oxides on the fin walls. Further, at the time of combustion when the temperature of the fins of the water heater becomes high, a reaction gas between the combustion gas and the fins produces high-temperature generated oxides on the fin walls. And with the long-term use of the water heater,
The deposition of these metal oxides on the fins becomes significant, and a fin blockage occurs in which the flow of combustion gas between the fins is obstructed. As a result, there is a risk that the passage of exhaust gas may be hindered and an oxygen-deficient combustion state may occur, and further, gas incombustibles may be after-fired and flame may leak out of the hood.

Conventionally, as a heat exchanger abnormality detecting device for this type of water heater, for example, as shown in Japanese Patent Laid-Open No. 63-123951, a water quantity sensor mounted on a hot water pipe having a heat exchanger is used. The output, the inlet side temperature sensor provided on the inlet side hot water supply pipe of the heat exchanger, and the heat transfer amount of the heat exchanger is calculated based on the output of the outlet side temperature sensor provided on the outlet side hot water supply pipe, It was comparing with the heating amount set by the ability switching knob. The fin blockage of the heat exchanger is determined 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.

[0004]

However, the above heat exchanger abnormality detecting device requires a water amount sensor, an inlet side temperature sensor, and an outlet side temperature sensor for the fin blockage determination, and the structure is complicated and the detection cost is high. There is a problem that it becomes expensive. The present invention is intended to solve the above problems, and an object of the present invention is to provide a heat exchanger abnormality detection device for a water heater, which can detect a fin blockage abnormality of the 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 claim 1 are a fin tube type heat exchanger having a water supply pipe and a hot water supply pipe, and this heat exchanger. In a water heater provided with a gas burner for heating, a temperature sensor provided downstream of the combustion exhaust of the heat exchanger,
Reference temperature setting means for setting a predetermined reference temperature, comparing the detected value of the temperature sensor and the reference temperature set value, and a comparison means for outputting a warning signal when the detected value becomes larger than the reference temperature set value, A warning display means for receiving a warning signal and displaying the warning signal is provided.

[0006] Further, the structural feature of the invention according to claim 2 is that in a water heater including 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. , A temperature sensor for detecting the temperature of the heat exchanger, a reference temperature setting means for setting a predetermined reference temperature, and a detection value of the temperature sensor and a reference temperature set value are compared,
This is because the comparison means for outputting a warning signal when the detected value becomes larger than the reference temperature set value and the warning display means for receiving and displaying the warning signal are provided.

Further, the constitutional feature of the invention according to claim 3 is that in the water heater provided with the fin clogging detection device according to claim 1 or 2, the warning signal by the comparing means is divided into two stages. This is because there is provided a combustion stop control means for separately outputting and for stopping the combustion operation by the burner in response to the second stage warning signal.

[0008]

As described above, the invention according to claim 1 is configured, so that, for example, the amount (input) of gas supplied to the burner is taken into consideration, and the amount of gas used in the area where the water heater is used is considered. A reference temperature set value that was determined in advance considering the property (heat generation amount) was compared with the detected value of the temperature sensor installed above the heat exchanger, and the detected value was greater than the reference temperature set value. At this time, the abnormality can be surely known by displaying the abnormality as the heat exchanger on the warning display means. In addition, this heat exchanger abnormality detection device uses only one temperature sensor, and has a very simple configuration compared to the conventional one. Therefore, the heat exchanger abnormality can be detected at low cost.

Further, according to the invention as claimed in claim 2, the temperature sensor provided on the pipe wall of the heat exchanger can detect the temperature of the heat exchanger whose temperature has risen due to the fin blockage. it can. Then, by comparing this detected value with a predetermined reference temperature set value, it is possible to detect the abnormality of the heat exchanger reliably and inexpensively, as in the case of the invention according to claim 1.

According to the invention of claim 3 as described above, the warning signal of the first stage warns the fin clogging abnormality of the heat exchanger, and the fin clogging progresses to the second stage. The warning signal is output and the burner burn operation is stopped in response to the warning signal. As a result, in addition to the effects of the invention according to claims 1 and 2, it is possible to prevent problems such as oxygen deficiency due to fin closure of the heat exchanger and leakage of flame out of the container. .

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a water heater according to the first embodiment. The 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 the upper portion of the combustion chamber 11. A water supply pipe P1 is connected to the inlet side of the heat exchanger 12, and a hot water supply pipe P2 is connected to the outlet side thereof. The water supply pipe P1 and the hot water supply pipe P2 are connected to the combustion chamber 1 as shown in FIG.
1, a water supply pipe P1 is connected to a water supply source (not shown) such as a water supply, and a hot water supply tap 21 is connected to the tip of the hot water supply pipe P2. 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 a proportional control valve 1 for adjusting the gas amount.
4a and a solenoid valve 14b for opening and closing the gas flow path are connected to a gas supply pipe PG, and gas is supplied from a gas supply source (not shown) to the burner 13. A spark electrode 13c connected to the high-voltage side terminal of the igniter 13b for igniting the supply gas is provided near the upper portion of the burner 13. And burner 13
The heat exchanger 12 is heated by the combustion of gas due to the ignition of the heat, and this heat is transferred to the water passing through the heat exchanger 12,
It becomes hot water and is discharged to the hot water supply pipe P2.

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

Next, an electric control device 30 for electrically controlling the operation of the water heater constructed as described above will be described with reference to the drawings. This electric control unit 30 is shown in FIG.
A control circuit 31 is provided as shown in FIG. Control circuit 3
Reference numeral 1 is composed of a microcomputer including a CPU, ROM, RAM, I / O, etc., and executes a "water heating control program" corresponding to the flowchart shown in FIG. The control circuit 31 also includes a temperature determination circuit that compares the reference temperature TB with the temperature detection value input T from the thermistor 16.

The reference temperature TB is set in advance in consideration of the combustion gas amount, the calorific value of the gas, and the like. Also, the temperature of the exhaust space at the time of initial use of the water heater when it is operated in the area where the water heater is actually installed at the initial stage of equipment installation, etc. is measured, and the reference temperature TB is calculated and determined based on the result. It becomes more accurate when set to. In this embodiment,
The reference temperature is set in two stages, that is, a first reference temperature TB1 that warns of a fin clogging abnormality and a second reference temperature TB2 that is a temperature higher than the first reference temperature TB2 that stops the combustion operation.

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. Further, on the output side of the control circuit 31, a heat exchanger abnormality display lamp 19 (not shown) provided on the front surface of the water heater 10 that lights up when the output of the thermistor 16 exceeds the reference temperature TB is displayed. It is connected via 32e. The drive circuits 32a to 32e receive the signal from the control circuit 31, and the igniter 13b, the proportional control valve 14a,
The energization of the solenoid valve 14b, the electric motor 17b, and the heat exchanger abnormality display lamp 19 is controlled.

Next, the operation of the embodiment configured as described above will be described. When a power source (not shown) is turned on, the control circuit 31 starts the execution of the "water heating control program" shown in FIG. 3 at step 40, and at step 41 it is judged whether or not water is flowing. When water supply is started in 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
b is operated to ignite the gas, and combustion control is started.
As a result, the heat exchanger 12 is heated, and the heat is transferred to the water flowing in from the water supply pipe P1 to perform boiling water, and is supplied to the hot water supply pipe P2.

Then, the control circuit 31 reads the first and second temperature reference values TB1 and TB2 in step 44, and inputs the detection value T of the thermistor 16 in step 45. Next, at step 46, the detected value T is compared with the first and second temperature reference values TB1 and TB2. When the heat exchanger is normal, the detected value T is lower than both the first and second temperature reference values TB1 and TB2.
Based on the determination of "O", the program is moved to step 49, and it is determined whether or not the water flow switch 22 is off, that is, whether or not the water is stopped. When hot water is being supplied, the program is returned to step 47 based on the determination of "NO", and the processes of steps 47 to 49 are repeated. Then, when the hot water tap 21 is closed and the water supply is stopped, the program is moved to step 50 based on the determination of “YES” in step 49, the “combustion control” is stopped, and the step 5
At 1, post-purging is performed to keep the temperature of the heat exchanger 12 below a certain level, and 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 the fins 12a
The accumulation of metal oxides in a leads to a so-called fin closed state in which the fin spacing is narrowed. When the fin is closed, the heat exchange amount of the heat exchanger 12 becomes small, and as a result, the temperature of the exhaust gas becomes higher than that when the heat exchanger is normal. In this way, when the fins are closed and the temperature T of the exhaust gas becomes higher than the first temperature reference value TB1 set in advance, the program moves to Step 53 based on the judgment of "YES" at Step 47. Then, the heat exchanger abnormality display signal 1 is output. In response to this, the drive circuit 32e
Causes the heat exchanger abnormality display lamp 19 to light up and display the heat exchanger abnormality.

Then, the fin closed state further progresses,
The second temperature reference value TB2 in which the temperature T of the exhaust gas is predetermined
When it becomes higher, the program is moved to step 54 based on the determination of "YES" in step 48, the "combustion control" is stopped, and the fan 17 is operated in step 55.
The rotation of a is stopped. Then, in 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 the blinking display of the combustion control stop due to the heat exchanger abnormality. And
In step 52, the execution of the program ends.

As described above, according to the first embodiment, by using one thermistor, the fin clogging abnormality of the heat exchanger of the water heater can be detected easily and inexpensively as compared with the conventional case. You can In addition, by stopping the combustion of the water heater in response to the detection of an abnormality in the heat exchanger, it is possible to prevent problems such as oxygen deficiency due to fin blockage and leakage of flame outside the container. The effectiveness of detecting a heat exchanger abnormality can be further enhanced.

Next, a second embodiment will be described with reference to the drawings. In the water heater according to the present embodiment, the thermistor 33 is directly attached to the wall surface of the heat exchanger 12, as schematically shown in FIG. That is, the fins of the heat exchanger 12 block the transfer of heat to the supplied water, and as a result, it is intended to detect that the outer wall temperature of the heat exchanger becomes higher than that in the normal state. The other structure is similar to that of the first embodiment. Also in the second embodiment configured as described above, the fin clogging abnormality of the heat exchanger of the water heater can be detected more easily and cheaply as in the first embodiment, as in the first embodiment.

In each of the above embodiments, the abnormality detection by the heat exchanger abnormality detection device is performed in two stages, the abnormality is displayed first, and the combustion state of the water heater is further detected at the second stage where the detected temperature is high. Although the stop is performed, 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 (No. 20 to No. 16) so that it can be used safely. Further, although the abnormality display reference temperature has two values, three or more reference temperatures may be provided and displayed according to the degree of fin clogging of the heat exchanger. Regarding the display mode of the heat exchanger abnormality display lamp,
The present invention is not limited to those shown in each of the above embodiments, and various modifications can be made. Further, as the abnormality display means of the heat exchanger, not only the lamp but also an acoustic display means such as a buzzer can be used. The heat exchanger abnormality detecting device for a water heater shown in each of the above-mentioned embodiments is used for a water heater in a kitchen or a washroom, but can also be used for a water heater for a bathtub or the like.

[Brief description of drawings]

FIG. 1 is a schematic diagram schematically showing a water heater according to a first embodiment 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 “hot water boiling control program” executed by the control circuit of FIG.

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

[Explanation of symbols]

10 ... Water heater, 11 ... Combustion chamber, 12 ... Heat exchanger, 12a
... Fins, 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.

Claims (3)

[Claims] 1. A water heater provided with 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 a temperature provided on a downstream side of combustion exhaust of the heat exchanger. A sensor, a reference temperature setting means for setting a predetermined reference temperature, and a detection value of the temperature sensor and the reference temperature set value are compared, and a warning signal is output when the detected value becomes larger than the reference temperature set value. And a warning display means for receiving and displaying the warning signal, the water heater including the fin clogging detection device. 2. A water heater provided with 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 a temperature sensor for detecting the temperature of the heat exchanger, A reference temperature setting means for setting a predetermined reference temperature is compared with the detected value of the temperature sensor and the reference temperature set value, and a warning signal is output when the detected value becomes larger than the reference temperature set value. A water heater equipped with a fin clogging detection device, comprising: comparison means and warning display means for receiving and displaying the warning signal. 3. A water heater equipped with the fin clogging detection device according to claim 1 or 2, wherein the warning signal by the comparison means is output in two stages.
A heat exchanger abnormality detection device for a water heater, comprising combustion stop control means for stopping a combustion operation by the burner in response to a second-stage warning signal.