JPH08219448A - Gas boiler with combustion abnormality detecting function - Google Patents

Abstract

PURPOSE: To secure safety in the use of equipment by stopping a gas burner when an output value is lowered associated with the closing of a fin of a heat exchanger in a gas boiler. CONSTITUTION: This gas boiler is provided with a heat exchanger 16 for which a water feed pipe 12 and a hot water delivery pipe 14 are provided and a gas burner 20 to heat the heat exchanger 16. A gas input value at the fully opened capacity of the gas burner is computed based on detection signals from a hot delivery water temperature sensor 30 to detect the temperature of hot water flowing through the hot delivery water pipe 14 with the fully opened capacity of the gas burner 20, a fed water temperature sensor 27 to detect the temperature of water flowing through the water feed pipe 12 and a flow rate sensor 26 to detect the amount of water flowing through the water feed pipe 12 or hot water flowing through the hot delivery water pipe 14. The input value calculated is compared with a reference input value and when it is judged to be lower, the combustion of the gas burner 20 is stopped.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas water heater in which hot water is obtained by heating a heat exchanger with a gas burner, and more specifically, fins of the heat exchanger are closed by a drain or the like. The present invention relates to a gas water heater with a combustion abnormality detection function, which detects combustion abnormality due to occurrence of the above and stops combustion safely.

[0002]

2. Description of the Related Art Conventionally, as is well known, this type of gas water heater is used when a combustion gas from a gas burner passes between heat collecting fins of a heat exchanger in which a large number of heat collecting fins are arranged in a row. The gas heat is collected by the heat collecting fins, and the heat transferred through the heat collecting fins heats the water flowing through the heat exchanger to obtain tap water.

[0003]

However, when drains such as combustion products adhere to the heat collecting fins of the heat exchanger due to the long-term use of the gas water heater, the gaps between the heat collecting fins become large. The heat is gradually blocked by the heat collecting fins, and the output value gradually decreases.

Further, since the air gap resistance between the heat collecting fins is narrowed and the air flow resistance is increased, the amount of air supplied to the gas burner is reduced, which promotes incomplete combustion. After all, there was a problem that the output value decreased.

The present invention has been made to solve the above-mentioned problems, and one of the objects of the present invention is to maximize the capacity of the gas burner when the heat efficiency is lowered due to the fin clogging of the heat exchanger. Focusing on the decrease of the output value, it is to provide a gas water heater in which the combustion of the gas burner can be safely stopped by determining the output value. A second aspect of the present invention is to provide a gas water heater in which the decrease in the thermal efficiency is judged by the hot water temperature and the combustion of the gas burner can be safely stopped by this. All of them are intended to ensure safety in using the gas water heater.

[0006]

In order to achieve this object, a gas water heater according to the present invention includes a heat exchanger provided with a water inlet pipe and a hot water outlet pipe, and a heat exchanger for heating the heat exchanger. And a hot water temperature detecting means for detecting the temperature of the hot water flowing through the hot water outlet pipe when the capacity of the gas burner is fully opened,
Inlet water temperature detecting means for detecting the temperature of water flowing through the water inlet pipe,
Flow rate detecting means for detecting the amount of water flowing through the water inlet pipe or hot water flowing through the hot water outlet pipe, the hot water temperature detecting means, the water entering temperature detecting means,
And an output value calculating means for calculating an output value when the gas burner capacity is fully opened based on the detection signal from the flow rate detecting means, and an output value calculated by this output value calculating means is compared with a reference output value. And an output value judging means for judging whether or not the gas burner is lower than this, and when the output value judging means judges that the calculated output value is lower than the reference output value, the combustion of the gas burner is stopped. The gist is that it is configured as described above. In this case, the reference output value used for the determination by the output value determining means may be either a constant value in advance or a value calculated during initial use.

The gas water heater of the present invention is further provided with a heat exchanger provided with a water inlet pipe and a hot water outlet pipe, and a gas burner for heating the heat exchanger, which is provided when the capacity of the gas burner is fully opened. The hot water temperature detecting means for detecting the temperature of hot water flowing through the hot water outlet pipe, and the hot water temperature at the time of full opening of the gas burner capacity detected based on the detection signal from the hot water temperature detecting means are compared with the hot water temperature serving as a reference. A hot water outlet temperature determining means for determining whether the temperature is low or not, and when the hot water outlet temperature determining means determines that the detected hot water temperature is lower than the reference hot water temperature, the combustion of the gas burner is stopped. It is a summary.

[0008]

According to the gas water heater according to the first aspect of the present invention having the above-mentioned structure, the water supplied to the heat exchanger through the water inlet pipe is heated by the gas burner and is obtained as the tap water from the hot water outlet pipe. However, in the combustion state of the gas burner, the temperature of the hot water flowing through the hot water outlet pipe, the temperature of the water flowing through the water inlet pipe, and the amount of water flowing through the water inlet pipe or the amount of hot water flowing through the hot water outlet pipe when the capacity of the gas burner is fully opened. Is detected, and the output value is calculated based on these detection signals. If the calculated output value is lower than the reference output value, it is determined that the combustion of the gas burner is stopped.

Further, according to the gas water heater according to the second aspect of the invention, when the hot water outlet temperature when the capacity of the gas burner is fully opened is detected, it is compared with the hot water outlet temperature which is a predetermined reference (normal time). If the temperature is lower than the reference temperature, it is determined that the combustion abnormality has occurred, and the combustion of the gas burner is stopped.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows a schematic configuration of a gas water heater to which the present invention is applied. In the gas water heater 10 shown in FIG. 1, a heat exchanger 16 having a water supply pipe 12 and a hot water discharge pipe 14 is arranged in a casing 18, and the heat exchanger 16 is arranged in the casing 18. A gas burner 20 for heating the is provided.

A gas proportional valve 24 is provided in the gas pipe 22 of the gas burner 20, and a water flow switch (flow rate sensor) for detecting the flow of water and its flow rate in the water supply pipe 12.
26 and an incoming water temperature sensor 27 that detects the temperature of the water, and a water governor 28 that regulates the flow of the water. On the other hand, the hot water outlet pipe 14 is provided with a hot water thermistor (hot water temperature sensor) 30 for detecting the hot water temperature, and the hot water outlet of the hot water pipe 14 is provided with a faucet (water faucet) 32.

On the input side of the burner controller 34 for controlling the operation of the gas water heater, the flow rate sensor 2 is provided.
6, a water inlet temperature sensor 27, a hot water outlet temperature sensor 30 and the like are connected, and a gas proportional valve 24 and the like are connected to the output side of the burner controller 34.

This gas water heater 10 has a faucet (water faucet) 32.
When the water flow switch (flow rate sensor) 26 is opened by opening
Then, the gas burner 20 is ignited, the heat exchanger 16 is heated, the water supplied from the water inlet pipe 12 is heated, and tap water is obtained from the tap pipe 14. At that time, a command is given from the burner controller 34 to the gas proportional valve 24 by the detection signal from the hot water sensor 30, and the opening is adjusted by controlling the proportional valve current value of the gas proportional valve 24 to keep the hot water temperature at the set temperature. The operation is controlled so as to lean.

Thus, according to the present invention, the output is calculated only when the capacity of the gas water heater is fully opened, and when the output is below a certain value calculated from the output of the normal time stored in advance, the heat exchanger is turned on. It is determined that it has deteriorated and the combustion is stopped. For example, when the capacity of the gas water heater is fully opened, the gas proportional valve is fully opened, and the capacity is fully opened when the time when the proportional valve current value is maximum (MAX) has elapsed.

The calculation method of the output is as follows: (T hot water-T water) × Q hot water = output (Kcal
/ M) T hot water = detected by a hot water thermistor T water = detected by an incoming water thermistor Q hot water = detected by a flow sensor

Furthermore, the output during normal operation is as follows: ・ Output guarantee when capacity is fully opened = 90% or more of maximum capacity (A) ・ Difference in gas calorific value = Output guarantee 100% for propane (LP) gas Above (B) ・ Decrease in thermal efficiency due to secular change = -5% (C) (Decrease within the range that does not cause abnormalities in combustion, etc. even if it decreases) From the above, the normal output is as follows. Become.

Normal output = (rated output) x 0.9 x 1 x 0.95 (Kcal / M) ↑ ↑ ↑ (A) (B) (C) This is a gas water heater (20 No.), the normal output of this gas water heater: 20 × 25 × 0.9 × 1 × 0.95 = 427.5K
cal / M

Calculation output (at proportional valve current MAX): T hot water = 37 ° C., T water = 5 ° C., Q hot water = 10 liter / M
Then, (37-5) × 10 = 320 Kcal / M 320 Kcal / M <427.5 Kcal / M, so it is determined to be abnormal, and combustion is stopped.

Next, the second embodiment of the present invention will be described. In this embodiment, deterioration of the heat exchanger is estimated based on the outlet heated water temperature and combustion is stopped. In the instantaneous gas water heater that can change the set temperature of hot water and controls the amount of hot water by detecting the hot water temperature, a temperature detecting means (hot water thermistor 30) is provided at the outlet of the heat exchanger and somewhere in the water passage. In addition, a limiter (constant flow valve-water governor 28) that regulates the maximum amount of passing water is provided, and a limiter (constant valve current determination circuit) that detects that the gas amount is fully opened is provided. Set the flow rate of the flow valve) to the gas burner 20
When the capacity is fully opened, it is set in advance so that it does not drop below the middle temperature (45 ° C), and at the set temperature below the middle temperature (45 ° C), the gas volume during use is fully opened, and the hot water thermistor 30 detects it after a certain period of time. The hot water temperature is detected by the signal,
If the hot water temperature does not rise to the set temperature, the combustion is stopped.

In this embodiment, it is noted that when the fins of the heat exchanger are blocked by a drain or the like, the thermal efficiency decreases from about 80% to about 20%, the fin blockage is estimated from the hot water temperature, and combustion is stopped. The purpose is to let. In a feedback (FB) -controlled gas water heater, the amount of gas is automatically increased in proportion to the decrease in thermal efficiency. Therefore, the constant flow valve regulates the maximum amount of water so that the capacity does not fully open when the temperature is low. Despite the fact that the fins are blocked and the thermal efficiency is drastically reduced, the amount of gas is fully opened,
The set low temperature hot water cannot be obtained.

Considering this as an example of a certain gas water heater (also No. 20), in this gas water heater, the maximum water amount of the constant flow valve and the maximum water amount at a water temperature of 0 ° C. are controlled at 9.4 liters / min. The output water temperature when the No. 20 is output and the capacity is fully opened is 20 × 25 / 9.4 = 53 ° C.
Output 90% guaranteed, output down due to variations in gas calorific value → no down for LP gas If the thermal efficiency deterioration due to long-term use is -5%,

[0022]

In this case, unless the performance of the constant flow valve is disturbed,
When the capacity is fully opened, hot water will not come out below 45.3 ° C. Therefore, in this case, when the temperature is set to 45 ° C. or lower, the proportional valve current is maximum (MAX), and if the hot water outlet temperature does not rise to the set temperature even after a certain period of time, it is determined to be abnormal and combustion is stopped. Stop. It is assumed that this control causes the heat exchanger to be abnormally clogged, or the performance of the constant flow valve to be incorrect. In any case, since it is abnormal, the combustion is stopped.

FIG. 2 is a supplementary explanation of this. The horizontal axis shows the amount of hot water (Q), and the vertical axis shows the hot water temperature (T). Assuming that the proportional valve current value is at the maximum (MAX), the variation of the input etc. of this gas water heater guarantees 90% of the output, and the maximum capacity line when 5% of deterioration due to aging of thermal efficiency is expected. Is represented by the solid curve indicated by "A" in the figure. In this solid curve "A", as shown in the above calculation formula,
When the amount of hot water (Q) = 9.4 liters / min, the hot water temperature (T) passes through the intersection of 45.3 ° C.

On the other hand, the maximum capacity line when the thermal efficiency of this gas water heater is abnormally decreased due to fin blockage of the heat exchanger or the like is represented by the broken line curve indicated by "B" in the figure. In this broken line curve “B”, the amount of hot water (Q) =
At 9.4 liters / min, the tap water temperature (T) was 45.
The temperature never exceeds 3 ° C., and it is determined that the combustion is abnormal.

For example, when the hot water outlet temperature is set to 37 ° C., in a normal condition, the proportional valve current value does not reach maximum (MAX) and hot water at 37 ° C. can be obtained. The line moves from the solid line curve “A” to the broken line curve “B” in FIG. 2, the tapping temperature falls below 37 ° C. and becomes A ° C., and the proportional valve current becomes maximum (MAX).

It is also conceivable that when the temperature is set to 45 ° C. or lower, regardless of the proportional valve current, if the hot water outlet temperature has not risen to the set temperature even after a certain period of time, it is judged as abnormal and the combustion is stopped. By determining whether the proportional valve current is MAX or not, it is possible to confirm that the FB control is operating normally and then determine that the FB control is abnormal and operate the safety device. It should be noted that the present invention is not limited to the above-described embodiments, and it goes without saying that various design changes or improvements can be made without departing from the spirit of the present invention.

[0028]

As is apparent from the above description, according to the gas water heater with the combustion abnormality detecting function of the present invention, the decrease in the thermal efficiency due to the fin clogging of the heat exchanger is promptly detected, and the gas burner is detected. Since the combustion of the gas is stopped, the safety in using the gas appliance is ensured.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an entire gas water heater to which the present invention is applied.

FIG. 2 is an amount (Q) of hot water and a temperature (T) of discharged hot water when fins of the heat exchanger in the gas water heater shown in FIG. 1 are clogged.
It is a figure showing the relation with.

[Explanation of symbols]

 10 Gas Water Heater 12 Water Supply Pipe (Inlet Pipe) 14 Hot Water Pipe 16 Heat Exchanger 20 Gas Burner 24 Gas Proportional Valve 26 Flow Sensor 30 Hot Water Temperature Sensor 34 Burner Controller

Claims (4)

[Claims] 1. A gas water heater comprising a heat exchanger provided with a water inlet pipe and a hot water outlet pipe, and a gas burner for heating the heat exchanger, wherein the temperature of the hot water flowing through the hot water outlet pipe when the capacity of the gas burner is fully opened. Hot water temperature detecting means for detecting, water temperature detecting means for detecting the temperature of water flowing through the water inlet pipe, flow rate detecting means for detecting the amount of water flowing through the water inlet pipe or hot water flowing through the hot water outlet pipe, and the water temperature detecting means , Output value calculation means for calculating the output value when the gas burner capacity is fully open based on the detection signals from the input water temperature detection means and the flow rate detection means, and the output value calculated by this output value calculation means An output value judging means for judging whether or not it is lower than the output value is provided, and the output value calculated by this output value judging means is a reference value. Abnormal combustion detection function gas water heaters, characterized in that the combustion of the gas burner is configured to be stopped when it is judged to be lower than the Toputto value. 2. The gas water heater with a combustion abnormality detecting function according to claim 1, wherein the reference output value used for the determination by the output value determining means is previously constant. 3. The gas water heater with a combustion abnormality detecting function according to claim 1, wherein the reference output value used for the determination by the output value determining means is a value calculated during initial use. . 4. A gas water heater comprising a heat exchanger provided with a water inlet pipe and a hot water outlet pipe, and a gas burner for heating the heat exchanger, wherein the temperature of the hot water flowing through the hot water outlet pipe when the capacity of the gas burner is fully opened. Hot water temperature detecting means for detecting, and hot water temperature detected by the hot water temperature detecting means is compared with the hot water temperature when the gas burner capacity is fully opened, which is detected based on the detection signal, to determine whether the hot water temperature is lower than this. A combustion abnormality detecting function, wherein the combustion temperature of the gas burner is stopped when the hot water temperature determination means determines that the detected hot water temperature is lower than the reference hot water temperature. Gas water heater.