JP3244991B2 - Gas water heater with combustion abnormality detection function - Google Patents

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 a heat exchanger is heated by a gas burner so that tap water can be obtained. More specifically, the fin of the heat exchanger is closed by a drain or the like. The present invention relates to a gas water heater with a combustion abnormality detection function which detects a combustion abnormality accompanying the operation and safely stops the combustion.

[0002]

2. Description of the Related Art Conventionally, this type of gas water heater is, as is well known, when a combustion gas by a gas burner passes between heat collecting fins of a heat exchanger in which a large number of heat collecting fins are arranged. Then, the gas heat is collected by the heat collecting fins, and the water transmitted through the heat exchanger is heated by the heat transmitted through the heat collecting fins, so that tap water is obtained.

[0003]

However, when drains such as combustion products adhere to the heat collecting fins of the heat exchanger due to long-term use of the gas water heater, the gap between the heat collecting fins becomes large. The fins are gradually closed (gradually), and the heat transfer of the heat collecting fins gradually deteriorates, and the output value decreases.

[0004] In addition, as the gap between the heat collecting fins becomes narrower, the airflow resistance increases, whereby the amount of air supplied to the gas burner also decreases, which promotes incomplete combustion. After all, there was a problem that the output value was decreasing.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and it is an object of the present invention to provide a gas burner having a maximum capacity when the heat efficiency is reduced due to clogging of fins of a heat exchanger. It is an object of the present invention to provide a gas water heater that pays attention to a decrease in an output value and safely stops the combustion of a gas burner by determining the output value. A second object of the present invention is to provide a gas water heater in which a decrease in the thermal efficiency is determined based on a tapping temperature, thereby stopping the combustion of the gas burner safely. In each case, the safety in using the gas water heater is to be ensured.

[0006]

In order to achieve this object, a gas water heater according to the present invention comprises, as one of them, a heat exchanger provided with a water inlet pipe and a hot water pipe, and heating the heat exchanger. Hot water temperature detecting means for detecting the temperature of hot water flowing through the tapping pipe when the gas burner is fully open,
An inlet water temperature detecting means for detecting a temperature of water flowing through the 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 pipe, the hot water temperature detecting means, the incoming water temperature detecting means,
And an output value calculating means for calculating an output value when the gas burner capacity is fully opened based on a detection signal from the flow rate detecting means, and comparing the output value calculated by the output value calculating means with a reference output value. Output value determination means for determining whether the calculated output value is lower than the reference output value.If the output value determination means determines that the calculated output value is lower than the reference output value, the combustion of the gas burner is stopped. The gist of the present invention is that the configuration is made as follows. In this case, the reference output value used for the determination by the output value determining means may be either a fixed value in advance or a value calculated at the time of initial use.

In the gas water heater according to the present invention, a heat exchanger provided with a water inlet pipe and a hot water pipe, a gas burner for heating the heat exchanger, and a function of the gas burner are provided.
Make sure that the tapping temperature is higher than the specified temperature when the power is fully open.
Maximum hot water flow rate limiting means for limiting the maximum water flow and tap water setting
When the temperature is set to the predetermined temperature or lower, the temperature is detected based on a detection signal from the hot water temperature detecting means for detecting a temperature of hot water flowing through the tapping pipe when the gas burner is fully opened. A tapping temperature determining means for determining whether or not the tapping temperature when the gas burner capacity is fully opened is lower than the set temperature by comparing with the set temperature. The tapping temperature determining means determines that the detected tapping temperature is lower than the set temperature. The gist of the invention is that the combustion of the gas burner is stopped when the gas burner is stopped.

[0008]

According to the first aspect of the present invention, the water supplied to the heat exchanger via the water inlet pipe is heated by the gas burner and is obtained as hot water from the hot water pipe. However, in the combustion state of the gas burner, the temperature of the hot water flowing through the tapping pipe when the capacity of the gas burner is fully opened, the temperature of the water flowing through the inlet pipe, and the amount of water flowing through the inlet pipe or the tapping pipe. Are detected, and an output value is obtained by calculation based on these detection signals. If the calculated output value is determined to be lower than the reference output value, combustion of the gas burner is stopped.

Further, according to the gas water heater according to the second aspect of the present invention, when the gas burner is fully opened, the tap water temperature is equal to or higher than a predetermined temperature.
The maximum water flow is limited so that
If the set temperature is set below this specified temperature, be sure to set
A constant temperature tap should be obtained, but the heat exchanger
If the thermal efficiency decreases due to blockage of the gas, the gas burner
Even if it is fully opened, it becomes impossible to obtain hot water at the set temperature, and it is determined that abnormal combustion has occurred, and combustion of the gas burner is stopped.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One 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 provided with a water supply pipe 12 and a tapping pipe 14 is provided in a casing 18 and the heat exchanger 16 The gas burner 20 which heats is provided.

The gas pipe 22 of the gas burner 20 is provided with a gas proportional valve 24, and the water supply pipe 12 is provided with a water flow switch (flow sensor) for detecting the flow and flow rate of water.
26 and an incoming water temperature sensor 27 for detecting the temperature of the water, and a water governor 28 for controlling the flow of the water are also provided. On the other hand, the tapping pipe 14 is provided with a tapping thermistor (tapping temperature sensor) 30 for detecting tapping temperature, and a tap (faucet) 32 is provided at the tapping outlet of the tapping pipe 14.

An input side of a burner controller 34 for controlling the operation of the gas water heater is provided with the flow sensor 2.
6, an incoming water temperature sensor 27, an outgoing water temperature sensor 30 and the like are connected, and an output side of the burner controller 34 is connected to a gas proportional valve 24 and the like.

The gas water heater 10 includes a faucet (faucet) 32.
The water flow switch (flow sensor) 26
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 water pipe 14. At this time, a command is given from the burner controller 34 to the gas proportional valve 24 based on the detection signal from the hot water sensor 30, and the opening degree is adjusted by controlling the proportional valve current value of the gas proportional valve 24 to maintain the hot water temperature at the set temperature. The operation is controlled so as to be drooped.

Thus, in the present invention, the output is calculated only when the capacity of the gas water heater is fully opened, and when the output is lower than a predetermined value calculated from the output in the normal state stored in advance, the heat exchanger is activated. It is determined that the fuel cell 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 when the time during which the proportional valve current value is the maximum (MAX) has elapsed, it is determined that the capacity is fully open.

The method of calculating the output is: (T hot water−T water) × Q hot water = output (Kcal
/ M) T hot water = detected by outflow thermistor T water = detected by incoming water thermistor Q hot water = detected by flow sensor

Further, the output at the time of normal operation is as follows: Output guarantee when the capacity is fully opened = 90% or more of the maximum capacity (A)-Due to the difference in the calorific value of the gas = Output guarantee 100% for propane (LP) gas Above (B)-Decrease in thermal efficiency due to aging = -5% (C) (Decrease in the range that does not cause abnormalities in combustion, etc. even if it falls) Given the above, the output during normal operation is as follows: Become.

Output under normal conditions = (Rated output) × 0.9 × 1 × 0.95 (Kcal / M) (A) (B) (C) This is a gas water heater (20). No.), the output of this gas water heater at normal time is: 20 × 25 × 0.9 × 1 × 0.95 = 427.5K
cal / M

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

Next, a second embodiment of the present invention will be described. In this embodiment, the deterioration of the heat exchanger is estimated based on the tap water temperature, and the combustion is stopped. In a momentary gas water heater in which the set temperature of tapping water can be varied, the tapping temperature is detected, and the amount of gas is controlled, a temperature detecting means (tapping thermistor 30) is provided at the outlet of the heat exchanger and somewhere in the water passage. A limiter (constant flow valve-water governor 28) for regulating the maximum passing water amount is provided, and means (proportional valve current determination circuit) for detecting that the gas amount is fully open is provided. 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.), then the gas volume at the time of use becomes fully open at the set temperature below the middle temperature (45 ° C. or less). Detect hot water temperature by signal,
If the tapping 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 drains or the like, the heat efficiency is reduced from 80% to about 20%, the fin blockage is estimated from the tapping temperature, and the combustion is stopped. The purpose is to let them. In a feedback (FB) control gas water heater, the amount of gas is automatically increased by the amount corresponding to the decrease in thermal efficiency. Therefore, the maximum flow rate is regulated by a constant flow valve so that the capacity is not fully opened when tapping at low temperature. However, if the fins are blocked and the thermal efficiency drops significantly, even if the gas volume is fully opened,
The set low temperature hot water cannot be obtained.

Considering this with an example of a certain gas water heater (also No. 20), the gas water heater has a constant flow valve maximum water amount and a maximum water amount at a water temperature of 0 ° C. controlled at 9.4 liter / min. The output temperature at the time of No. 20 output and the fully open capacity is 20 × 25 / 9.4 = 53 ° C. The conditions at this time are:
Output 90% guaranteed, output down due to variation in calorific value of gas → no down with LP gas Assuming that thermal efficiency degradation due to long-term use is -5%,

[0022]

In this case, unless the performance of the constant flow valve is deviated,
When the capacity is fully opened, the hot water below 45.3 ° C will not be discharged. Therefore, in this case, at the time of setting at 45 ° C. or less, if the tapping temperature does not rise to the set temperature even after a certain period of time when the proportional valve current is at the maximum (MAX), it is determined that an abnormality has occurred and combustion is performed Stop. By this control, it is inferred that the heat exchanger is clogged abnormally or the performance of the constant flow valve is out of order. In any case, the combustion is stopped because it is abnormal.

FIG. 2 supplementarily explains this. The horizontal axis indicates the amount of hot water (Q), and the vertical axis indicates the tapping temperature (T). Now, assuming that the proportional valve current value is in the maximum (MAX) state, the output of the gas water heater is guaranteed to be 90%, and the output is the maximum capacity when the thermal efficiency is estimated to be 5% due to aging. Is represented by a solid curve indicated by “A” in the figure. In this solid curve “A”, as shown in the above-described calculation formula,
When the quantity of hot water (Q) = 9.4 liter / min, the tapping temperature (T) passes through the intersection of 45.3 ° C.

On the other hand, when the thermal efficiency of the gas water heater is abnormally lowered due to clogging of the fins of the heat exchanger or the like, the maximum capacity line is represented by a broken line curve indicated by "B" in the figure. In the broken line curve “B”, the amount of hot water (Q) =
The tapping temperature (T) at 9.4 liter / min is 45.
The temperature does not reach 3 ° C. or higher, and it is determined that combustion is abnormal.

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

When the temperature is set to 45 ° C. or less, regardless of the proportional valve current, if the tapping temperature does not rise to the set temperature even after a certain period of time, it is conceivable that the control is determined to be abnormal and the combustion is stopped. By judging whether or not the proportional valve current is MAX, it is possible to confirm that the FB control is operating normally, and then determine that there is another abnormality and operate the safety device. It should be noted that the present invention is not limited to the above-mentioned embodiment at all, and it is needless to say 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, a decrease in thermal efficiency due to clogging of the fins of the heat exchanger, etc., is quickly detected, and the gas burner is detected. Since the combustion of the gas is stopped, safety in using the gas appliance is ensured.

[Brief description of the drawings]

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

FIG. 2 is a diagram showing the quantity of hot water (Q) and tapping temperature (T) when the fin of the heat exchanger in the gas water heater shown in FIG. 1 is blocked.
FIG.

[Explanation of symbols]

 Reference Signs List 10 gas water heater 12 water supply pipe (water inlet pipe) 14 tapping pipe 16 heat exchanger 20 gas burner 24 gas proportional valve 26 flow sensor 30 tapping temperature sensor 34 burner controller

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F23N 5/02 350 F23N 5/18 F23N 5/24 104 F24H 1/10 303

Claims (4)

(57) [Claims] In a gas water heater comprising a heat exchanger provided with an inlet pipe and a tapping pipe, and a gas burner for heating the heat exchanger, the temperature of hot water flowing through the tapping pipe when the gas burner is fully opened is determined. 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 pipe, and the hot water temperature detecting means Output value calculating means for calculating an output value when the gas burner capacity is fully opened based on detection signals from the incoming water temperature detecting means and the flow rate detecting means; and an output value calculated by the output value calculating means. Output value determining means for determining whether the output value is lower than the output value by comparing the output value with the output 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 a reference output value used for the judgment by the output value judging means is fixed in advance. 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 at the time of first use. . 4. A heat exchanger provided with a water inlet pipe and a hot water pipe , a gas burner for heating the heat exchanger,
When the burner's capacity is fully open, the tap water temperature exceeds the specified temperature.
Maximum hot water amount limiting means that limits the maximum passing water amount so that
And the set temperature of hot water is set to be equal to or lower than the predetermined temperature.
At the time , the hot water temperature detecting means for detecting the temperature of the hot water flowing through the tapping pipe when the gas burner capacity is fully opened, and the hot water temperature when the gas burner capacity is fully opened detected based on a detection signal from the hot water temperature detecting means is the set temperature. Hot water temperature determining means for determining whether or not the temperature is lower than the set temperature. When the detected hot water temperature is determined to be lower than the set temperature, the combustion of the gas burner is stopped. A gas water heater with a combustion abnormality detection function, characterized in that: