JPH09145158A - Gas hot water heater with abnormality detecting function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To judge an abnormality of combustion due to clogging of fins of a heat exchanger by obtaining thermal efficiency of a gas hot water heater by calculation without using an inlet water temperature thermister. SOLUTION: The title gas hot water heater has a heat exchanger 16 having a water inlet pipe 12 and a hot water discharging pipe 14 and a gas burner 20 for heating the heat exchanger 16, and when the gas hot water heater is used, thermal efficiency is calculated by using a tentative inlet water temperature Tc stored in a RAM memory of a burner controller 34, discharged water temperature Th detected by a discharged water temperature sensor 30, hot water flow rate by a water governor 28 and gas flow rate detected by a gas proportional control valve 24, and a judgment of an abnormal combustion due to clogging of fins of the heat exchanger 16 is made on the basis of the thermal efficiency. Combustion of the burner 20 is stopped as appropriate.

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 with an abnormality detecting function, and more specifically, to a gas having a function of detecting combustion abnormality due to the fins of the heat exchanger being blocked by a drain or the like. It relates to a water heater.

[0002]

2. Description of the Related Art Conventionally, in this type of gas water heater, when the fins of the heat exchanger are blocked by a drain or the like, the thermal efficiency is lowered, and by detecting this, the combustion of gas is stopped. There are various proposals of those having a function of causing the change. For example, in the application previously filed by the applicant, the incoming water temperature detected by the incoming water temperature thermistor provided in the incoming water pipe, the hot water temperature detected by the hot water outgoing temperature thermistor provided in the hot water outlet pipe, and the gas supplied to the gas burner. The thermal efficiency is calculated from the quantity and the combustion of the gas burner is stopped if the thermal efficiency is determined to be lower than a certain reference value.

[0003]

However, as can be seen from, for example, the one previously filed by the present applicant, it is necessary to calculate the thermal efficiency of this gas appliance by providing an inlet water temperature thermistor in the past. Was said to be a component of. Therefore, when manufacturing this gas appliance, it is necessary to install an inlet water temperature thermistor or an outlet hot water temperature thermistor, or wire to send and receive signals from these sensors and a gas proportional valve to the burner controller, which increases the product cost. It was also a factor.

The problem to be solved by the present invention is to provide a gas water heater with an abnormality detecting function for calculating the thermal efficiency without using the incoming water temperature sensor to judge the abnormality of combustion. This not only ensures the safety of using the gas equipment, but also achieves the reduction of the product cost associated with mounting the water temperature sensor on the equipment.

[0005]

In order to achieve this object, a gas water heater according to the present invention has a heat exchanger in which a large number of fins are arranged in a row, and a water inlet pipe and a hot water outlet pipe are arranged in the heat exchanger. In a gas burner for heating a vessel, an inlet water temperature storage means for storing a temporary inlet water temperature, a hot water temperature detecting means for detecting a temperature of hot water flowing through the hot water outlet pipe, and a hot water amount flowing through the hot water outlet pipe are detected. Hot water amount detecting means, a gas amount detecting means for detecting the gas amount of the gas burner, a temporary water temperature stored in the water temperature storing means, and the hot water temperature detecting means,
Thermal efficiency calculation means for calculating the thermal efficiency of this gas water heater based on the detection signals from the hot water amount detection means and the gas amount detection means, and whether or not combustion is abnormal is determined by the thermal efficiency calculated by this thermal efficiency calculation means The thermal gist of the gas burner is stopped when the thermal efficiency determining means determines that the combustion is abnormal.

According to the gas water heater thus constructed, the water supplied to the heat exchanger through the water inlet pipe is heated by the gas burner and obtained as the hot water from the hot water outlet pipe. At that time, the temperature of the hot water flowing through the hot water outlet pipe is detected by the hot water temperature detecting means, the amount of hot water flowing through the hot water outlet pipe is detected by the hot water amount detecting means, and the gas amount of the gas burner is detected by the gas amount detecting means. Then, in addition to the hot water temperature detected by each of these detection means, the hot water amount, and the gas amount, the thermal efficiency of this gas water heater is calculated by taking into consideration the temporary water temperature stored in the water temperature storage means. Based on the calculated thermal efficiency, it is determined whether the combustion is abnormal or not, and when it is determined that the combustion is abnormal, the combustion of the gas burner is stopped.

Further, in the gas water heater according to claim 1, the temporary water temperature stored in the water temperature storage means when the thermal efficiency judging means judges that the combustion is abnormal is the actual water temperature. Equipped with an inlet temperature checker that checks if there is a difference compared to the inlet temperature, and if this inlet temperature check shows that the actual inlet temperature ≥ the provisional inlet temperature, it is judged as combustion abnormality and the actual inlet temperature is exceeded. <In the case of the temporary water temperature, the temporary water temperature stored in the water temperature storage means is updated to the actual water temperature, and the thermal efficiency of this gas water heater is calculated again based on the updated value. It should be set to. By doing so, it is possible to avoid erroneously determining that combustion abnormality has occurred when there is a difference between the temporary water temperature stored in the water temperature storage means and the actual water temperature.

Further, in the gas water heater according to the first or second aspect, it is preferable to provide an abnormality display means for displaying the abnormality when the thermal efficiency calculating means determines that the combustion is abnormal. By doing so, the user of this gas appliance can easily and promptly know that this gas appliance is causing a combustion abnormality by the abnormality display, and the gas appliance maker or service station can be notified of the heat exchanger. Requests for replacement, maintenance, inspection, etc.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described in detail 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 water supply pipe 12 and a hot water discharge pipe 14 are connected to a heat exchanger 16 in which a large number of heat collecting fins are arranged in a row, and the heat exchanger 16 is a casing (inner body). A gas burner 20 that heats the heat exchanger 16 is disposed inside the casing 18.

The gas pipe 22 of the gas burner 20 is provided with a gas proportional valve 24, the water supply pipe 12 is provided with a water flow switch 26 for detecting the flow of water, and a water governor 28 for regulating the flow of the water. And so on. On the other hand, the hot water outlet pipe 14 is provided with a hot water outlet temperature thermistor (hot water temperature sensor) 30 for detecting the hot water temperature, and a tap 32 is connected to the hot water outlet of the hot water outlet pipe 14.

The burner controller 34 for controlling the operation of the gas water heater is connected to the water amount switch 26, the hot water temperature sensor 30 and the like, and the burner controller 34 is connected to the output side of the gas proportional valve 24. Etc. are connected. A RAM memory (not shown) built in the burner controller 34 stores a “temporary water temperature” in which the temperature of the water flowing through the water supply pipe 12 is set in advance.

A gas water heater 10 having such a structure
The water flow switch 26 is turned on by opening the faucet (hot water tap) 32. Then, the gas burner 20 is ignited by the ON signal of the water flow switch 26 to heat the heat exchanger 16, the water supplied from the water inlet pipe 12 to the heat exchanger 16 is heated, and tap water is obtained from the tap pipe 14. . At that time, the temperature of the hot water flowing through the hot water outlet pipe 14 is detected by the detection signal from the hot water temperature sensor 30, and the burner controller 34 gives a command to the gas proportional valve 24 to control the proportional valve current value of the gas proportional valve 24. As a result, the opening degree is adjusted, and the operation is controlled so that the outlet temperature of the hot water flowing through the outlet pipe 14 is maintained at the set temperature.

Thus, according to the present invention, the hot water outlet temperature of the heat exchanger 16 is detected to detect the gas proportional valve 2 of the gas burner 20.
In an instantaneous gas water heater that controls the amount of gas while adjusting the opening of No. 4, the heat efficiency is calculated each time the gas water heater is used, and the heat efficiency is compared with the normal heat efficiency. The fin blockage is estimated and the combustion is stopped safely. As one of the methods, a constant flow valve type is presented.

This constant flow valve type is a hot water temperature thermistor 30 as a hot water temperature detecting means provided at a hot water outlet of a heat exchanger in an instantaneous gas water heater for detecting hot water temperature and controlling a gas amount. And a water governor 28 as a maximum hot water amount limiter provided in any position of the water passage (in this practical example, provided in the water supply pipe 12), and a current value measuring circuit of the gas proportional valve 24 as a gas amount detecting means. Measured thermal efficiency = measured output / measured input is calculated from the detection signal from the burner controller 3 in advance.
The normal thermal efficiency stored in 4 is compared, and if the measured thermal efficiency is <normal thermal efficiency, it is estimated that the voids of the heat collecting fins of the heat exchanger 16 are blocked by the drain of combustion products, and the gas burner 20 is used. Combustion can be safely stopped.

FIG. 2 is a flow chart for explaining a routine for judging abnormal combustion in the gas water heater 10.
Explaining this flowchart, first, when the faucet (hot water tap) 32 is opened (step 1), the water inlet temperature TC at the time of opening the tap is stored in a RAM memory of a computer built in the burner controller 34 (step). 2). The incoming water temperature TC stored in the RAM memory is set so that only the outlet hot water temperature thermistor 30 is energized when the remote controller is OFF when the gas water heater 10 is not used. When only water is flown without ignition, and remote controller O
In the state of N, the minimum temperature of the water flowing through the hot water outlet pipe 14 detected by the detection signal from the hot water outlet temperature thermistor 30 at the time of opening the plug after a long time unused state, that is, at the cold start is set as the incoming water temperature each time. It is updated and stored.

Next, the thermal efficiency η of the gas water heater in this state is obtained by computer calculation (step 3). This thermal efficiency η is the above RA for the time being.
Temporary water temperature TC stored in the M memory and the temperature of the hot water flowing through the hot water outlet pipe 14 sent to the computer by the detection signal from the hot water discharge temperature thermistor 30 at any time Th Water governor 28
The maximum set hot water amount (Qw) and the gas amount (Q by the detection signal from the proportional valve current value measuring circuit of the gas proportional valve 24).
Since the measured output value and the measured input value are obtained by the following mathematical expressions 1 and 2 based on g), the measured output value is divided by the measured input value (measured thermal efficiency = measured output value). Value / measured input value).

[0017]

(Equation 1)

[0018]

(Equation 2)

Next, the thermal efficiency η obtained in step 3
Thus, it is determined whether the combustion abnormality is caused by the fin clogging of the heat exchanger 16 (step 4). This judgment depends on the thermal efficiency η ₁ in the normal combustion state, for example, due to the difference in the equipment of the gas water heater, the difference in the calorific value of the fuel gas used, the operating environment, the performance of the heat exchanger, etc. Judgment will be made in comparison with the value set as a temporary standard. In this embodiment, as a guideline for the thermal efficiency η _{1 in} the normal fuel state, a coefficient K (K is K is added to the thermal efficiency η ₀ that is the reference in the initial performance of this gas water heater.
(1 or less) is set.

In step 4, the thermal efficiency η obtained by the calculation is lower than the thermal efficiency η _{1 in} a normal combustion state, that is, the fins of the heat exchanger 16 are clogged and combustion abnormality occurs (step 4). , "YES"), the combustion of the gas burner 20 is temporarily stopped (step 5). Then, the heat exchanger is cooled by stopping the combustion while water is flowing, and the water flows through the hot water outlet pipe 14. Therefore, the temperature of the "water" flowing through the hot water outlet pipe 14 is detected by the detection signal from the hot water outlet thermistor 30. Is detected (step 6). Since the temperature TC _{1 of} the water detected in this step 6 is not the “temporary inlet temperature” described above but the actual temperature of the water flowing through the inlet pipe 12, the actual temperature TC ₁ of the water is By comparing with the incoming water temperature TC, it is judged whether or not the actual incoming water temperature TC ₁ ≧ the temporary incoming water temperature TC (step 7).

[0021] Then the judgment of step 7, the actual incoming water temperature TC ₁ ≧ tentative incoming water temperature TC between the actual temperature TC ₁ and tentative incoming water temperature TC of the water (step 7, "YE
S ”), it is not an error to judge that the heat exchanger is clogged with fins based on the value of the thermal efficiency η obtained by the calculation in step 3, so an“ abnormality display ”is given. (Step 8), this determination routine ends.

It should be understood that the "abnormality display" in the above-mentioned step 8 includes means for attaching a blinking lamp for displaying an abnormality to the gas water heater, sounding an alarm, and the like.

Next, in step 7 described above, the actual water inlet temperature TC ₁ <temporary water inlet temperature TC (step 7,
If "NO"), it is determined that the temporary water temperature TC stored in the RAM memory is the actual water temperature T.
It is replaced with C ₁ to update the incoming water temperature (step 9). Then, in response to a command from the controller, the gas burner 20 is automatically ignited and combustion is restarted (step 10). Then, returning to step 3, the thermal efficiency η
Is performed.

Calculation formula of thermal efficiency η at this time (Formula 1)
The actual incoming water temperature TC ₁ updated and stored in the RAM memory is used as the incoming water temperature TC used as the algebra of the.
Then, if it is determined from the calculation result that the fins of the heat exchanger 16 are still clogged and the combustion abnormality is occurring (step 4, “YES”), the combustion is temporarily stopped as in the previous time (step 5). The abnormality display is made (step 8) by re-checking the incoming water temperature (steps 6 and 7).

On the other hand, if it is judged in the above step 4 that the fins of the heat exchanger 16 are not clogged and the combustion abnormality does not occur from the calculation result of the thermal efficiency η (step 4, “NO”), the gas burner is naturally operated. The combustion is continued (step 11), and this determination routine ends.

Thus, in the present invention, as described in the above embodiment, the "temporary water inlet temperature TC" is stored in advance in the RAM memory of the computer of the burner controller 34, and the faucet (hot water tap) is opened. When the lever water heater is put into use, the "temporary water inlet temperature TC" stored in the RAM memory, the outlet water temperature Th from the outlet hot water temperature thermistor 30, and the temperature (Qw) by the water governor 28. , And the gas efficiency (Qg) from the gas proportional valve 24 and other data, the thermal efficiency η of the gas appliance is calculated. Therefore, as is generally known in the art, it is not necessary to provide the water inlet pipe 12 with a water inlet temperature thermistor for detecting the temperature of the water flowing therein.

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. For example, although the constant flow valve type is shown in the above embodiment, other types (for example, a type in which a flow sensor is provided in a tap pipe or the like to detect a hot water flow)
And so on.

[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 can be promptly detected. In addition, since the input water temperature thermistor is not required, it is possible to reduce the cost of the product by saving the labor of wiring to attach the input water temperature thermistor to the equipment, ensuring safety in using gas appliances and lowering the product cost. It will be achieved at the same time.

[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 flowchart illustrating a routine for determining combustion abnormality in the gas water heater shown in FIG.

[Explanation of symbols]

 10 Gas Water Heater 12 Water Supply Pipe (Water Intake Pipe) 14 Hot Water Pipe 16 Heat Exchanger 20 Gas Burner 24 Gas Proportional Valve 28 Constant Flow Valve (Water Governor) 30 Hot Water Temperature Sensor (Hot Water Temperature Thermistor) 34 Burner Controller

Claims (3)

[Claims] 1. A gas water heater equipped with a water inlet pipe and a hot water outlet pipe in a heat exchanger in which a large number of fins are arranged in a row, and a gas burner for heating the heat exchanger is provided. Inlet temperature storage means for storing, hot water temperature detecting means for detecting the temperature of hot water flowing through the hot water outlet pipe, hot water amount detecting means for detecting the hot water amount flowing through the hot water outlet pipe, and gas amount detection for detecting the gas amount of the gas burner Means, the provisional water temperature stored in the water temperature storage means, and the thermal efficiency of this gas water heater is calculated based on the detection signals from the hot water temperature detecting means, the hot water amount detecting means and the gas amount detecting means. A thermal efficiency calculation means for determining and a thermal efficiency determination means for determining whether or not combustion is abnormal based on the thermal efficiency calculated by the thermal efficiency calculation means, and when the thermal efficiency determination means determines that combustion is abnormal A gas water heater with an abnormality detecting function, characterized in that the combustion of the gas burner is stopped. 2. The gas water heater according to claim 1,
Furthermore, when the thermal efficiency determination means determines that combustion is abnormal, the incoming water temperature stored in the incoming water temperature storage means is checked to see if there is a difference compared with the actual incoming water temperature. A check means is provided, and if the actual water temperature ≧ temporary water temperature is judged by this water temperature check means, it is judged as combustion abnormality as it is, and if the actual water temperature <temporary water temperature, then the water temperature storage means stores it in the water temperature storage means. A gas water heater with an abnormality detecting function characterized in that the stored temporary water temperature is updated to the value of the actual water temperature and the thermal efficiency of this gas water heater is calculated again based on the updated value. . 3. The gas water heater according to claim 1 or 2, further comprising abnormality display means for displaying the abnormality when the thermal efficiency calculation means determines that combustion is abnormal. A gas water heater with an abnormality detection function.