JPH08219447A - Gas boiler with combustion abnormality detecting function - Google Patents

Abstract

PURPOSE: To secure the safety of a gas boiler by preventing a drop in heat efficiency attributed to the clogging of a fin in a heat exchanger by stopping the combustion of a gas burner when the heat efficiency calculated is judged to be lower than a reference heat efficiency. CONSTITUTION: In this gas boiler 10, opening a faucet 32 turns ON a flow rate sensor 26 and a gas burner 20 is ignited to heat a heat exchanger 16 so that water supplied from a water feed pipe 12 is heated to obtain hot delivery water from a hot water delivery pipe 14. At this point, a command is provided to a gas proportional valve 24 from a burner controller 34 by a detection signal from a hot delivery water sensor 30 and the opening thereof is adjusted by controlling a proportional valve current value of the gas proportional valve 24 to control the operation so that the temperature of hot delivery water is kept at a set temperature. Heat efficiency is calculated at each use of the gas boiler 10 and when the heat efficiency calculated is judged to be lower than a reference heat efficiency stored previously in the burner controller 34, 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 (step by step), the heat transfer of the heat collecting fins gradually deteriorates, and the heat efficiency decreases.

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

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to stop combustion of a gas burner when the heat efficiency is lowered due to fin clogging of a heat exchanger. The purpose is to provide a gas water heater. This is intended to ensure safety in using the gas water heater.

[0006]

To achieve this object, a gas water heater according to the present invention comprises a heat exchanger provided with an inlet pipe and an outlet pipe, and a gas burner for heating the heat exchanger. Hot water temperature detecting means for detecting the temperature of hot water flowing through the hot water outlet pipe, water temperature detecting means for detecting the temperature of water flowing through the hot water inlet pipe, and flow rate detection for detecting the amount of water flowing through the hot water inlet pipe or hot water flowing through the hot water outlet pipe. Means, gas amount detecting means for detecting the amount of gas supplied to the gas burner, and thermal efficiency for calculating thermal efficiency based on detection signals from the hot water temperature detecting means, the incoming water temperature detecting means, the flow rate detecting means and the gas amount detecting means. Computation means and thermal efficiency determination means for comparing the thermal efficiency calculated by this thermal efficiency computing means with the reference thermal efficiency to determine whether it is lower than this, the thermal efficiency calculated by this thermal efficiency determination means is higher than the reference thermal efficiency It is an Abstract that combustion of the gas burner is configured to be stopped when the yarn is determined. In this case, the value of the reference thermal efficiency used for the determination by the thermal efficiency determining means may be the calculated value at the time of initial use, or the average value of the results of multiple times (N times) used may be the calculated value.

[0007]

According to the gas water heater 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 obtained 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 hot water inlet pipe, the amount of water flowing through the hot water inlet pipe or the hot water flowing through the hot water outlet pipe, and the amount of gas supplied to the gas burner are detected. Based on this, the thermal efficiency is calculated. When the calculated thermal efficiency is lower than the reference thermal efficiency, it is determined that the combustion of the gas burner is stopped.

[0008]

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 on 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 on 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.

The flow sensor 2 is provided on the input side of the burner controller 34 for controlling the operation of the gas water heater.
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. Hot water temperature sensor 30 at that time
A command is given from the burner controller 34 to the gas proportional valve 24 by a detection signal from the controller, and the opening is adjusted by controlling the proportional valve current value of the gas proportional valve 24 so that the hot water outlet temperature is maintained at the set temperature. Is controlled.

Thus, in the present invention, the thermal efficiency is calculated each time the gas water heater is used and compared with the normal thermal efficiency to estimate the fin blockage of the heat exchanger and stop the combustion. As one method, a flow sensor type is presented.

This flow rate sensor type is an instantaneous gas water heater for detecting hot water temperature to control the amount of gas, and a hot water thermistor 30 as hot water temperature detecting means provided at a hot water outlet of a heat exchanger, and water supply. A water supply thermistor 27 as a water supply temperature detecting means provided in the passage portion, a flow rate sensor 26 as a flow rate detecting means provided somewhere in the water passage, a current value measuring circuit of the gas proportional valve 24 as a gas amount detecting means, etc. By the detection signal from

Measured thermal efficiency = output / input is calculated, normal thermal efficiency stored in advance in the burner controller is compared, and if measured thermal efficiency <normal thermal efficiency, fin blockage of the heat exchanger is estimated, and combustion is performed. Is to stop.

This will be described in detail below. That is, in the above-described equation of measured thermal efficiency = output / input, the output and the input are as in the following equations 1 and 2.

[0016]

[Equation 1]

[0017]

[Equation 2]

In the equation (1), the incoming water temperature (T water) is detected by the thermistor at the outlet of the heat exchanger for a long time,
The minimum temperature in units of one day may be obtained and used as a substitute. In that case, the feed water temperature thermistor 27 is not necessary in the configuration. Further, in the case where the output fluctuates in the formula 1, as a modified example thereof, the integral formula shown in brackets in the formula 1 may be used. Then, from this equation 2, the equation (1) shown in the following equation 3 is obtained.

[0019]

(Equation 3)

Now, in the structure showing the relationship between the gas proportional valve and the gas governor shown in FIG. 2, when the pressure of the gas nozzle (P nozzle in the figure) is controlled by energizing the electromagnetic coil of the gas proportional valve, The balance equation with the load of the gas governor is the following equation (4). The position of each symbol used in the equation 4 is as shown in the above-mentioned structural drawing 2.

[0021]

[Equation 4]

From the equation (4), W≈F ₀ , A≈
When set to A ′, the following equation 5 is obtained.

[0023]

(Equation 5)

Then, the relational expression of the following expression 6 can be obtained by the expression (1) of the expression 3 and the expression (2) of the expression 5 this time.

[0025]

(Equation 6)

Since the proportional valve current changes during the hot water discharge control, the input can be calculated, for example, by integrating the proportional valve current output at a certain time. Now, as shown in the relationship diagram of FIG. 3 in which the horizontal axis represents time and the vertical axis represents the proportional valve current value, it means that the proportional valve Max controls t time = maximum input. Then, the maximum input gas amount and the gas input amount at the time of measurement are as shown in the following Equation 7, respectively.

[0027]

(Equation 7)

The following equation (8) is obtained from equations (3) and (4).

[0029]

(Equation 8)

For example, when a certain gas water heater is specified in the equation (8), its Q gas Max = 37500
Since Kcal / H and IMax = 120 mA are determined, the input can be obtained from the proportional valve current of I and the measurement time of t. Now the normal thermal efficiency is

Instrument difference: Nozzle diameter, gas nozzle pressure, heat exchanger performance, combustion air-fuel ratio variation, thermistor, flow rate sensor, barcon variation, etc. Difference due to calorific value of gas used Difference due to usage environment: temperature, humidity, atmospheric pressure Hot water discharge temperature, hot water flow rate, heat exchanger performance due to incoming water temperature Considering deterioration of thermal efficiency within the range where normal combustion is possible due to aging And then decided. Then, the normal thermal efficiency is obtained according to the following equation (9).

[0032]

[Equation 9]

Regarding the value of k1 in the equation (9), the purpose of the calculation is to estimate the fin blockage due to the lowering of the thermal efficiency, so the direction in which the thermal efficiency increases due to each variation is not considered. For example, if the thermal efficiency and the coefficient (k1) of the initial performance are set as in the following expression 10 in the arithmetic expression of this expression 9, the normal thermal efficiency is as shown in the following expression 11.

[0034]

[Equation 10]

[0035]

[Equation 11]

The normal value of η may be (I) set for each gas type and selectively set using a gas type connector or the like. (II) Settings may be stored for each of the hot water discharge temperature, the hot water discharge amount, and the incoming water temperature. (III) Obtain the initial measured thermal efficiency in the initial state at the site,
If this value is set as the η initial value and is calculated by the following equation 12, the abnormality detection level is further increased.

[0037]

(Equation 12)

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.

[0039]

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 a schematic configuration diagram of a gas proportional valve in the gas water heater shown in FIG.

FIG. 3 is a diagram for explaining calculation of a gas input amount when a proportional valve current value changes during hot water discharge control.

[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 27 Inlet Water Temperature Sensor 30 Outlet Water Temperature Sensor 34 Burner Controller

Claims (3)

[Claims] 1. A gas water heater equipped 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, wherein hot water temperature detecting means for detecting the temperature of hot water flowing through the hot water outlet pipe. A water temperature detecting means for detecting the temperature of the water flowing through the water inlet pipe, a flow rate detecting means for detecting the amount of water flowing through the water inlet pipe or the hot water flowing through the hot water outlet pipe, and a gas detecting the amount of gas supplied to the gas burner. Quantity detection means, thermal efficiency calculation means for calculating thermal efficiency based on detection signals from the hot water temperature detection means, incoming water temperature detection means, flow rate detection means and gas amount detection means, and the thermal efficiency calculated by this thermal efficiency calculation means It comprises a thermal efficiency determination means for determining whether or not it is lower than the reference thermal efficiency, when the calculated thermal efficiency is determined to be lower than the reference thermal efficiency of the gas burner by this thermal efficiency determination means. A gas water heater with a combustion abnormality detection function, characterized in that the combustion is stopped. 2. The gas water heater with a combustion abnormality detection function according to claim 1, wherein the value of the reference thermal efficiency used for the determination by the thermal efficiency determination means is a calculated value at the time of initial use. 3. The combustion abnormality according to claim 1, wherein the value of the reference thermal efficiency used for the determination by the thermal efficiency determination means is an average value of results obtained by using it a plurality of times (N times). Gas water heater with detection function.