KR19990038880A - Float switch failure detection method - Google Patents

Abstract

The present invention relates to a method for detecting a failure of a gas boiler float switch, and more particularly, when a failure occurs in a float switch detecting a water level inside a water tank in order to compensate for insufficient heating water during boiler use. The present invention relates to a float switch failure detection method of a gas boiler which can detect and notify a user.

Float switch failure detection method of the present invention, a microcomputer with a program for controlling the entire stroke, a float switch for detecting the water level stored in the water tank, and the automatic replenishment for replenishing the water tank In a gas boiler comprising a valve and a gas valve for supplying gas for combustion in a burner, the microcomputer senses whether the maximum time required for water replenishment has elapsed while the float switch is turned on and the automatic refill water valve is turned on. The first step to do; A second step of ignoring the on-state signal input from the float switch in the microcomputer after the maximum time has elapsed; A third step of supplying gas to the burner so as to combust at the lowest heating value by controlling the gas valve in the state of switching to the heating mode; A fourth step of measuring a rate of change of heating water temperature by using a temperature detecting unit and determining that there is no water in the water tank and performing a fire extinguishing operation when the rate of change of temperature rises above the reference value; And a fifth step of indicating a float switch failure if the temperature change rate does not exceed the reference value.

Description

Float switch failure detection method

The present invention relates to a method for detecting a failure of a gas boiler float switch, and more particularly, when a failure occurs in a float switch detecting a water level inside a water tank in order to compensate for insufficient heating water during boiler use. The present invention relates to a float switch failure detection method of a gas boiler which can detect and notify a user.

Since gas boilers do not cause pollution due to their ease of use and low emission of environmental pollutants, they are increasingly being used for home and industry. Gas boilers are used to heat indoors or to supply hot water by using combustion heat generated when burning gas. 1 and 2 is a schematic view showing an embodiment of a conventionally used domestic gas boiler, the former is a schematic diagram of the boiler, the latter is an electrical wiring diagram of the boiler with reference to this briefly describe the operating state.

As shown in FIG. 1, when the gas valve 1 is opened, gas flows into the burner 3 along the gas supply pipe 2, and the burner 3 mixes and combusts gas and air at an appropriate ratio. The combustion gas is discharged through the exhaust flue 5 after heating the heat exchanger 4 while rising. The heating water heated in the heat exchanger (4) is transferred to the water tank (6) or the hot water heat exchanger (7) along the connected pipe, and the heating water is heated by the rotation direction of the bidirectional pump (8) for indoor heating. It flows out through the water supply pipe 9 and flows directly into the hot water heat exchanger 7 for hot water use. That is, when hot water is used, the direct water flows into the hot water heat exchanger 7 through the direct water supply pipe 10, and the hot water heat exchanger 7 heats the direct water with hot water and flows out into the hot water discharge pipe 11.

The flow switch 13 detects the inflow of water and inputs a water inflow signal to the microcomputer 20 of FIG. 2. In the microcomputer 20, the bidirectional pump 8 is operated in the direction of using hot water. Then, the heating water of the heat exchanger (4) flows into the hot water heat exchanger (7) via the water tank (6) and the bidirectional pump (8) by driving the bidirectional pump (8), and the hot water heat exchanger (7). From the flow back to the heat exchanger (4). Here, the heating water flows in isolation from the direct water, which receives the heat from the heating water, becomes hot water, and flows out into the hot water discharge pipe 11.

On the other hand, when the water in the water tank 6 becomes low due to vaporization or the like, water is replenished. At this time, the microcomputer 20 opens the automatic refill water valve 15 in response to the water level signal from the float switch 6a. Operated to supply water directly to the water tank (6). The automatic supplement water valve 15 is installed on the supplementary water supply pipe 16 connected to the direct water supply pipe 10 while being installed at one outlet side of the hot water heat exchanger 7, and the supplementary water supply pipe 16 is It is connected to the water tank (6). In the heating mode, the heating water discharged from the heat exchanger (4) moves through the water tank (6), the two-way pump (8), the heating water supply pipe (9), and passes through the room to dissipate heat, and the heating water return pipe (140) Then, the process returns to the hot water heat exchanger 7 and the heat exchanger 4. The operating state of the block circuit diagram of Fig. 2 is the same as that described above, and thus a detailed description thereof will be omitted.

If you use the gas boiler for a long time, water evaporates naturally, so you need to replenish water. This water replenishment is performed by detecting the water level by the float switch 6a installed inside the water tank 6. When the water level measured by the float switch 6a is below the prescribed level, the microcomputer 20 detects this and outputs a control signal to the automatic refill water valve 15 to supply direct water. When the automatic refill water valve 15 is opened, the direct water supplied through the direct water supply pipe 10 passes through the automatic refill water valve 15 and flows into the water tank 6.

Conventionally, when the water level introduced through the automatic refill water valve 15 reaches the prescribed level, the float switch 6a detects this and notifies the microcomputer 20 to detect that the water level is full. However, if the float switch (6a) measuring the water level failure occurs, even if the water reaches the full water level, the supply is not stopped and continues to be supplied, the water is wasted or the water is not supplied properly, the heat exchanger (4) There was a problem of being burned out.

The present invention has been made to solve the above problems, an object of the present invention is to detect this in the event of a failure in the float switch for detecting the water level in the water tank to compensate for the lack of heating water during boiler use The present invention provides a method of detecting a failure of a float switch of a gas boiler which can notify a user.

Float switch failure detection method of the present invention for achieving the above object, a microcomputer with a program for controlling the entire stroke, a float switch for sensing the water level stored in the water tank, and water in the water tank A gas boiler comprising an automatic refill water valve for replenishment and a gas valve for supplying gas for combustion in a burner, wherein the maximum time required for refilling water is set when the float switch is turned on and the automatic refill water valve is turned on. A first step of detecting from the microcomputer whether elapsed; A second step of ignoring the on-state signal input from the float switch in the microcomputer after the maximum time has elapsed; A third step of supplying gas to the burner so as to combust at the lowest heating value by controlling the gas valve in the state of switching to the heating mode; A fourth step of measuring a rate of change of heating water temperature by using a temperature detecting unit and determining that there is no water in the water tank and performing a fire extinguishing operation when the rate of change of temperature rises above the reference value; And a fifth step of indicating a float switch failure if the temperature change rate does not exceed the reference value.

1 is a schematic configuration diagram of a gas boiler conventionally used;

2 is a partial block circuit diagram of the gas boiler of FIG.

3 is a graph showing a state of temperature change, ⓐ is a graph showing a heating supply water temperature, ⓑ is a heating return temperature change,

4 is a flow chart illustrating the method of the invention.

<Explanation of symbols for main parts of the drawings>

1: gas valve, 2: gas supply pipe,

3: burner, 4: heat exchanger,

5: exhaust year, 6: water tank,

7: hot water heat exchanger, 8: bidirectional pump,

9: heating water supply pipe, 10: direct water supply pipe,

11: hot water discharge pipe, 12: control unit,

13: flow switch, 14: heating return pipe,

15: automatic refill water valve, 16: replenishment water supply pipe,

17: salt voltage meter, 18: igniter,

19: temperature detection unit, 20: microcomputer.

Hereinafter, the float switch failure detection method of the present invention will be described in detail with reference to the accompanying drawings.

The method of the present invention is a method for detecting a failure in a float switch for replenishing water by sensing a water level in a water tank, and a water replenishment is completed after a water replenishment signal by a float switch is input. It is a method to detect the failure state by measuring the temperature change when the maximum time does not return after the elapse of time.

The method of the present invention as described above, can be performed using the circuit of the conventional gas boiler shown in Figure 2, the following steps: the maximum required for water replenishment with the float switch is on and the automatic refill water valve is on A first step of detecting from the microcomputer whether the time has elapsed; A second step of ignoring the on-state signal input from the float switch in the microcomputer after the maximum time has elapsed; A third step of supplying gas to the burner so as to combust at the lowest heating value by controlling the gas valve in the state of switching to the heating mode; A fourth step of measuring a rate of change of heating water temperature by using a temperature detecting unit and determining that there is no water in the water tank and performing a fire extinguishing operation when the rate of change of temperature rises above the reference value; And a fifth step of indicating a float switch failure if the temperature change rate does not exceed the reference value.

The method of the present invention can be applied even when the gas boiler is in operation or not. If the water replenishment signal is input from the float switch 6a for water replenishment due to insufficient water in the water tank 6 while the boiler is in operation or in the standby state, the microcomputer 20 recognizes this and automatically replenishes the replenishment water for replenishment. Open the valve 15. Water supplied from the open automatic water refill valve 15 is introduced into the water tank 6 through the replenishment water supply pipe 16.

When a failure occurs in the float switch 6, there are two cases. That is, the signal from the float switch 6a indicates that there is no water or that there is always water. In the absence of water, the float switch 6a does not detect the water level even after the maximum time that the water tank 6 is filled by supplying water from the automatic refill water valve 15 so that the automatic refill water valve 15 ) Will remain open. In the presence of water, it is always recognized that water is present. Therefore, water shortage occurs and expensive heat exchangers are damaged by overheating.

In the state where water shortage is detected and the water replenishment stroke is performed, the microcomputer 20 ignores the state signal input from the float switch 6a when the maximum estimated time elapses and forcibly switches to the heating mode. Switching to the heating mode can be achieved by changing the flow path of the bidirectional pump 8. After switching to the heating mode, the microcomputer 20 controls the gas valve 1 to supply the gas amount so that combustion is performed in the burner 3 with the minimum heating value of the boiler. The minimum calorific value combustion lasts for a predetermined time.

While performing the combustion stroke, the microcomputer 20 senses the heating water temperature change rate ΔT / t using the temperature sensing unit 19. The temperature change rate may be, for example, a value such as 2 ° C./min (2 ° C. temperature rise per minute). Of course, it is apparent to those skilled in the art that this value has different values depending on the capacity of the boiler, the amount of heat generated, and the like. Although the temperature sensing unit 19 is shown as measuring the temperature of the heating supply water in the present invention, those skilled in the art to which the present invention belongs may be attached to the heating water return pipe 14 to measure the heating return temperature. It is obvious.

The measurement result of the rate of temperature change is compared with other reference values stored in the microcomputer 20. In other words, the temperature change rate in the normal combustion state is stored in the microcomputer 20 so that the reference value and the measured change rate are compared. The reference value may be calculated in advance by experiment or calculation and stored in the memory device.

As a result of the comparison, when the rate of change of temperature rises above the reference value, this indicates that there is no water in the water tank 6. That is, since the water supplementation is not performed due to the malfunction of the automatic refill water valve 15 or the shortage and low water pressure, the microcomputer 20 performs a fire extinguishing stroke to prevent burnout. For the extinguishing stroke, the microcomputer 20 outputs a control signal to the gas valve 1 to cut off the gas supply to stop combustion in the burner 3. At this time, the bidirectional pump 8 and the fan (not shown) continue to operate for heat dissipation. When the fire extinguishing administration is completed, the microcomputer 20 displays a state without water to the user. This water shortage may be caused by a malfunction of the automatic replenishment water valve 15, but is mainly caused by a water replenishment not being properly performed while the fault state of the float switch 6a is maintained in an off state (always filled with water).

The method of the present invention can be applied to both models to control the boiler using the heating water supply temperature or to control the boiler using the heating return temperature. Figure 3 shows the change in the heating water temperature in the absence of water, ⓐ shows the change in the heating supply water temperature, ⓑ the temperature change of the heating return water. That is, the heating supply water responds quickly to heat, so the temperature rises rapidly and the rate of change of temperature also rises accordingly.

However, the heating return corresponds to the temperature after some time has elapsed, so it can be seen that the temperature gradually increases while maintaining a constant temperature for a predetermined time. Therefore, it can be seen that the method of the present invention can be applied by providing a slight delay time (D) when temperature control is performed using the heating return temperature. The delay time (D) may vary depending on the boiler and is preferably set to about 5 minutes.

If the rate of change of temperature satisfies the threshold, it means that the water is replenished normally. Therefore, the microcomputer 20 determines that a failure occurs in the float switch 6a installed in the water tank 6. At this time, the boiler was in a combustion operation and the user could indicate the failure of the float switch 6a while performing normal operation. If a fault is found, the user can stop using the boiler and replace the float switch 6a to use the boiler.

As described above, according to the present invention, when a failure occurs in the float switch for detecting the water level inside the water tank in order to replenish the heating water shortened during the use of the boiler, it is advantageous in that it can be detected and notified to the user.

Although the invention has been described in detail only with respect to the described embodiments, it will be apparent to those skilled in the art that modifications and variations can be made within the spirit and scope of the invention, and such variations or modifications will belong to the appended claims. .

Claims (2)

Micom 20 with a built-in program for controlling the entire stroke, a float switch 6a for detecting the water level stored in the water tank 6, and automatic for replenishing water in the water tank 6 In a gas boiler comprising a make-up water valve 15 and a gas valve 1 for supplying gas necessary for combustion in the burner 3, A first step of detecting by the microcomputer 20 whether the maximum time required for water replenishment has elapsed while the float switch 6a is turned on and the automatic refill water valve 15 is turned on; A second step of ignoring the on-state signal input from the float switch 6a in the microcomputer 20 after the maximum time has elapsed; A third step of supplying gas to the burner 3 so as to combust at the lowest calorific value by controlling the gas valve 1 in the state of being switched to the heating mode; A fourth step of measuring a rate of change of heating water temperature using the temperature detecting unit 19 and determining that there is no water in the water tank 6 and performing a fire extinguishing operation when the rate of change of temperature rises above the reference value; And Float switch failure detection method, characterized in that it comprises a fifth step of indicating a failure of the float switch (6a) if the temperature change rate does not exceed the reference value. The method of claim 1, wherein the rate of change of the heating water temperature in the fourth step increases rapidly when temperature control is performed using the heating water supply temperature, and rapidly increases after a delay time (D) when temperature control is performed using the heating return temperature. Float switch failure detection method characterized in that.