METHOD FOR OPERATING SAFELY UNDER RESIDUAL FIRE IN GAS BOILER

摘要

PURPOSE: A method for operating safely under residual fire in gas boiler is provided to prevent racing of a gas boiler by detecting a water level as being in low level upon lack of water in a duct of a gas boiler with a sensor for detecting low water level positioned in the duct, detecting a temperature of hot water with a first thermistor at an outlet port of heating water and a second thermistor at an inlet port of heating water flowing back, determining abnormal overheating condition, and then controlling the boiler to be ignited or extinguished. CONSTITUTION: A method for operating safely under residual fire in gas boiler comprises the following steps: a step for applying power source to a system of gas boiler(S10); a step for detecting whether water level is low or not with a sensor for detecting low water level(S12); a step for stopping combustion operation by carrying out an abnormal mode, if the water level is detected as low from a detection of water level, but operating a circulating pump circulating hot water in the duct, if not so(S14); a step for identifying whether the circulating pump is operated or not based on a response signal regarding to the operation of the circulating pump(S16); a step for carrying out the abnormal mode, if the response signal is abnormal operation, but, if not so, detecting the revolution frequency of the circulating pump and then determining whether the normal revolution frequency of the circulating pump is maintained in a constant time period(S18); a step for carrying out the abnormal mode, if the revolution frequency of the circulating pump is abnormal, but, if not so, turning on an ignitor and igniting to the burner(S20); a step for detecting whether a flame load which detects whether the burner is fired or not is turned on or not(S22); a step for measuring the variation of temperature difference(delta T) between a temperature at an outlet port of hot water and a temperature at an inlet port of hot water flowing back with a first and a second thermistors(S24); a step for detecting whether the temperature difference is kept in an equilibrium state during the fixed number of times within a predetermined time period or not(S26); and a step for stopping the combustion operation, if the temperature difference is decided as not being in an equilibrium state from the detection, but carrying out normal combustion operation(S28), if the temperature difference is in an equilibrium state.