METHOD FOR CONTROLLING ROTATIONAL FREQUENCY OF EXHAUST FAN AND SUPPLY AMOUNT OF GAS OF GAS BOILER

摘要

PURPOSE: A controlling method of the rotational frequency of an exhaust fan and the supply amount of gas of a gas boiler is provided to drive an exhaust fan and to supply gas in optimum state by controlling the supply amount of gas to supply gas proper to the rotational frequency of an exhaust fan and to be adapted to the change of aging of a wind pressure switch. CONSTITUTION: A fan driving voltage supplied to an exhaust fan is lowered gradually from the maximum value, and the fan driving voltage at the moment of which a wind pressure switch is turned off is sensed. If the wind pressure switch is on, the fan driving voltage is gradually lowered and supplied. A lowest driving voltage of an exhaust fan is set up by the fan driving voltage supplied to the exhaust fan at the step right before the off of the wind pressure switch by sensing the exhaust fan driving voltage at the moment of which the wind pressure is off. The amount of gas supplied in the driving of the exhaust fan by the supply of lowest driving voltage is set up to the lowest supply amount of gas. When the wind pressure switch is on, the exhaust fan is driven by the fan driving voltage by a predetermined supply amount of gas to be proportional to the sensed fan driving voltage and then the gas is continuously supplied by the predetermined supply amount of gas.