EXPLOSION IGNITION PREVENTING METHOD IN COMBUSTION DEVICE

PURPOSE: To enable an explosion ignition preventing method of a combustion device by a method wherein there are provided a proportional valve capable of varying a gas flow rate in a fuel gas flow passage, a first solenoid valve for opening or closing the gas flow passage, a second solenoid valve for forming a closed space together with the first solenoid valve and further a gas pressure applying step for opening the solenoid valve for a predetermined period of time and a pressure releasing step are carried out. CONSTITUTION: A hot water feeding relay contact point 34 is turned on at a gas pressure applying step and a hot water supplying solenoid valve is opened for a specified period of time. With such an arrangement as above, a gas pressure is applied in a closed space between the hot water feeding solenoid valve and a proportional valve and then a diaphragm of the proportional valve returns to a position near its normal state. At a gas releasing step, any number of relay contact points of hot water feeding capability changing-over relay contact points 35a to 35c are turned on and any number of solenoid valves of the hot water feeding capability changing-over solenoid valves are opened for a predetermined period of time. With such an arrangement as above, a pressure within the closed space between the proportional valve and the hot water feeding capability changing-over solenoid valve returns to a surrounding atmospheric pressure and further the diaphragm of the proportional valve returns to its normal position.