| 摘要 |
PURPOSE: A control method of an air pressure switch is provided to prevent cold water from tapping in stop of heating or in use of hot water by turning off a gas boiler with a head wind. CONSTITUTION: A microcomputer(31) checks the status of a gas boiler. The microcomputer keeps the gas boiler standby or detects on/off of an air pressure switch depending on whether the gas boiler is ignited or not. If the air pressure switch is switched on, the microcomputer keeps combustion stroke regular. Otherwise, the microcomputer outputs a control signal to a fan motor(13a) to drive a fan(13) at the maximum rpm(revolutions per minute). After that, the microcomputer checks on/off of the air pressure switch again. If the air pressure switch is switched on, the microcomputer outputs a control signal to the fan motor to reduce the rpm of the fan down to normal rpm stepwise. If the air pressure switch is switched off during the process, the microcomputer drives the fan at specific rpm immediately before switching off. The microcomputer returns to the first step for checking on/off of the switch with keeping the normal rpm. Therefore, hot water is supplied continuously and cold water is prevented from tapping.
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