Method for decreasing the possibility of a fire alarm producing a false alarm

摘要

The method involves providing combustion gas sensor (2) comprising a gas-sensitive FET (4). An evaluation unit (5) is provided to evaluate the moisture-dependent magnitude of sensor signal, while applying additional potential change in the form of square wave voltage to the gate of FET to vary the sensor signal. A fire alarm (1) is set to avoid a false alarm caused by moisture in a fault mode, when specific evaluation result is present. An independent claim is included for fire alarm.