The ICM2910 consists of a series of 11 Fenwal OEM Replacement DSI Controls. When the thermostat initiates a “Call for Heat”, the ICM2910 will perform a hardware check. After the hardware check, the ICM2910 will start a pre-purge where applicable. Once the pre-purge has ended, the spark source and the gas valve relay are energized simultaneously for the duration of the trial for ignition period. A flame rectification circuit confirms the presence of the flame. Upon flame detection, the spark source is turned off. If flame is not sensed, the control will turn off the spark source and gas valve and start an inter-purge where applicable before the next trial for ignition. If flame is not detected after the trial(s) for ignition, the control will enter a hard lockout. To clear the hard lockout, remove the input voltage to the control or recycle the thermostat's heat call.