Abstract: A system for controlling the pilot and main burner gas valves of a gas furnace or the like, including a pilot spark ignitor and a pilot flame sensor. A main burner valve control circuit for energizing the spark ignitor until a pilot flame is sensed and then energizing the main burner valve solenoid to provide gas to the main burner. A pilot solenoid valve control circuit for controlling application of power to the ignitor circuit and the pilot and main solenoids. A safety turn on control circuit which permits operation of the pilot valve and ignitor circuit for only a limited period of time to provide a fail safe operation of the ignition system.

Abstract: A system for controlling the pilot and main burner gas valves of a gas furnace or the like, including a pilot spark ignitor and a pilot flame sensor. A system with both pilot and main burners normally off, with the pilot burner being turned on when the thermostat switch closes and with the main burner being turned on when the pilot flame is established, with the main burner being turned off whenever the pilot flame goes out. An electronic circuit with the flame sensor as an input for switching the main burner valve solenoid on and off, with the electronic circuit having a fail safe configuration such that failure of any component between the flame sensor and the relay controlling the main valve solenoid will result in the solenoid being unenergized.

Abstract: A system for controlling the pilot and main burner gas valves of a gas furnace or the like, including a pilot spark igniter and a pilot flame sensor. A relay having a first standby mode providing power to the spark igniter circuit when the thermostat switch is closed and the pilot valve solenoid is energized, and a second operating mode disconnecting power from the spark igniter circuit and providing power to the main valve solenoid when a flame is sensed at the pilot burner. A fast responding, stable and failsafe circuit for operating the relay utilizing a 24 volt supply, with a 48 volt supply provided only for the flame sensor.