Abstract: A forced air gas heating furnace system includes a thermostat having a transformer for converting the typical household 115Vac to a 24V thermostat ac control voltage, and a switch, the thermostat elements connected to the junction of an ac to dc converter, a digital control circuit and a TRIAC. The dc output is connected to a dc voltage regulator which outputs Vcc for a digital control circuit. The gate of the TRIAC is connected to the output of the digital control circuit, and operates in response thereto for selectively triggering the TRIAC for passing the 24Vac transformer control power to a solenoid operated gas valve.