How it works
Most Hot Surface Electronic Ignition Furnaces
Sequence of operation:
1. The furnace must have power and the switch to the unit must be in the on position.
2. The thermostat in the home on the wall needs to be set to call for heat.
3. The combustion air fan will come on and will activate the vacuum switch.
4. The control board will confirm the vacuum switch has been activated and will turn on the hot surface igniter.
5. After a preset time designed into the control board, to allow the hot surface igniter to heat to ignition temperature, the gas valve will activate delivering gas to the furnace.
6. A flame sensor will sense that the flame has been established and the hot surface igniter will shut off.
7. After a preset time designed into the control board for the above operations to take place and the furnace to reach heating temperature the fan delivering heat to the home will come on.
8. When the temperature in the home reaches the thermostat setting the furnace will turn off. The fan delivering heat to the home will remain on for a short period of time programmed into the control board to allow the furnace to cool down and efficiently use the heat that was produced in the furnace. Then the fan will shut off and the furnace will wait for the next call for heat from the thermostat and the sequence will repeat.