That allows heat to be dissipated from the heat exchanger. This process happens with a small delay in the blower shutting down.
That is so warm or hot air is delivered throughout the supply ducts.įurthermore, the next step in the gas furnace sequence of operation is the thermostat is satisfied and shutting everything down. The reason for this is that the heat exchanger needs to warm up before the blower turns on. That controls the time when the blower turns on. Blower control is either on a timer or a temperature sensor. The next step depends on the manufacturer of the control board. The heat exchanger is getting ready for the next part of the gas furnace sequence of operation. In the case of direct ignition, the main burner is already burning, and the heat exchanger is heating up. The intermittent pilot lights the main burners. Once the control board is satisfied that the flame is proven burning, either it opens the main valve. A single wire runs from the flame sensor to the ignition control board or module. A flame sensor that touches the flames when the burner ignites takes care of this issue. Most manufacturers use the flame rectification method to ensure the flame is burning. In that case, with no flame, the furnace would create an explosion hazard. That proves the gas is being consumed and not spewing into the environment.
#Furnace won t ignite trial
The trial for ignition includes a flame proving to ensure there is, in fact, a flame. See our article for electronic ignition gas furnace types. You could have hot surface ignition, direct spark, intermittent pilot, or possibly some other ignition. Depending on the type of electronic ignition gas furnace, the source of ignition starts a trial for ignition. The gas furnace control board checks the safety circuit to ensure all the safeties are closed.Īfter safeties are confirmed to be good, the control board sends a signal to start the ignition process. The induced draft motor pulls air through the heat exchanger(s).Ībove all, safety is vital. The difference being the forced draft blower blows air through the heat exchanger(s). Some furnaces have either a forced draft motor, and others have an induced draft motor. The induced draft or forced draft motor engages. A signal for the gas furnace control board to put everything into motion. This completion of the heating circuit in the gas furnace sequence of operation is a signal. The thermostat completes a primary circuit for heating. The thermostat is the first part of the sequence of operations for the gas furnace. The house is cold, and the furnace needs to come on to heat the house. On most electronic ignition gas furnaces sequence of operation but not all the sequence will occur in the following manner: The Sequence of Operation - Electronic Ignition | Electronic Ignition Gas Furnace Problems and TroubleshootingĬall for heat at the thermostat. The Sequence for Most Electronic Ignition Gas Systems Electronic Ignition Gas Furnace Problems and Troubleshooting