A flame sensor performs the same function as thethermocoupleon a gas water heater with a standing pilot. A standing pilot is one that is always burning, and the job of a thermocouple is to shut off the gas if the pilot goes out. A gas furnace has an electronic igniter instead of a st...
When you take the cover off the furnace, do a simple test by turning up the thermostat to call for heat and watching the flames. You want to make sure the flames in all the burners are the same size; if one of the flames is smaller than the others, buildup on the burner has gotte...
replace the ignitor, hook up the connectors and turn on the power. Test the ignitor by turning up the thermostat to force the furnace to start. If problems persist, it may be time for a new ignitor.