Also put your finger on the gas solenoid and have someone turn on the heater. Do you feel a click? If so then most likely the tube or jet is plugged. Disassemble and clean out the parts in alcohol and blow out with compressed air. If there is no click on the solenoid then head towards the control board.
Corrosion in the gas lines causes the jet to plug. It only takes a tiny grain to plug the jet.
|