- Category: Common GAS FURNACE Heating Issues
- Published: 21 November 2013
PILOT OUT – On a “standing-pilot” furnace, the pilot light is not burning and the furnace will not come on.
POSSIBLE PROBLEM & DESCRIPTION
- Many older gas furnaces utilize a “standing pilot” (a small pilot flame that burns continuous inside the burner compartment).
- Standing pilot furnaces require a thermocouple to ensure that the pilot is lit before allowing the main gas valve to open.
- If a standing pilot furnace will not come on, check to see if the pilot is burning.
- If the pilot flame goes out, you may try relighting it. If it will not stay lit, the most likely cause is a bad thermocouple.
Dirty Pilot Orfice - Qualified Technician Recommended
- In order for a thermocouple to properly function, it must have a sufficient heat source to activate. If the pilot orfice becomes clogged, the pilot burner may not be able to produce enough heat to activate the thermocouple.
- The pilot flame should be strong enough that the flame surrounds the sensing element of the thermocouple.
Bad Gas Valve - Qualified Technician Recommended
- If the thermocouple is good and the pilot flame is sufficiently burning but the pilot will not stay lit, there is a possibility that the main gas valve is faulty.