Symptoms
- No heat and no small blue flame visible at the pilot assembly
- Furnace completely unresponsive to thermostat calls for heat
- May have gone out due to a draft or run of its own accord
Likely causes
- CommonDraft or airflow blew the pilot outA gust from a nearby vent, door, or window can extinguish a small flame.
- CommonWeak or failing thermocoupleA thermocouple nearing failure can let the pilot go out more easily or fail to reignite.
- PossibleGas supply interruptionA brief utility outage or closed valve can extinguish the pilot.
- PossibleDirty pilot orifice producing an unstable flameA weak, flickering flame is more prone to going out.
What to do
- Find the lighting instructions, usually printed on a label inside the furnace access panel.
- Turn the gas control knob to Off and wait about 5 minutes for any residual gas to clear.
- Turn the knob to Pilot, press and hold it in, and light the pilot with a long lighter or match at the opening indicated.
- Keep holding the knob in for the time specified (usually 30–60 seconds) until the flame stays lit on its own.
- Release the knob slowly; if the pilot goes out, repeat once, then turn the knob to On and restore the thermostat call for heat.
- If it won't stay lit after two attempts, stop and treat it as a thermocouple issue rather than continuing to try.
Tools and parts
- Long lighter or fireplace match
When to call a pro
Call a technician if the pilot won't relight or stay lit after two attempts, or anytime you smell gas.
Safety
Use caution
Always wait the full clearing time before relighting, follow the printed instructions exactly, and stop immediately if you smell gas.