You have an older furnace with a standing pilot light. You hold the button in to light it, it catches, but the moment you let go it dies.
You probably came here because…
- Older furnace (usually pre-2000) with a standing pilot
- Pilot lights when you hold the reset button in
- The moment you release the button, the pilot goes out
- You may need to repeat this multiple times before it holds
What’s actually happening
This is almost always the thermocouple – a small metal probe that sits in the pilot flame. When it's hot, it generates a tiny voltage that tells the gas valve to keep the gas on. When it goes bad or gets dirty, that voltage drops and the gas valve shuts.
Thermocouples are cheap ($20-30 part) and easy to replace. It's a 20-minute job for a tech, an hour if you're doing it yourself the first time.
The other, less common cause is a bad gas valve or a draft blowing the pilot out. Newer furnaces don't have this problem because they use hot-surface ignitors instead of standing pilots.
What we do about it
Try to relight it correctly
Turn the gas valve to Pilot. Hold the reset button down for 30-60 seconds (not 10) while you light the pilot with a long lighter. Keep holding for another 30 seconds after it lights, then release. If it dies immediately, thermocouple is bad.
Check for drafts
If the furnace is in an unfinished basement or garage, wind whistling through a vent or open window can blow out a pilot. Look for obvious drafts near the furnace.
Replace the thermocouple
Not a scary repair. Shut off the gas, remove the thermocouple (two screws and a nut on the gas valve), take it to a hardware store for a match, install the new one. Or call us and we'll do it in an hour.
When to just call
If you smell gas at any point, or if you have trouble relighting the pilot correctly, do not force it. Older furnaces with pilot issues are often near end-of-life. Call (423) 637-1846 and we'll fix it – or tell you honestly if it's time to plan a replacement.
Ready to fix it?
Call the family that’s been doing this in the Sequatchie Valley since 1996.