When a furnace pilot light won’t stay lit, the cause is usually a worn thermocouple, a dirty pilot orifice, a draft, or a gas supply problem. First, find out whether your furnace even has a pilot. Older furnaces often have a standing pilot that burns all the time, while newer ones use an electronic igniter and have no pilot flame at all, so the troubleshooting is different. Here is how to tell which you have, what to check, and when to stop.
A standing pilot is a small flame that burns all the time, visible through a small window or behind the lower panel. A newer furnace uses a hot surface igniter, a small element that glows orange for a few seconds, and then the burners light. There is no flame waiting in the background.
If you are not sure, look at the label inside the furnace door. A pilot-lit furnace will have lighting instructions with a gas knob marked Off, Pilot, and On. A furnace with an igniter will not. If it has a pilot, it is an older furnace. Some furnaces have an intermittent pilot that a spark lights each time heat is called for; those are not relit by hand.
In the Sacramento area, a furnace sits idle for most of the summer. The first cold morning in the fall is when a dusty orifice, a webbed-over pilot tube, or a tired thermocouple finally shows itself.
On a newer furnace, the same symptom shows up differently. The igniter glows and the burners light, then shut off after a few seconds. That points to the flame sensor, a thin metal rod in the burner flame that proves the burners are on. When carbon coats the rod, the furnace cannot sense the flame and closes the gas valve. After a few failed tries, many furnaces lock out for a while.
If the igniter never glows, it may be cracked or worn out. Cleaning a flame sensor and testing an igniter are jobs for a technician, and a heating tune-up each fall is a good time to have both looked at. The maintenance plan is $14.49 a month per system, with a cooling tune-up in spring and a heating tune-up in fall.
Follow the lighting instructions on the label inside your furnace. Steps and wait times differ by model. The general sequence looks like this:
Stop and do not try again if:
Call us if the pilot will not stay lit after two careful tries, if the burners light and then drop out, if the igniter never glows, or if you would simply rather not work around a gas appliance. Our furnace and heating repair team will find out why it keeps going out and tell you what failed ($89 service call). If you are in Sacramento, see furnace repair in Sacramento.
If your furnace has a standing pilot and keeps giving you trouble, it is also worth a conversation about age. A new furnace uses electronic ignition rather than a flame burning all day, and we install Amana. See furnace installation and replacement to learn about your options.
Call Bronco at 916-675-1062, Monday to Friday, 8 to 5. Tell us what the furnace is doing.
Monday to Friday, 8am to 5pm.
When the heat goes out in cold weather, how the call is handled matters. This is a Google review from a Bronco customer whose heater went out, word for word.
“Our heater had gone out during these chilly temperatures, and while some companies might not have treated it with urgency, Jennifer absolutely did. … Phil arrived, bright and early, he’s a friendly and easy-to-talk-to guy who took the time to clearly explain the issue and what needed to be done.”
Yes, if you smell no gas, the label gives instructions, and you follow them exactly. If the pilot will not stay lit after two tries, stop and call a technician rather than repeating the steps.
That usually means the thermocouple is not generating enough current to hold the gas valve open. It may be worn, sooty, or out of position in the flame. It is a small part, but replacing it involves gas connections, so leave it to a technician.
Mostly blue, steady, and wrapping around the tip of the thermocouple. A yellow, orange, or flickering flame often means a dirty orifice or a combustion problem and should be checked.
Check for drafts first, then relight it once by the label. If it keeps going out, the cause is usually the thermocouple, the orifice, or the gas valve, and all three need a technician.
