Why Is the Furnace Pilot Light Going Out?

A pilot light that keeps going out is usually caused by a draft, a dirty pilot assembly, a worn thermocouple or flame sensor, or a problem with the gas supply. Some of those are simple, and some involve gas components that only a licensed technician should touch.

First, a safety point. If you ever smell gas, leave the house, do not flip switches, and call your gas provider or emergency services from outside. Do not relight anything until the smell is gone and a professional has checked it.

How a standing pilot works

Older furnaces keep a small flame burning all the time. That flame heats a safety device called a thermocouple, which produces a tiny electrical signal that tells the gas valve it is safe to stay open. If the flame goes out, the signal stops and the valve closes so gas does not keep flowing. When the pilot will not stay lit, that safety system is doing its job, and your task is to find out why it was triggered.

Newer furnaces skip the standing pilot and use an electronic igniter with a flame sensor. The idea is the same, and the symptoms are similar: the burner lights, then shuts off after a few seconds.

Common reasons the flame goes out

• A draft or downdraft from the flue or nearby vents blowing the flame out
• A dirty pilot orifice partly blocked by dust or soot, giving a weak, flickering flame
• A worn or misaligned thermocouple that no longer senses heat properly
• A gas valve or regulator that is not delivering steady pressure
• A dirty flame sensor on an electronic ignition furnace

The Tri-Cities is dusty, especially after harvest season and windy spells, and a furnace that sat idle all summer often picks up a layer of it. That is one reason problems show up on the first cold nights.

What you can safely check

Start with the basics. Make sure the thermostat is set to heat and calling for warmth, the furnace switch is on, and the filter is clean, since a clogged filter can cause overheating that shuts a furnace down. If your manual describes a relighting procedure and you are comfortable following it exactly, that is fine once. If the pilot goes out again, stop.

Repeated relighting is not a fix. Cleaning a pilot assembly, replacing a thermocouple, or adjusting gas pressure is work for a licensed technician, because mistakes involve gas and combustion.

Why a yearly tune-up helps

Most pilot problems build slowly. Dust collects, parts wear, and connections loosen. A yearly furnace inspection catches those things before they leave you cold in the middle of winter. Most furnaces last 15 to 20 years, and a unit that has reached that range and keeps losing its flame may be worth a conversation about replacement.

When replacement enters the conversation

An older furnace with a standing pilot is not automatically a problem, and many run safely for years with good care. But if the pilot problems keep coming back, if the heat exchanger shows wear, or if repairs are stacking up, it is reasonable to compare the cost of another repair with the value of a newer, more efficient unit. A technician can give you an honest read on which side of that line your furnace is on, and you are free to take your time deciding. If you do replace it, ask about the ignition style and venting of the new unit so you know what to expect from it.

If your pilot will not stay lit, Air-Tech can help. Call (509) 392-2021 during office hours, Monday to Friday, 8 to 5, and remember that the company also offers 24-hour emergency service when a cold night will not wait.