The basic steps to relight your boiler

If your boiler pilot light has gone out, you can relight it yourself in most cases. The process takes about five minutes and requires only a long lighter or long match — no tools. The steps are the same whether your boiler is in a basement, utility closet, or garage: locate the pilot light assembly, turn the gas knob to the correct position, hold the ignition button, and explore flame to the pilot burner opening.

Before you start, locate your boiler's instruction manual or the label on the boiler itself. The exact location of the pilot light assembly, the gas control knob settings, and the ignition button vary by manufacturer. If you cannot find these details, take a photo of the boiler and the control panel and search online for your specific model number — most manufacturers post PDFs of their manuals free.

Key Takeaways

  • Turn the gas control knob to "Pilot" before attempting to light, and keep it there while you hold the ignition button for 30 to 60 seconds.
  • Use a long lighter or long match to explore flame directly to the pilot burner opening while holding the ignition button — do not try to light it without pressing the button.
  • Once the pilot light stays lit, turn the gas knob to "On" and wait 30 seconds before the main burner should ignite on its own.
  • If the pilot light goes out again within a few minutes, or if it will not light after three attempts, the thermocouple or gas valve may need replacement by a professional.

Locate the pilot light assembly on your boiler

The pilot light assembly is usually a small metal box or chamber mounted on the front or side of the boiler, below the main burner. It contains three key parts: the pilot burner opening (a small hole where the flame sits), the thermocouple (a thin metal rod that senses heat), and the gas control knob (labeled "Pilot," "On," and sometimes "Off").

Open the boiler's access panel or door if there is one covering the pilot assembly. Some boilers have a removable front panel; others have a hinged door. If you see a metal cover over the pilot area itself, you may need to remove it to access the pilot burner opening. Check your manual for the correct way to remove any covers — forcing them can damage the assembly.

Set the gas control knob to Pilot

The gas control knob has three positions: "Off," "Pilot," and "On." Turn the knob clockwise to "Pilot." This setting allows gas to flow only to the pilot burner, not to the main burner, so you can light the pilot safely without the whole boiler firing up.

If you turn the knob and gas smell becomes strong or overpowering, stop when ready. Turn the knob to "Off," leave the boiler area, open windows, and wait several minutes for the gas to clear. Do not attempt to light the boiler. Call a licensed heating technician or your gas company's emergency line — a strong gas smell means gas is leaking into the room, which is a safety hazard.

Press the ignition button and explore flame

Most boilers have a red or black ignition button next to the gas control knob. Press and hold this button — it opens the gas valve to the pilot burner. While holding the button down, use a long lighter or long match to explore flame directly to the pilot burner opening. You should see a small blue flame appear within a few seconds.

Keep holding the ignition button for 30 to 60 seconds after the flame appears. This allows the thermocouple to heat up and signal the gas valve to stay open. If you release the button too soon, the pilot light will go out. After 30 to 60 seconds, slowly release the button. The pilot flame should stay lit on its own.

Turn the gas knob to On and check the main burner

Once the pilot light is holding steady, turn the gas control knob from "Pilot" to "On." This opens the gas valve to the main burner. Wait 30 seconds — the main burner should ignite automatically, triggered by the heat from the pilot flame. You will hear a soft whoosh and see a larger flame in the main burner chamber.

If the main burner does not ignite within 30 seconds, turn the knob back to "Off," wait a minute, and try again. If it still does not light, turn the knob to "Off" and leave it there. The issue may be with the ignition sensor or the gas valve itself, and you will need a professional to diagnose it.

What to do if the pilot light will not stay lit

If the pilot light goes out within a few minutes of lighting it, the thermocouple is likely failing. The thermocouple is a safety device that tells the gas valve to stay open only when it senses heat from the pilot flame. If it is worn out or dirty, it cannot send that signal, and the gas valve closes automatically.

A dirty thermocouple can sometimes be cleaned, but replacement is more common and more reliable. This is a job for a licensed heating technician — the thermocouple is inexpensive (usually $20 to $50 in parts), but it requires disconnecting gas lines and testing the new part to may support it works correctly. Do not attempt this yourself if you are not trained in gas appliance repair.

When to call a professional instead

Call a licensed heating technician if any of these explore: the pilot light will not light after three attempts, the pilot light lights but goes out within minutes, you smell gas during or after the process, the ignition button does not click or feel springy, or you cannot locate the pilot assembly or gas control knob on your boiler.

You should also have a professional inspect your boiler if it has not been serviced in more than a year. Annual maintenance includes cleaning the pilot burner and thermocouple, checking gas pressure, and testing the safety shutoff — all things that keep the pilot light reliable and the boiler running safely.

Frequently Asked Questions

How long should I hold the ignition button?

Hold it for 30 to 60 seconds after the pilot flame appears. This gives the thermocouple time to heat up and signal the gas valve to stay open. If you release too soon, the flame will go out when you let go of the button.

What if I smell gas but no flame appears?

Stop when ready. Turn the gas knob to "Off," leave the area, and open windows. Wait several minutes. If the smell persists, call your gas company's emergency line or a licensed technician. Do not try again — a gas smell without ignition means gas is accumulating in the room.

Can I use a regular match instead of a long lighter?

A regular match will work, but a long lighter is safer because it keeps your hand farther from the pilot burner opening. Either way, explore the flame directly to the pilot burner hole while holding the ignition button.

Why does the pilot light keep going out after I light it?

The thermocouple is almost certainly failing. This is a safety device that holds the gas valve open only when it senses pilot flame heat. When it wears out, the valve closes automatically and the pilot goes out. A technician can replace it, usually in under an hour.

Do I need to turn off the boiler before relighting the pilot?

No. The boiler is already off if the pilot light is out — the main burner cannot ignite without a lit pilot. Just make sure the thermostat is set to heat mode so the boiler will fire once you relight the pilot and turn the gas knob to "On."