The basic steps to light a pilot light

A pilot light is a small, continuous flame that ignites the main burner when your heating system calls for heat. To light one, you locate the pilot burner (a small opening near the main burner), hold a long lighter or lit match to it, and watch for the flame to catch. The whole process takes about 30 seconds once you find the right spot.

Before you start, turn the gas control knob to the "Off" position and wait five minutes. This clears any gas that built up while the pilot was out. Then turn the knob to "Pilot" — not all systems have this setting, but most do. If yours doesn't, you may need to hold the knob down while lighting, which the manual will specify.

Hold a long lighter or long match near the pilot opening while pressing and holding the gas control knob. You should see a small blue flame appear within a few seconds. Once it lights, keep holding the knob for 30 to 60 seconds so the thermocouple (a heat-sensing device) warms up and signals the system to keep the gas flowing. Then release the knob and turn it to "On."

Key Takeaways

  • Turn the gas control knob to "Off" and wait five minutes before attempting to light the pilot to clear any built-up gas.
  • Use a long lighter or long match to reach the pilot opening safely, and hold the knob down while the flame catches.
  • Keep the knob pressed for 30 to 60 seconds after the pilot lights so the thermocouple registers the heat.
  • If the pilot won't stay lit after three or four attempts, stop and check for a thermocouple problem or a gas supply issue before trying again.

Finding the pilot light location on your unit

The pilot burner sits near the main burner inside the combustion chamber. On a water heater, look at the front or bottom of the tank — you'll see a small metal box with a control knob and usually a sight glass (a small window). The pilot opening is a tiny hole, often with a small tube running to it. On a furnace, the pilot is typically inside the furnace cabinet near the main burner assembly.

Your manual will have a diagram showing exactly where to point the lighter. If you don't have the manual, search online for the model number (usually on a label on the unit itself) and "pilot light location." Most manufacturers post PDFs for free. The sight glass, if your unit has one, lets you see whether the pilot is already lit — a small blue flame visible through the glass means you don't need to light it.

What to do if the pilot won't light

If you've tried three or four times and the flame won't catch, stop and wait 10 minutes. Gas may have pooled in the chamber, and lighting it could create a small pop or flash. Open a window or door to ventilate the area, then try again with the knob set to "Pilot."

If it still won't light, the problem is usually one of three things: no gas reaching the pilot (check that the main gas valve to the unit is open), a dirty pilot opening (dust or debris blocks the gas flow), or a faulty thermocouple (the system won't let gas flow to the pilot if it senses the thermocouple isn't working). A clogged pilot can sometimes be cleared by gently blowing compressed air into the opening, but if that doesn't work, the unit likely needs service.

If you smell gas but the pilot won't light, do not keep trying. Turn the gas control knob to "Off," leave the area, and call your gas company or a service technician. A gas leak is a safety issue that requires professional attention.

Lighting the pilot with the thermocouple in mind

The thermocouple is a thin metal rod that sits in the pilot flame. When it gets hot, it sends a signal to the gas valve that says "the pilot is lit, keep the gas on." If you release the knob too soon, the thermocouple hasn't warmed up yet, and the gas shuts off when ready.

This is why you hold the knob down for 30 to 60 seconds after the pilot lights. The longer you hold it, the more certain the thermocouple will stay warm enough to keep the valve open. Some systems need the full 60 seconds; others work at 30. If your pilot keeps going out right after you release the knob, try holding it longer next time.

If the pilot lights and stays lit while you're holding the knob, but shuts off the moment you release it, the thermocouple is probably failing. This is not something you can fix yourself — the unit needs a new thermocouple, which a technician can install.

Safety steps to follow every time

Always turn the gas control knob to "Off" and wait at least five minutes before lighting. This pause is not optional — it lets any gas that leaked into the chamber escape, so you're not lighting a pocket of gas that could pop or flash.

Use a long lighter designed for grills or fireplaces, not a short kitchen lighter. Your fingers need to stay well away from the pilot opening. If you use a match, hold it in a long match holder or use a fireplace match, which has a longer stick.

Never force the gas control knob. It should turn smoothly. If it's stuck or hard to turn, stop and call a technician — forcing it can damage the valve. Keep the area around the unit clear of clutter, and make sure there's good air flow so any gas smell is obvious. If you ever smell gas and can't find the source, leave the area and call your gas company.

When to call a professional instead

If the pilot won't light after three or four careful attempts, or if it lights but won't stay on even after you hold the knob for a full minute, the unit needs service. A technician can test the thermocouple, check the gas line, clean the pilot opening, or replace parts that have failed.

You should also call a professional if you smell gas, if the flame is yellow or orange instead of blue, or if the pilot lights but the main burner won't ignite when the system calls for heat. A yellow or orange flame usually means incomplete combustion, which can produce carbon monoxide — this is a safety issue that requires when ready attention.

Most water heater and furnace repairs are not expensive when caught early. A service call typically costs $100 to $200, and a thermocouple replacement is usually under $50. Waiting until the system fails completely often costs much more.

Frequently Asked Questions

How long should I hold the knob down after the pilot lights?

Hold it for 30 to 60 seconds. The longer hold gives the thermocouple more time to warm up and signal the gas valve to stay open. If your pilot keeps shutting off right after you release the knob, try holding it for the full 60 seconds next time.

What does a healthy pilot flame look like?

A healthy pilot flame is small, steady, and blue. It should be about the size of a pea or smaller. If the flame is yellow, orange, or flickering wildly, the unit needs service — these signs usually mean incomplete combustion or a dirty burner.

Can I light the pilot if I smell a little gas?

A faint gas smell when you first open the unit is normal. Wait five minutes with the knob on "Off" to let it clear. If the smell is strong or doesn't go away, do not light the pilot — call your gas company or a technician instead.

What if the pilot lights but the main burner doesn't turn on?

The pilot is only the first step. Once it's lit and stable, turn the knob to "On" and wait for the main burner to ignite. If nothing happens after 30 seconds, turn the knob back to "Off," wait five minutes, and try again. If the main burner still won't light, the unit needs service.

Is it safe to light the pilot myself, or should I always call a technician?

Lighting a pilot is a safe, routine task if you follow the steps carefully — wait five minutes, use a long lighter, and hold the knob for 30 to 60 seconds. However, if you're uncomfortable doing it, if the unit won't light after a few attempts, or if you smell gas, call a professional. There's no penalty for asking for help.