Light the pilot by holding the control knob in the "Pilot" position while you ignite the flame

Most wall heaters light the same way: you turn the control knob to "Pilot," hold a lit match or lighter to the pilot opening, and watch for a small blue flame to appear. Once it's lit, you keep the knob pressed in the "Pilot" position for 30 to 60 seconds so the thermocouple—a heat-sensing device—warms up and tells the gas valve the pilot is burning. Then you release the knob and turn it to "On" or the temperature setting you want. If the pilot goes out within a few minutes, the thermocouple probably isn't working and you'll need a professional to replace it.

The exact steps depend on your heater's design, but the principle is always the same: you're manually lighting a small flame that will then hold the main gas valve open. Without that pilot flame, the main burner won't ignite when you call for heat.

Key Takeaways

  • Turn the control knob to "Pilot," then use a match or lighter to ignite the small flame at the pilot opening while looking through the viewing window.
  • Hold the knob in the "Pilot" position for 30 to 60 seconds after ignition so the thermocouple heats up and keeps the gas valve open.
  • If the pilot lights but goes out within minutes, the thermocouple is failing and requires professional replacement.
  • If you smell gas but cannot light the pilot after several tries, turn off the heater and call a technician—do not keep attempting to light it.

Locate the pilot opening and viewing window

Before you try to light anything, find where the pilot flame actually is. Most wall heaters have a small window or opening on the front or side of the unit where you can see the pilot burner. Look for a label that says "Pilot" or an arrow pointing to a small hole. Some heaters have a clear glass or plastic window so you can watch the flame ignite; others have just an opening you light through.

If you cannot find the pilot opening, check the heater's manual or look on the back of the control panel cover—many manufacturers print a diagram there. The opening is usually near the control knob and thermocouple, which is a thin metal rod sticking out from the burner assembly.

Turn the knob to "Pilot" and prepare to ignite

Locate the control knob on the front of the heater. It typically has three positions: "Off," "Pilot," and "On" (or a temperature dial). Turn it slowly to the "Pilot" position. You should hear a soft hissing sound—that's gas flowing to the pilot burner. If you smell a strong gas odor, stop and wait a few minutes for it to clear before trying again.

Have your match or lighter ready before you turn the knob. A long-handled lighter or long fireplace match works better than a short match because the pilot opening is often recessed and hard to reach. Do not use a cigarette lighter if you can avoid it—the angle is awkward and your hand gets too close to the opening.

Light the pilot and hold the knob down

Once the knob is in the "Pilot" position and gas is flowing, bring your lit match or lighter to the pilot opening. You should see a small blue flame ignite. The moment it lights, keep the control knob pressed firmly in the "Pilot" position—do not release it yet.

Hold the knob down for 30 to 60 seconds. During this time, the thermocouple (the thin metal rod near the flame) is heating up. The thermocouple generates a tiny electrical signal that tells the gas valve "the pilot is burning, keep the main valve open." If you release the knob too soon, the thermocouple won't be warm enough and the pilot will go out as soon as you let go.

Release the knob and turn it to "On"

After 30 to 60 seconds, slowly release the control knob. The pilot flame should stay lit. If it goes out when ready, wait a minute for the heater to cool, then repeat the process—you may not have held the knob long enough for the thermocouple to reach full temperature.

Once the pilot is holding steady, turn the knob from "Pilot" to "On" or to your desired temperature setting. The main burner should ignite within a few seconds, and you should feel warm air coming from the heater. If the main burner does not light, turn the knob back to "Off," wait a minute, and try again. If it still won't light after two attempts, stop and call a technician.

What to do if the pilot won't stay lit

If the pilot lights when you hold the knob down but goes out as soon as you release it, the thermocouple is not generating enough signal to hold the gas valve open. This is the most common reason a pilot won't stay lit. A thermocouple usually fails because it is bent, dirty, or straightforward worn out after years of use.

Do not keep trying to light it. A failing thermocouple cannot be cleaned or adjusted by a homeowner—it must be replaced by a professional. Call a heating technician and describe what is happening. Replacement usually takes less than an hour and costs between $150 and $300, depending on your region and the heater model.

When to stop trying and call a professional

If you smell gas but the pilot will not light after three or four careful attempts, turn the control knob to "Off" and do not try again. A strong gas smell with no ignition means gas is flowing but something is preventing combustion—either the pilot opening is blocked, the ignition source is not hot enough, or there is a gas leak. All of these are safety issues that require professional diagnosis.

Similarly, if the pilot lights and holds steady but the main burner will not ignite when you turn the knob to "On," the problem is downstream in the main burner assembly or gas line. This also needs a technician. Do not attempt to force the heater to work by adjusting knobs or trying different settings—you risk gas buildup in the room.

Frequently Asked Questions

How long should I hold the knob in the pilot position?

Hold it for 30 to 60 seconds. The exact time depends on how quickly your thermocouple heats up, but most heaters need at least 30 seconds. If you release too soon, the pilot will go out. If you hold it longer, that is fine—there is no harm in waiting a full minute.

What if I cannot reach the pilot opening with my lighter?

Use a long-handled fireplace match or a long-reach lighter designed for candles. If the opening is very recessed, you can also try a thin wooden stick or a straightened paperclip with a match taped to the end, though a proper long match is safer and easier.

Is it normal for the pilot to be blue?

Yes. A healthy pilot flame is small, steady, and blue or blue-tipped. If it is yellow or orange, the burner may be dirty or the air-to-gas mixture may be off, but the heater will still work. A yellow pilot is not an emergency, but it is worth mentioning to a technician during a service call.

Can I light the pilot if the power is off?

Yes. The pilot light itself does not need electricity—it is lit by a match or lighter and held open by the thermocouple's heat signal. However, the main burner and fan will not work without power, so you will have a lit pilot but no heat output. If your heater has lost power, restore it and try lighting the pilot again.

What does it mean if the pilot lights but smells like rotten eggs?

That smell is mercaptan, an odor added to natural gas so you can detect leaks. A faint smell during ignition is normal, but a strong persistent smell means gas is leaking somewhere in the line or burner assembly. Turn off the heater, open windows, and call a technician or your gas company's emergency line.