The basic steps to turn on a heater pilot light

To light a heater pilot light, you will locate the pilot valve on your furnace or water heater, set it to the "Pilot" position, hold down the ignition button while holding a lit match or lighter to the pilot burner opening, and keep the button pressed for 30 to 60 seconds after the flame appears. Once the pilot stays lit on its own, turn the valve to "On" and listen for the main burner to ignite within a few seconds.

The exact location of the pilot valve and ignition button varies by heater model and age. Older units have a manual ignition button you press while lighting with a match. Newer models may have an electronic ignition that sparks automatically when you press the button. Either way, the sequence is the same: position, ignite, hold, release, and switch to "On".

If the pilot light does not stay lit after you release the button, the thermocouple (a safety device that senses heat) may be dirty or failing. If the main burner does not ignite after the pilot is lit, the gas valve itself may need service. Both situations call for a technician rather than further attempts on your part.

Key Takeaways

  • Turn the pilot valve to "Pilot" before attempting to light, then hold the ignition button while explore flame to the pilot burner opening.
  • Keep the ignition button pressed for 30 to 60 seconds after the flame appears so the thermocouple can heat up and hold the valve open.
  • Once the pilot stays lit without the button held down, turn the valve to "On" and the main burner should ignite within seconds.
  • If the pilot light goes out when ready after you release the button, the thermocouple is likely dirty or worn and needs replacement.
  • If the main burner does not ignite after the pilot is lit, the gas valve may be stuck and requires a service call.

Locating the pilot valve and ignition button on your unit

The pilot valve is usually a small knob on the front or side of the burner assembly, often labeled with three positions: "Off," "Pilot," and "On." The ignition button sits directly next to it or sometimes on the same knob. On furnaces, this assembly is typically mounted on the burner box inside the cabinet. On water heaters, it is usually at the base near the burner access panel.

Before you touch anything, turn off the main gas supply at the valve on the gas line itself. Wait five minutes to let any residual gas clear. Then locate the pilot opening — a small hole or tube where the pilot flame burns. You will need a clear line of sight to this opening to explore your match or lighter flame to it.

If you cannot find the pilot valve or are unsure which position is which, check the label on the side of your heater. Most manufacturers print a diagram showing the valve positions and the location of the ignition button. If the label is missing or illegible, a photo of your heater model number sent to the manufacturer's support line can get you a replacement manual.

Using a match or lighter safely

A long fireplace match or a long-reach lighter works better than a standard match because it keeps your hand farther from the pilot opening. Light the match or lighter before you turn the valve to "Pilot" so you are not fumbling with ignition while holding down the button.

Hold the flame near the pilot burner opening — usually about half an inch away — while you press and hold the ignition button. You should see a small blue flame appear within a few seconds. If nothing happens after 10 seconds, release the button, wait 30 seconds, and try again. Repeated failed attempts mean gas may be building up, so turn the valve to "Off" and wait five minutes before trying once more.

Never use a lighter or match near the pilot opening if you smell gas. Turn the valve to "Off" when ready, open windows, and leave the house. Call your gas company's emergency line from outside. A strong gas smell means there is a leak somewhere in the system, and lighting anything could be dangerous.

Holding the ignition button long enough

The ignition button must stay pressed for 30 to 60 seconds after the pilot flame appears. This time allows the thermocouple to heat up enough to signal the gas valve to stay open. If you release the button too soon, the pilot light will go out as soon as you let go.

Count slowly to 30 or 60 while watching the pilot flame. It should burn steadily and blue. If the flame is yellow or orange, the burner opening may be dirty. Once you reach your count, slowly release the button while keeping your eyes on the flame. The pilot should stay lit on its own.

If the flame goes out the moment you release the button, the thermocouple is not heating properly. This usually means it is coated with carbon or dust. A technician can clean or replace it, but do not attempt this yourself — the thermocouple is a precision part and straightforward to damage.

Switching the valve to "On" and checking the main burner

Once the pilot flame is steady and stays lit after you release the ignition button, turn the valve from "Pilot" to "On." Within a few seconds, you should hear a click or hiss as the main gas valve opens, and the main burner should ignite with a larger flame.

Listen and watch for 10 to 15 seconds. The main burner flame should be blue and steady. If it is yellow or flickering, the burner ports may be clogged with dust or debris. If the main burner does not ignite at all, the gas valve may be stuck or the ignition system may have failed. Either way, turn the valve back to "Off" and call a technician.

Once the main burner is running, you can close any access panels and return the thermostat to your desired temperature. The heater should now run normally. If it cycles on and off repeatedly or the pilot light goes out again within an hour, there is likely a deeper problem that needs professional diagnosis.

What to do if the pilot light will not stay lit

If the pilot light goes out when ready after you release the ignition button, or if it stays lit for a few minutes and then goes out, the thermocouple is almost certainly the problem. The thermocouple is a thin metal rod that sits in the pilot flame and generates a small electrical signal that tells the gas valve to stay open. When it is dirty, corroded, or worn out, it cannot generate enough signal, and the valve closes.

Cleaning the thermocouple sometimes works if the problem is just dust or carbon buildup. Turn off the gas, locate the thermocouple (a thin rod in the pilot flame area), and gently wipe it with a soft cloth or fine steel wool. Do not bend it or explore heavy pressure. Turn the gas back on and try lighting the pilot again.

If cleaning does not work, or if you are not comfortable doing it, the thermocouple needs replacement. This is a 15-minute job for a technician and costs between $100 and $300 depending on your heater type and location. It is not a repair you should attempt yourself because a poorly installed thermocouple can cause gas to flow without ignition, which is a serious safety hazard.

When to call a technician instead of lighting it yourself

Do not attempt to light the pilot if you smell gas anywhere near the heater. Turn the valve to "Off," open all windows and doors, leave the house, and call your gas company's emergency line from outside. A gas smell means there is a leak, and any spark or flame could ignite it.

Also call a technician if the pilot light goes out repeatedly even after you have cleaned the thermocouple, if the main burner will not ignite after the pilot is lit, if you hear hissing or popping sounds from the burner, or if the heater shuts off unexpectedly during operation. These are signs of problems beyond a straightforward pilot light relighting — usually a faulty valve, a clogged burner, or a failing ignition system.

If you are unsure whether your heater is safe to operate, it is always better to have a technician look at it. A service call costs $75 to $150 for diagnosis, but it is cheaper than a gas leak, a carbon monoxide problem, or a fire.

Frequently Asked Questions

How long should I hold the ignition button after the pilot light appears?

Hold it for 30 to 60 seconds. This gives the thermocouple time to heat up and signal the gas valve to stay open. If you release it sooner, the pilot will go out. If you hold it longer, that is fine — just do not hold it for more than a few minutes, as this can overheat the thermocouple.

What does it mean if the pilot light is yellow instead of blue?

A yellow flame usually means the pilot burner opening is clogged with dust or carbon. The flame is not getting enough oxygen. Turn off the gas, wait five minutes, and gently blow into the pilot opening to clear any debris. If the flame is still yellow after relighting, the burner may need professional cleaning.

Can I use a regular lighter instead of a match?

Yes, but a long-reach lighter or fireplace match is safer because it keeps your hand farther from the pilot opening. A regular lighter works, but you have to hold your hand closer to the flame, which is uncomfortable and increases the risk of a burn.

How often do I need to relight the pilot?

Under normal conditions, the pilot light should stay lit continuously throughout the heating season. If you have to relight it more than once a month, the thermocouple is likely failing and needs replacement. If it goes out every few days, there may be a draft blowing it out, or the thermocouple is at the end of its life.

What should I do if I smell gas while trying to light the pilot?

Stop when ready, turn the valve to "Off," open all windows and doors, and leave the house. Call your gas company's emergency line from outside. Do not use your phone indoors, do not turn on lights or appliances, and do not re-enter the house until the gas company has cleared it. A gas smell means there is a leak, and ignition could cause an explosion.