Light the pilot light by turning the gas knob to "Pilot," pressing and holding the ignition button while holding a lit match or lighter to the pilot opening, then releasing the button after 30 seconds
The pilot light on a boiler is a small flame that ignites the main burner when your heating system calls for heat. If it has gone out, you can relight it yourself in most cases—it takes about five minutes and requires only a match or lighter. The exact steps depend on whether your boiler has an automatic ignition button or requires a manual flame.
Before you start, locate the boiler's control panel. You will see a gas knob with three positions: "Off," "Pilot," and "On." You will also see a small opening where the pilot light sits, usually marked with a label or diagram on the panel itself. If your boiler has been off for more than a few minutes, wait another minute before lighting to let any residual gas clear.
Key Takeaways
- Turn the gas knob to "Pilot" and hold it there while you ignite the flame with a match or lighter held at the pilot opening.
- Keep the knob pressed in for 30 seconds after the flame catches so the thermocouple can heat up and sense the flame.
- If the pilot light goes out when ready after you release the knob, the thermocouple may be faulty and will need replacement by a technician.
- Once the pilot light stays lit, turn the gas knob to "On" to restore normal heating operation.
- If you smell gas at any point, stop, leave the area, and call your gas company's emergency line—do not try to light the pilot again.
Step-by-step: Lighting the pilot with an ignition button
If your boiler has a red or black ignition button on the control panel, use this method. Turn the gas knob to "Pilot" and hold it down firmly. Press and hold the ignition button at the same time. You should hear a clicking sound as the button creates sparks near the pilot opening. Hold both the knob and button for 10 to 15 seconds.
Watch the pilot opening—you should see a small blue flame appear. Once the flame is lit, continue holding the knob down for another 15 to 20 seconds. This allows the thermocouple (a heat-sensing device) to warm up enough to recognize the flame and keep the gas valve open. After 30 seconds total, release the knob. The pilot light should stay lit.
If the flame goes out as soon as you release the knob, wait a few minutes and try again. If it happens a second time, the thermocouple is likely worn out and needs replacement—this is a job for a heating technician. Do not keep trying to light it repeatedly, as this wastes gas and can create a safety hazard.
Step-by-step: Lighting the pilot with a match or lighter
Older boilers without an ignition button require a manual flame. Turn the gas knob to "Pilot" and hold it down. Use a long match or a lighter with an extended nozzle to reach the pilot opening safely. Hold the flame near the opening for a few seconds until you see the blue pilot flame ignite.
Once lit, keep the knob pressed down for 30 seconds so the thermocouple can heat up. After 30 seconds, slowly release the knob. The pilot light should remain lit. If it goes out, wait two minutes and repeat the process. If it continues to go out, the thermocouple needs service.
Be careful not to touch the boiler casing or any metal parts near the pilot opening while lighting—they may be hot. If you have long hair or loose clothing, tie them back before you begin.
What to do if the pilot light will not stay lit
A pilot light that goes out when ready after you release the knob almost always means the thermocouple is failing. The thermocouple is a small metal rod that sits in the pilot flame and sends a signal to the gas valve to stay open. When it is worn out, it cannot sense the heat from the pilot flame, so the valve closes and the gas shuts off.
Replacing a thermocouple requires removing the control panel and disconnecting the old part, then installing a new one. This is not a difficult repair, but it does require turning off the gas and working with small connections. Most homeowners call a heating technician for this job rather than doing it themselves. The cost is usually between $150 and $300 for parts and labor.
In the meantime, if your boiler has a manual ignition button, you can keep relighting the pilot each time it goes out. This is inconvenient but safe as long as you follow the steps correctly. Do not leave the boiler unattended while the pilot is lit if you know the thermocouple is faulty.
Safety checks before and after lighting
Before you touch anything on the boiler, smell the air around the control panel. If you detect a strong rotten-egg or sulfur smell, this is the scent of natural gas. Do not light the pilot. Instead, leave the area when ready, go outside, and call your gas company's emergency line. A gas leak is a serious hazard and must be handled by professionals.
After the pilot light is lit and you have turned the knob to "On," listen for the main burner to ignite within a minute or two. You should hear a whoosh sound as the main flame starts. If the main burner does not ignite after two minutes, turn the knob back to "Off" and wait five minutes before trying again. If it still will not ignite, the boiler may have a different problem and needs a technician's inspection.
Check that the pilot flame is blue, not yellow or orange. A yellow or orange flame means incomplete combustion and usually indicates a dirty pilot opening. If the flame is discolored, turn the knob to "Off" and let the boiler cool for 10 minutes, then try lighting again. If the color does not improve, the pilot opening may need cleaning by a technician.
Common mistakes that prevent the pilot from lighting
The most common mistake is not holding the knob down long enough. Many people release it after just a few seconds, before the thermocouple has warmed up. The thermocouple needs the full 30 seconds of heat to work properly. If you release too early, the gas valve will close and the flame will go out.
Another mistake is turning the knob all the way to "On" before the pilot is lit. The knob must be in the "Pilot" position while you light the flame. Only after the pilot is burning steadily for 30 seconds should you turn it to "On."
A third mistake is using a match that is too short. If you cannot reach the pilot opening safely without burning your fingers, use a longer match, a lighter with an extended nozzle, or ask someone else to hold the knob while you light the flame. Never lean over the boiler or put your face close to the opening.
When to call a heating technician instead
If you smell gas and cannot identify where it is coming from, call a technician or your gas company when ready. Do not try to light the pilot yourself. A gas leak can be dangerous and requires professional detection and repair.
If the pilot light will not light at all—meaning you see no spark from the ignition button and no flame appears when you hold a match to the opening—the gas supply to the pilot may be blocked. This could be a clogged pilot opening, a closed gas valve, or a problem with the gas line. A technician can diagnose and fix this.
If the boiler is very old (more than 20 years), has a cracked casing, or makes unusual noises, have a technician inspect it before you attempt to light the pilot. Some boilers are not safe to operate without professional service.
Frequently Asked Questions
How long should I hold the knob down after the pilot lights?
Hold it for a full 30 seconds after the flame appears. This gives the thermocouple time to heat up and signal the gas valve to stay open. If you release too early, the flame will go out.
What does a healthy pilot flame look like?
A healthy pilot flame is blue with a small yellow tip at the very top. It should be about half an inch tall and steady. If the flame is mostly yellow or orange, or if it flickers constantly, the pilot opening may be dirty and needs cleaning by a technician.
Can I light the pilot if I smell a faint gas odor?
A very faint smell near the boiler is normal when the pilot first lights, as the burner warms up. However, if the smell is strong, lingers after a few minutes, or comes from elsewhere in the house, do not light the pilot. Leave the area and call your gas company's emergency line.
How often do pilot lights go out?
A healthy pilot light should stay lit indefinitely unless the thermocouple fails, the gas supply is interrupted, or there is a draft blowing it out. If your pilot light goes out once a month or more, the thermocouple is likely wearing out and should be replaced soon.
Do I need to turn off the gas before lighting the pilot?
No. The gas knob controls the flow of gas to the pilot. When you turn it to "Pilot," a small amount of gas flows to the pilot opening, ready to be lit. You do not need to turn off the main gas supply to the boiler.