The basic steps to relight a pilot light
Relighting a pilot light is usually a five-minute job that does not require a technician. Most boilers have a reset button or a dial you turn to "Pilot," a spark igniter you press, and a flame that catches within seconds. If your boiler has been off or the pilot blew out, you can restart it yourself by following the manufacturer's sequence—which is printed on a label inside the boiler door or in your manual.
The process is the same whether your boiler uses a piezo spark igniter (a button you press) or an electronic igniter (a switch you flip). The key is doing the steps in order and waiting the right amount of time between them, because rushing causes the gas to disperse and you have to start over.
Key Takeaways
- Turn the control dial to "Pilot" and hold it there while you ignite, usually for 30 seconds after the flame appears.
- Use the spark button or electronic igniter to light the pilot—do not use a match or lighter unless the manual explicitly says to.
- If the pilot will not stay lit after three attempts, turn the gas off and wait five minutes before trying again.
- A pilot light that goes out repeatedly usually means a faulty thermocouple or a draft problem, not a relighting failure.
- If you smell gas at any point, stop, leave the area, and call your gas company's emergency line.
Locate the pilot light assembly and the control dial
Open the boiler door or access panel. You will see a small burner assembly with a thin metal tube running to it—that tube carries gas to the pilot. Next to or on the burner assembly, you will find a control dial or knob labeled with settings like "Off," "Pilot," and "On." Some boilers have the dial on the front of the unit; others have it on the gas valve itself, which sits near the burner.
Find the igniter next to the pilot burner. If it is a button, it will be labeled "Spark" or "Ignite." If it is electronic, there will be a switch or button on the control panel. Check your boiler's manual or the label inside the door for the exact location—manufacturers place these in different spots, and the label will show you a diagram.
Turn the dial to "Pilot" and prepare to ignite
Turn the control dial fully to the "Pilot" setting. Do not turn it to "On" yet. Hold it there—you will keep holding it throughout the ignition process. This keeps gas flowing to the pilot burner while you light it.
Look at the pilot burner opening. You should see a small metal electrode or spark gap near the burner tip. This is where the spark will jump to ignite the gas. Make sure there is no debris, dust, or old carbon blocking the opening. If you see buildup, use a dry cloth or a small brush to clear it gently.
Press the igniter button or switch and watch for flame
While holding the dial on "Pilot," press the spark button or flip the electronic igniter switch. You should hear a clicking sound (for a piezo igniter) or see a small spark jump near the burner. Press or hold the igniter for two to three seconds, then release. The pilot flame should appear within a few seconds—it will be a small blue flame, usually about the size of a match head.
If no flame appears after three seconds, wait a moment and try again. Do not press the igniter more than three times in a row, because gas will build up and become harder to ignite. If it does not light after three attempts, turn the dial to "Off," wait five minutes for the gas to clear, and try again from the beginning.
Hold the dial and keep the flame burning for 30 seconds
Once the pilot flame appears, keep holding the dial on "Pilot." Do not turn it to "On" yet. Hold it there for 30 seconds while the flame burns. This allows the thermocouple—a heat-sensing device next to the pilot—to warm up and signal the gas valve that it is safe to keep the gas flowing.
Watch the flame while you hold the dial. It should be steady and blue. If it flickers or goes out before the 30 seconds are up, release the dial, wait a moment, and start over. A flame that will not stay lit during this hold period usually means the thermocouple is failing or there is a draft blowing the flame out.
Turn the dial to "On" and test the main burner
After 30 seconds, slowly turn the dial from "Pilot" to "On." The main burner should ignite within a few seconds. You will hear a whoosh as the burner lights, and you should see a larger flame in the main combustion chamber. If the main burner lights and stays lit, the pilot light is working correctly.
Set your thermostat to a comfortable temperature and listen for the boiler to cycle normally. The burner should run for a few minutes, then shut off when the water reaches the set temperature. If everything sounds and looks normal, you are done.
What to do if the pilot will not stay lit
If the pilot lights but goes out as soon as you release the dial, or if it lights and then goes out within a few minutes, the thermocouple is likely faulty. The thermocouple is a safety device that tells the gas valve the pilot is burning; if it does not sense heat, it shuts off the gas. A worn thermocouple cannot send that signal, so the gas cuts off even though the pilot is lit.
A thermocouple costs between $15 and $40 and takes 10 to 15 minutes to replace if you are comfortable with basic tools. You unscrew the old one from the gas valve and screw in the new one. However, if you are not confident working inside the boiler, call a technician. A pilot that goes out repeatedly is also a sign of a draft problem—if your boiler room has a strong air current or an open window, close it and try again.
When to call a technician instead
Stop and call a technician if you smell gas during or after relighting. Do not try again. Leave the area, open windows, and call your gas company's emergency line. A gas smell means there is a leak somewhere in the system, and it is not safe to continue.
Also call a technician if the pilot lights on the first try but then goes out within minutes, even after you have held the dial for the full 30 seconds. This pattern usually means the thermocouple is failing or the gas valve is not opening properly. You can try relighting once more, but if it happens again, the boiler needs professional service. Do not keep relighting a boiler that will not hold a pilot—repeated attempts can damage the igniter or flood the combustion chamber with gas.
Frequently Asked Questions
Can I use a lighter or match to light the pilot instead of the spark button?
Only if your boiler manual says to. Most modern boilers have an electronic or piezo igniter and should not be lit with an open flame—it is unsafe and can damage the igniter. Check the label inside the boiler door or your manual first. If it says "manual ignition," a long lighter or match is acceptable, but the spark button is always safer.
How long should I hold the dial on "Pilot" before turning it to "On"?
Hold it for 30 seconds after the flame appears. This gives the thermocouple time to heat up and signal the gas valve. If you turn the dial to "On" too quickly, the main burner may not stay lit because the thermocouple has not warmed enough yet.
What does it mean if the pilot lights but the main burner will not ignite?
The pilot is working, but the main burner igniter or the gas valve controlling the main burner may be faulty. Try turning the dial back to "Off," waiting 30 seconds, and turning it to "On" again. If the main burner still will not light, the boiler needs professional service.
Is it normal for the pilot light to go out in winter?
No. A pilot light should stay lit year-round unless the boiler is turned off. If it goes out in winter, it is usually because of a draft from an open window, a failing thermocouple, or a problem with the gas valve. Check for drafts first, then relight. If it goes out again within a few days, call a technician.
What if I have tried relighting three times and it still will not stay lit?
Stop trying and wait five minutes for any gas to clear. Then try once more. If it still will not stay lit after that attempt, turn the boiler off and call a technician. Repeated failed attempts can flood the combustion chamber with gas, which is a safety hazard.