The basic steps to relight your boiler pilot
To turn on a boiler pilot light, you need to locate the pilot valve (usually a small knob on the front of the boiler), set it to the "Pilot" position, hold down the ignition button while holding a lit match or lighter to the pilot opening, and keep the valve button pressed for 30 to 60 seconds after the flame catches. Once the pilot stays lit on its own, turn the valve knob to "On" to restore heat to your home.
The exact location and labeling of controls varies by boiler model, so check your manual first — most manufacturers include a diagram on the boiler itself or in a pocket on the casing. If you cannot find the pilot valve or ignition button, or if the pilot will not stay lit after several attempts, the boiler likely needs a service call rather than a manual restart.
Key Takeaways
- The pilot valve is usually a small knob on the front of the boiler marked "Pilot," "On," and sometimes "Off."
- You must hold the valve button down while igniting the pilot with a match or lighter, then keep holding for 30 to 60 seconds so the thermocouple can sense the flame.
- If the pilot lights but goes out as soon as you release the button, the thermocouple may be dirty or faulty and requires professional cleaning or replacement.
- A pilot that will not light after three or four attempts, or one that lights but smells like gas, means you should stop trying and call a heating engineer.
Locating the pilot valve and ignition button
The pilot valve is a small knob, usually brass or steel, mounted on the front of the boiler near the bottom. It typically has three positions marked: "Pilot," "On," and sometimes "Off." Next to or below it is a small button you press to trigger the ignition spark or to hold open the gas valve while you light the pilot manually.
Before you touch anything, turn off the main gas supply to the boiler if the pilot has been out for more than a few hours. Wait five minutes to let any residual gas clear. Then locate the pilot opening — a small hole or tube near the valve, usually with a viewing window so you can see the flame once it lights.
If your boiler has an electronic ignition system (common in newer models), the ignition button may be labeled "Ignition" or "Start" and will produce a clicking sound when pressed. If your boiler uses a standing pilot that you light manually with a match, you will see the pilot opening more clearly and will need a lighter or long match to reach it safely.
Setting the valve and igniting the pilot
Turn the pilot valve knob to the "Pilot" position. Press and hold the ignition button — you should hear clicking if it is electronic, or see a spark near the pilot opening. While holding the button, bring a lit match or lighter to the pilot opening. The pilot flame should catch within a few seconds and burn blue.
Keep the valve button pressed down for 30 to 60 seconds after the flame appears. This time allows the thermocouple (a safety sensor below the pilot flame) to heat up and signal the valve that it is safe to stay open. If you release the button too soon, the pilot will go out because the thermocouple has not warmed enough to hold the valve open.
Once 60 seconds have passed, slowly release the button while watching the pilot flame. If it stays lit, turn the valve knob to "On." The main burner should ignite within a few seconds, and you will hear the boiler begin to heat. If the pilot goes out as you release the button, wait a minute and repeat the process — it sometimes takes two or three attempts for the thermocouple to respond.
Why the pilot goes out and when to stop trying
A pilot that lights but extinguishes the moment you release the button usually means the thermocouple is too cold, too dirty, or faulty. Dirt on the thermocouple tip prevents it from sensing the flame properly. If relighting does not work after three attempts, the thermocouple likely needs professional cleaning or replacement — continuing to try will waste gas and time.
A pilot that will not light at all after several attempts suggests either no gas is reaching the pilot (a blocked line or closed valve upstream), or the ignition system is not working. Smell the air near the pilot opening: if you detect a strong gas smell but no flame, stop when ready and call a heating engineer. Do not attempt to force ignition if gas is present but not lighting.
A pilot that lights but burns yellow or orange instead of blue, or one that produces a hissing sound, also warrants a professional inspection. These signs can indicate a dirty burner, improper gas pressure, or incomplete combustion — all safety concerns that require service.
Safety steps before and after relighting
Before you begin, make sure the room is well ventilated. Open a window or door to allow fresh air to circulate, especially if the pilot has been out for several hours and gas may have accumulated. Never attempt to relight a pilot in a sealed room.
Keep your face and hands clear of the pilot opening when you light it. The flame can flare up briefly, and you do not want to be in its path. Use a long match or a lighter with an extended nozzle so your fingers stay well away from the opening.
After the pilot is lit and the main burner is running, check that the boiler is heating normally. Feel the pipes or radiators to confirm warmth is building. If the boiler fires up but then shuts down after a few minutes, or if it cycles on and off repeatedly, the thermostat or a safety switch may be faulty — call a heating engineer rather than relighting the pilot again.
When to call a heating engineer instead
If the pilot will not stay lit after two or three careful attempts, if you smell gas but cannot get a flame, or if the pilot lights but the main burner does not ignite, the boiler needs professional service. Continuing to attempt relighting wastes gas and delays the repair.
Similarly, if the boiler has been serviced recently and the pilot went out shortly after, contact the engineer who performed the service — they may have left a valve partially closed or disturbed a connection. If the pilot goes out repeatedly over several days or weeks, the thermocouple is almost certainly worn and needs replacement by a may have access to technician.
Most heating engineers can visit within 24 to 48 hours for a pilot light issue. In the meantime, your home will not heat, so prioritize the call if the weather is cold. Many engineers offer emergency or same-day service for heating problems, though this usually costs more than a standard appointment.
Frequently Asked Questions
How long should I hold the ignition button down?
Hold the button for 30 to 60 seconds after the pilot flame appears. This gives the thermocouple time to heat and signal the valve to stay open. If you release too soon, the pilot will extinguish. If it still goes out after 60 seconds, wait a minute and try again — the thermocouple may need a second attempt to respond.
What does the pilot flame look like when it is working?
A healthy pilot flame is blue with a small yellow tip, about the size of a pea, and burns steadily without flickering. If the flame is mostly yellow or orange, or if it flickers constantly, the pilot needs cleaning or adjustment by a professional. A blue flame that is too small or too large also indicates a problem.
Can I relight the pilot if I smell gas?
If you smell a strong gas odor and the pilot will not light, stop and do not try again. Leave the room, open windows, and call your gas company or a heating engineer when ready. A gas smell with no flame can mean a leak or a safety issue that requires professional attention before any relighting attempt.
How often do boiler pilots go out?
A pilot that goes out once every few years is normal and usually caused by a draft or a temporary issue. A pilot that goes out weekly or monthly suggests the thermocouple is wearing out, the burner is dirty, or there is a draft problem in the boiler room. If this happens, have the boiler serviced to identify and fix the cause.
Do I need to turn off the gas before relighting?
If the pilot has been out for more than a few hours, turn off the main gas supply and wait five minutes before relighting. This clears any gas that may have accumulated in the boiler. If the pilot just went out moments ago, you can relight it when ready without shutting off the gas, but always may support the room is ventilated.