Most boilers have a pilot light, but not all of them
A pilot light is a small, continuously burning flame inside your boiler that ignites the main burner when heat is needed. Most traditional gas boilers use one. However, newer boilers often use electronic ignition instead — a spark or hot surface that lights the burner on demand, without a flame burning all the time.
Whether your boiler has a pilot light depends on its age and type. If your boiler is more than 10 to 15 years old, it almost certainly has one. If it was installed in the last decade, it may have electronic ignition. Oil boilers typically use electronic ignition rather than pilot lights. The only way to know for certain is to look at your boiler or check the manual that came with it.
Key Takeaways
- Traditional gas boilers use a pilot light — a small flame that stays lit to ignite the main burner when your heating system calls for heat.
- Newer boilers often have electronic ignition instead, which uses a spark or heating element to light the burner and saves gas by not burning a flame continuously.
- A pilot light that goes out repeatedly usually means a faulty thermocouple, a clogged pilot tube, or a draft problem — not always a reason to replace the boiler.
- If your boiler has a pilot light and it goes out, you can relight it yourself by following the instructions on the boiler door, though some situations require a technician.
How to tell if your boiler has a pilot light
Look at the front of your boiler. If you see a small glass window or opening and can see a small blue flame inside, you have a pilot light. The flame should be steady and blue, not yellow or orange. If you cannot see inside the boiler easily, open the access panel on the front — the instructions are usually printed on the inside of the door.
Another way to check is to look at the control knob on the front of the boiler. If it has settings labeled "Pilot," "On," and "Off," your boiler uses a pilot light. If the knob only says "On" and "Off," or if there is no manual knob at all, your boiler likely has electronic ignition.
You can also check your boiler's manual or the nameplate on the side of the unit, which lists the model number. Search that model number online along with "pilot light" to find out what ignition system it uses.
Why some boilers switched away from pilot lights
A pilot light burns gas continuously, even when your boiler is not heating your home. This wastes energy and costs money over time. Modern boilers with electronic ignition only use fuel when the burner actually fires, making them more efficient. A boiler with electronic ignition can save 5 to 15 percent on gas costs compared to one with a pilot light, depending on how often your heating runs.
Electronic ignition is also more reliable in some ways. A pilot light can blow out from drafts, vibration, or a faulty thermocouple. Electronic ignition has fewer moving parts and fewer things that can fail. However, electronic ignition systems do require electricity to work, so they will not function during a power outage — whereas a boiler with a pilot light can still heat your home if the power goes out, as long as the gas supply is on.
What to do if your pilot light keeps going out
If your boiler has a pilot light and it goes out repeatedly, the problem is usually one of three things: a faulty thermocouple (the safety device that tells the gas valve the pilot is lit), a clogged pilot tube, or a draft blowing the flame out. A thermocouple costs $15 to $30 to replace and is the most common reason a pilot light will not stay lit.
Before calling a technician, check for obvious drafts near the boiler — an open window, a door to the outside, or a vent fan running nearby can blow out a pilot light. Close the draft source and try relighting the pilot. If it stays lit, you have solved the problem.
If the pilot light goes out again within a few hours or days, the thermocouple is likely failing. This is a job for a technician, as it involves working with the gas line. Do not attempt to replace it yourself unless you have experience with gas appliances.
How to relight a pilot light yourself
If your boiler's pilot light has gone out and you want to relight it, the steps are usually printed on the inside of the access panel or in your boiler's manual. The general process is: turn the control knob to "Off," wait five minutes for any gas to clear, then turn it to "Pilot." Hold a lit match or lighter near the pilot opening while pressing and holding the ignition button (or knob, depending on the model) for 30 to 60 seconds. Once the pilot lights, keep holding the button for another 30 seconds, then release it. If the pilot stays lit, turn the knob to "On."
If the pilot will not light after three attempts, stop and call a technician. Do not keep trying — repeated attempts can allow gas to build up inside the boiler, which is a safety hazard. If you smell gas at any point, leave the house and call your gas company's emergency line.
Pilot lights versus electronic ignition: cost and reliability
| Feature | Pilot Light | Electronic Ignition |
|---|---|---|
| Continuous gas use | Yes — flame burns all the time | No — ignition only when needed |
| Energy efficiency | Lower | Higher (5–15% savings typical) |
| Works during power outage | Yes | No |
| Common failure points | Thermocouple, clogged pilot tube, drafts | Spark electrode, ignition module, sensor |
| Typical repair cost | $150–$400 for thermocouple or cleaning | $200–$600 for ignition module |
When to replace a boiler with a pilot light
A boiler with a pilot light can last 15 to 20 years or longer if maintained well. If your pilot light goes out once or twice a year and a technician fixes it for $150 to $300, that is normal maintenance. However, if the pilot light fails multiple times per year, or if your boiler is more than 20 years old, replacing it with a newer, more efficient model may make financial sense.
Newer boilers with electronic ignition are more efficient and have lower operating costs. The upfront cost of a new boiler is $3,000 to $8,000 depending on the size and type, but the energy savings and fewer repairs can offset that cost over 10 to 15 years. If your current boiler is old and breaking down frequently, a technician can advise you on whether repair or replacement makes more sense.
Frequently Asked Questions
Can I convert my boiler from a pilot light to electronic ignition?
No, you cannot retrofit electronic ignition onto a boiler designed for a pilot light. The two systems require different burner assemblies, gas valves, and control boards. Upgrading would mean replacing the entire boiler, not just the ignition system.
Is it safe to leave a pilot light on all the time?
Yes, pilot lights are designed to burn continuously and safely. However, they do waste gas and cost money to run. If you want to save energy, turning off the pilot light during warm months (if your boiler has a manual shutoff) can reduce costs, though you will need to relight it when heating season begins.
Why is my pilot light yellow or orange instead of blue?
A yellow or orange pilot light usually means the burner is not getting enough air or the gas mixture is wrong. This can reduce heating efficiency and should be checked by a technician. A healthy pilot light is always blue.
What does it mean if my pilot light is very small or hard to see?
A weak or dim pilot light often indicates a clogged pilot tube or low gas pressure. A technician can clean the tube or check the gas supply. Do not ignore this — a weak pilot light may go out unexpectedly.
Do all oil boilers have pilot lights?
No, most oil boilers use electronic ignition with a spark electrode rather than a pilot light. Oil burners ignite the fuel on demand, similar to modern gas boilers with electronic ignition.