Why won't my pilot stay lit on my boiler?
Abigail Rogers
Updated on March 13, 2026
If it's not staying lit though, then you're probably dealing with a thermocouple issue. The thermocouple of a boiler system is a long metal wire that acts as a heat sensor for the pilot light. If the pilot light goes out, then the electrical current stops, and the gas valve closes.
In respect to this, why won't my pilot stay lit on my boiler?
If it's not staying lit though, then you're probably dealing with a thermocouple issue. The thermocouple of a boiler system is a long metal wire that acts as a heat sensor for the pilot light. If the pilot light goes out, then the electrical current stops, and the gas valve closes.
One may also ask, why does my pilot light go out when I release the pilot light knob? If you're able to light the pilot light, but it goes out when you release the control knob, the thermocouple probably needs replacing. The thermocouple is a safety device that shuts off gas flow if it senses the pilot light is out, but when damaged it loses its regulatory ability.
Similarly, it is asked, what do you do if your furnace pilot light won't stay lit?
Check the Thermocouple
If your pilot light won't stay alight, it might be the thermocouple. Sometimes dust buildup collects on the thermocouple and blocks the sensor. Try cleaning the thermocouple and then relighting the pilot light. If it continues to go out, the thermocouple might need to be replaced.
Why does my pilot light keep turning off?
Usually, a problem with the thermocouple causes the pilot light to go out. The thermocouple is the small copper rod that the pilot light hits. The thermocouple's job is to shut a gas safety valve if the pilot light goes out. That's important because gas is always being supplied to the pilot to keep the flame lit.
Related Question Answers
How much does it cost to replace a thermocouple?
The thermocouple is an apparatus that senses whether the pilot light is lit and triggers the gas control valve. Repairs typically cost about $150 to have it done professionally, though a new thermocouple itself only costs about $20 on average.What are the symptoms of a bad thermocouple?
Failed Thermocouple Symptoms- The first is signs of contamination on the tube, which can include discoloration, cracks, or pinholes.
- Next, check the wiring for any signs of wear or corrosion like missing insulation or bare wire.
How do you fix a boiler that won't ignite?
If you still can't light your boiler, there could be debris blocking the jet. Boiler pilot light jets are relatively cheap to replace but can also be removed, cleaned and re-installed. Your heating engineer will be able to advise you on the best course of action and replace the jet accordingly.How do I get the pilot light back on my boiler?
How do you relight the pilot light on a boiler?- Turn the gas to 'pilot. '
- Press and hold the reset switch for one minute and hold a flame to the pilot light at the same time.
- If all is working as expected, return any casing/doors and turn the gas from 'pilot' to 'on.
Should the pilot light always be on in a boiler?
The pilot light is the blue flame that always stays lit under your boiler. When heat is required, the pilot light will inflame that gas and send it to the burners. The pilot light must always stay on or gas will easily escape. If the pilot light keeps turning off, then your boiler is not working.Does a boiler pilot light always stay on?
Since the pilot light needs to remain active, your furnace is always consuming some gas. It's not a lot—usually just a few therms of gas a month—but that obviously adds up over time. There is a safety issue as well. Pilot lights can develop problems that cause them to burn inefficiently.Where is the thermocouple on my boiler?
The wires in a boiler thermocouple are usually alloys of nickel and chromium and nickel and aluminum. The fused end is positioned inside or just above the pilot flame, and the other ends of the wires are attached to a voltage sensor that operates the gas valve.Is it dangerous if the pilot light goes out on furnace?
If your pilot light repeatedly goes out, this is a likely culprit. If this flame sensor should fail, gas will continue to flow even after the pilot light has been extinguished, causing a safety hazard, and requiring immediate repair.What could be the problem if the pilot does not stop when the pilot lights?
If your pilot light won't stay lit, the thermocouple is very likely the culprit. Sometimes it's referred to as the "flame sensor." It's a safety mechanism that shuts the gas off should the pilot go out. If the thermocouple fails to shut off the gas, all the gas flowing through the furnace could get into your home.Why does my furnace only run for a few minutes?
If your furnace only runs for a few minutes then flips off automatically, the flame sensor might be faulty. The flame sensor is responsible for monitoring the gas burner. The problem can be solved by merely cleaning the flame sensor, but if the issue persists, you may have to get the flame sensor replaced.How do I stop the wind from blowing out my pilot light?
Because of a natural knowledge of many basements being drafty, a firebox is around the pilot light to prevent it from blowing out. If there are any significant gaps in your firebox, your pilot light will go out regularly. To address this, check your firebox for any significant gaps.Can you bypass a thermocouple?
To bypass the thermocouple: Move the tilts switch wire aside. Remove your thermocouple from the heater using an 8mm wrench. Pull the valve housing aside using your 13mm socket wrench.When did furnaces stop using pilot lights?
Newer gas furnaces (since about 2010) do not have a traditional pilot light that burns all the time. Instead they use electronic ignition systems that light only as needed.Do I need to turn gas off if pilot light goes out?
If the pilot light goes out on a storage or instantaneous hot water heater, space heater or a ducted heater, you will not have a gas leak. This is because all modern gas appliances with pilot lights have a fail-safe device that closes off the gas to the appliance in the case when the pilot may go out.Will a pilot stay lit with a bad thermocouple?
The thermocouple, which operates as a safety device, turns the gas supply off when the pilot light goes out. It consists of a heat sensor connected to a solenoid; when the sensor is not heated by the pilot flame, the solenoid closes the gas supply line. When a thermocouple fails, the pilot light won't stay lighted.What do you do when your pilot light goes out?
Pilot Light Instruction Guide:- Turn off furnace, boiler, or water heater at thermostat or power switch.
- Locate the gas valve and turn knob from on or off (depending where it was) to pilot position.
- Hold down red button, which sends gas to the pilot burner.
- At the same time hold match to pilot burner.
Can you clean your thermocouple?
The best way to clean your thermocouple is to use either a piece of steel wool or the coarse side of a sponge to gently clean off any soot or other remnants. You can use a pencil eraser to clean between the threads of the screw that connects the thermocouple to the control valve of your system.How do you know if your pilot light is out?
How to Tell If the Pilot Light Is Out- Locate the front cover panel on your furnace. It should be a little door that's easily visible.
- If your pilot light is on, it should be easy to see – your eyes will be drawn to the little flame.
- If you don't see a flame, your pilot light is out.
- If there is a flame, check the color.
