Tips To Help You Troubleshoot A Gas Furnace Pilot Light That Keeps Going Out

2 February 2017
 Categories: , Articles


If you have a gas furnace in your home, then you have an efficient HVAC system that heats your house with very little waste. This may be good news for your energy bills, but you may run into an issue with your heater every now and then. One common issue you may experience is when the pilot light keeps going out. This is a problem that may have a few different causes. To learn about a few and also how to resolve the problem, keep reading.

Broken Thermocouple

The thermocouple on your gas furnace is a small device that is used to test the temperature of the pilot light flame. The small part sits right in front of the pilot light. It contains wires inside that become heated when the furnace lights. These wires produce a certain voltage when they come into contact with heat. This voltage is recorded and interpreted. If the thermocouple senses that the pilot light is lit, then it will allow gas to flow through the supply valve. When the device senses that the pilot light is off, then the supply valve is shut. This keeps gas from flowing through the supply line when the pilot light is not on. 

Thermocouples will wear down over time and become more sensitive than they should. They also may stop working completely and keep the gas supply valve closed at all times. If your thermocouple is old or if you have no idea when it was last changed, then try replacing it to fix your pilot light problem. 

Thermocouples are wired into your heating system. You can find the end of the device sitting right in front of the pilot light. The device will look like a round tube. Locate the tube and use a wrench to release the nut that keeps the tube secured in the mounting bracket. Pull the tube out of the bracket and also release the wired end from its attachment. Purchase a new thermocouple that matches the old one. Slip the new device into place, making sure the tube end sits upright. Screw the nut back into place and plug the wiring in. 

Once the new thermocouple is in place, test the unit to see if the pilot light stays on.

Dirty Pilot Light

Sometimes the pilot light will not stay lit because there is a great deal of dirt, soot, and other debris around the light opening. You can remove some of the debris to see if this resolves the problem. You will need to allow your heating unit to cool down completely if the system was recently running. Afterwards, remove the front cover from the unit. Look for any flakes or rust that may have accumulated inside. Use a shop vacuum to remove the debris. Also, locate the pilot light. It may sit on the bottom of the unit, or it may be located closer to the top of the device. This depends on the type of heater you have. 

Inspect the pilot light and look for black or brown accumulations of debris. If you see these, then use a wire brush to lightly scrub them away. Metal files work well to clean away debris that is difficult to remove. If you notice stains, then use a bit of rubbing alcohol to release them. Alcohol is also a good choice around the opening of the pilot light so gas can flow freely.

When you complete your cleaning, look for signs of pits, holes, or breaks around the pilot light. If you see these things, then it should be replaced. Speak with your HVAC professional about the replacement so gas leaks can be controlled both during the repair and afterwards. Not only does this help to retain an efficient system, but it keeps you safe from possible explosion issues.