How To Light A Pilot Light on A Furnace

Posted by: Mas Broto
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How To Light A Pilot Light on A Furnace

One common issue you may experience in an old furnace is when the pilot light keeps going out. This is a problem that may have a few different causes. To learn about how to light a pilot light on a furnace, keep reading.

Is my pilot light go out on my furnace? Can I relight this? Or should I call for Help?

How a Pilot Light Works

The pilot light in a gas furnace is a continuously burning flame that ignites the burners. When the pilot light is hot enough and working correctly, the main gas valve in the pilot assembly is kept open by what’s called a thermocouple. A thermocouple is an electronic device that monitors the pilot light and shuts off the gas valve to the burners if there is not enough heat.

Why Does a Pilot Light Go Out?

Pilot lights can go out for different reasons or burn inefficiently, including due to:

  • Faulty thermocouple
  • Dirt buildup around the pilot light
  • Strong draft
  • Bad gas valve
  • Flue or chimney problems

One of the first things you should determine if your pilot light goes out is if a strong draft may have caused it. If the pilot light is lit, but there is still a problem, check the color of the flame, which should burn bright blue.

A yellow flame means there is not enough heat, and the thermocouple will thus shut off the gas valve. In some cases, the thermocouple may be loose, broken, or otherwise malfunctioning.

Dirt buildup can also cause problems with the pilot light, for instance, by restricting the amount of air needed for the flame to burn efficiently.

Since combustion furnaces use safety equipment that turns the pilot off should a problem develop, many homeowners opt to call their HVAC contractor to relight the system.

If the pilot light keep going out, there could be a problem with the pilot light itself or with the thermocouple. The thermocouple will shut off the gas to the furnace if its temperature drops, which is a prominent safety feature on furnaces with standing pilots. This part is located close to the pilot, which keeps it warm. As it loses heat due to an extinguished pilot, it shuts off the gas supply.

An interruption in the gas supply into the home can also turn off the pilot, and it’s easy enough for most people, even with limited mechanical experience, to light. It takes a while for the pilot’s thermocouple to warm, however, so anyone attempting it should have a long match or the kind of light that can withstand a hot flame for over a minute.

The thermocouple is a device that must stay hot for the gas to enter the furnace. It can get dirty over time or wear out. It may be hard to find a replacement, in which case, a call to the HVAC dealer is in order. These companies have access to a full range of products for HVAC equipment.

Sometimes the pilot goes out because it has dirt or an obstruction inside it that a small screwdriver or blast of air may dislodge. If the thermocouple has had enough time to warm and the pilot goes out again, it’s time to call in a professional to diagnose and repair the problem.

Other situations could exist that make it difficult to light the pilot. If any of the other safety switches have turned the gas off, it could be a loose wire, a control panel issue, or a problem with the gas line.

Since combustion furnaces use safety equipment that turns the pilot off should a problem develop, many homeowners opt to call their HVAC contractor to relight the system.

Relighting a Pilot Light on a Furnace

This is the basic guideline on how to light a pilot light on a furnace if it goes out.

#1 Consult Your Manual

Most furnaces have instructions on them as to how to relight the pilot light if it goes out. The furnace manual will be a better guide because it will be specific to your model instead of general guidance.

#2 Turn OFF the Gas

Turn the gas to the OFF position and leave it for at least five minutes. This action is to allow any residual gas to dissipate.

#3 Find Your Pilot Light

The pilot light is usually located at the bottom of the furnace. It is a small burner that lights the larger furnace burners. If it’s on, you should be able to see a small flame. Your pilot light might have gone out from a draft, and you’ll need to relight the pilot light.

#4 Reset and Light

Hold the lit match to the pilot light while pushing the reset button on the pilot control panel. Keep this button depressed until the pilot light relight. And then, set the gas valve to the ON status.

#5 Wait to see if the pilot light stays on

If it’s still not working even after you’ve relighted the pilot light, something else is wrong with your furnace. You may want to contact a professional to help you with the furnace repair.

It’s important that the directions are followed carefully for safety reasons, so if you are unsure how to relight the pilot light in your gas furnace, don’t hesitate to call your local HVAC technician.

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Mas Broto

Have been in the heating and air conditioning (HVAC) industry for over 20 years. He is person that will grow and thrive to learn more about the HVAC industry throughout his career. Mas Broto is also a blogger, who's dedicated to bringing you the best knowledge to get ahead in the game of life.

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