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How to Check a Gas Pilot Light

How to Check a Gas Pilot Light

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Gas pilot light

We know at Gibson's Heating & Plumbing, Inc., while electronic ignition furnaces have been around for a while now, you may still have a gas furnace with a standing pilot light that remains lit all the time. The standing pilot light works in conjunction with a thermocouple to control the ignition of the burners and the flow of gas. The thermocouple senses if the pilot flame is hot enough to ignite the fuel to the burner.

If you have an old furnace that uses a pilot light, it needs to be kept clean burning and properly adjusted to ensure that the furnace operates safely and efficiently.

What Is a Gas Pilot Light?

Usually, when discussing what a “light” is, we’re referencing a light bulb inside of a modern-day machine. However, this is not the case with your gas furnace. A pilot light is actually a flame inside your furnace that is supplied by the gas line and should always be lit. Your thermostat sends a message to your furnace when your house is too cool. As the fuel (gas) enters your furnace, it is ignited by the pilot light and the result is heat. So basically your pilot light is responsible for combusting your fuel source, which is how your furnace creates heat. If you notice your pilot light goes out, your furnace will no longer produce heat and you should have a furnace repair technician take a look.

Inspecting a Gas Furnace Pilot Light Flame

Remove the furnace cover panel to expose the burner assembly and pilot. You should be able to clearly see the flame of the pilot light.

The first thing to check is the color of the flame. A natural gas flame should be a bright blue color with a small amount of yellow at the very tip. A propane flame will have more of a bluish-green flame with a tinge of yellow at the tip. The flame should strong enough to cover about 1/2 inch at the end of the thermocouple tip.

If the flame is too strong and not adjusted correctly, it will be blue and may make a hissing sound as the flame crosses the thermocouple. The pilot should be adjusted to reduce the intensity of the flame.

A yellow flame is caused by lack of oxygen and incomplete combustion. If the pilot light is a weak yellow flame it will not get hot enough to heat the thermocouple to the temperature needed to enable the gas valve to open. This is often caused by a dirty pilot tube tip.

A split flame is usually caused by debris inside the pilot tube.

A flickering or wavering flame is usually caused by a draft. Check to see if there are sources of drafts in the room and take steps to reduce the effects on the furnace.

How to Tell If a Gas Pilot Light Is Out

Since a gas pilot light is truly a burning flame, many different scenarios can cause this flame to go out. If a wind draft enters your home near the furnace and a burst of air gets to the furnace, this could put the flame out. If your propane tank has run out of gas, this could also result in an extinguished pilot light.

Besides natural and environmental causes of your gas light going out, there could also be an issue with the thermocouple, which is a safety device that signifies to the gas valve that the flame has gone out. If this is the source of your problem, you will notice that you can start the pilot flame, but it won't stay lit. Also make sure that any debris surrounding the pilot orifice is cleaned and removed.

Is Your Pilot Light Repeatedly Going Out? Call Gibson's Heating & Plumbing, Inc to Schedule a Furnace Repair

Here to assist you, Gibson's Heating & Plumbing, Inc is ready when you call. Our trained Fort Wayne HVAC technicians are experienced in furnace repairs and offer convenient solutions for getting your home's heat back. Give us a call today!


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