What Causes A Pilot Light To Go Out?

What Causes A Pilot Light To Go Out

While most modern gas furnaces are lit with an electronic ignition, if you have an older furnace, there’s a good chance that you have a standing pilot flame that starts your heating system. The purpose of a standing pilot light (where the flame stays lit at all times) is to serve as a small ignition flame for the gas burner.

One common reason that an older furnace fails to operate is a result of the pilot light going out. But why does this happen?

Learn some of the most common issues that result in a pilot light going out, and ultimately a system shutdown here:

Age & Condition Of Heating System

If your gas or propane furnace has a standing pilot light, there's a good chance that it is 20+ years old. A heating system that is that old is likely to have many parts and components that have become dirty, worn and inefficient through the years; any combination of these parts failing can lead to a pilot light going out.

Cracked Heat Exchanger

A cracked heat exchanger is something we often see in older heating systems and is common reason that your pilot light may go out. Simply put, a crack in the heat exchanger will impact the air pressure and venting inside the combustion chamber, which directly effects the flame inside. Depending on the location of the crack, air can be blown inside the heat exchanger and onto the flame.

Gas Valve & Gas Supply Issues

The pilot light depends on a reliable source of gas or propane in order to stay lit. Any issues with the gas valve that supplies that gas to the flame, whether it be dirty or malfunctioning, can result in that flame going out. It's also possible that your gas supply has run low or out entirely, which will also cause the flame to blow out.

Thermocouple Malfunction

The thermocouple on your heating system is a safety device that determines whether or not your furnace pilot light is lit. It is positioned very close to the flame, and when lit, the pilot light tells the thermocouple to keep the gas line open. A thermocouple that is dirty or malfunctioning will often shut off your gas supply in error, causing the pilot light to go out and your furnace to stop working.

Improper Venting & Airflow

Sometimes a pilot light can go out as a result of some source of wind or air simply blowing it out. If this happens, there could be an issue with how your flue pipe is set up or how your system is venting.


Is It Safe To Light Your Own Pilot Light?

Regardless of the reason that your pilot light goes out, many homeowners are unaware if it is safe to re-light that pilot themselves. In some cases it *might* be safe to re-light your pilot light; however, specifically when you are dealing with a gas-related issue, we always recommend having this done by a professional.

An experienced HVAC service technician can help perform this task safely, as well as help determine the reason why it may have went out to help avoid a system breakdown in the future and ensure the safe operation of your system.

Ready to make the call for help? Our team would be happy to help!
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