What It Means When a Pilot Light Doesn’t Burn Blue

Updated January 17, 2024

Gas heating systems are the most common way that people keep their homes warm. Natural gas furnaces are still the most popular type of residential heater, and gas-powered boilers are the top type of boiler system used for radiant heating. The conventional way that gas heaters work is with a pilot light that ignites the burners to create combustion gas. Standing pilot lights have started to give way to either intermittent pilot lights (when turning on with an electric spark only as needed) or electronic ignition systems that need no pilot light at all. But if you have a furnace or boiler that still has a pilot light, you should inspect it a few times during the winter to make sure the pilot light’s flame is burning a steady blue. If it isn’t, you should call for a repair technician.

What the pilot light color means

The color of the pilot light should be blue because that means that only natural gas—without any other condensates—is reaching the pilot light through the gas main. The principal chemical compound found in natural gas is methane, and methane burns blue. You might see touches of red and yellow at the edge of the flame, which is normal and nothing to worry about.

When the flame’s color changes to red, yellow, or green, it means that something else has entered the gas and is burning along with the methane. It could be rust, excess air in the system, oil, dirt, and grime. These can give off toxic chemicals when they burn, so you need to have them repaired right away. A yellow pilot light can also mean that there is a carbon monoxide leak. Switch off your heating system and call a technician without delay!

Golden Rule offers the heating repair services you need in the greater Des Moines, Iowa market.

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