Reading the Flame in Your Gas Fireplace

What the Colors Mean

Gas burns blue when it mixes well with air. Many gas fireplaces and log sets are deliberately set to show yellow and orange flames, because that looks more like wood, so some yellow is by design. Your owner's manual usually shows what the flame should look like for your model, and that picture is the best guide.

Flames That Point to a Problem

These usually come from a dirty burner or air shutter, logs that have shifted out of place, the wrong amount of media on the burner or a vent problem. None are things to fix by bending parts or moving the burner yourself.

• Tall, lazy yellow flames that lick the logs or the glass
• Black soot on the logs, the glass or the top of the firebox
• A gas fireplace flame too high for the setting, or one that roars
• Flames that lift off the burner or flicker in one spot
• A sharp or sooty smell while the fireplace runs

Gas Fireplace Soot and Sooty Glass

Gas fireplace soot is a sign that something is off. A light white film on the glass is common and cleans off; soot on gas fireplace glass is black and greasy and means the fuel is burning incompletely. Turn the fireplace off, let it cool and arrange a service. The technician cleans the burner, checks the air shutter and the log placement, and confirms the vent is clear.

Embers, Media and Log Placement

Glowing embers and the sand or vermiculite on the burner pan are part of how the flame is shaped. Too much media, or logs set even slightly off the maker's diagram, blocks burner ports and turns the flame yellow and sooty. When you clean the logs, put each one back exactly where the diagram shows.

When to Call for Service

Call for service when the flame changes suddenly, soot appears, the pilot will not stay lit or you notice a smell. If you smell gas, leave the house and call the gas utility from outside. A yearly service keeps the flame looking the way the maker intended.