How to Stop Soot at a Gas Fireplace

Gas fireplaces and gas fireplace inserts allow you to enjoy the look and texture of a wood-burning fireplace with no work and mess. Gas-fueled fireplaces and fire-log places have been carefully “tuned” to produce yellow flames with minimum soot formation. Should you experience a buildup of soot on your gas fireplace, there is a problem which requires attention — however if you get the soot issue early, you can quit the buildup before it becomes a significant issue.

Check for Soot

You might not notice the beginning of a soot buildup issue with the unaided eye. To test for soot, turn off the fire and allow the logs to cool. Have a clean, white cloth and rub it on the ceramic gas logs in the fireplace and also on fireplace doors, if you have them. Should you visit thick black marks on the fabric, then you have a soot issue. Another sign of soot is a buildup of small clumps of a black, powdery, ash-like material on the ceramic logs and glass fireplace doors.

Reasons for Buildup

The most frequent causes of soot buildup in a gas fireplace are ceramic fire-logs which were moved out of proper position and burner ports which are clogged. If the fire-logs shift out of place, they can interfere with the flame path that ensures clean burning of the gasoline, leading to soot formation on the logs and doors. The other main source of soot is polluted ports around the gas burner, which triggers an incomplete or unbalanced burn and also creation of soot on the logs and doors. In either case, clean off the firelogs and doors, and be sure the logs are in the exact position specified by the gas burner’s producer. If the burner has clogged ports, clean them in accordance with the manufacturer’s directions or have the fireplace trader clean them.


The correct fuel-air mixture on your fireplace produces pretty yellow flames with minimum soot buildup. Open-front gas fireplaces often have an air conditioned to the gas line feeding the burner, such as correcting the fuel-air mix. On fireplace models with glass doors, adjustable vent shutters beneath the doors regulate the quantity of combustion air. The air shutter or air ports have to be clean and unobstructed, and kept in proper place. If the flame becomes starved for air, it is going to produce excessive soot.

Old Age

Gas fireplace sets eventually wear out or rust out, causing them to emit gasoline in another manner and quantity than they did when new. This different flame pattern may cause “dirty” burning and soot buildup. The fire-logs themselves could have broken or cracked, impinging on the flame path and interfering with good combustion. Another possible issue is blockage of the fireplace exhaust vent or chimney. If you can’t find any problem with your gas fireplace however nevertheless experience excessive soot buildup, have your gas supplier check to see whether the gas regulator feeding your home or fireplace is adjusted and functioning properly.

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