Why Is My LP Boiler Making Soot?

Maintenance

• A poorly maintained boiler is less efficient then a well-maintained boiler. This can lead to a number of problems, soot production among them. In order to keep your boiler running at peak efficiency, clean it regularly and have a professional technician inspect and service your equipment once every year or two years. A thorough cleaning should include all accessible parts of the boiler, as well as the flue, chimney and ductwork.

Draft Issues

• In some cases, boiler soot can be the result of draft issues. The root cause of this usually has to do with your chimney or flue. The chimney or flue may be clogged, improperly sized or installed in such a way that the draft is not adequate. There might also be a problem with your barometric damper, the weighted door-like device that controls the draft.

Air-to-Fuel Ratio

• The mix of air and fuel that burns in your LP boiler is important for efficiency. If the ratio is not just right, your boiler will not run as clean as it should. This will cause excessive soot and might also lead to carbon monoxide production, a serious and potentially fatal issue. If you suspect that your boiler is producing carbon monoxide gas, contact an HVAC professional immediately.

Incomplete Combustion

• Incomplete combustion occurs when the fuel in your boiler does not burn completely. Unburned or partially burned fuel can leak back into the combustion chamber, where it reignites at the beginning of the next cycle. This is a serious issue that can result in carbon monoxide as well as soot. If you are experiencing puffbacks -- small explosions that blow soot into your home when your boiler ignites -- this is probably the cause. Puffbacks are more common in oil-burning equipment, but they can occur in LP boilers, as well.

Impure Fuel

• Impurities in your fuel can result in unusually high soot production. This is fairly rare in LP gas-burning boilers, but it is not unheard of.