What Does It Mean When White Smoke Comes Out of My Chimney Flue?

White smoke coming from your chimney isn't necessarily a bad sign. Depending on the heating equipment installed in your home, wispy white smoke could be a normal byproduct of operation. The smoke can also be an indication of a fuel problem if your home heating equipment burns oil. A licensed technician can help you determine if the source of the smoke is normal combustion or an issue requiring immediate attention.

White smoke coming from your chimney flue is actually steam produced from condensation as a byproduct of fuel burning. It's common to see the smoke and think there's something wrong with your chimney, but this is not the case. The clouds are a normal part of fireplace or boiler operation and shouldn't be cause for concern. According to "Modern Building Services," a building industry journal, pluming is the term for the look of condensation clouds flowing from a chimney or flue system.

Pluming can be an unsightly problem for your home depending on the position of your chimney or flue system. Poorly angled vents in your flue system can cause chimney smoke to plume in front of your windows or blow back into your home. This can obscure the view out of your windows whenever your furnace or fireplace is in operation and allow particles carried in the smoke to settle inside your house.

If your home uses a high-efficiency boiler, condensation will be present in your chimney or flue system the majority of the time the boiler is in operation. The construction of the chimney and flue in your home must be sufficient to withstand the almost constant presence of water vapor. Substandard construction methods can expose your chimney or flue to corrosion or joint leaks and promote the growth of bacteria. An older home may not have sufficient joint sealant or corrosion-resistant material to effectively handle the presence of condensation in the flue or chimney.

In the case of a burner or furnace that runs on heating oil, white smoke flowing from your chimney may be a sign of a mixture problem within the burner. A functioning oil burner generates little smoke during operation. Excessive levels of oxygen within the combustion chamber can cause inefficient fuel burning and lead to the dense, white smoke emanating from your chimney. A licensed technician will need to examine and clean the burner's internal components to remove particle buildup. This should correct the issue and allow the burner or furnace to run normally.