Flue Deposits

Believe it or not, the corrosive chemical our House Detective in Richmond was talking about is sulfuric acid. When fuel oil, coal, and some other fuels are burned, they break down into water vapor, carbon dioxide and sulfuric acid—a chemical so powerful it can eat right through a flue liner.

And having a flue made of transite is not the only thing that can be a cause of deposits. Just about anything that keeps a flue too cool can be a culprit. For example, a flue that is too big won?t have enough draft. The exhaust will cool, and the acid vapor will condense onto the inside of the liner. Or if you switch to a new higher-efficiency furnace without shrinking the flue, again, exhaust will cool and acid vapor will condense.

Have your flues inspected by a chimney sweep or heating professional. It's the only way to be sure. Any time you change the setup of one of your fuel-burning appliances, you should have a professional do a check of the vents and flues system-wide, to make sure they're the right size.