Chimneys, Inside and Out

Whether it is an extension of a fireplace or a furnace, you should have your chimney cleaned or "swept" at least once a year, for several reasons.

 First, creosote often adheres to the inside of the fireplace chimney. Because of its chemical nature, creosote can actually ignite, rapidly causing a chimney fire and potential damage to the rest of the home.

Burning wood at a relatively low temperature (your cooking stove flame is actually hotter than a fireplace) causes incomplete combustion of the oils found naturally in the wood. When the smoke from a fire rises into a chimney, the residual chemicals may stick to the inside of the chimney liner. This residue becomes creosote.

Second, soot and dust build-up can clog a chimney and diminish heat output. A furnace flue may accumulate a layer of sulfuric acid or chlorine, which can cause erosion and big problems down the road.

A good rule of thumb is to not ever assume your chimney is functioning properly, even if you rarely use it. Animals, leaves and moisture from a buildup of snow or rain need to be taken care of before safe use of your fireplace.

A thorough check for any shifting of the chimnye that may have occurred over the years is also recommended. Years ago, chimneys were built with a section near the top made of terracotta, over time, these sections sometime move, causing the potential for leaks of carbon monoxide through the seams and even a backdraft.

In addition to a good cleaning, chimney inspection includes checking for leaks in the flashing around the chimney, which can cause wood rot and condensation. This, in turn, can damage electrical wiring and present a fire hazard.

by  Joseph Coupal