While wood-burning stoves and fireplaces are a cozy and rustic addition to any home, they require regular maintenance in order to work at effective and safe levels. The flue and chimney used to vent the stove become coated with smoke and residue from burning wood and need to be cleaned and inspected regularly to ensure the longevity of the stove and the safety of your home.
Creosote and Soot
Soot is the general buildup from wood fires, and while it is difficult to remove, it is not damaging or harmful in any way. Creosote, on the other hand, is the thick, sticky, tar-like substance left behind from burning wood that coats the inside of chimneys and flues. It is highly flammable and, when left to build up in thick layers, creates a fire hazard for homes. It also prevents the flue and chimney from operating properly. Regularly cleaning the flue and chimney helps keep the risks of smoke and fire to a minimum.
One of the most common chimney-cleaning materials is copper sulfate, which is added to the wood while burning. It interacts with the creosote, which burns and then breaks away sections. It is a more effective method than the traditional “let your fire burn hot for 15 minutes every session” to burn away creosote, as the copper sulfate eats away at the creosote lining at lower burning temperatures. However, one problem with using copper sulfate is that it creates sulfuric acid, which over time can damage metal chimneys, so it should only be used on stone, concrete and nonmetal flues and chimneys. The average life of a chimney is between 35 and 40 years when cared for properly.
Similar to copper sulfate, common table salt can be used on an occasional basis to help burn away the creosote within a flue and chimney. The sodium chloride creates a mild acid when combined with the moisture in the burning wood and can eat away thin coatings of creosote. However, sodium chloride is only safe for use on brick, stone and concrete chimneys, as the acid will eat away at metal chimneys.
A variety of commercial flue and chimney cleaners are available at your local home improvement store. They are used in conjunction with chimney brushes, which are either round or square and are made to fit standard flues. However, professional chimney inspectors recommend regular brushing every two to three months as opposed to regular use of chemicals, which over time will harm chimneys and cause chemical buildups. Refer to the manufacturer's guidelines for specific instructions regarding application and use of any chemicals.
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- Chimneys.com: Chimney Cleaning: Chemical Chimney Cleaners
- Popular Science: How to Control Creosote for Safer Wood Burning
- Michigan State University Extension: Chimney Problems
- The Frugal Senior: Keep Your Chimney Clean
- Rangemoors: A Guide to Flues and Chimneys for Solid Fuel and Wood Burning Appliances