Chimney Cleaning: Chemical Chimney Cleaners
You've seen advertisements for products touted to "clean your chimney." Are they effective? Are such products a replacement for the services of live, trained, professional chimney sweeps?
Chemical products intended to treat creosote deposits are available in numerous forms, including chemically-impregnated sawdust/wax firelogs, powders intended to be tossed onto a burning fire, and sprays for application onto firewood before ignition.
Chimney cleaning: the purpose of chemical additives
Because wood burned in a fireplace or wood stove rarely undergoes complete combustion, smoke containing vaporized residues of the wood rises with the heat and then condenses and collects on the inner walls of the flue or smoke passageway.
These residues, known as creosote, are highly flammable and provide the fuel for chimney fires. Deposits in the flue or connector pipes may also obstruct the passage of smoke. Therefore it is desirable to keep creosote deposits to a minimum.
The deposit may be light and powdery, thick and chunky, tacky and gummy, or even hard and glassy like smooth, black shellac, depending on burning and chimney conditions. The first type of deposit is easy to brush out of the flue, while other types may adhere tenaciously to the surface of the flue. These deposits can be difficult to remove from flue walls even with sharp scrapers.
Claims of chemical chimney cleaner products range from decreasing the amount of future creosote buildup to completely eliminating creosote from a dirty chimney. For example, the widely advertised Chimney Sweeping Log distributed in the U.S. by Joseph Enterprises "inhibits the rate of creosote buildup and reacts with most chimney deposit to reduce the adhesiveness," to "achieve a complete cleaning of the inside surface of your chimney" according to their promotional literature.
Chimney cleaning: the effectiveness of chemical additives
Chimney professionals have found some products so effective in certain situations that they sell them to their customers. Professional chimney sweeps may ask customers to use the product to treat creosote deposits prior to mechanical sweeping, or to minimize deposits in between scheduled maintenance.
On the other hand, chemical chimney cleaning products may or may not be effective in a given situation. Flue systems that tend to develop excess creosote are usually relatively cool compared with better performing systems, due to factors such as poor combustion or less-than-optimal flue design. There may not be sufficient heat in the system for chemical reactions to occur needed to loosen creosote from the flue surfaces.
Chimney cleaning: no substitute for professional maintenance
If you are using a fireplace or wood stove, do not be tempted to think of using a chemical chimney cleaning product as a way to get by without hiring the services of a professional chimney sweep.
Many fireplace and wood stove chimneys do not provide a straight path from the firebox to the outside. "If chemical chimney cleaning products perform as claimed and cause debris in the chimney to fall, that debris still needs to be removed from the smoke shelf, baffle, catalytic combustor, or offset in order to ensure a properly functioning chimney," according to the Chimney Safety Institute of America, a non-profit educational institution focused on the prevention of chimney and venting hazards.
Chimney cleaning: chimney inspection
Chimneys, fireplaces and vents should be inspected at least once a year by a qualified person, according to the National Fire Protection Agency. Chimney inspections often reveal hidden problems with a chimney structure that could be potentially hazardous.
Chimney cleaning: if needed, use chemical additives in tandem with a professional chimney sweep
As wood burner, your goal should be to burn cleanly and not create excessive smoke or creosote. A well operated, well designed system in which the fireplace or wood stove is matched with an appropriate chimney will generally not tend to form excessive creosote. Deposits in the flue are usually light and easily removed, and chemical treatments are not needed.
A chimney professional can check your chimney and may recommend the use of a chemical chimney cleaning product, if needed to facilitate future cleaning. If so, ask him or her about operating procedures that will help you burn wood in your fireplace or wood stove without forming excessive creosote. He or she may suggest improvements to your chimney system.
Chimney sweep: how do I find a capable chimney professional?
Ask around in your community for a chimney sweep with a good reputation. A well-earned good reputation is the public's "seal of approval."
Chimney professionals also demonstrate their competency through certification programs. A current list of CSIA Certified Chimney Sweeps® is available at http://www.csia.org You c.an also find a list of chimney professionals at www.chimneys.com
Careful wood burners will take the advice of the Chimney Safety Institute of America: "Chimney maintenance is best achieved through annual inspections and mechanical sweeping by trained professional chimney sweeps as frequently as needed."