A dirty chimney with only a quarter inch of soot contains the highly flammable substance called creosote.  A hot fire around 1000 degrees F. could easily ignite this substance into a roaring chimney fire.  At the height of a chimney fire, the creosote can burn at temperatures exceeping 2000 degrees F.  Flames and flying embers can easily land on the roof and ignite the wood framing of your home.  the intense heat can cause the flue to crack or collapse thus causing the interior walls of your house to burst into flames.

Creosote in chimneys comes in several stages.  in its flakey, soot form, it is easily brushed away leaving safe and clean flue walls.  When it appears as hard, brittle deposits, the chimney sweep's extra efforts in brushing will remove most of the build-up.  But nasty glazed variety is truly the most dangerous form, and the most difficult to remove from your home's wood burning system.  And until recently, glazed creosote was almost impossible to remove in many instances.

Glazed creosote in your chimney is recognizable by its dense, shiny tar-like appearance.  This unpleasant substance is basically wood tar which has become baked onto the walls of the chimney or flue lining.  Once it gets burning in your chimney, it is extremely difficult to extinguish.

Unfortunately, there is no such thing as creosote-free wood burning.  Creosote accumulation will occur no matter what kind of wod is burned and no matter what kind of wood burning system is used.  What determines the type of creosote and its severity is how the fuel is burned.  Solid fuel authorities agree that the amount of smoke, the temperature of the fire and the regulation of air (turbulence) are the major variables which determine the amount of build-up.  A  low burning fire, for example, will result in incomplete combustion, the number one cause of glazed creosote accumulation.  An improperly installed fireplace insert, one that allows the smoke to cool too quickly in the firebox, is another situation which causes severe glazing.  To combat this problem, flue gases should be kept between 250 degrees and 500 degrees F. if creosote accumulations are to be reduced in amounts and in thichness.  (Be sure to ask your chimney sweep about proven methods to assure correct burning.)

If your chimney sweep has alread diagnosed glazed creosote as a problem in your chimney take his or her advice seriously.  DO NOT continue to use your affected fireplace or woodstove.  The simple fact is that a hot fire could easily ignite the glazed creosote and result in a dangerous chimney fire.  And a low burning fire under such hazardous conditions will only worsen the glazed creoste problem.

Call us and we will solve this serious condition for you. Remember to have us sweep your wood burning appliance every year or every cord of wood, which ever comes first.

Call the main office for an appointment at (781) 233-2321
Serving all of eastern MA. and southeastern NH.