SUMMIT-B 091013-20
5
Creosote
Formation and Need for Removal
When wood is burned slowly, it produces tar and other organic
vapours, which combine with expelled moisture to form creosote.
The creosote vapours condense in the relatively cool chimney fl ue
of a slow burning fi re. As a result, creosote residue accumulates
on the fl ue lining. When ignited, this creosote makes an extremely
hot fi re. The chimney connector and chimney should be inspected
periodically (at least once every two months) during the heating
season to determine if a creosote buildup has occurred. If creosote
has accumulated (3 mm. or more), it should be removed to reduce
the risk of a chimney fi re.
1. Highest smoke densities occur when a large amount of wood
is added to a bed of hot coals and the air inlet is closed. The
heated wood generates smoke, but without ample air, the smoke
cannot burn. Smoke-free, clean burning requires small fuel
loads, two or three logs at a time or 1/4 to 1/2 of fuel load and
leaving the air inlet relatively wide open, especially during the
fi rst 10 to 30 minutes after each loading, when most of the smoke
generating reactions are occurring. After 30 minutes or so, the air
inlet can be turned down substantially without excessive smoke
generation. Wood coals create very little creosote-producing
smoke.
2. The cooler the surface over which the wood smoke is passing,
the more creosote will be condensed. Wet or green wood
contributes signifi cantly to creosote formation as the excess
moisture that is boiled off cools the fi re, making it difficult for the
tars and gases to ignite, thus creating dense smoke and poor
combustion. This moisture-laden smoke cools the chimney,
compounding the problem by offering the smoke the ideal place
to condense.
In summary, a certain amount of creosote is inevitable and must
be lived with. Regular inspection and cleaning is the solution.
The use of dry, seasoned wood and ample combustion air will
help to minimize the buildup.
Chimney Fires
The result of excessive creosote buildup is a chimney fi re. Chimney
fi res are dangerous. Chimney inside temperatures can exceed
2000° F. This causes much higher than normal temperatures in
the chimney and on its exterior surfaces. Thus ignition of nearby or
touching combustible material is more likely during a chimney fi re.
Proper clearances are critical during such a fi re.
Chimney fi res are easy to detect; they usually involve one or more
of the following:
-Flames and sparks shooting out of the top of the chimney
-A roaring sound
-Vibration of the chimney
In Case of a Chimney Fire
1. Prepare to evacuate to ensure everyone's safety. Have a well
understood plan of action for evacuation. Have a place outside
where everyone is to meet.
2. Close air inlet on stove.
3. Call local fi re department. Have a fi re extinguisher handy.
Contact your local municipal or provincial fi re authority for
further information on how to handle a chimney fi re. It is most
important that you have a clearly understood plan on how to
handle a chimney fi re.
4. After the chimney fi re is out, the chimney must be cleaned and
checked for stress and cracks before starting another fi re. Also
check combustibles around the chimney and the roof.
- The services of a competent or certifi ed installer, (certifi ed by the
Wood Energy Technical Training program (WETT) - in Canada,
Hearth Education Foundation (HEARTH) - in U.S.A.,) are strongly
recommended.
Avoiding a Chimney Fire
There are two ways to avoid chimney fi res:
1. Do not let creosote build up to a point where a chimney fi re is
possible.
2. Do not have fi res in the heater that may ignite chimney fi res.
These are very hot fi res, such as when burning household trash,
cardboard, Christmas tree limbs, or even ordinary fuel wood;
(e.g.. with a full load on a hot bed of coals and with the air inlet
excessively open.)
NOTE: WHEN CLEANING THE CHIMNEY, ALWAYS COVER THE
BAFFLE AIR TUBE THAT PROVIDES AIR TO THE BAFFLE
AFTER YOU REMOVE THE BAFFLE.
