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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 accu-
mulates 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 big chimney
fi re is possible.
2. Do not have fi res in the heater that may ignite chimney
fi res. These are 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)
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