a.) Atmospheric Pressure and Air Supply
Atmospheric pressure affecting the draft from a chimney can be either outside the home, inside
the home or both. Outside the home, a high-pressure day (clear and cool) generally creates a
better draft in the chimney than a low-pressure day (overcast and damp). Inside the home,
normal household appliances, such as clothes dryers and forced air furnaces compete for air
resulting in inadequate amounts of air available to fuel a fire and create a condition known as
negative pressure. Under extreme conditions of negative pressure the combustion by-products
can be drawn from the chimney and into the house. This condition is commonly referred to as
down drafting.
There are several factors that impact the amount of air available in the home. Increased
amounts of insulation vinyl windows, extra caulking in various places and door seals can all
keep heat in but may also make a home too airtight. If you are in doubt about whether or not
there is sufficient air in your home for your stove, curtail from using those appliances known to
consume the air where possible, or open a window or door to allow air to enter the home.
b.) Environmental Conditions
High trees, low lying house location such as in a valley, tall buildings or structures surrounding your
house and windy conditions can cause pool draft or down drafting.
c.) Cold Chimney Temperature
Avoid cold chimney temperatures by burning a hot fire for the first fifteen to forty minutes, being
careful not to over fire. If any part of the chimney or parts of the stove start to glow, you are over
firing the stove. Where possible, install a temperature gauge on the chimney so temperature
drops can be seen.
d.) Chimney Installation and Maintenance
Avoid using too many elbows or long horizontal runs. If in doubt, contact a chimney expert
and/or chimney manufacturer for help. Clean chimney, rain caps and especially spark arrester
regularly, to prevent creosote build-up, which will significantly reduce chimney draw and
possibly a chimney fire.
10.) Should I close or open the air control fully when shutting down the stove?
When shutting down the stove, fully open the air control. This allows the chimney
temperatures to remain as high as possible for as long as possible. Cold chimney
temperatures create creosote.
Note: This sheet is intended as an aid and does not supercede any local, provincial or state
requirements. Check with officials or authorities having jurisdiction in your area.
Manufactured by:
CFM CENTURY A division of CFM Corporation Mississauga, Ontario L5N 8A3
HELPFUL HINTS WORTH REPEATING
continued
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