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9.8 Supply of Combustion Air
In Canada, wood inserts are not required to have a supply of combustion air from outdoors
because research has shown that these supplies do not give protection against house
depressurization and may fail to supply combustion air during windy weather. However, to protect
against the risk of smoke spillage due to house depressurization, a carbon monoxide (CO)
detector/alarm is required in the room in which the insert is installed. The CO detector will
provide warning if for any reason the wood insert fails to function correctly.
9.8.1 Air Supply in Conventional Houses
The safest and most reliable supply of combustion air for your wood insert is from the room in
which it is installed. Room air is already preheated so it will not chill the fire, and its availability is
not affected by wind pressures on the house. Contrary to commonly expressed concerns, almost
all tightly-sealed new houses have enough natural leakage to provide the small amount of air
needed by the insert. The only case in which the wood insert may not have adequate access to
combustion air is if the operation of a powerful exhaust device (such as a kitchen range exhaust)
causes the pressure in the house to become negative relative to outdoors.
If you do install an air supply through the wall of the house, be aware that its pressure can be
affected during windy weather. If you notice changes in wood insert performance in windy weather,
and in particular if smoke puffs from the insert, you should disconnect the outdoor air duct from the
insert and remove the duct. In some windy conditions, negative pressure at the duct weatherhood
outside the house wall may draw hot exhaust gases from the insert backwards through the duct to
outdoors. Check the outdoor air duct for soot deposits when the full system is cleaned and
inspected at least once each year.
Destination 1.5 Insert Installation and Operation Manual
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