Everest Fireplace Installation and Operation Manual
60 ______________________________________________________________________________
7.10
SUPPLY OF COMBUSTION AIR
In Canada, wood fireplaces are not required to have a supply of combustion air from outdoors.
Some research has shown that these supplies do not give protection against house
depressurization and may fail to supply combustion air during windy weather. 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 fireplace is installed. The CO detector will provide warning if
for any reason the wood fireplace fails to function correctly.
7.10.1
AIR SUPPLY IN CONVENTIONAL HOUSES
The safest and most reliable supply of combustion air for your wood fireplace 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. Almost all new houses have enough natural leakage
to provide the amount of air needed by the fireplace. The only case in which the wood fireplace
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 fireplace performance in windy
weather, and in particular if smoke puffs from the fireplace, you should block the outdoor air duct
or close the damper in a case where a damper was installed.
In some windy conditions, negative pressure at the duct weather hood outside the house wall
may draw hot exhaust gases from the fireplace backwards through the duct to outdoors.
