Hearthstone Quality Home Heating Products, Inc
® Green Mountain Insert 70 (Model 8450)
22
S
UPPLY OF
C
OMBUSTION
A
IR
In Canada, wood inserts are not required to have a
combustion air supply from outside. Research has
shown that outside air supply do not compensate
for the depressurization of the house and may not
be sufficient to provide a supply of combustion air in
windy weather. However, to reduce the risks
against smoke spillage due to house
depressurization, a carbon monoxide (CO) detector
is required in the room where the insert is installed.
The CO detector will provide warning if for any
reason the wood insert fails to function correctly.
The safest and most reliable supply of combustion
air for a 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 a 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 an air intake is installed through the wall of the
house, its pressure can vary during windy weather.
If there are changes in wood insert performance in
windy weather, and in particular if smoke puffs from
the insert, the air duct should be disconnected from
the insert to determine if it is the cause of the
problem. In some windy conditions, negative
pressure at the duct weather hood 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.
Figure 20
– Supply of Combustion Air
