Specifications

CW2500 Insert Installation and Operation Manual

There are two reasons why the

chimney in the house at right will cold

backdraft when it is cold outside and

there is no fire burning in the insert.

First, the chimney runs up the outside

of the house, so the air in it is colder

and denser than the warm air in the

house. And second, the chimney is

shorter than the heated space of the

house, meaning the negative pressure

low in the house will pull outside air

down the chimney, through the insert

and into the room. Even the finest

insert will not work well when

connected to this chimney.

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 where 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.