Osburn 1700-I, Installation And Operation Manual

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Page 34 Installation and Operation Manual - Osburn 1700-I
ENGLISH
10. The Venting System
10.1 General
The venting system, made of the chimney and the liner inside the chimney, acts as the engine
that drives the wood heating system. Even the best insert will not function safely and efficiently
as intended if it is not connected to a suitable chimney and liner system.
The heat in the flue gases that pass from the insert into the chimney is not waste heat. This heat
is what the chimney uses to make the draft that draws in combustion air, keeps smoke inside
the insert and safely vents exhaust to outside. The heat in the flue gas can be seen as the fuel
the chimney uses to create draft.
10.2 Block-off Plate
To reduce the possibility of a cold air back draft from the masonry chimney into the room, the
installation of a sheet metal block-off plate
(A) is recommended. When fabricating the block-off
plate, cut the pipe hole slightly larger than the liner diameter and pass the liner through the hole.
Install the block-off plate and secure it with masonry nails. Seal the joints between the plate and
the chimney with high temperature silicone and use stove cement to seal between the pipe and
the plate.
In Canada, the CSA B365 Standard permits «Roxul» type wool to be stuffed around the liner as
it passes through the throat area as an alternative to a sheet metal block-off plate. However, this
method is less efficient than using a plate.
A
Figure 25: Block-off Plate Figure 26: Block-off Plate
10.3 Suitable Chimneys
This wood insert will provide optimum efficiency and performance when connected to a 6"
diameter chimney liner. The connection to a chimney having a diameter of at least 5" (Canada
only) is permitted if it allows the proper venting of combustion gases and that such application
is verified and authorized by a qualified installer. Otherwise, the diameter of the flue should be
6". The reduction of the liner diameter to less than 6" should only be done if the total height of
the masonry chimney is greater than 20 feet.