The Venting System; General; Block-Off Plate; Suitable Chimneys - Osburn 2000 Installation And Operation Manual

2000 Insert Installation and Operation Manual
9 THE VENTING SYSTEM
9.1 GENERAL
The venting system, made up of the chimney and the liner inside the chimney, acts as the engine
that drives your 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. You can think of heat in the flue gas as the fuel the
chimney uses to make draft.
9.2 BLOCK‐OFF PLATE
To reduce the possibility of a cold air draft from the masonry chimney to get into the room when
the insert in not working, the installation of a sheet metal block‐off plate ((A) in the drawing
below) is recommended. Once you have made the block‐off plate to the proper dimension, cut the
pipe hole slightly larger than the liner's diameter and then install the liner through this hole. Set
the Block‐off plate in place and secure with masonry nails into mortar joints. Finally, seal the joints
between the plate and the wall with high temperature silicone, and then use stove‐furnace
cement to seal between the pipe and the hole.
In Canada, CSA B365 Standard permits the use of ''Roxul'' type wool 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 inferior to the use of a sheet metal block‐off plate.
9.3 SUITABLE CHIMNEYS
Your wood insert will provide optimum efficiency and performance when connected to a 6‐inch
diameter chimney liner. The connection to a chimney having a diameter of at least 5 inches
(Canada only) is permitted, if it allows the proper venting of combustion gases and that such
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