Heatmax Furnace Installation and Operation Manual
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8 The venting system
8.1 General
The venting system, made up of the chimney and the connecting pipe between the furnace
and the chimney, acts as the engine that drives your wood heating system. Even the best
furnace will not function safely and efficiently as intended if it is not connected to a suitable
chimney.
The heat in the flue gases that pass from the furnace and chimney connector 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 furnace and safely vents exhaust to
outside. You can think of heat in the flue gas as the fuel the chimney uses to make draft.
8.2 Suitable chimneys
Your wood furnace will provide optimum efficiency and performance when connected to a
6-inch diameter chimney flue system. The connection to a chimney having a diameter of at
least 5 inches (Canada only) or no more than 7 inches 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 inches.
To be suitable, a factory-built metal chimney must comply with UL 103 HT (U.S.A.) or ULC
S629 (Canada).
