VERTICAL VENTING
When vertical single venting is used minimum duct size is
Illus. B
If the length of the duct run or quantity of elbows used exceeds the above noted specifications, the cross section area of the duct work must be increased in proportion to the number of elbows or duct run added.
IMPORTANT: For extended duct work runs, the cross section area of the duct can only be increased to an extent. For extended duct work runs, a professional HVAC firm should be consulted for proper venting information.
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