ADC ADG-75D Installation And Operation Manual page 20

IMPORTANT: For extended duct work runs, the cross section area of the duct work can only be
increased to an extent. When the duct work approaches the maximum limits noted in
this manual, a professional heating venting air conditioning (HVAC) firm should be
consulted for proper venting information.
ALL duct work should be smooth inside with no projections from sheet metal screws or other
obstructions which will collect lint. When adding ducts, the duct to be added should overlap
the duct to which it is to be connected. ALL duct work joints must be taped to prevent
moisture and lint from escaping into the building. Inspection doors should be installed at
strategic points in the exhaust duct work for periodic inspection and clean-out of lint from the
duct work.
NOTE: Where the exhaust duct passes through a wall, ceiling, or roof made of combustible materials,
the opening must be 2-inches larger (all the way around) than the duct. The duct must be
centered within this opening.
a. Outside Duct Work Protection
1) To protect the outside end of horizontal duct work from the weather, a 90° elbow bent
downward should be installed where the exhaust exits the building. If the duct work travels
vertically up through the roof, it should be protected from the weather by using a 180° turn to point
the opening downward. In either case, allow at least twice the diameter of the duct between the duct
opening and the nearest obstruction.
IMPORTANT: DO NOT use screens or caps on the outside of opening of exhaust duct work.