Filter
Top Products
113406-1 www.amdry.com 13
IMPORTANT: Exhaust back pressure measured by a manometer at each basket (tumbler) exhaust
duct area must be no less than 0 and must not exceed 0.3 inches (0.74 mb) of water
column (W.C.).
It is suggested that the ductwork from each dryer not exceed 15 feet (4.57 meters) with no more than three
(3) elbows (excluding dryer connections). If the ductwork exceeds 15 feet (4.57 meters) or has numerous
elbows, the cross-sectional area of the ductwork must be increased in proportion to the length and number
of elbows in it. In calculating duct size, the cross-sectional area of a square or rectangular duct must be
increased twenty percent (20%) for each additional 15 feet (4.57 meters). The diameter of a round
exhaust duct should be increased ten percent (10%) for each additional 10 feet (3.04 meters). Each 90º
elbow is equivalent to an additional 40 feet (12.19 meters), and each 45º elbow is equivalent to an additional
20 feet (6.09 meters).
IMPORTANT: For extended ductwork runs, the cross section area of the ductwork can only be
increased to an extent. Maximum proportional ductwork runs cannot exceed 15 feet
(4.57 meters) more than the original limitations of 15 feet (4.57 meters) with three (3)
elbows. When the ductwork approaches the maximum limits as noted in this manual,
a professional heating, ventilating, and air-conditioning (HVAC) firm should be
consulted for proper venting information.
ALL ductwork 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 ductwork 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 ductwork for periodic
inspection and cleaning of lint from the ductwork.