American Dryer Corp ID-170 specification

It is suggested that the ductwork from each dryer not exceed 20 feet (6.09 meters) with no more than two

(2)elbows (excluding dryer connections). If the ductwork exceeds 20 feet (6.09 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 20 feet (6.09 meters) The diameter of a round exhaust duct should be increased ten percent (10%) for each additional 15 feet (4.57 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 20 feet (6.09 meters) more than the original limitations of 20 feet (6.09 meters) with two (2) elbows. When the ductwork approaches the maximum limits as noted in this manual, a professional heating, venting, 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.