American Dryer AD-202 Installation Manual page 26

IMPORTANT: For extended ductwork runs, the cross section area of the ductwork can only be
increased to an extent. 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.
NOTE: When the exhaust ductwork passes through a wall, ceiling, or roof made of combustible
materials, the opening must be 2-inches (5.08 cm) larger than the duct (all the way around).
The duct must be centered within this opening.
Outside Ductwork Protection
To protect the outside end of the horizontal ductwork from the weather, a 90° elbow bent downward
should be installed where the exhaust exits the building. If the ductwork 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, louvers, or caps on the outside opening of the exhaust
ductwork.
3. Multiple Dryer (Common) Venting
If it is not feasible to provide separate exhaust ducts for each dryer, ducts from individual dryers may be
channeled into a "common main duct." The individual ducts should enter the bottom or side of the main
duct at an angle not more than 45° in the direction of the flow and should be spaced at least 60-3/16"
(152.87 cm) apart. The main duct should be tapered, with the diameter increasing before each individual
20-inch (50.8 cm) (for 202DR 12-inches [30.4 cm]) duct is added.
Where common venting is used, the length of the horizontal ductwork run, from the last dryer (nearest to
where the ductwork exits the building) in the common duct to the outside exhaust outlet, must not exceed
20 feet (6.1 meters).
The minimum duct size from each dryer into the common duct must be 20-inches (50.8 cm) (for 202DR
12-inches [30.4 cm]) in diameter, and must not have more than one (1) 45° elbow (connection into the
common duct) and one (1) 90° elbow (dryer connection). Total run of the duct between the dryer and the
common duct connection must not exceed 15 feet (4.57 meters).
IMPORTANT: This dryer is not provided with a back draft damper. When exhausted into a multiple
(common) exhaust line, a back draft damper must be installed at each dryer duct.
IMPORTANT: No more than three (3) dryers should be connected to one (1) main common duct.
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