American Dryer Corp. AD-115ES - Manual (Page 21)

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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 exhaust 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.
2. Single Dryer Venting
a. Horizontal Venting
Where possible, it is suggested to provide a separate exhaust duct for each dryer. The exhaust duct
should be laid out in such a way that the duct work travels as directly as possible to the outdoors with as
few turns as possible. It is suggested that the use of 90° turns in ducting be avoided; use 30° or 45° angles
instead. The shape of the exhaust duct work is not critical so long as the minimum cross section area is
provided.
IMPORTANT: Minimum duct size for a gas dryer and 60 Kw or 72 Kw electric dryer is 14-inches
(35.56 cm) for a round duct or 12-1/2" by 12-1/2" (31.75 cm by 31.75 cm) for a
square duct. The minimum duct size for a steam dryer or 80 Kw electric dryer is
16-inches (40.64 cm) for a round duct or 14-1/2" by 14-1/2" (36.83 cm by
36.83 cm) for a square duct. DUCT SIZE MUST NOT BE REDUCED
ANYWHERE DOWN STREAM OF THE DRYER.
IMPORTANT: Exhaust back pressure measured by a manometer at each basket (tumbler) exhaust
duct area should not exceed 0.3 inches of water column (0.74 millibars).