JLA D90, Installation Manual

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12 JLA Limited 113374 - 4
When single dryer venting is used, the ductwork from the dryer to the outside exhaust outlet should not exceed 20
feet (6.09 meters). In the case of multiple (common) dryer venting, the distance from the last dryer to the outside
exhaust outlet
should not exceed 20 feet (6.09 meters). The shape of the ductwork is not critical as long as the
minimum cross-sectional area is provided. It is suggested that the use of 90º turns be avoided; use 30º and/or 45º
bends/angles instead. The radius of the elbows
should preferably be 1-1/2 times the diameter of the duct. Excluding
basket (tumbler)/dryer elbow connections or elbows used for outside protection from the weather, no more than two
(2) elbows
should be used in the exhaust duct run. If more than two (2) elbows are used, the cross-sectional area
of the ductwork must be increased in proportion to the number of elbows used.
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.
IMPORTANT: Exhaust back pressure measured by a manometer in the exhaust duct must be no less than 0
and must not exceed 0.3 inches (0.74 mb) of water column (W.C.).
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.
2. Single Dryer 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 ductwork travels as directly as possible to the outdoors with as few turns as possible. It
is suggested that the use of 90° turns in the ducting be avoided; use 30° and/or 45° angles instead. The shape of the
exhaust ductwork is not critical as long as the minimum cross section area is provided.
IMPORTANT: The minimum duct size for a gas unit is 16-inches (40.64 cm) for a round duct and
14-1/4” x 14-1/4” (36.2 cm x 36.2 cm) for a square duct.
THE DUCT SIZE MUST NOT
BE REDUCED ANYWHERE DOWNSTREAM OF THE DRYER .