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2.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 45º in the direction of the airflow.
IMPORTANT: No more than eight (8) dryers should be connected to one (1) main common duct.
NOTE: Refer to the illustration on page 15 for examples of multiple dryer (common) venting.
The main duct may be any shape so long as the minimum
IMPORTANT: For extended duct work runs, the
IMPORTANT: Exhaust back pressure measured by a manometer at the dryer’s exhaust duct area must not exceed 0.3 inches of water column (W.C.) - 0.74 mb - when both baskets (tumblers) are operating.
The duct work 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 duct work joints must be taped to prevent moisture and lint from escaping into the building. Also, inspection doors should be installed at strategic points in the exhaust duct work for periodic inspection and cleaning.
NOTE: When the exhaust duct work passes through a wall, ceiling, or roof made of combustible materials, the opening must be
To protect the outside end of the horizontal duct work from the weather, a 90º 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 180º turn to point the opening downward. In either case, allow at least twice the diameter of the duct between the duct opening and nearest obstruction.
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