Installation manual

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, venting, 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.

a. Outside Ductwork Protection

1) To protect the outside end of 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) 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) 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: The ML-190 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.