Vertical Venting

suggested that the use of 90° turns be avoided; use 30° and/or 45° angles instead. The radius of the elbows should preferably be 1-1/2 times the diameter of the duct. Including basket (tumbler)/dryer elbow connections or elbows used for outside protection from the weather, no more than one (1) elbow should be used in the exhaust duct run. If more than one (1) elbow is used, the cross-sectional area of the ductwork must be increased. 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.

When single dryer venting is used, the length of the ductwork from the dryer to the outside exhaust outlet must not exceed 15 feet (4.6 meters). The minimum diameter of this ductwork must be at least 8-inches (20.32 cm). In the case of multiple (common) dryer venting, the distance from the last dryer to the outside exhaust outlet must not exceed 15 feet (4.6 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 angle instead. The radius of the elbows should preferably be 1-1/2 times the diameter of the duct. Including basket (tumbler)/dryer elbow connections or elbows used for outside protection from the weather, no more than three

(3)elbows should be used in the exhaust duct run. If more than three (3) elbows are used, the cross-sectional area of the ductwork must be increased. 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.).

Minimum ductwork diameter for horizontal and vertical venting is 8-inches (20.32 cm).

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.

As per the National Fuel Gas Code, “Exhaust ducts for type 2 clothes dryers shall be constructed of sheet metal or other noncombustible material. Such ducts shall be equivalent in strength and corrosion resistance to ducts made of galvanized sheet steel not less than 0.0195-inches (26 gauge [0.05 mm]) thick.”

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.

Single Dryer Venting

When 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

Minimum duct size for a dryer that is vented

!horizontally is 8-inches (20.32 cm) for a round duct

or an equivalent of 54 square inches (348.4 square centimeters). The duct size must not be reduced anywhere downstream of the dryer.

Exhaust back pressure measured by a manometer at each basket (tumbler) exhaust duct area must be no less than 0 and must not exceed 0.3 inches (0.74 mb) of water column (W.C.).

Minimum duct size for a dryer that is vented vertically is 8-inches (20.32 cm) for a round duct or an equivalent of 54 square inches (348.4 square centimeters). The duct size must not be reduced anywhere downstream of the dryer.

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