Maytag MLG-30PDA Installation Manual page 8

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 26 gauge (0.0195-
inches [0.50 mm]) thick."
The ductwork 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. Single or independent dryer venting
is recommended. It is suggested that the use of 90° turns
be avoided; use 30° and/or 45° bends instead. The radius
of the elbows should preferably be 1-1/2 times the diameter
of the duct. All ductwork should be smooth inside with no
projections from sheet metal screws or other obstructions,
which will collect lint. When adding ducts, overlap the duct
being 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: It is recommended that exhaust or booster
fans not be used in the exhaust ductwork system.
Exhaust back pressure measured by a manometer/
magnehelic in the exhaust duct must be no less than 0 and
must not exceed 0.3 in WC (0.75 mb).
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.
The ductwork for this dryer must be suitable for the appliance
category in accordance with national installation regulations
of the country of destination.
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 (refer
to the diagram).
IMPORTANT: Do not use screens, louvers, or caps on the
outside opening of the exhaust ductwork.
8
Single Dryer Venting (8-Inch Duct)
IMPORTANT: A minimum exhaust duct size of 8-inches
(20.3 cm) must be used.
For an 8-inch (20.3 cm) run where a maximum of two elbows
are used (refer to the illustration below), the ductwork from
the dryer outlet must not exceed 10 feet (3.0 meters).
This calculation of 10 feet (3.0 meters) compensates or
allows for the use of a maximum of two elbows. Refer to the
illustration below.
SINGLE DRYER VENTING
If the length of the duct run or quantity of elbows used exceeds
the above noted specifications, the cross-sectional area of
the ductwork may need to be increased.
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 noted in this manual, a professional HVAC firm
should be consulted for proper venting information.
Single Dryer Venting (10-Inch Duct)
IMPORTANT: A minimum exhaust duct size of 10-inches
(25.4 cm) must be used for extended runs.
For a 10-inch (25.4 cm) run where a maximum of two elbows
are used (refer to the illustration below), the ductwork from
the dryer outlet must not exceed 45 feet (13.7 meters).
This calculation of 45 feet (13.7 meters) compensates or
allows for the use of a maximum of two elbows. Refer to the
illustration below.
Maytag Co. 113543 - 3