ADC AD-25V Installation Manual page 10

NOTE: 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."
Single Dryer Venting
IMPORTANT: For exhaust duct runs over 85 feet (25.9
meters) a minimum size of 10-inches (25.4 cm) must be
used.
Horizontal Venting
When a single 8-inch (20.32 cm) horizontal vent is used, the
ductwork to the outlet cannot exceed 85 feet (25.9 meters),
refer to Illus. A below. This calculation of 85 feet (25.9 meters)
compensates or allows for the use of a maximum of only
one elbow (which is the outside outlet protection).
Illus. A
Vertical Venting
When vertical single 8-inch (20.32 cm) venting is used, the
ductwork from the dryer to the outside outlet cannot exceed
55 feet (16.7 meters) (refer to Illus. B below). This calculation
compensates for the use of a maximum of three elbows
including the two elbows creating the 180° (turned downward)
outside outlet.
Illus. B
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If the length of the ductwork run or quantity of elbows used
exceeds the above noted specifications, the cross-sectional
area of the ductwork must be increased in proportion to the
number of elbows or duct run added.
IMPORTANT: For extended ductwork runs, the cross-
sectional area of the ductwork can only be increased to an
extent. For extended ductwork runs, a professional HVAC
firm must be consulted for proper venting information.
Multiple Dryer (Common) Venting
If it is not feasible to provide separate exhaust ducts for each
dryer, ducts for individual dryers may be channeled into a
common main duct. Each dryer is provided with a back draft
damper. 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 airflow.
The main common duct may be any shape as long as the
minimum cross-sectional area is provided. The main duct
should be tapered with the diameter increasing before each
individual 8-inch (20.32 cm) duct is added (refer to Illus. C for
Horizontal Venting and Illus. D for Vertical Venting on the
following page).
IMPORTANT: No more than four dryers maximum should
be connected to one main common duct with a vertical run.
NOTE: Distance between dryer single ducts being
connected to the main common duct must be a minimum
of 34-1/4" (87 cm) dryer width.
Ductwork should be laid out in such a manner where
allowances are made at rear area of the dryer for removal
of rear service panels or guards.
The illustrations on the following page show the minimum
cross section area for multiple dryer venting. These figures
must be increased in proportion if the main duct run from the
last dryer to where it exhausts has numerous elbows or is
unusually long.
IMPORTANT: For extended ductwork runs, the cross
section area of the duct can only be increased to an extent.
For extended ductwork runs, a professional HVAC firm
must be consulted for proper venting information.
Refer to the following page for Multiple Dryer Horizontal
Venting and Vertical Venting examples/illustrations.
IMPORTANT: Exhaust back pressure measured by a
manometer at the dryer exhaust duct area must be no less
than 0 and must not exceed 0.3 in WC (0.74 mb).
Dryer must never be operated without the lint filter/
screen in place, even if an external lint collection
system is used.
American Dryer Corp.
WARNING
!
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