15
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.).
IMPORTANT:
Minimum ductwork diameter for horizontal venting is 10-inches (25.4 cm) and for
vertical venting the minimum is 12-inches (30.48 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.
a. Outside Ductwork Protection
1) 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.
2. Single Dryer Venting
Where 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 so long as the minimum cross-sectional area is
provided.
IMPORTANT:
Minimum duct size for a dryer that is vented horizontally is 10-inches (25.4 cm) for a
round duct or an equivalent of 80 square inches (516.3 square centimeters).
THE
DUCT SIZE
MUST NOT BE
REDUCED ANYWHERE DOWNSTREAM
OF THE DRYER.
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.
