15
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 so 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).
IMPORTANT:
No more than four (4) dryers maximum
should be
connected to one (1) 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
page 16
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 heating, venting, and air
conditioning (HVAC) firm
should be
consulted for proper venting information.
Refer to
page 16
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 inches (0.74 mb) of water column
(W.C.).
