20
American Dryer Corp.
113247 - 3
!
!
Important
ADH-75 and ADH-120: No more than 4 dryers
should be connected to 1 main common duct.
ADH-170
Multiple Dryer Venting with 20-Inch (50.8 cm) Diameter
4,400 cfm (124.59 cmm) Exhaust Connections at Common Duct
!
Multiple Dryer (Common) Venting
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 as
noted in this manual, a professional HVAC firm should be
consulted for proper venting information.
If it is not feasible to provide separate exhaust ducts for each
dryer, ducts from individual dryers may be channeled into a
“common main duct.” The individual ducts should enter the
bottom or side of the main duct at an angle not more than 45º
in the direction of airflow. The main duct should be tapered,
with the diameter increasing before each individual duct is
added. The minimum diameter of the individual ductwork
must be at least Dimension A (12-inches [30.48 cm] for the
ADH-75; 18-inches [45.72 cm] for the ADH-120; 20-inches
[50.8 cm] for the ADH-170).
The illustration on the right shows the minimum cross-
sectional area for multiple dryer round or square venting.
These figures must be increased if the main duct run from
the last dryer to where it exhausts to the outdoors is longer
than Dimension B (20 feet [6.096 meters]) or has more than
1 elbow in it.
ADH-75
Multiple Dryer Venting with 12-Inch (30.48 cm) Diameter
1,200 cfm (33.98 cmm) Exhaust Connections at Common Duct
NUMBER OF DRYERS
4
3
2
1
MINIMUM CROSS-
SECTIONAL AREA
SQ IN
315
254
200
115
SQ CM
2032
1638
1290
729
MINIMUM ROUND
DUCT DIAMETER
IN
20
18
16
12
CM
51
46
41
30
NUMBER OF DRYERS
4
3
2
1
MINIMUM CROSS-
SECTIONAL AREA
SQ IN
455
380
255
115
SQ CM
2935
2452
1645
742
MINIMUM ROUND
DUCT DIAMETER
IN
24
22
20
18
CM
61
56
51
46
NUMBER OF DRYERS
3
2
1
MINIMUM CROSS-
SECTIONAL AREA
SQ IN
707
531
315
SQ CM
4561
3426
2032
MINIMUM ROUND
DUCT DIAMETER
IN
30
26
20
CM
76
66
51
ADH-120
Multiple Dryer Venting with 18-Inch (45.72 cm) Diameter
2,500 cfm (70.79 cmm) Exhaust Connections at Common Duct
NOTE 1
Opening must be 2-inches (5.08 cm) larger than the duct (all the way
around). The duct must be centered within this opening.
NOTE 2
Distance should be 2 times the diameter of the duct to the nearest
obstruction.
Important
ADH-170: No more than 3 dryers should be
connected to 1 main common duct.
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