Individual Venting; Manifold Venting - Equipment Marketers GA025L Installation Operation & Maintenance

Exhaust Requirements

Individual Venting

For maximum efficiency and performance, it is preferred to
exhaust tumble dryer(s) individually to the outdoors.
IMPORTANT: At no point may the cross sectional area
of installed venting be less than the cross sectional
area of the exhaust outlet of the tumble dryer.
The exhaust duct must be designed so the static back pressure
measured 12 inches (305 mm) from the exhaust outlet does
not exceed the maximum allowable pressure specified on the
installation sticker on the rear of the tumble dryer.
NOTE: Static back pressure must be measured with
the tumble dryer running.
The maximum allowable length venting is 14 feet (4.3 m)
and two 90° elbows or equivalent. If the equivalent length
of a duct required for an installation exceeds the maximum
allowable equivalent length, the diameter of a round duct must
be increased by 10% for each additional 20 feet (6.1 m) . Cross
section area of a rectangular duct must be increased by 20% for
each additional 20 feet (6.1 m) . Refer to Table 3 to determine
equivalent venting.
Duct Diameter
8 in. (203 mm)
10 in. (254 mm)
12 in. (305 mm)
14 in. (356 mm)
16 in. (406 mm)
18 in. (457 mm)
Equivalent Length (meter) = 1.17 x Duct Diameter (mm)
Table 3
Example: A 12 inch (305 mm) diameter duct's equivalent length
of 14 feet (4.3 m) of duct and two 90° elbows is:
50
Equivalent Length of
Rigid Straight Duct
One 90° elbow = 9.3 ft.
(2.83 m)
One 90° elbow = 11.6 ft.
(3.5 m)
One 90° elbow = 14 ft.
(4.3 m)
One 90° elbow = 16 ft.
(4.9 m)
One 90° elbow = 18.7 ft.
(5.7 m)
One 90° elbow = 21 ft.
(6.4 m)
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Equivalent Length
= 14 ft. (4.3 m) + (2) 90° elbows
= 14 ft. (4.3 m) + 14 ft. (4.3 m) + 14 ft. (4.3 m)
= 42 ft. (12.8 m)
With the tumble dryer in operation, airflow at any point in the
duct should be at least 1200 feet/min. (366 m/min.) to ensure
that lint remains airborne. If 1200 feet/min. (366 m/min.) per
minute cannot be maintained, schedule monthly inspections and
cleaning of the ductwork.
NOTE: The maximum length of a flexible metal duct
must not exceed 7.87 ft. (2.4 m) as required to meet
UL2158, clause 7.3.2A.

Manifold Venting

While it is preferable to exhaust tumble dryers individually to
the outdoors, a main collector duct may be used if it is sized
according to Figure 20 One Manifold Assembly and Figure 21
Two Manifold Assemblies. This illustration indicates minimum
diameters, and should be increased if the collector length
exceeds 14 feet (4.3 m) and two 90° elbows. The diameter of a
round duct must be increased by 10% for each additional 20 feet
(6.1 m) . Cross sectional area of a rectangular or square duct
must be increased 20% for each additional 20 feet (6.1 m) .
Refer to Table 4 to determine equivalent ducting sizing. The
collector duct may be rectangular or square in cross section, as
long as the area is not reduced. Provisions MUST be made for
lint removal and cleaning of the collector duct.
The vent collector system must be designed so the static back
pressure measured 12 inches (305 mm) from the exhaust outlet
does not exceed the maximum allowable pressure of 0.5 W.C.I.
(1.3 bar) as specified on the installation sticker on the rear of
tumble dryer. Static back pressure must be measured with all
tumble dryers vented into the collector operating.
NOTE: Never connect a tumble dryer duct at a 90°
angle to the collector duct. Refer to Figure 19 . Doing
so will cause excessive back pressure, resulting in
poor performance. Never connect two tumble dryer
exhaust ducts directly across from each other at the
point of entry to the collector duct.
With the tumble dryer in operation, airflow at any point in the
duct should be at least 1200 feet/min. (366 m/min.) to ensure
that lint remains airborne. If 1200 feet/min. (366 m/min.) cannot
be maintained, schedule monthly inspections and cleaning of the
ductwork.
Part No. 70476301ENR6