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Exhaust Requirements
70458101 (EN)
32
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 305 mm (12 inches) 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 4.3 m
(14 feet) 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 6.1 m (20 feet). Cross section area of a
rectangular duct must be increased by 20% for each
additional 6.1 m (20 feet). Refer to
Table 4
to
determine equivalent venting.
Example: A 305 mm (12 inch) diameter duct’s
equivalent length of 4.3 m (14 feet) of duct and two
90° elbows is:
Equivalent Length
= 4.3 m (14 ft.) + (2) 90° elbows
= 4.3 m (14 ft.) + 4.3 m (14 ft.) + 4.3 m (14 ft.)=
12.8 m (42 ft.)
With the tumble dryer in operation, airflow at any
point in the duct should be at least 366 m/min.
(1200 feet/min.) to ensure that lint remains airborne. If
366 m/min. (1200 feet/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 2.4 m (7.87 ft.) 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 13
. This
illustration indicates minimum diameters, and should
be increased if collector length exceeds 6.1 meters
(20 feet). Manifold duct may be rectangular in cross
section, as long as area is not reduced. Provisions
should be made for lint removal and cleaning of duct.
Manifold duct must be tapered, as shown in
Figure 11
.
Individual tumble dryer ducts must enter manifold
duct at a 45° angle in the direction if airflow.
The vent collector system must be designed so the
static back pressure measured 305 mm (12 inches)
from the exhaust outlet does not exceed the maximum
allowable pressure of 1.3 bar (0.5 W.C.I.) 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 11
.
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 366 m/min.
(1200 feet/min.) to ensure that lint remains airborne. If
366 m/min. (1200 feet/min.) cannot be maintained,
schedule monthly inspections and cleaning of the
ductwork.
Figure 11
Duct
Diameter
Equivalent Length of Rigid
Straight Duct
254 mm (10 in.)
305 mm (12 in.)
356 mm (14 in.)
406 mm (16 in.)
457 mm (18 in.)
One 90° elbow = 3.5 m (11.6 ft.)
One 90° elbow = 4.3 m (14 ft.)
One 90° elbow = 4.9 m (16 ft.)
One 90° elbow = 5.7 m (18.7 ft.)
One 90° elbow = 6.4 m (21 ft.)
Equivalent Length (meter) = 1.17 x Duct Diameter (mm)
Table 4
T438I