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Exhaust Requirements
45
70458301ENR6
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 19
and
Figure 20.
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 18
.
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.
Figure 18
T438I
