Exhaust Requirements
Part No. 70476501ENR7
41
Duct Diameter
Equivalent Length of
Rigid Straight Duct
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:
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 13 One Manifold Assembly and Figure 14
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
. 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 12
Summary of Contents for GA120L
Page 2: ......
