IM 738-2
57
Preparing Unit for Operation:
Adjusting Scroll Dampers
Adjusting Scroll Dampers
Two sets of scroll dampers are provided in the housing of the
twin 15" x 6" supply fan to allow control of air volume to each
fan wheel. At the factory, these dampers are fully closed,
unrestricting airflow. If fan paralleling occurs, correct it by
loosening the adjustment screw on top of the fan housing (see
Figure 73) and slightly lowering the rod until air distribution
between the fans is even.
Figure 73. Scroll damper adjustment
Adjusting Supply Fan Thrust Restraints
Thrust restraints are provided when housed double-width fans
are mounted on springs. After the spring mounts are adjusted
for level operation when the fan is running, check the thrust
restraints. With the fan off, set the adjustment nuts so the
spring is slightly compressed against the angle bolted to the
fan housing frame. Refer to Figure 74. When the fan is turned
on, the fan moves back to a level position and the thrust
restraint springs compresses.
Figure 74. Thrust restraint adjustment
Adjustment assembly
Scroll damper
N u t " B "
S p r i n g l i p
W a s h e r
N u t " "
F a n B u l k h e a d
J a m N u t " A "
J a m N u t " A "
T h r u s t R e s t r a i n t A n g l e
F a n H o u s i n g F r a m e
S e e D e t a i l " A "
D e t a i l " A "
Thrust restraint adjustment (with fan off)
1. Loosen jam nuts “A.”
2. Turn nut “C” until spring cup and washer contact thrust restraint
angle.
3. Turn nut “B” until spring is compressed by two turns of nut “B.”
Summary of Contents for RDT-135c
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