IM-738 Page 49
Adjustment of 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, correction can
be made by loosening the adjustment screw on top of the fan
housing (see Figure 62) and slightly lowering the rod until
air distribution between the fans is even.
Figure 62. Scroll Damper Adjustment
Adjustment of Supply Fan Thrust
Restraints
Thrust restraints are provided when housed double-width
fans are mounted on springs. After the spring mounts have
been adjusted for level operation when the fan is running, the
thrust restraints should be checked. With the fan off, the
adjustment nuts should be set so the spring is slightly com-
pressed against the angle bolted to the fan housing frame.
Refer to Figure 63. When the fan is turned on, the fan will
move back to a level position and the thrust restraint springs
will compress.
Figure 63. Thrust restraint adjustment
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".
4.Tighten jam nuts "A".
A d j u s t m e n t A s s e m b l y
S c r o l l D a m p e
N u t " B "
S p r i n g C l i p
W a s h e r
N u t " C "
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 "
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