56
IM 738-2
Preparing Unit for Operation:
Spring Isolated Fans
Preparing Unit for Operation
Figure 70. RDT spring mount hold down fasteners
Spring Isolated Fans
Releasing Spring Mounts
The optional spring-mounted supply and return fans are locked
down for shipment. Hold-down fasteners are located at each
spring mount. Remove these fasteners before operating the
fans. Figure 71 shows a typical spring mount. Note that the
3/8" hold-down bolt securing the fan base to the unit cross
channel must be removed.
After removing the hold-down fasteners, rock the fan assembly
by hand to check for freedom of movement.
Figure 71. Spring mounted hold-down fasteners, all units
Figure 72. Fan spring mount adjustment
* Grossly out-of-adjustment thrust restraints can affect this dimension.
Recheck after thrust restrains are adjusted.74
Adjusting Spring Mounts
During operation, all fans should ride level, with the bottom of
the fan base approximately 3/8" (10mm) above the top of the
unit’s cross channel. Unhoused single-width “plug” fans will
also ride at this level when at rest.
When not operating, housed double-width fans ride lower at
the discharge end of the fan base than at the motor end. When
the fan is operating against a static pressure, it should run
level. If not, level the assembly as follows (see Figure 72):
1
Loosen the 1 5/16" jam nut above the fan base.
2
Using a large, straight blade screwdriver, turn the 5/8"
leveling screw clockwise to lower the fan base,
counterclockwise to raise the fan base.
3
When properly adjusted, retighten the jam nut.
Relief Damper Tie-Down
Economizer sections with a 30" or 40" return fan have a relief
damper that is tied down for shipping. Remove the two
brackets and two screws before operation to allow free
movement of dampers. Access is from inside the economizer
section.
WARNING
Moving machinery hazard. Can cause severe injury or death.
Before servicing equipment, disconnect power and lock off.
More than one disconnect may be required to de-energize unit.
Hold-down
fasteners
Hold-down
fasteners
This bracket is added,
and these 3/8" tie downs
are used for 15–30 ton units.
This bracket is added,
and these 3/8" tie downs
are used for 15–30 ton units.
WARNING
Moving machinery hazard. Can cause severe injury or death.
Start the fans for the first time according to the “Check, Test,
and Start Procedures” on page 100. If this is not done,
equipment damage, severe personal injury, or death can occur.
3 /8 " ± 1 /4 "
W IT H F A N
R U N N IN G !
Leveling
screw
Spring
mount
assembly
Cross
channel
Jam nut
Fan base
Summary of Contents for RDT- 036c
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