24
Step 10 — Install Plenums (if Required) —
The
installation of 50XC plenums is applicable to all vertical dis-
charge 50XCW units.
The following tools are required:
•
5
/
16
-in. nut driver
• adequate lifting device
• utility knife
• safety glasses
• work gloves
Install as follows:
1. Apply
3
/
4
-in. wide by
1
/
4
-in. thick gasket tape supplied
with unit to the bottom of mounting angles located on all
four sides of the plenum. Ensure edge of gasket is even
with inside edge of plenum walls and that there are no
gaps in between insulation strips. See Fig. 24.
2. Using appropriate lifting device, lift plenum and place on
top of 50XCW unit. Center plenum across both the width
and depth directions.
3. Using a
5
/
16
-in. nut driver, secure plenum mounting an-
gles to 50XCW unit using 3 no. 10
5
/
8
-in. long screws
provided with plenum. Install 3 screws along each ple-
num side and 5 screws along plenum front and rear
mounting angles.
4. Adjust four-way deflection vanes as needed to ensure ad-
equate airflow distribution
.
Step 11 — Check Fan Sheave and Belt Align-
ment —
Factory-supplied drives are pre-aligned and ten-
sioned, however, Carrier recommends checking the belt ten-
sion and alignment before starting the unit. Always check
the drive alignment after adjusting belt tension.
To install sheaves on the fan or motor shaft, remove any
rust-preventive coating on the shaft. Make sure the shaft is
clean and free of burrs. Add grease or lubricant to bore of
sheave before installing. Mount sheave on the shaft; to pre-
vent bearing damage, do not use excessive force (i.e., a
hammer). Place sheaves for minimum overhang (see
Fig. 25).
Each factory-assembled fan, shaft, and drive sheave as-
sembly is precision aligned and balanced. If excessive unit
vibration occurs after field replacement of sheaves, the unit
should be rebalanced. To change the drive ratio, reselect and
replace the motor sheave, not the fan sheave.
After 24 hours of unit operation, the drive belts may
stretch. Check the belt tension after 24 hours of operation
and adjust if necessary. Periodically check belt tension
throughout the run-in period, which is normally the initial
72 hours of operation.
ALIGNMENT — Make sure that fan shafts and motor
shafts are parallel and level. The most common causes of
misalignment are nonparallel shafts and improperly located
sheaves. Where shafts are not parallel, belts on one side are
drawn tighter and pull more than their share of the load. As
a result, these belts wear out faster, requiring the entire set
to be replaced before it has given maximum service. If
IMPORTANT: Lockout and tagout all power supplies
to equipment and controls prior to servicing unit. Fol-
low all safety codes, including working at safe heights.
Fig. 24 — 50XCW Plenum Unit
a50-8645
MODEL
UNIT
SIZE
A
B
C
D
E
WGT
(lb)
50XCW900-200A00
06
51.3
14.0
26.8
30.0
10.0
65
50XCW900-201A00
08
51.3
14.0
26.8
45.0
10.0
65
50XCW900-202A00
12
66.0
14.0
28.9
60.0
10.0
80
50XCW900-203A00
14
66.0
19.0
28.9
48.0
15.0
80
50XCW900-204A00
16
86.0
19.0
28.9
60.0
15.0
115
50XCW900-205A00
24
86.0
19.0
28.9
80.0
15.0
115
NOTE: Dimensions are in inches.
Fig. 25 — Determining Sheave-Shaft Overhang
A39-376