5
Tochange fan speed:
1. Shut off unit power supply.
2. Loosen belt by loosening fan motor mounting nuts.
(See Fig. 5.)
3. Loosen movable pulley flange setscrew. (See Fig. 6.)
4. Screw movable flange toward fixed flange to increase
speed and away fromfixed flange to decrease speed.
Increasing fan speedincreases load on motor. Do not
exceed maximum speedspecified.
5. Set movable flange at nearest keyway of pulley hub
and tighten setscrewto torque specifications.
Toalign fa n and motor pulleys:
1. Loosen fan pulley setscrews.
2. Slide fan pulley along fan shaft. Make angular align-
ment by loosening motor from mounting.
3. Tighten fan pulley setscrews and motor mounting
bolts to torquespecifications.
4. Recheck belt tension.
C07075
Fig. 6 --Supply --FanPulley Adjustme nt
Bearings
This fan system uses bearings featuring concentric split
locking collars. The collars are tightened through a cap
screw bridging the split portion of the collar. The cap
screw has a Torx T25 socket head. Tot ighten the locking
collar: Hold the locking collar tightly against the inner
race of the bearing and torque the cap screw to65--70
in--lb(7.4--7.9Nm). See Fig. 7.
C08121
Fig. 7 --Tightening Locking Collar
Motor
When replacing the motor, also replace the external--tooth
lock washer (star washer) under the motor mounting base;
this is part of the motor grounding system. Ensure the
teeth on the lock washer are in contact with the motor’s
painted base. Tightenmotor mounting bolts to 120 +/-- 12
in--lbs.
Changing fan wheel speed by changing pulleys: The
horsepower rating of the belt is primarily dictated by the
pitch diameter of the smaller pulley in the drive system
(typically the motor pulley in these units). Do not install a
replacement motor pulley with a smaller pitch diameter
than provided on the original factory pulley. Change fan
wheel speed by changing the fan pulley (larger pitch
diameter to reduce wheel speed,smaller pitch diameter to
increase wheel speed) or select a new system (both
pulleysand matching belt(s)).
Before changing pulleys to increase fan wheel speed,
check the fan performance at the target speed and airflow
rate to determine new motor loading (bhp). Use the fan
performance tables or use the Packaged RooftopBuilder
software program. Confirm that the motor in this unit is
capable of operating at the new operating condition. Fan
shaft loading increases dramatically as wheel speed is
increased.
To reduce vibration, replace the motor’s adjustable pitch
pulley with a fixed pitch pulley (after the final airflow
balance adjustment). This will reduce the amount of
vibrationgenerated by the motor/belt--drive system.
COOLING
UNIT OPERATION AND SAFETY HAZARD
Failure to follow this warning could cause personal
injury,death and/or equipment damage.
This system uses PuronRrefrigerant which has
higher pressures than R--22and other refrigerants. No
other refrigerant may be used in this system. Gauge
set, hoses, and recovery system must be designed to
handle Puron refrigerant. If unsure about equipment,
consult the equipment manufacturer.
!WARNING

CondenserCoil

The condenser coil is fabricated with round tube copper
hairpins and plate fins of various materials a nd/or coatings
(see Model Number Format in the Appendix to identify
the materials provided in this unit). The coi l may be
one--rowor composite--type two--row.Composite two--row
coils are two single--row coils fabricated with a single
return bend end tubesheet.

CondenserCoil Maintenance and Cleaning

Recommendation

Routine cleaning of coil surfaces is essential to maintain
properoperation of the unit. Elimination of contamination
and removal of harmful residues willgreatly increase the
48TC