035-17311-000 REV A (1200)
20
Unitary Products Group
START-UP
PHASING
Predator
units are properly phased at the factory. Check for
proper compressor rotation. If the blower or compressors
rotate in the wrong direction at start-up, the electrical connec-
tion to the unit is misphased. Change the incoming line con-
nection phasing to obtain proper rotation. (Scroll
compressors operate in only one direction. If the scroll is
drawing low amperage, has similar suction and discharge
pressures, or producing a high noise level, the scroll is mis-
phased).
SUPPLY AIR INSTRUCTIONS
CHECKING SUPPLY AIR CFM
The RPM of the supply air blower will depend on the required
CFM, the static pressure resistances of the unit accessories
(see Tables 14), and the static pressure resistance of the air
duct system. With this information, the RPM for the supply air
blower can be determined from the blower performance data
(see Tables 16 - 27). Table 28 provides drive information for
the sheaves supplied with the unit.
The supply air CFM must be within the limitations shown in
Table 15.
BLOWER ROTATION
Check for proper supply air blower rotation. If the blower is
rotating backwards, the line voltage at the unit point of power
connection is misphased (See ‘PHASING.’).
BELT TENSION
The tension on the belt should be adjusted as shown in Fig-
ure 20.
Scroll compressors require proper rotation to oper-
ate correctly. Units are properly phased at the fac-
tory. Do not change the internal wiring to make the
blower condenser fans, or compressor rotate cor-
rectly.
TABLE 15: SUPPLY AIR LIMITATIONS
Unit Size
Minimum
Maximum
090
2250
3750
120
3000
5000
150
3750
6250
FIGURE 20 : BELT ADJUSTMENT
P
rocedure for adjusting belt tension:
1. Loosen six nuts (top and bottom) A.
2. Adjust by turning (B).
3. Never loosen nuts (C)
4. Use belt tension checker to apply a perpendicu-
lar force to one belt at the midpoint of the span as
shown. Deflection distance of 4mm (5/32”) is
obtained
To determine the deflection distance from normal
position, use a straight edge form sheave to
sheave as reference line. The recommended
deflection force is as follows: Tension new belts at
the max, deflection force recommended for the
belt section. Check the belt tension at least two
times during the first 24 hours of operation. Any
retensioning should fall between the min. and
max. deflection force values.
5. After adjusting, retighten nuts (A
).
