035-18525-001-B-0203
Unitary Products Group
11
SUPPLY AIR BLOWER ADJUSTMENT
The RPM of the supply air blower will depend on the
required CFM, the unit accessories and the static resis-
tances of both the supply and the return air duct sys-
tems. With this information, the RPM for the supply air
blower can be determined from the blower perfor-
mance in Table 8 .
Knowing the required blower RPM and the blower
motor HP, the setting (turns open) for the supply air
motor pulley can be determined form Table 5 .
Each motor pulley has:
1. A threaded barrel with two (2) flats (or notched
recesses) 180 degrees apart.
2. A movable flange with one setscrew.
After the movable flange has been rotated to the
proper number of “turns open”, the set screw
should be tightened against the flat on the barrel to
lock the movable flange in against the flat on the
barrel to lock the movable flange in place. If the
pulley includes a locking collar, the locking collar
must be loosed to adjust the setting of the movable
flange.
3. The tension on the belt should be adjusted for a
deflection of 3/16 of an inch per foot of belt span
with an applied force of 2 to 3 pounds. This adjust-
ment is made by moving the blower motor mount-
ing plate. Refer to Figure 7. Turning the
adjustment bolt (B) moves the motor mounting
plate up or down. Note - Never loosen the tow nuts
(C). Two hex nuts (A) have to be loosened to
move the mounting plate and retighten after the
mounting plate has been moved to the proper posi-
tion.
FIGURE 7: FIELD WIRING DIAGRAMS FOR POWER SUPPLY
COOLING ONLY UNITS AND UNITS WITH
STEAM OR HOT WATER COIL ACCESSORY
TERMINALS ON
SUPPLY AIR
BLOWER MOTOR
CONTACTOR
10M
GROUND
SCREW
POWER WIRING,
DESCONNECT SWITCH
AND FUSING TO BE
SUPPLIED BY FIELD
LINE VOLTAGE
POWER SUPPLY
*Not required on 060 (1-Phase
only) All other units are 3-Phase.
TERMINALS
ON FUSE HOLDER
IN ELECTRIC HEAR
CONTROL BOX
GROUND LUG
IN ELECTRIC HEAT
CONTROL BOX
POWER WIRING,
DESCONNECT
SWITCH
AND FUSING
(OR CIRCUIT
BREAKER)
TO BE SUPPLIED
BY FIELD
3-PHASE
LINE VOLTAGE
POWER SUPPLY
NOTE: USE COPPER
CONDUCTORS ONLY
WIRE IN ACCORDANCE WITH LOCAL
AND NATIONAL ELECTRICAL CODES
UNITS WITH ELECTRIC HEAT ACCESSORY
FIGURE 8: FIELD WIRING DIAGRAM COOLING
(COOLING ONLY)
Y
Y
G
TERMINAL
BLOCK TB1
ON BLOWER
UNIT
*
R
R
G
B
COOLING
TO
COND.
UNIT
24-VOLT
CONTROL
WIRING
TYPICAL TERMINALS
ON THERMOSTAT
Y
NOTE: See PN 036-13335-002
for applicable thermostats.
TABLE 6: SUPPLY AIR BLOWER MOTOR PULLY
ADJUSTMENT
TURNS
OPEN
BLOWER DRIVE RANGE (RPM)
549-716
5
549
4
582
3
625
2
655
1
685
0
716
