035-16626-000-E-0103
12
Unitary Products Group
The 3” dimension must equal or exceed the negative
static pressure developed by the supply air blower. If it
does not the condensate will not drain properly and
may overflow the drain pan. The trap must be at least
2-1/2” deep to maintain a water seal under all operat-
ing conditions, especially during blower start-up.
NOTE: The unit may have to be raised off the floor to
allow enough height for the trap.
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 6.
Knowing the required blower RPM and the blower
motor HP, the settings (turns open) for the supply air
motor pulley can be determined from Table 6.
Each motor pulley has:
1. A threaded barrel with two flats (or notched
recesses 180° apart.
2. A movable flange with one set screw.
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 mov-
able flange in place. If the pulley includes a locking
collar, the locking collar must be loosened to adjust the
setting of the movable flange.
Note the following:
1. The supply air CFM must be within the limitations
shown in Tables 7 and 8.
2. All pulleys can be adjusted in half turn increments.
3. The tension on the belt should be adjusted for a
deflection of 3/16” per foot of belt span with an
applied force of 2 to 3 pounds. This adjustment is
made by moving the blower motor mounting plate.
Refer to Figure 14. Turning the adjustment bolt (B)
moves the motor mounting plate up or down. 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 position.
NOTE: Never loosen the two nuts (C) (shown in Fig-
ure 14)
4. All pulleys are factory aligned.
5. All supply air motor pulleys are factory set at 3
“turns open”.
After the supply air blower motor is operating, adjust
the resistances in both the supply and the return duct
system to balance the air distribution throughout the
conditioned space. The job specification may require
that this balancing be done by someone other than the
equipment installer.
FIGURE 13 - RECOMMENDED DRAIN PIPING
5 "
2 - 1 / 2 "
P L A S T I C
E L L
S T E E L
S T U B
C O N N E C T I O N
H O S E C L A M P S
E V A P O R A T O R
C O I L
D R A I N P A N
D R A I N
P L U G
TABLE 6: SUPPLY AIR BLOWER MOTOR PULLEY
ADJUSTMENT
TURNS
OPEN
DRIVE RANGE
625-810 RPM
827-986 RPM
5
625
827
4
662
859
3
699
891
2
736
923
1
773
955
0
810
986
