035-18525-001-B-0203
12
Unitary Products Group
4. All pulleys are factory aligned.
5. All supply air motor pulleys are factory set at 2
“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 specifi-
cations may require that this balancing be done by
someone other than the equipment installer.
To check the supply air CFM after the initial balancing
has been completed:
1. Drill two (2) 5/16-inch holes in the side panel as
shown in Figure 8.
2. Insert at least 8" of 1/4 inch tubing into each of
these holes for sufficient penetration into the air-
flow on both sides of the evaporator coil.
3. Using an inclined manometer, determine the pres-
sure drop across a dry evaporator coil. Since the
moisture on an evaporator coil may vary greatly,
measuring the pressure drop across a wet coil
under field conditions would be inaccurate. To
assure a dry coil, the refrigerant system should be
de-activated while the test is being run.
4. Knowing the pressure drop across a dry coil, the
actual CFM through the unit can be determined
from the curve in Figure 9.
If the CFM is above or below the specified valve, the
supply air motor pulley may have to be readjusted.
After on hour of operation, check the belt and pulleys
for tightness and alignment.
After readings have been obtained, remove the tubes
and seal up the drilled holes in the side panel. 5/16"
dot plugs (P/N 029-12880) are available through nor-
mal York parts ordering procedures.
FIGURE 9: TYPICAL MOTOR MOUNTING
ASSEMBLY
B
A
(DO NOT LOOSEN)
MOTOR
MOTOR MOUNT
C
FIGURE 10: HOLE LOCATIONS FOR PRESSURE
DROP READINGS
Failure to properly adjust the total system air
quantity can result in extensive blower dam-
age.
5 / 1 6 "
H O L E
5 / 1 6 "
H O L E
1 8 "
7 "
2 2 "
1 0 "
E V A P O R A T O R
C O I L
F I L T E R S
C O I L S E C T I O N
