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KHA180, 240
3−
3−Slide base back into original position when
finished servicing. Replace the clamp and blower
wiring in the previous location on the blower motor
base. Reconnect wiring to K3 if it was disconnected.
4− Replace retained screws on either side of the sliding
base.
5− Tighten two bolts on motor pulley side.
IMPORTANT − Align top edges of blower motor base and
mounting frame base parallel before tightening two bolts
on the other side of base. Motor shaft and blower shaft
must be parallel.
6− Tighten two bolts on other side of base.
D−Determining Unit CFM
1− The following measurements must be made with a
dry indoor coil and with air filters in place. Run blower
without a cooling demand. Measure the indoor
blower shaft RPM.
2− With all access panels in place, measure static
pressure external to unit (from supply to return).
3− Referring to page 10, use static pressure and RPM
readings to determine unit CFM. Use page 11 when
installing units with any of the optional accessories
listed.
4− The blower RPM can be adjusted at the motor pulley.
Loosen Allen screw and turn adjustable pulley
clockwise to increase CFM. Turn counterclockwise to
decrease CFM. See figure 5. Tighten Allen screw after
adjustment. Do not exceed minimum and maximum
number of pulley turns as shown in table 1.
TABLE 1
MINIMUM AND MAXIMUM PULLEY ADJUSTMENT
Belt
Minimum
Turns Open
Maximum
Turns Open
A Section
No minimum
5
B Section
1*
6
*No minimum number of turns open when B belt is used on
pulleys 6" O.D. or larger.
E−Blower Belt Adjustment
Maximum life and wear can be obtained from belts only if
proper pulley alignment and belt tension are maintained.
Tension new belts after a
24−48
hour period of operation.
This will allow belt to stretch and seat grooves. Make sure
blower and motor pulley are aligned as shown in figure 6.
1− Loosen four screws securing blower motor to sliding
base. See figure 5.
2−
To increase belt tension −
Turn belt tension adjusting screw to the left, or
counterclockwise, to tighten the belt. This increases
the distance between the blower motor and the
blower housing.
To loosen belt tension −
Turn the adjusting screw to the right, or clockwise to
loosen belt tension.
FIGURE 6
PULLEY ALIGNMENT
BELT
BLOWER
PULLEY
MOTOR
PULLEY
NOT ALIGNED
ALIGNED
F−Check Belt Tension
Overtensioning belts shortens belt and bearing life.
Check belt tension as follows:
1− Measure span length X. See figure 7.
MEASURE BELT TENSION
FIGURE 7
DEFLECTION 1/64" PER INCH OF SPAN
OR 1.5mm PER 100mm OF SPAN
FORCE
2− Apply perpendicular force to center of span (X) with
enough pressure to deflect belt 1/64" for every inch
of span length or 1.5mm per 100mm of span length.
Example: Deflection distance of a 40" span would be
40/64" or 5/8".
Example: Deflection distance of a 400mm span
would be 6mm.
3− Measure belt deflection force. For a used belt, the
deflection force should be 5 lbs. (35kPa) . A new belt
deflection force should be 7 lbs. (48kPa).
A force below these values indicates and
undertensioned belt. A force above these values
indicates an overtensioned belt.
G−Field−Furnished Blower Drives
For field−furnished blower drives, use pages 10 and 11 to
determine BHP and RPM required. Reference page 10 to
determine the drive number and table 2 to determine the
manufacturer’s model number.
