Lennox KGC Series Unit Information page 20

INSTALLATIONS WITH DUCTWORK
ROOFTOP UNIT
SUPPLY
MAIN
DUCT RUN
1 - Loosen four bolts securing motor base to mounting
frame. See FIGURE 7.
2 - To increase belt tension -
Turn both adjusting bolts to the right, or clockwise,
to move the motor outward and tighten the belt. This
increases the distance between the blower motor
and the blower housing.
To loosen belt tension -
Turn the adjusting bolts to the left, or counterclockwise
to loosen belt tension.
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.
3 - Tighten two bolts on each side of the motor mounting
base. This secures the mounting base to the frame.
PULLEY ALIGNMENT
ALIGNED
MOTOR
BELT
PULLEY
NOT ALIGNED
FIGURE 9
LOCATION OF STATIC PRESSURE READINGS
RETURN AIR
READING LOCATION
TURN
FIRST BRANCH
OFF OF MAIN RUN
SUPPLY AIR
READING
LOCATION
BLOWER
PULLEY
INSTALLATIONS WITH CEILING DIFFUSERS
ROOFTOP UNIT
SUPPLY AIR
READING
LOCATION
FIGURE 8
F-Check Belt Tension
Overtensioning belts shortens belt and bearing life. Check
belt tension as follows:
1 - Measure span length X. See FIGURE 10.
MEASURE BELT TENSION
DEFLECTION 1/64" PER INCH OF SPAN
OR 1.5mm PER 100mm OF SPAN
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 new 2 and 3hp
belt, the deflection force should be 5.0-7.0 lbs. (35-
48kPa). For a new 5hp belt, the deflection force
should be 7-10lbs. (48-69kPa).
A force
undertensioned belt. A force above these values
indicates an overtensioned belt.
G-Field-Furnished Blower Drives
See BLOWER DATA for field-furnished blower drives to
determine BHP and RPM required. Reference TABLE 2
MANUFACTURER'S NUMBERSfor drive component
manufacturer's numbers
Page 20
RETURN AIR
READING
LOCATION
SUPPLY
TURN
DIFFUSER
FORCE
FIGURE 10
below these values indicates an