Lennox LGT156H Installation Instructions Manual page 16

D-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 into pulley grooves.
Make sure blower and motor pulley are aligned. See figure
16.
1- Loosen four screws securing blower motor to sliding
base. See figure 15.
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.
3- Tighten four screws securing blower motor to sliding
base once adjustments have been made.
PULLEY ALIGNMENT
ALIGNED
MOTOR
BELT
PULLEY
NOT ALIGNED
FIGURE 16
E-Check Belt Tension
Overtensioning belts shortens belt and bearing life.
Check belt tension as follows:
1- Measure span length X. See figure 17.
LGT/LCT156, 180, 210, 240, 300
BLOWER
PULLEY
Page 16
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
undertensioned belt. A force above these values
indicates an overtensioned belt.
MEASURE BELT TENSION
DEFLECTION 1/64" PER INCH OF SPAN
OR 1.5mm PER 100mm OF SPAN
FIGURE 17
F-Field-Furnished Blower Drives
For field-furnished blower drives, use page 16 to
determine BHP and RPM required. Reference page 17 to
determine the manufacturer's model number.
G-Minimum Airflow For Optional Electric Heat
Electric Heat kW
15
30
45
60
90
values indicates
FORCE
Minimum CFM
5200
5200
5200
5200
6000
and