AAON V3-E - Manual (Page 19)

19
Belts
Belt drive misalignment is one of the most common
causes of premature belt failure. A belt can be
destroyed in a matter of days if the drives have been
aligned incorrectly.
The most common tool for measuring misalignment is
a straightedge. Hold the straightedge flush across one
pulley to gauge the degree of misalignment of the two
sheaves. The maximum allowed misalignment is one
half degree of angular misalignment, and 1/10
th
of an
inch per foot between sheave centers for parallel
misalignment.
Figure 19a, Angular Misalignment
Corrected by moving the position of the motor.
Figure 19b, Parallel Misalignment
Corrected by adjusting sheaves on one, or both shafts.
Frequent belt tensioning is highly recommended. Most
belt manufacturers would suggest a retensioning after
as little as 8 hours of operation. A simplified method of
adjusting tension is to gauge the amount of force
required to deflect the belt by 1/64
th
of an inch per inch
of distance between sheave centers. For example, if
the sheaves are 20 inches apart, then the amount of
deflection with the forces listed below is 20/64
th (5/16 th )
of an inch.
Figure 19c, Belt Deflection
Indoor Coils
Coils should be inspected and cleaned annually to
ensure there is no obstruction to airflow. Dirty
evaporator coils will eventually freeze up, and often
result in a time consuming, and expensive service call.
Clean filters will help to prevent dirt from accumulating
on the evaporator, however the evaporator should be
cleaned annually with a soft bristled brush, and/or a
non-corrosive coil cleaning solution.
Heating
Electric
Set thermostat in the heat mode; call for heat to
engage all electric heat strips. Check blower for
proper rotation and voltage. Measure the amperage
and voltage. Compare them to the nameplate data.
If applicable, check remote heat pump condensing unit
as per the manufacturer’s recommendations.
Steam or Hot Water
Set thermostat in the heat mode. Observe supply
blower for proper rotation and voltage. Check boiler or
hot water operation according to the manufacturer’s
instructions. Check control flow valves for correct
operation and settings per the manufacturer’s
instructions.
Straightedge
Pulley
Pulley
Belt
Straightedge
Pulley Pulley
Belt
Sheave Centers
Force
Deflection = 1/64 th in.
per inch of length
Deflections required for:
“A” belts: 4 to 6 lbs.
“B” belts: 6 to 10 lbs.
“C” belts: 10 to 18 lbs.