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Troubleshooting
WARNING
Before taking any corrective action, make certain unit
is not capable of operation during repairs.
Problem
Excessive Noise
Low CFM
High CFM
Static Pressure Wrong
High Horsepower
Fan Doesn't Operate
Overheated Shaft
Bearing
Excessive Vibration
*Always check motor amps and compare to nameplate rating. Excessive fan speed may overload the motor and
result in motor failure. Do not exceed the maximum cataloged RPM of the fan.
NOTE: Always provide the unit model and serial numbers when requesting parts or service information.
Cause
Corrective Action
Adjust wheel and/or inlet cone.
Wheel rubbing (inlet)
Tighten wheel hub or bearing collars on shaft.
Tighten Sheaves on motor/fan shaft. Adjust belt tension. Align
V-belt drive
sheaves properly (see V-Belt Drives section). Replace worn belts or
sheaves.
Replace defective bearing(s). Lubricate bearings.
Bearings
Tighten collars and fasteners.
Clean all dirt off wheel. Check wheel balance, rebalance in place if
Wheel unbalance
necessary.
Fan
Check wheel for correct rotation. Increase fan speed.*
Duct system
See page 3.
Fan
Decrease fan speed.
Duct system
Resize ductwork. Access door, filters, grilles not installed.
Duct system has more
Change obstructions in system. Use correction factor to adjust for
or less restriction than
temperature/altitude. Resize ductwork. Clean filters/coils. Change
anticipated
fan speed.*
Filters need to be cleaned or replaced. To remove the existing
filters, open the top hood panel(s). The filters can now be removed
by lifting them vertically and out of their racking. Be sure to
carefully note the quantity and size of the filters being removed as
Dirty filters
some LSF units utilize multiple filters sizes. After the filters have
• Model LSF
been cleaned, or new filters are ready to be installed, place the
filters back into the racks in the reverse order of which they were
removed. When all filters are in place, close and secure the top
roof panels.
Fan
Check rotation of wheel. Reduce fan speed.
Resize ductwork. Check proper operation of face and bypass
Duct system
dampers. Check filters and access doors.
Check fuses/circuit breakers. Check for switches turned off or
Electrical supply
disconnected. Check for correct supply voltage.
Drive
Check for broken belts. Tighten loose pulleys.
Assure motor is correct horsepower and not tripping overload
Motor
protector.
Lubrication
Check for excessive or insufficient grease in the bearings.
Replace damaged bearing. Relieve excessive belt tension. Align
Mechanical
bearings. Check for bent shaft.
Adjust tightness of belts. Replacement belts should be a matched
Belts
set.
Check alignment of shaft, motor and pulleys. Adjustable pitch
System unbalance
pulleys with motors over 15 hp are especially prone to unbalance.
Check wheel balance, rebalance if necessary.
Centrifugal, Industrial and Filtered Supply
15
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