Centrifugal, Industrial and Filtered Supply
15
Troubleshooting
Problem
Cause
Corrective Action
Excessive Noise
Wheel rubbing (inlet)
Adjust wheel and/or inlet cone.
Tighten wheel hub or bearing collars on shaft.
V-belt drive
Tighten Sheaves on motor/fan shaft. Adjust belt tension. Align
sheaves properly (see V-Belt Drives section). Replace worn belts or
sheaves.
Bearings
Replace defective bearing(s). Lubricate bearings.
Tighten collars and fasteners.
Wheel unbalance
Clean all dirt off wheel. Check wheel balance, rebalance in place if
necessary.
Low CFM
Fan
Check wheel for correct rotation. Increase fan speed.*
Duct system
See page 3.
High CFM
Fan
Decrease fan speed.
Duct system
Resize ductwork. Access door, filters, grilles not installed.
Static Pressure Wrong
Duct system has more
or less restriction than
anticipated
Change obstructions in system. Use correction factor to adjust for
temperature/altitude. Resize ductwork. Clean filters/coils. Change
fan speed.*
Dirty filters
• Model LSF
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
some LSF units utilize multiple filters sizes. After the filters have
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.
High Horsepower
Fan
Check rotation of wheel. Reduce fan speed.
Duct system
Resize ductwork. Check proper operation of face and bypass
dampers. Check filters and access doors.
Fan Doesn’t Operate
Electrical supply
Check fuses/circuit breakers. Check for switches turned off or
disconnected. Check for correct supply voltage.
Drive
Check for broken belts. Tighten loose pulleys.
Motor
Assure motor is correct horsepower and not tripping overload
protector.
Overheated Shaft
Bearing
Lubrication
Check for excessive or insufficient grease in the bearings.
Mechanical
Replace damaged bearing. Relieve excessive belt tension. Align
bearings. Check for bent shaft.
Excessive Vibration
Belts
Adjust tightness of belts. Replacement belts should be a matched
set.
System unbalance
Check alignment of shaft, motor and pulleys. Adjustable pitch
pulleys with motors over 15 hp are especially prone to unbalance.
Check wheel balance, rebalance if necessary.
*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.
WARNING
Before taking any corrective action, make certain unit
is not capable of operation during repairs.
