Centrifugal Inline Fans
8
®
6. The adjustable motor pulley is factory set for the
RPM specified. Speed can be increased by closing
or decreased by opening the adjustable motor
sheave. Two groove variable pitch pulleys must be
adjusted an equal number of turns open or closed.
Any increase in speed represents a substantial
increase in the horsepower required by a unit. Motor
amperage should always be checked to avoid
serious damage to the motor when speed is varied.
Operation
1. Before starting up or operating fan, check all
fasteners for tightness. In particular, check the
setscrews in wheel hub (and pulleys, if applicable).
2. While in the OFF position or before connecting the
fan to power, turn the fan wheel by hand to be sure it
is not striking the venturi or any obstacle.
3. Start the fan and shut it off immediately to check
rotation of the wheel with directional arrow in the
motor compartment, see Figure 10.
4. When the fan is started, observe the operation and
check for any unusual noises.
5. With the system in full operation and all ductwork
attached, measure current input to the motor and
compare with the nameplate rating to determine if
the motor is operating under safe load conditions.
6. Keep inlets and approaches to fan clean and free
from obstruction.
Inspection
Inspection of the fan should be conducted at the
first 30 minute and 24 hour intervals of satisfactory
operation.
30 Minute Interval
Inspect bolts, setscrews and motor mounting bolts.
Adjust and tighten as necessary.
24 Hour Interval
Check all internal components. On belt drive fans only,
inspect belt alignment and tension. Adjust and tighten
as necessary.
IMPORTANT
The fan has been checked for mechanical noises at
the factory prior to shipment. If mechanical noise
should develop, suggested corrective actions are
offered in the Troubleshooting section.
IMPORTANT
Over-tightening will cause excessive bearing wear and
noise. Too little tension will cause slippage at start-up
and uneven wear.
IMPORTANT
Adjust (tighten) belt tension after the first 24-48 hours
of operation.
PROBLEM
CAUSE
CORRECTIVE ACTION
Excessive noise
or vibration
Wheel unbalance
Clean all dirt off wheel. Check wheel balance, rebalance in
place if necessary.
Bad bearings
Replace.
Belts too tight or too loose
Adjust tension, see Figure 12.
Wheel improperly aligned and
rubbing
Center wheel on inlet, see Figure 9.
Loose drive or motor pulleys
Align and tighten. See “Pre Start-Up Checks”,
on pages 7 and 8.
Foreign objects in wheel or
housing
Remove objects, check for damage or unbalance.
Reduced airflow
System resistance too high
Check system: Proper operation of backdraft or control
dampers, obstruction in ductwork, clean dirty filters.
Unit running backwards
Correct. See Wheel Rotation on page 7.
Excessive dirt buildup on wheel
Clean wheel.
Improper wheel alignment
Center wheel on inlet, see Pre Start-Up Checks and Figure 9.
WARNING
Before taking any corrective action, make certain unit
is not capable of operation during repairs.
AVERTISSEMENT
Avant d’entreprendre toute action corrective, s’assurer
que l’appareil ne pourra pas fonctionner durant les
réparations.
Troubleshooting
