45
Supply Fans
SB Series units are equipped with direct drive
backward curved plenum supply fan
assemblies that deliver the air volume
specified according to unit size and job
requirements.
Fan Air Flow Adjustment
A specific air volume is delivered by the fans
with air volume bands in the blower wheels,
Electronically Commutated Motors (ECM),
or Variable Frequency Drives (VFD). Field
air flow adjustment may be required at
startup.
Air volume bands for the wheels are sized
according to the unit’s air delivery
specifications and can also be ordered from
the factory for field installation.
Electrically Commutated Motor Airflow
Adjustment
Figure 25 - Typical wiring diagram with EC
motor
If the application is for the motor to run at a
constant speed, the potentiometer can be
utilized without any change. If the
application is to vary the motor speed for
changing conditions, remove the jumper
indicated on the terminal strip (red wire).
Figure 26 - Shows the jumper that is to be
removed (jumped between S1 and S2).
Note, the potentiometer is still active in the
electrical loop. Refer to Figure 25.
Set the potentiometer dial for the maximum
fan speed for a particular application.
Maximum fan speed is determined by the
ECat submittal. Typically, this max speed
will be the rpm set at the factory.
The fan speed can be modulated using the 0-
10 VDC input signal.
To check fan output from the factory, the
potentiometer can be dialed to 100%. By
sending a 5V signal*, for instance, the rpm
can be measured and this reading can be
converted to cubic feet of air moved by the
fan.
It is advised that a medium range signal* be
utilized for this procedure. The highest
signal sent by the controller must then be
determined by adjustment.
Filters
Do not operate the unit without filters in
place. Check unit for correct filter placement
during startup. Operation of the equipment
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