Utility and Centrifugal Fans
10
®
Rota
tio
n
Rota
tio
n
Turning
Vanes
POOR
GOOD
Turning
Vanes
GOOD
Three fan wheel diameters
Move the fan to the desired location. Check and
tighten fasteners throughout the unit and then fasten
securely through mounting holes provided in the base
angles. The unit must be set level (shimming may be
necessary). Flexible duct connections and vibration
isolators should be used where noise is a factor.
The motor voltage and ampere rating must be
checked for compatibility with the electrical supply
prior to final electrical connection. Supply wiring to the
fan must be properly fused, and conform to local and
national electrical codes.
The discharge is factory set as specified by customer
order, however, certain sizes can be rotated to
other discharge positions in the field if necessary.
If rotating the fan housing, accommodations may
need to be made for the fan to drain properly. The
USFD-100, USF-200, and USF-300, all sizes, have
field rotatable housings. For the USF-400 and CSW,
rotatable housings are standard on sizes 30 and
less, arrangements 1, 9 and 10, and Class 0, I and
II. Class III and IV are not field rotatable. Removal of
the housing bolts allows the discharge to be rotated
to the clockwise positions shown above. For DB
discharge position, a portion of the frame angle must
be removed.
Fan rotation is always specified from the drive side of
the housing.
USF-200
USF-300 and USF-400
CW UB
CCW UB
CCW TH
CW TH
CSW
CW BH
CCW BH
CW BAU
CCW BAU
CW UB
CCW UB
CCW TH
CW TH
CW DB
CCW DB
CW TAU
CCW TAU
CW BH
CCW BH
CW BAU
CCW BAU
CW UB
CCW UB
CCW TH
CW TH
CW TAU
CCW TAU
USFD-100
CW UB
CW TH
Discharge Positions
Inlet Spin
- Inlet spin is a frequent cause of reduced
fan performance. The change in fan performance is a
function of the intensity of spin and not easily defined.
The best solution is proper duct design and airflow
patterns. Turning vanes reduce the effects of inlet
spin.
Installations with inlet or discharge configurations
that deviate from this manual may result in reduced
fan performance. Restricted or unstable flow at the
fan inlet can cause pre-rotation of incoming air or
uneven loading of the fan wheel yielding large system
losses and increased sound levels. Free discharge
or turbulent flow in the discharge ductwork will also
result in system effect losses. Refer to the following
diagrams for the most efficient installation conditions.
Ducted Inlet Installations
Inlet Duct Turns
- Installation of a duct turn or
elbow too close to the
fan inlet reduces fan
performance because air
is loaded unevenly into
the fan wheel. To achieve
full fan performance,
there should be at least
three fan wheel diameters
between the turn or
elbow and the fan inlet.
POOR
Installation
