COOK CFS - Manual (Page 2)

2
Wheel-to-Inlet Clearance
The correct wheel-to-inlet clearance is critical to proper
fan performance. This clearance should be verified before
initial start-up since rough handling during shipment could
cause a shift in fan components. Refer to wheel/inlet draw-
ing for correct overlap.
Adjust the overlap by
loosening the wheel hub
and moving the wheel along
the shaft to obtain the cor-
rect value.
A uniform radial gap
(space between the edge of
the cone and the edge of
the inlet) is obtained by
loosening the inlet cone
bolts and repositioning the
inlet cone.
Use of Variable Frequency Drives
Motors -
Motors that are to be operated using a Variable Fre-
quency Drive (VFD) must be VFD compatible. At a mini-
mum, this must be a Premium Efficiency motor with Class F
insulation. Motors that are not supplied by Loren Cook
Company should have the recommendation of the motor
manufacturer for use with a VFD.
Grounding -
The fan frame, motor and VFD must be connected to a
common earth ground to prevent transient voltages from
damaging rotating elements.
Wiring -
Line reactors may be required to reduce over-voltage
spikes in the motors. The motor manufacturer should be
consulted for recommended line impedence and usage of
line reactors or filters, if the lead length between the VFD
and the motor exceeds 10 feet (3m).
Fan -
It is the responsibility of the installing body to perform
coast-down tests and identify any resonant frequencies
after the equipment is fully installed. These resonant fre-
quencies are to be removed from the operating range of
the fan by using the “skip frequency” function in the VFD
programming. Failure to remove resonant frequencies
from the operating range will decrease the operating life of
the fan and void the warranty.
Wiring Installation
All wiring should be in accordance with local ordinances
and the National Electrical Code, NFPA 70. Ensure the
power supply (voltage, frequency, and current carrying
capacity of wires) is in accordance with the motor name-
plate.
Size Overlap
100 - 165 3/16”
180 - 245 1/4”
270 - 300 5/16”
330 - 365 3/8”
Free Discharge
Avoid a free discharge into the plenum. This will result in
lost efficiency because it doesn’t allow for a static regain.
Discharge Duct Turns
Where possible, allow 3 duct diameters between duct
turns or elbows and the fan outlet. Refer to Discharge Duct
Turns drawing on Page 2.
Damper and Curb Installation
a. Minimum roof opening dimensions can be found
within the CFS catalog.
b. The optional duct adapter fits on the curb to locate the
top of the duct before the fan is installed. Ductwork
requires additional support.
c. The typical damper try (optional) extends below the
curb top 38 inches. A clear 17-1/2 inches is required
to access the damper tray panel (see drawing above).
Should a longer damper tray be required, extended
lengths are available.
NOTICE! It may be necessary to add support beneath
the load carrying sides of the blower and curb.
Correct Incorrect
Correct
MIN
3 DIA.
Incorrect
Minimum
Roof Opening
Motorized
Intake Damper
Damper Tray
Duct Adapter
Damper and Curb Installation Components