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RT-SVX34V-EN
Verifying Proper Fan Rotation
WARNING
Rotating Components!
Failure to disconnect power before servicing could
result in rotating components cutting and slashing
technician which could result in death or serious
injury.
Disconnect all electric power, including remote
disconnects before servicing. Follow proper lockout/
tagout procedures to ensure the power can not be
inadvertently energized.
Using to as a reference, momentarily jump across the test
terminals to start the Minimum Ventilation Test.
The Exhaust Fan will start anytime the economizer damper
position is equal to or greater than the exhaust fan setpoint.
The economizer will drive to the minimum position setpoint,
exhaust fans may start at random, and the supply fan will
start.
Once the supply fan has started, check for proper rotation.
The direction of rotation is indicated by an arrow on the fan
housing.
If the fan is rotating backwards, open the main power
disconnect switch upstream of the unit terminal block or the
unit factory mounted disconnect switch.
WARNING
Hazardous Voltage!
Failure to disconnect power before servicing could
result in death or serious injury.
Disconnect all electric power, including remote
disconnects before servicing. Follow proper lockout/
tagout procedures to ensure the power can not be
inadvertently energized. Verify that no power is
present with a voltmeter.
Confirm that brown, orange, and yellow wire are on L1, L2,
L3 for the supply fan power harnesses. Make necessary
interchange if they are not.
Note: Interchanging “Load” side power wires at the supply
fan contactor will only affect the Fan Rotation.
Ensure that the voltage phase sequence at the main
unit terminal block or the unit mounted disconnect
switch is ABC as outlined in “Electrical Phasing,” p.
38.
Verifying Proper Air Flow (CFM)
1. All systems - Set the minimum position setting for the
economizer to 0º using the setpoint potentiometer
located on the Economizer Actuator in the return
section with the supply fan “On” and rotating in the
proper direction:
VFD's - With the O/A dampers fully closed, read the
amperage displayed on the VFD screen and compare it
to the motor nameplate.
Note: On VAV applications, the VFD will be under
control of the discharge Static Pressure setpoint
for the first six minutes of this test mode. Verify
that the VFD output is at 60 Hz before measuring
the fan motor amps.
If the actual amperage exceeds the nameplate value,
static pressure is less than design and air flow is too
high. If the actual amperage is below the nameplate
value, static pressure is greater than design and air
flow is too low.
2. To determine the actual CFM (within + 5%), plot the
fan's operating RPM and the theoretical BHP onto the
appropriate Fan Performance Curve in to .
Theoretical BHP Formula: [(Actual Motor Amps)/(Motor
Nameplate Amps)] x 100
Where the two points intersect, read straight down to
the CFM line. Use or to select a new fan drive if the
CFM is not within specifications.
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