Startup
RT-SVX34F-EN
59
Verifying Proper Fan Rotation
Using
Table 31, p. 56
to
Table 36, p. 58
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.
Interchange any two of the field connected power wires at
the unit terminal block or factory mounted disconnect
switch.
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. 54
.
Verifying Proper Air Flow (CFM) -
CV or VFD's
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:
CV applications - Measure the amperage at the supply
fan contactor and compare it with the full load amp
(FLA) rating stamped on the motor nameplate.
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 ( 5%), plot the
fan's operating RPM and the Theoretical BHP onto the
appropriate Fan Performance Curve in
Figure 47, p. 62
and
Figure 48, p. 62
.
Theoretical BHP Formula:
Where the two points intersect, read straight down to the
CFM line. Use
Table 45, p. 69
to select a new fan drive if the
CFM is not within specifications.
WARNING
Rotating Components!
The following procedure involves working with live and
exposed rotating components. Have a qualified or
licensed service individual who has been properly
trained in handling exposed rotating components,
perform these tasks. Failure to follow all safety
precautions could result in rotating components
cutting and slashing technician which could result in
death or serious injury.
WARNING
Hazardous Voltage!
Disconnect all electric power, including remote
disconnects before servicing. Follow proper lockout/
tagout procedures to ensure the power can not be
inadvertently energized. Failure to disconnect power
before servicing could result in death or serious injury.
Actual Motor Amps
Motor Nameplate Amps
----------------------------- -------------------------------------------
Motor HP Theoretical BHP
=
r
