Verifying Proper Air Flow (Cfm) - Cv; Or Vfd's - Trane Voyager Commercial Installation, Operation And Maintenance Manual

Interchange any two of the field connected power wires
at the unit terminal block or factory mounted
disconnect switch.
N N o o t t e e : : 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.
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
Figure 50. Supply fan performance curves 27.5 - 35 ton — 60Hz
RT-SVX34R-EN
66.
2. To determine the actual CFM (within + 5%), plot the
amperage displayed on the VFD screen and
compare it to the motor nameplate.
N N o o t t e e : : 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.
fan's operating RPM and the theoretical BHP onto
the appropriate Fan Performance Curve in
50, p. 75 to Figure 53, p.
Theoretical BHP Formula: [(Actual Motor Amps)/
(Motor Nameplate Amps)] x 100
Where the two points intersect, read straight down
to the CFM line. Use Table 48, p. 79
82 to select a new fan drive if the CFM is not within
specifications.
S S t t a a r r t t u u p p
Figure
77.
or Table 52, p.
75