Greenheck Fan VSU Make-Up Air Unit with Direct-Fired Gas Heater 470654 - Manual (Page 14)

14 Model VSU Make-Up Air
®
NOTE
The most accurate way to measure the air volume is
by using a pitot traverse method downstream of the
blower. Other methods can be used, but should be
proven and accurate.
IMPORTANT
Changing the air volume can significantly increase
the motor’s amps. If the air volume is changed,
the motor’s amps must be checked to prevent
overloading the motor.
NOTE
To ensure accuracy, the dampers are to be open
when measuring the air volume.
Motor Check
Measure the motor’s voltage, amps and RPM. Compare
to the specifications. Motor amps can be reduced by
lowering the motor RPM or increasing system static
pressure.
Air Volume Measurement and Check
Measure the unit’s air volume (cfm) and compare it with
the rated air volume. If the measured air volume is off,
adjust the fan’s RPM by changing/adjusting the drive.
Check the Voltage
Before starting the unit, compare the supplied voltage,
hertz, and phase with the unit and motor’s nameplate
information.
Check the Blower Rotation
Open the blower access door
and run the blower momentarily
to determine the rotation. Arrows
are placed on the blower scroll to
indicate the proper direction or
reference the example shown to
the right.
WARNING
Check the housing, blower, and ductwork for any
foreign objects before running the blower.
WARNING
Disconnect and lock-out all power and gas before
performing any maintenance or service to the unit.
Failure to do so could result in serious injury or death
and damage to equipment.
NOTE
To reverse the rotation on three phase units,
disconnect and lock-out the power, then interchange
any two power leads.
NOTE
To reverse the rotation on single phase units,
disconnect and lock-out the power, then rewire the
motor per the manufacturer’s instructions.
IMPORTANT
If the blower is rotating in the wrong direction, the unit
will move some air, but will not perform as designed.
Be sure to perform a visual inspection to guarantee
the correct blower rotation.
Check for Vibration
Check for unusual noise, vibration or overheating of the
bearings. Reference the Troubleshooting section for
corrective actions.
IMPORTANT
Excessive vibration may be experienced during
the initial start-up. Left unchecked, it can cause a
multitude of problems including structural and/or
component failure.
IMPORTANT
Generally, fan vibration and noise is transmitted
to other parts of the building by the ductwork. To
minimize this undesirable effect, the use of heavy
canvas duct connectors is recommended.
SUP HP
MCA
EXH HP
MOP
VOLTS HZ PH
Voltage, Hertz, Phase
Blower Rotation
Blower
Housing
R
o
ta
tio
n
IMPORTANT
Additional starters and overloads may be provided in
the make-up air control center for optional exhaust
blowers. Any additional overloads must be checked
for proper voltage, amps and RPMs.
Electrical Nameplate
Start-Up - Blower
SPECIAL TOOLS REQUIRED
• Voltage Meter (with wire probes)
• Amperage Meter
• Pressure Gauges – (refrigerant)
• Tachometer
• Thermometer
• Incline manometer or equivalent