23
Packaged and Split Rooftop Ventilator
SPECIAL TOOLS REQUIRED
• Voltage Meter (with wire probes)
• Amperage Meter
• Pressure Gauges – (refrigerant)
• Tachometer
• Thermometer
• Incline manometer or equivalent
Start- Up Procedure
The unit will be in operational mode during start-up. Use
necessary precautions to avoid injury. All data must be
collected while the unit is running.
o
Make sure Pre-Start-Up checklist is complete.
o
Jumper R to G, R to Y1, and R to Y2 (if applicable) on
the control board.
o
Turn the disconnect on. After 3 minutes compressors
will come on. Make sure all fans and compressors
are rotating the correct direction.
o
Allow the unit to run until the refrigerant system
stabilizes. Approximately 1-2 minutes.
Voltage Imbalance
In a 3-phase system, excessive voltage imbalance
between phases will cause motors to overheat and
eventually fail. Maximum allowable imbalance is 2%.
To determine voltage imbalance, use recorded voltage
measurements in this formula.
Key:
V1, V2, V3 = line voltages as measured
VA (average) = (V1 + V2 + V3) / 3
VD = Line voltage (V1, V2 or V3) that
deviates farthest from average (VA)
Formula:
% Voltage Imbalance = [100 x (VA-VD)] /VA
Pre-Start-Up Checklist - Packaged DX
o
Disconnect and lock-out all power switches.
o
Remove any foreign objects that are located in the
unit.
o
Check all fasteners, set-screws, and locking collars
on the fans, bearings, drives, motor bases and
accessories for tightness.
o
Rotate the fan wheels and energy recovery wheels
by hand and ensure no parts are rubbing.
o
Filters can load up with dirt during building
construction. Replace any dirty pleated filters and
clean the aluminum mesh filters in the intake hood.
o
Verify that non-motorized dampers open and close
properly.
o
Check the tightness of all factory wiring connections.
o
Verify control wire gauge.
o
Verify diameter seal settings on the energy recovery
wheel.
o
Verify proper drain trap installation.
o
Check condensing fans for any damage or
misalignment. Spin the blades and make sure they
don’t contact any parts and are free turning without
any resistance.
o
Look over the piping system.
o
Inspect all coils within the unit. Fins may get
damaged in transit or during construction. Carefully
straighten fins with a fin comb.
o
If there is an indirect gas-fired furnace in this unit,
refer to the manual provided with this unit for Pre-
Start-Up information.
o
This unit contains a crankcase heater for each
compressor which needs power supplied to it 24
hours prior to start-up. If start-up is scheduled in 24
hours, unlock the disconnect power and energize
unit.
© 2017 Mitsubishi Electric US, Inc.
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