IM 1125-7 • REBEL ROOFTOPS
94
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Economizer Start-Up
1 .
Check whether the outdoor air is suitable for free cooling.
2 .
At the keypad, set the cooling setpoint low enough so the
controller calls for cooling.
3 .
Place the unit into cooling mode through the keypad
menu .
4 .
Observe the outdoor air dampers:
a .
If the outdoor enthalpy is low, the control algorithm
should start to modulate the dampers open to
maintain the discharge air setpoint.
b .
If the outdoor enthalpy is high, the dampers should
maintain their minimum position.
NOTE:
It may not be possible to check the economizer
operation in both low and high enthalpy states on the
same day. If this is the case, repeat this procedure on
another day when the opposite outdoor air enthalpy
conditions exist.
Compressor Start-Up
With the supply fan operational, prepare for compressor
operation .
1 .
Verify that the crankcase heaters are operating.
These
should operate for at least 24 hours before starting
the compressors .
Perform the Following Procedure:
1 .
At the keypad, set the cooling setpoint low enough so
that the controller will call for cooling.
2 .
Verify that compressor #1 starts. If the compressor motor
hums but does not run, verify that it is phased correctly
between the inverter board and compressor.
3 .
The compressor should operate continuously while there
is a call for cooling. If the compressor cycles on and off
on its low pressure switch, perform the following:
a .
Verify that the circuit is not short of refrigerant.
b .
Check for low airflow across the evaporator coil.
c. Check for clogged filters.
d .
Check for restricted ductwork.
e .
Check for very low temperature return air entering the
unit .
f .
Verify that the liquid line components, expansion
valve, and distributor tubes are feeding the
evaporator coil.
g. Verify that all air handling section panels are closed.
4 .
Verify that the condenser fans are cycling and rotating
properly (blowing air upward). When the compressor
starts, at least one condenser fan should also start.
Checking Subcooling
Following are recommendations for checking subcooling:
1 .
Run unit until it reaches steady state. Close the unit
section doors. Running the unit with its doors open will
affect system operation.
2 .
Subcooling can be read from the MicroTech III unit
controller.
CAUTION
Low ambient temperature hazard . Can cause
compressor damage .
Do not attempt to start up and
check out the refrigeration system when the outdoor air
temperature is below 0°F.
NOTICE
Venting refrigerant to atmosphere is not allowed per
most local laws and/or codes.
Содержание Rebel DPS003A
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