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4.0 CHARGING
4.1 Voltage Phase Check
4.1.1 Evaporator
Prior to charging, the correct voltage phasing should be checked on the indoor evaporator. Check
blower direction on the evaporator by momentarily energizing the fan motor. Reverse any two of
the three line voltage wires at the line voltage fi eld connection point to change the blower rotation.
Although the scroll compressor is phase dependent, units shipped from the factory are run tested
ensuring compressor rotation is consistent with the evaporator fan motor. However, a fi eld change-
out of the compressor may require checking proper phase. An out of phase compressor will draw
relatively low amps and both suction and discharge pressures will remain nearly equal.
4.1.2 Secondary Heat Exchanger
See separate Installation, Operation and Maintenance (IOM) Manual for air cooled condensers or
fl uid coolers for the detail on the secondary heat exchanger.
4.2 Air Cooled Systems
4.2.1 Fan Speed Control System Charging (Units with Remote Outdoor Condenser)
The standard outdoor air cooled condenser provided by Data Aire has fan speed control. The fan
speed controller does not require fi eld adjustment or programming.
After refrigerant piping is properly completed, connect the refrigerant drum to the low side and
charge with vapor. For systems with R-407C, charge with approximately 2.55 lbs. per nominal ton.
Systems with R-410A require 3 lbs. per nominal ton.
For example, a model DTAD-0312 is a nominal 3 ton unit. Charge with about 7.65 lbs. of refrigerant
if R-407C, 9 lbs. if R-410A. It is likely that more refrigerant will be required to complete the charging
procedure for additional piping between the evaporator and the condenser. Make sure all hoses
are properly purged. From a vacuum, feed liquid refrigerant into the high side of the system until
the pressures equalizes. At this point there will be about 70-80% of the total charge in the system.
A quick and easy way to run the blower and compressor is by using the manual switches provided
with the microprocessor (located in the control module). Switch the blower and compressor manual
switches to the ON position. All automatic control is disabled but safety switches will remain func-
tional.
WARNING: Before starting a compressor, the crankcase heater should be energized
for a minimum of 12 hours to reduce the possibility of liquid slugging on start-up. Failure
to energize the crankcase heater could result in compressor damage. If the system is
charged from a vacuum, the pre-heating of the compressor is not necessary.
Start the evaporator fan and compressor. Check the liquid line sight-glass to get a feel for the ap-
proximate charge. Bubbles in the sight-glass are not unusual at this point and can be caused by
fl ashing from liquid line pressure drop, low sub-cooling or low charge. It is likely more refrigerant
will be required to complete the charging procedure.
(39 paginas)
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