Refrigerant Charging And Recovery; Low Side Repairs - Trane RTAA-70 Installation & Maintenance Manual

RTAA-SVX01A-EN

Refrigerant Charging and Recovery

If the refrigerant charge needs to be adjusted, be certain to monitor the
subcooling and superheat measurements. The subcooling needs to be
between 10 F and 20 F when the unit is running fully loaded. The ambient
temperature is between 75 F and 100 F and the leaving water temperature is
between 40 F and 55 F . Refer to Figures 1, 2 and 21.
CAUTION
Equipment Damage!
The evaporator water flow must be established and maintained
while adjusting the charge. Refrigerant pressures below 65 psig
can cause freezing and rupturing of the evaporator tubes.

Low Side Repairs

If the refrigerant charge needs to be isolated in the high side of the unit,
perform the following procedures:
1. Press the STOP key and send the unit through a stopping mode.
2. Place a manifold gauge set on the backseat port of the liquid line service
valve before actually closing the valve.
3. Close the liquid line service valve.
4. While the unit is in the STOP mode, enable Service Pumpdown for the
specific compressor. Service Pumpdown is found under the Service
Tests menu.
NOTE: Service Pumpdown can only be enabled for one compressor at a
time. Only one pumpdown per compressor can be performed, until the unit
has been reset. If these requirements are not met and Service Pumpdown is
enabled, the screen will display "PROHIBITED" for one second and then
return to disable.
With Service Pumpdown enabled, the Restart Inhibit will be ignored, the EXV
will be prepositioned and the selected compressor will start and run for one
minute.
5. Once the compressor stops, close the discharge service valve on the
compressor.
6. The remaining refrigerant needs to be recovered from the suction service
valve and the liquid line Schrader valve. Attach the inlet of a recovery sys-
tem to the backseat port on the suction service valve and the Schrader
valve between the liquid line service valve and the filter drier. Attach the
outlet of the recovery system to the manifold gauge set that is already
attached to the access port on the liquid line service valve. The
condenser will be used as the storage vessel.
7. Complete all necessary repairs.
8. Evacuate out of the backseat port on the suction service valve and from
the Schrader valve between the liquid line service valve and the filter
drier.
9. Break the vacuum by adding refrigerant to the service port on the suction
valve.
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