Liebert CR035 - 4.2.2 Refrigerant Charge For Air-Cooled (A) Units

24 Chapter 4 Refrigeration Connections
Liebert.CRV Series Air Conditioner User Manual
4. Make the system vacuum up to 0.3mbar (absolute) and after 3 hours check if 1.3mbar (absolute) have not been
exceeded. This condition warrants the humidity lower than 50ppm inside the system. If the complete vacuum is not
possible, this means that there are some leaks (to be removed according to the instructions in 6 below).
Never use the compressor to create a vacuum (this invalidates its guarantee).
5. Break the vacuum as follows:
1) Close the cock (10a) for the vacuum pump (10).
2) Open the cock of the refrigerant cylinder (11a) until the system reaches a pressure value of about 1 bar. Repeat
this procedure using a Schrader valve on high pressure side near liquid receiver.
Warning
The refrigerant must be introduced and charged by taking only liquid fluid from the cylinder.
3) At this point both the vacuum pump and the refrigerant cylinder can be disconnected as follows:
 Close the cylinder cock (11a).
 Close the way 1/4" SAE of the Rotalock cocks and of the connected Schrader valves.
6. Inspect all connections/joints using a leak detector. If a leak is found, empty the pipes and the condenser, seal the
leak and repeat the instructions in 3 ~ 6.
7. Now the machine is ready for completing the charge and the start-up.
8. Charge the refrigerant (only liquid) by means of the charge valve placed at the evaporator inlet.
4.2.2 Refrigerant Charge For Air-Cooled (A) Units
1. Start the unit as described in 7.1 First Start-up (Or After Long Standstill).
2. Manually start the compressor at 100% modulation (ensure the unit is not in the dehumidification phase).
3. Guarantee a constant condensation temperature (preferably 45°C); if necessary, partially obstruct the condenser
coil surface or limit its ventilating power to obtain these conditions.
4. Charge the unit until the working conditions of the entire refrigeration circuit have become normal.
5. Using a manometer to measure the suction pressure and calculate the evaporating temperature, check that the
evaporating temperature is above 0°C.
6. Verify that the superheat is 5K ~ 8K (refer to 9.1 Setting Thermostatic Expansion Valve).
4.3 Refrigeration Circuits
Refer to Appendix 5 Refrigeration & Hydraulic Circuit.