NOTE: : You must establish and maintain a minimum 20 psig (138 kPa) for the compressor to operate.
11. Check the subcooling using the Schrader port on the liquid line just before the expansion valve, or at the
Schrader near the inlet connections. Affix a thermocouple on the pipe next to the Schrader port you use.
Superheat should be around 13°F (7.2°C) before verifying subcooling.
12. After adjusting the refrigerant charge, allow the system to operate an additional 15 minutes before checking the
need for further adjustment.
NOTE: A digital scroll compressor can have a clear unit sight glass on the liquid line only when operating at 100%
capacity. When operating below 100% capacity, the unit sight glass may show bubbles with each 15 second unloading
cycle.
Approximate Load Subcooling
kW °F °C
2 circuits 300 12 6.7
1 circuit 150 14 7.8
Subcooling should be within ± 3°F (1.7°C)
Adjust load during charging to get customer's desired supply fluid temperature.
Adjust flow rate to get customer's desired dT at the Vertiv™ CoolPhase CDU.
Table 5.11 Target Subcooling
13. Repeat steps 10 through 12 for Compressor Circuit 2.
14. Run both circuits simultaneously to verify sub-cooling meets the 2-circuit value.
15. Change E177.1 and E177.2 back to five minutes after both circuits are charged.
5.7.1 Additional Compressor Oil
Once the circuits are topped off with refrigerant, more compressor oil may need to be added to each circuit if the final charge
is over 10 pounds of the calculated refrigerant charge. Record this additional oil amount on the manilla tag hanging on the
compressor service valve.
5 Refrigerant Piping Requirements Proprietary and Confidential ©2024 Vertiv Group Corp. 57
Vertiv™ CoolPhase CDU Installer/User Guide
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