NOTICE
Risk of refrigerant overcharge. Can cause equipment damage.
Do not use the sight glass as an indicator when charging Liebert MC condenser systems.
The system must be fully piped and evacuated before it can be charged. See Evacuation and Leak-
testing Air-cooled SystemswithoutReceivers on the previous page.
Liebert MC condensers are charge-sensitive and require accurate calculation of the system charge to
avoid overcharging. To avoid overcharge, the following additional guidelines are recommended to ensure
trouble-free operation.
• When charging system in an outdoor ambient below 50°F (10°C), recheck the subcooling
against Table 5.9 on the facing page when the ambient is above 60°F (15.6°C)
• The indoor space should be maintained at 70 to 80°F (21 to 26.7°C) return air before final
charge adjustments are made.
• Charging unit at greater than 80°F (26.7°C) return air and low outdoor ambient temperature
may result in the unit being overcharged.
• Charge by subcooling measurement at the indoor unit. See Table 5.9 on the facing page for
target subcooling temperatures.
• Pressure and temperature measuring instruments should be capable of measuring to ±10psig
(68.9kPa) and ± 2°F (1.1°C) for best subcooling measurement.
To calculate the charge for the system:
1. Check the nameplate on the indoor unit for refrigerant type to be used. Unit control
configurations differ depending on refrigerant type.
2. The unit must be operating. Refer to the following if necessary:
• Checklist for Completed Installation on page57 to operate the system.
• The operating manual for the Liebert MC Condenser.
Manuals are available at https://www.vertivco.com/en-us/support/.
3. Calculate the amount of charge for the system. See Refrigerant Charge Requirements for
Air-cooled Systems on page36.
4. Accurately weigh in as much of the system charge as possible before starting the unit. Do not
exceed the calculated charge by more than 0.5 lb (.23kg).
5. Turn on the Liebert MC disconnect switch.
Vertiv | Liebert® PDX™ and PCW™ Installer/User Guide | 40
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