Superheat And Refrigerant Charge Optimization - Liebert PX018 Installer's/User's Manual

7. Turn on the Liebert PDX/PCW disconnect switch, and operate the unit for 30 minutes using
the charging function for each circuit of the system.
• You must operate the indoor fan using the "Diagnostic" menu of the LiebertiCOM control.
• A minimum 20 psig (138 kPa) must be established and maintained for the compressor to
operate.
• The charging function operates the compressor at full capacity and closes the EEV. The
reheat and humidifier are disabled.
• The charging function can be reset as many times as required to complete unit charging.
NOTICE
Risk of improper operation. Can cause compressor failure. Operating the unit with the EEV
closed can cause compressor failure.
NOTE: A digital-scroll compressor can have a clear sight glass only when operating at 100% capacity.
When operating with a receiver, the sight glass might not become clear even when operating at 100%
capacity. When operating below 100%, the sight glass may show bubbles with each 15-second
unloading cycle.
Refrigerant-level Sight Glasses on the Unheated Receiver
There are 2 refrigerant-level sight glasses on each receiver at the condenser. Refrigerant level will vary
with outside temperature and return-air temperature at the indoor unit. Check the refrigerant level after
the unit has been on for at least 15 minutes and the return-air temperature is stable and between 75°F to
85°F (24 to 29°C).
Sight Glass Levels
• 40°F (4.5°C) and lower-bottom sight glass is 3/4 full.
• 40°F (4.5°C) and higher-bottom sight glass is full.
If the return air temperature cannot be maintained between 75°F to 85°F (24 to 29°C) (due to lack of
load), then the liquid level in the receiver must be adjusted to the following if return air is between 65°F to
75°F (18 to 29°C):
• 40°F (4.5°C) and lower-Charge to the bottom of the top sight glass.
• 40°F (4.5°C) and higher-top sight glass is 1/4 full.

5.2.7 Superheat and Refrigerant Charge Optimization

Superheat on All Liebert PDX Units
Compressor suction superheat for all unit types should be in range of 8 to 15°F (4.4 to 8.3°C). See
Determining Suction Superheat
for superheat measurement and adjustment methods.
Vertiv | Liebert® PDX™ and PCW™ Installer/User Guide |
on page 84 and Adjusting Superheat Setting with the TXV on page 84
47