T-CU11-OCT22-0
Page 16
Installation
System Charging
Once system evacuation has been completed, the system could be charged with the approved refrigerant. Refrigerant
must be charged with liquid on the high-pressure side to the extent possible, with the compressor in OFF condition and
service valves must be closed. The service port on the receiver outlet rotolock valve (liquid line) can be used for initial
charge.
If additional charge is needed, it should be added as liquid, in a controlled manner to the low side of the system with all
service valves turn to OPEN position and compressor operating.
For the adjustment of refrigerant charge until the installation reaching a level of stable nominal working condition,
slowly throttling liquid in through schrader valve on the suction service valve. Charge system until reaching suction
superheat 6~12K at desired evaporating temperature. Suction superheat, suction, and condensing pressures
(temperatures) should be monitored. During optimizing charging
, ensure oil sight glass doesn’t start foaming.
A proper refrigerant charge should secure stable condition at minimum and maximum heat load within the limits of the
condensing unit’s application envelope.
•
Minimum heat load conditions, which occurred during winter. Condenser should not be flooded by liquid
refrigerant, receiver and liquid line should be able to contain remaining charge at this condition.
•
Maximum heat load conditions, which occurred during summer. All evaporators are working with maximum
air/liquid flow via evaporators and refrigerant charge should be enough to feed to all evaporators.
Refrigerant charge by judging the liquid sight glass does not guarantee as 100% correct
way.
System maximum charge is approximated =
(Receiver Internal volume of Liquid Line) * 0.9
When the compressor operates under stabilized conditions, the oil level must be visible in the sight glass. Foam filling
the oil sight glass indicates presence of large concentration of liquid to the compressor.
No additional oil is required for installation with good oil returns, line runs up to 25m. Additional oil might be required if
lines exceeded 25m, with minimum oil level must not lower than ¼ of sight glass. Top-up the oil while compressor is
idle, via suction schrader connector with a suitable pump.
Ensure an adequate liquid charge has been introduced to the high side of the system before starting to ensure a
minimum operating pressure on the suction side of 0.5 bar is maintained, otherwise overheating of the scroll and rotary
and subsequent damage may occur.
Never install a system in the field and leave it unattended with no charge, or with the service valves closed without
securely locking out the system. This will prevent unauthorized personnel from accidentally operating the system and
potentially running the compressor by operating the compressor without charge.
Table 8: Internal Volume of Liquid Line
Liquid Line (Volume)
OD (inch) OD (mm) ID (ID)
L/m
3/8
9.5
7.9
0.05
1/2
12.7
10.7
0.09
5/8
15.9
13.5
0.14
3/4
19.1
16.7
0.22
Liquid Line (Dimension)