Sterlco GC Series Central Chiller - Manual (Page 23)

GC Series Central Chillers Chapter 3: Installation 23 of 79
Refrigerant Charge Determination. The approximate amount of refrigerant charge required
by the system varies based on the total length of the refrigerant lines and the size of the
chiller. Referring to Figure 6, determine the amount of charge based on the model of the
chiller and the amount of charge based on discharge and liquid line sizes and lengths. Add
these three numbers together to find the final operating charge. The final operating charge
must be verified by running the system and checking the liquid line sight glass.
Figure 6: Refrigerant Charge Determination
Chiller
Model
Condenser and Chiller Charge (LBS of R-410a)
Minimum Design Ambient - °F
60 50 40 30 20 10 0 -10 -20
GCRC-70 25 25 25 26 31 34 36 38 40
GCRC-90 30 30 30 32 37 41 44 47 49
GCRC-105 51 51 51 52 52 58 63 67 71
GCRC-140 51 51 51 51 51 51 55 55 65
GCRC-175 70 70 70 70 70 70 76 76 88
GCRC-210 80 80 80 80 80 80 80 88 94
Line Size
OD (inches)
Discharge Line
LBS of R-410a
Liquid Line
LBS of R-410a
Per 100ft (31m)
7/8 2.1 20.0
1-1/8 3.7 34.1
1-3/8 5.6 52.0
1-5/8 7.9 73.6
2-1/8 13.7 128.0
2-5/8 21.2 197.4
Note:
The amounts listed above are based on 100 feet of pipe.
Actual amounts will be in direct proportion to the actual
length of the piping.
Oil Charge Determination. The remote air-cooled central chillers are factory charged with
the amount of oil required without field-installed piping. Additional oil required is dependent
on the amount of additional refrigerant added.
Calculate the amount of additional oil required by using the following formula:
Pints of oil (Copeland Ultra 22cc) = lbs of R-410a added for field installed piping / 100.