AAON V3 Series - Purge Circuit; Adjusting Refrigerant Charge; Figure 24 - Hot Gas Purge Circuit

40
a sub-cooling value between 2.8 and 8.3°C
(5-15°F), but a cooling only unit with hot gas
reheat and a vertical liquid rise of 9.1 m (30
ft) must charge to a sub-cooling value of at
least between 4.4 and 8.3°C (8-15°F). DO
NOT OVERCHARGE. Refrigerant
overcharging leads to excess refrigerant in
the condenser coils resulting in elevated
compressor discharge pressure.
Table 15 - Acceptable Microchannel Air-Cooled Condenser Coil Liquid Sub-
Cooling Values (Metric)
Table 16 - Acceptable Microchannel Air-Cooled Condenser Coil Liquid Sub-Cooling Values
(Imperial)
Cooling Mode Liquid Sub-Cooling Values(°F)
Ambient
(°F)
Evaporator Coil Saturation Temperature (°F)
40
45
48
50
55
67
9 - 14
8 - 13
8 - 13
7 - 12
5 - 10
72
10 - 15
9 - 14
9 - 14
8 - 13
7 - 12
82
10 - 15
10 - 15
10 - 15
9 - 14
7 - 12
95
10 - 15
10 - 15
10 - 15
9 - 14
8 - 13
105
11 - 16
11 - 16
10 - 15
10 - 15
8 - 13
115
10 - 15
11 - 16
11 - 16
11 - 16
9 - 14
Notes:
1. Microchannel condenser coils are more sensitive to charge. The system must be
running in cooling mode with compressor, supply airflow & condenser fan speed at
full load. The sub-cooling value changes depending on the ambient temperature
reading and the evaporator coil saturation temperature. To find the correct sub-cooling
value, find the ambient temperature on the first column and follow that across to the
SST (4.4-12.8°C [40-55°F]).
2. Superheat for Microchannel condenser coils must be between 4.4 and
8.3°C (8 - 15°F).
Cooling Mode Liquid Sub-Cooling Values(°C)
Ambient
(°C)
Evaporator Coil Saturation Temperature (°C)
4.4
7.2
8.9
10.0
12.8
19.4
5.0 - 7.8
4.4 - 7.2
4.4 - 7.2
3.9 - 6.7
2.8 - 5.6
22.2
5.6 - 8.3
5.0 - 7.8
5.0 - 7.8
4.4 - 7.2
3.9 - 6.7
27.8
5.6 - 8.3
5.6 - 8.3
5.6 - 8.3
5.0 - 7.8
3.9 - 6.7
35.0
5.6 - 8.3
5.6 - 8.3
5.6 - 8.3
5.0 - 7.8
4.4 - 7.2
40.6
6.1 - 8.9
6.1 - 8.9
5.6 - 8.3
5.6 - 8.3
4.4 - 7.2
46.1
5.6 - 8.3
6.1 - 8.9
6.1 - 8.9
6.1 - 8.9
5.0 - 7.8