AAON CF Series - Table 11 - Charge to Flood Fin and Tube Condenser Coil for Ambient above 21.3°C (70°F); Table 12 - Charge to Flood Microchannel Condenser Coil for Ambient above 21.3°C (70°F); Table 13 - % Charge to Flood Condenser Coil for Ambient below 21.3°C (70°F)

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additional charge amount required for the
system when running in cold ambient
conditions. For units with Microchannel
Condenser coils, use Table 12 to find the
additional charge amount required for the
system when running in cold ambient
conditions.
Table 12 - Charge to Flood Fin and Tube
Condenser Coil for Ambient
Above 21.3°C (70°F)
CF Size
# of
circuits
Per Circuit
Charge (lbs)
CF 2, 3
1
4.9
CF 4, 5, 6, 7
1
6.2
CF 9, 11
2
9.1
CF 13, 15
2
12.1
CF 16, 18
2
13.1
CF 20, 25, 30
2
17.5
CF 26, 31, 40
2
18.0
4
9.1
CF 50, 60, 70
2
43.8
4
22.1
Table 13 - Charge to Flood Microchannel
Condenser Coil for Ambient Above 21.3°C
(70°F)
CF Size
# of
circuits
Per Circuit
Charge (lbs)
CF 2, 3, 4
1
5.6
CF 5, 6, 7
1
10.2
CF 9, 11
2
5.6
CF 13, 15
2
10.2
CF 16, 18
2
13.3
CF 20, 25, 30
2
13.3
CF 26, 31, 40
2
19.5
4
9.7
CF 50, 60, 70
2
29.8
4
14.9
For units equipped with low ambient
refrigerant flood back option being charged
in the winter when the ambient
temperature is cold:
1. If the ambient is below 21°C (70°F),
charge to approximately 0.6-1.1°C (1-
2°F) of sub-cooling measured at the inlet
to the expansion valve. Once enough
charge has been added to get the
evaporator superheat and sub-cooling
values to the correct setting more charge
may need to be added. If the ambient
temperature is -17.8°C (0°F) no more
charge is required. Ambient
temperatures above -17.8°C (0°F) will
require a percentage of the per circuit
charge values from Table 6 (for fin and
tube condenser coils) or Table 7 (for
microchannel condenser coils). Using
your ambient temperature, find the
percentage value from Table 8, and
multiply the Per Circuit Charge value
from Table 6 (for fin and tube condenser
coils) or Table 7 (for microchannel
condenser coils) and the % value to
determine the additional charge amount.
Table 14 - % Charge to Flood Condenser
Coil for Ambient Below 21.3°C (70°F)
Condenser
Ambient
Temperature
°C (°F)
Percentage
Per Circuit
Charge from
Table 6 or
15.6 (60)
60%
10.0 (50)
37%
4.4 (40)
24%
-1.1 (30)
15%
-6.7 (20)
8%
-17.8 (0)
0%
2. Check the unit for proper operation
once the ambient temperature is above
26.7°C (80°F).
Example: A CF size 31 with tandem
compressors and Fin and Tube
Condenser Coils where the ambient
temperature is 4.4°C (40°F).