AAON RN Series User Manual

57
Table 17 - Acceptable Microchannel Air-Cooled Condenser Coil Liquid Sub-
Cooling Values
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 microchannel 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 (40-55°F).
2. Superheat for Microchannel condenser coils must be between 8 - 15°F
Adjusting Sub-cooling and Superheat
Temperatures
The system is overcharged if the sub-cooling
temperature is too high and the evaporator is
fully loaded (low loads on the evaporator
result in increased sub-cooling) and the
evaporator superheat is within the
temperature range as shown in the table
above (high superheat results in increased
sub-cooling).
Correct an overcharged system by reducing
the amount of refrigerant in the system to
lower the sub-cooling.
The system is undercharged if the superheat
is too high and the sub-cooling is too low.
Correct an undercharged system by adding
refrigerant to the system to reduce superheat
and raise sub-cooling.
If the sub-cooling is correct and the superheat
is too high, the expansion valve may need
adjustment to correct the superheat.
Freeze Stat Startup
Freeze Stat is an adjustable temperature
sensor (-10 to 70°F) mounted on the tubing
of the first cooling circuit and wired to de-
energize all cooling circuits if tubing
temperature falls below setpoint. Option is
used to prevent freezing of evaporator coil.
Recommended Setting: 32° F to 35º F
DO NOT OVERCHARGE!
Refrigerant overcharging leads to
excess refrigerant in the condenser
coils resulting in elevated compressor
discharge pressure.
CAUTION

AAON RN Series Specifications

General

Category	Heat Pump
HSPF	Up to 10.0
Refrigerant	R-410A
Compressor Type	Scroll
Efficiency	High
Series	RN
Voltage Options	208-230/460V
Unit Weight	Varies with model
Dimensions	Varies with model