AAON RN-140 - Manual (Page 77)

77
Table 25 - Acceptable Refrigeration
Circuit Values
Air-Cooled Cond./Air-Air Heat Pump
Sub-Cooling 12-18°F
Sub-Cooling with
Hot Gas Reheat
15-22°F
Superheat 8-15°F
Water-Cooled Cond./Water Source Heat
Pump
Sub-Cooling 4-8°F
Superheat 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 TXV may need
adjustment to correct the superheat.
DO NOT OVERCHARGE!
Refrigerant overcharging leads to
excess refrigerant in the condenser
coils resulting in elevated compressor
discharge pressure.
CAUTION
Thermal expansion valve must be
adjusted to approximately 8-15°F of
suction superheat. Failure to have
sufficient superheat will damage the
compressor and void the warranty.
CAUTION