AAON V3-E - Manual (Page 35)

35
Subtract the saturated temperature from the
measured suction line temperature to
determine the evaporator superheat.
Compare calculated superheat to the table
below for the appropriate unit type and
options.
Table 4 - Acceptable Air-Cooled
Refrigeration Circuit Values
Air-Cooled Condenser / Air-Source Heat
Pump
Sub-Cooling 12-18°F
Sub-Cooling with
Hot Gas Reheat
15-22°F
Superheat 8-15°F
Table 5 - Acceptable Water-Cooled
Refrigeration Circuit Values
Water-Cooled Condenser / Water Source
Heat Pump
Sub-Cooling 6-10°F
Sub-Cooling with
Hot Gas Reheat
8-12°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. Before
adjusting the TXV, verify the sensing bulb is
in the correct position according to Figure 9
and follows the guidelines below.
1. The suction line is clean where the
sensing bulb is attached.
2. The entire length of the sensing bulb is in
contact with the suction line.
3. The sensing bulb should be placed several
inches downstream of the equalizer line.
Thermal expansion valve must be
adjust to approximately 8-15°F of
suction superheat. Failure to have
sufficient superheat will damage the
compressor and void the warranty.
CAUTION
DO NOT OVERCHARGE!
Refrigerant overcharging leads to
excess refrigerant in the condenser
coils resulting in elevated compressor
discharge pressure.
CAUTION
DO NOT OVERCHARGE!
Refrigerant overcharging leads to
excess refrigerant in the condenser
coils resulting in elevated compressor
discharge pressure.
CAUTION