Air innovations 99H0360-10, Installation, Operation And Maintenance Manual, Page: 50 / 85

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If you are not sure how to measure superheat or sub-cooling :
Superheat
•
Get an accurate suction line temperature on the suction line as close to the compressor inlet as possible. At
same time, attach a compound pressure gauge set to the system so as to read the low side suction pressure at
the suction service valve port (back seated valve stem to allow un-restricted refrigerant flow from evaporator
back to the compressor). Convert suction pressure to a saturated temperature as derived from a
pressure/temperature chart. Since the suction line temperature is the higher value, subtract the saturated
temperature from it to derive your superheat. If your wine cellar is already at specified conditions e.g., 57° F
(13°C), 55% RH), and if your superheat is very low, or zero, you may have overcharged your system
.
Sub-Cooling
•
With your compound pressure gauge set still installed with the high side connect to the valve port on the liquid
receiver (back seated valve stem to allow un-restricted refrigerant flow from condenser to evaporator). Convert
this liquid pressure to a saturated temperature from pressure/temperature chart. Next, obtain your liquid line
temperature by getting an accurate reading on the liquid line BEFORE the TXV expansion on the indoor side.
Obtain this temperature entering the evaporator unit. Subtract the liquid line temperature from the saturated
liquid temperature to derive the system sub-cooling
.
System Charging Amount:
Note: Each DS & WGS Model condensing unit is shipped with 16oz/.453kg of refrigerant charge
already, to be taken into account for below total amounts based on 25’/7.62 meters interconnect
length.
For system charge adjustments compared to 25’/7.62 meters factory baseline:
DS025, DS050, WGS40, WGS75 if
1/4”/.635cm OD (outside diameter) liquid line,
adjustments will be ~ .50oz/foot & .0465kg/meter
DS088, WGS100, DS200, WGS175 if
3/8”/.952cm OD (outside diameter) liquid line,
adjustments will be ~ 1.0oz/foot & .093kg/meter
For reference: Suggested total system charge based on factory testing using 25 feet (7.62 meters) of
interconnected piping in table below.
DS025 59-ounce total charge
WGS40 58-ounce total charge (1.64 kg)
DS050 55-ounce total charge
WGS75 64-ounce total charge (1.81 kg)
DS088 105-ounce total charge
WGS100 106-ounce total charge (3.01 kg)
DS200 108-ounce total charge
WGS175 110-ounce total charge (3.12 kg)