37
When the compressor starts, monitor closely the suction pressure, head pressure, compressor VFD
display and the EEV. Watch for any alarms that you might see. During startup, you might see some
alarms such as:
- “C1 Low Pressure”: If suction pressure is below 50 psi, make sure to add more
refrigerant per recommended charge calculation shown above
- “Compressor VFD Alarm”: This alarm shows up when the compressor is called upon
for cooling requirement, but either the VFD has stopped the compressor, or the
compressor is experiencing a Low or High pressure alarm.
Finish charging by slowly opening the valve on the refrigerant manifold set to meter liquid refrig-
erant into the low side of the system, with the compressor operating at a speed of 6000 RPM (or
200Hz), make sure to obtain the required sub-cooling and verify superheat shown in the table
below. The unit should be allowed to stabilize for 15 to 20 minutes to verify key measurements.
Function R-410A Conditions
Discharge Pressure 340 to 415 PSIG (2344 to 2861 kPa)
Suction Pressure 104 to 165 PSIG (717 to 1138 kPa)
Superheat
10 to 12°F (5.56 to 6.67°C) Dierential
Sub-Cooling
10 to 12°F (5.56 to 6.67°C) Dierential
Depending on ambient conditions, at compressor’s
maximum speed
Measure the superheat at the compressor suction line at least 6 inches (152 mm) away from the
compressor. Compare suction pressure and temperature reading between the dap4 and the manifold.
If the dierence between the manifold reading and dap4 reading is more than 5%, check for the EEV
wiring and any possible alarms on dap4, or EEV driver. Measure sub-cooling at the liquid line.
When charging is complete, add the correct amount of oil, if the line run exceeds longer than 20m
or 66ft. This procedure must be conducted with the system running at high load (compressor at full
speed). (Ref to page. 43)
ALWAYS use original Danfoss POE oil 160SZ from new cans.
Oil addition is calculated based on refrigerant charge, shown in the table below
Additional Oil Required (oz)
Note: Additional oil is only needed if pipe run is longer than 20m or 66ft.
Total Refrigerant Weight
(lbs.)
Danfoss Variable Speed
Compressor
Danfoss Fixed Speed
Compressor
20 12 6
30 18 9
40 25 12
50 31 15
To Next Page
Loading...
