Table 23 Target Subcooling For Ambient Outdoor Temperature - Emerson Liebert CRV User Manual

NOTE
To determine subcooling measurement, a liquid line pressure reading (at the factory-installed
Schrader tap) needs to be measured along with obtaining a temperature reading on the liquid
line. Convert the liquid line pressure reading into a temperature by utilizing a Pressure-
Temperature Guide or Table 25. The difference between this converted temperature and the
actual temperature will determine the system's subcooling. For R-407C make sure to use the
saturated liquid temperature to calculate subcooling.
Table 23 Target subcooling for ambient outdoor temperature
Ambient Temp Subcooling
°F (C°) °F (C°)
0 (-17.8) 22 (12.0)
10 (-12.2) 22 (12.0)
20 (-6.7) 22 (12.0)
30 (-1.1) 22 (12.0)
40 (4.4) 22 (12.0)
50 (10.0) 21 (11.7)
60 (15.6) 19 (10.8)
70 (21.1) 17 (9.3)
80 (26.7) 13 (7.2)
90 (32.2) 9 (5.0)
95 (35.0) 7 (3.9)
100 (37.8) 5 (2.9)
105 (40.6) 3 (1.8)
110 (43.3) 1 (0.7)
125 (51.7) 0
DPN002411, Rev. 3
8. Verify the subcooling calculated from measured values at the evaporator against the subcooling
reading of the Liebert MC control [menu ID F50 & F51]. If the subcooling calculated with gauges
differs from the Liebert MC subcooling by more than 3°F (1.7°C), then adjust the charge amount
to achieve the target subcooling per Table 23 based the Liebert MC control subcooling. Failure to
check measured subcooling with refrigerant gauges vs. Liebert MC subcooling may result in an
overcharged system. See Note below and Table 24 for corrections to Liebert MC subcooling that
may be required based on condenser elevation above the indoor evaporator.
NOTE
The evaporator subcooling will be greater than the condenser subcooling when the Liebert MC
is mounted higher than the indoor evaporator. Subcooling adjustment is needed when the
Liebert MC is more than 40 ft. (12m) above evaporator.
NOTE
Subcooling should be viewed at the Liebert MC condenser for a minimum of 1 minute and the
subcooling should be approximately ±2°F before recording subcooling to be compared against
subcooling from the field refrigerant gauges and thermometers.
Refrigerant Connections for Air-Cooled Units
45
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Liebert CRV