Emerson Liebert MC Microchannel Outdoor Condenser 28 - 220kW User Manual
Piping
37
Liebert
®
MC
™
Sample Calculations
The Liebert MC is 40 ft (12.2m) above the evaporator of an R-407C system. The outdoor ambient
from the Liebert MC condenser control menu ID F02, is 94.8°F (34.9°C). The liquid pressure is
300psig (2068kPa) and 113°F (45°C). The subcooling from the Liebert MC control is 5°F (2.8°C).
Determine the subcooling and verify the calculated subcooling against the reading of the Liebert
MC control [menu ID F50 & F51].
Evaporator Subcooling Calculation
Subtract Line 6 (Measured Line Temperature) from Line 5 (Liquid Pressure converted to
Temperature) to obtain Calculated Subcooling.
Elevation Correction
Subtract Line 3 (Correction for Condenser Elevation above Evaporator) from Line 8 (Calculated
Subcooling) to obtain Corrected Subcooling.
Verification Against MC Condenser
Subtract Line 7 (MC Condenser Subcooling Reading) from Line 9 (Corrected Subcooling) to obtain
Difference.
• If Line 10 (Difference value) is less than ± 3°F (±1.7°C), NO charge adjustment is needed.
• If Line 10 (Difference value) is less than -3°F (-1.7°C), add additional charge.
• If Line 10 (Difference value) is less than -3°F (-1.7°C), add additional charge.
If Line 10 (Difference value) is greater than +3°F (+1.7°C), the system is overcharged and
some of the charge must be removed.
Refrigerant Type
R-407C
1.
Ambient Temperature
94.8°F (34.9°C)
2.
Condenser Elevation
40 ft (12.2m)
3.
Condenser Elevation Temperature Correction
4°F (2.2°C)
4.
Liquid Line Pressure
300psig (2068kPa)
5.
Liquid Pressure Converted to Temperature
120.3°F (49.0°C)
6.
Measured Liquid Line Temperature
113.2°F (45.1°C)
7.
MC Condenser Subcooling Reading
(Menu ID F50 for Circuit #1 or
Menu ID F51 for Circuit #2)
5°F (2.8°C)
Line 5
120.3°F
(49.0°C)
Line 6
-113.2°F
(45.1°C)
8.
Calculated Subcooling
7.1°F or 7°F
(3.9°C or (4°C)
Line 8
7°F
(3.9°C)
Line 3
-4°F
- (2.2°C)
9.
Corrected Subcooling
3°F
(1.7°C)
Line 9
3°F
(1.7°C)
Line 7
-5°F
-(2.8°C)
10. Difference
-2°F
(-1.1°C)
Table 14
Difference in subcooling measurements—Indoor minus outdoor
Liebert MC Elevation Above
Evaporator, ft (m)
Subcooling Elevation Correction - °F (°C)
80 (24)
60 (18)
40 (12)
20 (6)
Refrigerant
R-407C
10 (5.5)
7 (3.8)
4 (2.2)
1 (0.6)
R-410A
6 (3.3)
4 (2.2)
2 (1.1)
0 (0.0)
* Assumes liquid line is sized for no more than 2°F (1.1°C)pressure drop.
DPN002411, Rev. 3
DPN002411, Rev. 3