Trane CXAO Installation Operation & Maintenance page 43

5.5 Refrigerant replacement procedure
1) If the unit has exhausted the refrigerant, it is
necessary fi rst of all to establish the causes, before
carrying out any replenishment operation. The leak
must be looked for and repaired. Oil stains are a good
indicator, as they can appear in the vicinity of a leak.
However, this is not necessarily always a good search
criterion. Searching with soap and water can be a
good method for medium to large leaks, while an
electronic leak searching device is required to fi nd the
position of small leaks.
2) Add refrigerant to the system through the service
valve located on the intake pipe or through the
Schrader valve located on the evaporator entry pipe.
3) The refrigerant can be added under any load condition
between 25 and 100% of the circuit. Intake overheating
must be between 4 and 6°C.
Table - Pressure/Temperature
°C Bar
-14 0.71
-12 0.85
-10 1.01
-8 1.17
-6 1.34
-4 1.53
-2 1.72
0 1.93
2 2.15
4 2.38
6 2.62
8 2.88
10 3.15
RF-SVX003A-GB
Table Pressure/Temperature of HFC-134
°C Bar
12 3.43
14 3.73
16 4.04
18 4.37
20 4.72
22 5.08
24 5.46
26 5.85
28 6.27
30 6.70
32 7.15
34 7.63
36 8.12
Refrigerant replacement procedure
4) Add enough refrigerant to fi ll the liquid pilot lamp
entirely, until the passage of bubbles inside stops.
Add an extra 2 or 3 kg of refrigerant as a reserve, to fi ll
the undercooler if the compressor is operating at 50 –
100% load.
5) Check the undercooling value by taking the liquid
pressure and the liquid's temperature near the
expansion valve. The undercooling value must be
between 4 and 8 °C and between 10 and 15°C units
with an economiser. The subcooling value will be
between 50% and 75% of the thermal load.
6) With ambient temperature above 16°C, all ventilators
should be on.
7) A system overcharge will entail a rise in the
compressor's discharge pressure, owing to excessive
fi lling of the condenser section pipes
°C Bar
38 8.63
40 9.17
42 9.72
44 10.30
46 10.90
48 11.53
50 12.18
52 13.85
54 13.56
56 14.28
58 15.04
60 15.82
62 16.63
°C Bar
64 17.47
66 18.34
68 19.24
70 20.17
72 21.13
74 22.13
76 23.16
78 24.23
80 25.33
82 26.48
84 27.66
86 28.88
88 30.14
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