Refrigerant Replacement Procedure - Trane CGCN Installation Operation & Maintenance

Refrigerant replacement procedure

1. If the unit has exhausted the refrigerant, it is necessary first 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 find 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.
4. Add enough refrigerant to fill the liquid pilot lamp entirely, until the passage of bubbles inside stops. Add
an extra 2-3 kg of refrigerant as a reserve, to fill the under cooler 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 economizer. The undercooling value will be lower 75 to 100% of the load and above 50% of the
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 filling
of the condenser section pipes
°C Bar
-20 4,04
-18 4,35
-16 4,67
-14 5,02
-12 5,38
-10 5,76
-8 6,16
-6 6,58
-4 7,03
-2 7,50
0 7,99
2 8,50
4 9,04
Pressure/Temperature R410A
°C Bar
6 9,61
8 10,20
10 10,82
12 11,46
14 12,14
16 12,85
18 13,58
20 14,35
22 15,15
24 15,99
26 16,85
28 17,76
30 18,70
°C Bar
32 19,68
34 20,69
36 21,75
38 22,84
40 23,98
42 25,16
44 26,39
46 27,65
48 28,97
50 30,33
52 31,75
54 33,21
56 34,72
°C Bar
58 36,29
60 37,91
62 39,59
64 41,32
66 43,11
68 44,97