E/0204/39/47
CONNECTION OF REFRIGERANT CIRCUIT
NOTE: in this paragraph with distance* is meant the length of the liquid line, including the bends,
between the internal and the external units.
TABLE 1: Standard diameters of R407c pipes
NOTE 1):
maximum distance* between the evaporating and motor-condensing units must not exceed 30 m
for R407c refrigerant.
NOTE 2):
maximum height difference covered by connecting pipes must not exceed 3 m (either if condensing
unit is over or under evaporating unit).
NOTE 3):
with larger pipe diameters, the gas speed inside the intake pipe is unsufficient and problems of oil
transport occur. In the table above you can see in which cases this problems occurs. In this case
the following measures have to be carried out:
• All the horizontal piping sections must have a minimum slope of 1/250 towards the compressor;
• At the evaporator outlet a trap (siphon) must be installed in order to help the oil suction.
Model
Piping distance*
Gas pipe
diameter [mm]
Liquid pipe
diameter [mm]
Problems
CST40
up to 10 m
14
8
no
up to 15 m
16
10
no
up to 20 m
18
10
yes
up to 30 m
18
10
yes
CST50
up to 10 m
16
8
no
up to 15 m
18
10
no
up to 20 m
18
10
no
up to 30 m
22
10
yes
CST60
up to 10 m
16
10
no
up to 15 m
18
12
no
up to 20 m
22
12
no
up to 30 m
22
12
no
CST80
up to 10 m
18
10
no
up to 15 m
22
16
no
up to 20 m
22
16
no
up to 30 m
22
16
no
