Manual code 75803707A.0708
Page 22 of 64
4.7.4 SOLENOID VALVE ON THE LIQUID LINE
The scroll compressors installed on TECNAIR LV air conditioners will not be damaged by the presence of any
liquid refrigerant in the crankcase. However, when the refrigeration circuit is shutdown in the summer season, i.e. when
the external temperature is just a few degrees higher than the internal temperature, the liquid refrigerant flows towards
the compressor (the coldest point of the circuit) and, depending on the quantity of refrigerant in the system, floods it
partially or completely. In this case, the high pressure switch may trip at the next startup.
It is therefore necessary to compare the refrigerant charge in the circuit, calculated as the sum of the contents of
the various components of the circuit, with the maximum quantity compatible with correct operation without the solenoid
valve on the liquid pipe, as indicated in the table below.
Compressor
Size
Rated power (Hp) Rated power (kW)
Maximum quantity of refrigerant (kg)
21
2 6 2,8
31
3 10 3,6
41
3,5 11 5,4
51
5 15 5,4
71
6,5 22 5,4
81
7,5 24 7,3
101
10 30 10,0
131
12 40 12,5
151
15 46 13,5
Table of maximum compatible refrigerant quantities per circuit without installation of solenoid valve on liquid
pipe
In the case that the calculated charge is greater than the maximum compatible quantity, it will be necessary to
install a solenoid valve on the liquid line, which, by closing when the compressor is shut down, will prevent the refrigerant
from flowing back towards the compressor through the liquid pipe.
Obviously it is also necessary to prevent refrigerant from flowing back to the compressor through the discharge
line. This is achieved by installation of the non-return valve on the discharge lines. The latter valve, unlike the solenoid
valve, is not offered by TECNAIR LV as an optional accessory as it must be installed when the refrigeration circuit
external to the machine is installed, while the solenoid valve is installed inside the machine itself.
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