Gree GWC09AA, Installation And Service Manual

Page: 43 / 136

GREE Service Manual GWC09AA / K5NNA6A Page 43
Refrigerant recovery
Before starting service work on the refrigerant circuit, the existing refrigerant
must be removed. When carrying out removal of the refrigerant, the following
must be considered:
•
The recovery cylinder must be permitted for the use of R-290 (especially
regarding the pressure and the compatibility of the connectors and the
valves).
•
The recovery machine must be suitable for operation with R-290. Impor-
tantly, the recovery machine must not itself be an ignition source.
•
The filling of the recovery cylinder should be monitored closely by control-
ling the weight. It is recommended to place and then to leave the cylinder
on a digital scale. Pay attention not to overfill the cylinder. The cylinder is
only allowed to be filled up to 80% of its complete volume by liquid refrig-
erant.
•
The pressure must be controlled in order to ensure that the permissible
pressure of the cylinder is not exceeded at any time.
•
After filling, the cylinder must be marked with the mass and the type of
refrigerant recovered.
•
The recovery machine should be operated until the pressure reduces to
0.3 bar absolute pressure. R-290 is soluble to oil. This may lead to a rise
in pressure because the refrigerant vaporises from oil. It may be neces-
sary to operate the recovery machine for a second or even a third time.
•
Small amounts of R-290 can be vented in safe manner to the environ-
ment.
•
Remaining amounts of HC absorbed by the oil can be extracted from the
system using a vacuum pump in combination with an exhaust vent hose.
•
A second “two way excess” recovery cylinder can be used in serial con-
nection to act as an oil-separator.
•
After the systems‘ pump out, the system should be flushed with oxygen-
free dry nitrogen (OFDN) in order to ensure no flammable gas are inside
the system.