Application guidelines
55
FRCC.PC.023.A7.22
Single compressors
Specific application recommendations
Suction line accumulator
Water utilizing systems
The use of a suction line accumulator is strongly
recommended in reversible-cycle applications.
This because of the possibility of a substantial
quantity of liquid refrigerant remaining in the
evaporator, which acts as a condenser during the
heating cycle.
This liquid refrigerant can then return to the
compressor, either flooding the sump with
refrigerant or as a dynamic liquid slug when
the cycle switches back to a defrost cycle or to
normal cooling operations.
Sustained and repeated liquid slugging and
floodback can seriously impair the oil’s ability to
lubricate the compressor bearings. This situation
can be observed in wet climates where it is
necessary to frequently defrost the outdoor
coil in an air source heat pump. In such cases a
suction accumulator becomes mandatory.
Apart from residual moisture in the system
after commissioning, water could also enter the
refrigeration circuit during operation. Water in
the system shall always be avoided. Not only
because it can shortly lead to electrical failure,
sludge in sump and corrosion but in particular
because it can cause serious safety risks.
Common causes for water leaks are corrosion and
freezing.
Corrosion
: Materials in the system shall be
compliant with water and protected against
corrosion.
Freezing
: When water freezes into ice its volume
expands which can damage heat exchanger
walls and cause leaks. During off periods water
inside heat exchangers could start freezing when
ambient temperature is lower than 32°F. During
on periods ice banking could occur when the
circuit is running continuously at too low load.
Both situations should be avoided by connecting
a pressure and thermostat switch in the safety
line.
