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2.2 - Version W
Direct expansion water-condensed units
Refrigerating circuit
The 4-6-8 models are provided with a
single refrigerating circuit, the units
5-7-9 have two refrigerating circuits. The
refrigerating circuit includes the compres
sor and the thermal expansion valve with an
external equalizer controlling the refriger
ant flow to the evaporator so as to keep a
steady overheating degree. Before the
thermal expansion valve there is a sight
glass enabling the visual check of the re
frigerant charge. A dryer filter is installed in
the liquid line for better cleaning and less
humidity in the circuit. On-off valves are
installed as standard to help the extraordi
nary maintenance of the circuits.
A suitably sized safety valve is installed af
ter the condenser; the valve is equipped
with flanged connections to allow the refrig
erant to be discharged outside through
suitable pipes. All low temperature parts of
the refrigerating circuit are insulated. The
refrigerating circuit is also provided with a
high pressure switch and a low pressure
switch. The low pressure switch has auto
matic resetting, whereas - for safety rea
sons due to possible high pressure in the
compressor - the high pressure switch
has manual resetting. The pressure switch
calibration values are shown in the installa
tion manual supplied with the machine.
Condenser
The units are provided with a built-in stainless steel water condenser with braze-welded plates; this ad
vanced exchanger type gives the highest efficiency in heat exchange. In addition, a certain oversizing of
the exchanger has been provided so as to reduce pressure drops (and energy consumption of the water
pump) as much as possible and thus to allow the unit to operate with the external chiller in closed circuit,
even at high outdoor temperatures.
The units shall operate with throwaway water, tower water or water in closed circuit with external chill
er. In the operation with closed circuit, the water is cooled by the outdoor air in a heat exchanger; in this
case, to avoid unwished ice formation during winter, it is advisable to obtain the mixture always with a gly
col percentage (refer to the installation manual for the suitable percentages). The circulation of the water-
glycol mixture is forced (the pump is not supplied). If throwaway water or tower water is used, when instal
ling the unit fit a mechanical filter on the water line to protect the condenser against possible impurities
contained in the water (for the condenser cleaning see the installation manual).
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