26
6 - Control (continued)
Flow switch
A flow switch must be installed, to prevent the unit working in case
of insufficient circulation of the chilled fluid.
WARNING
The electrical flow switch must be carefully
installed, according to the instructions given by
the Manufacturer.
The electrical flow switch must be installed on the pressing side
of the circulation pump for the fluid, just upstream of the heat
exchanger’s inlet. The electrical flow switch must be installed in a
horizontal straight length of piping, in a position reasonably far (both
upstream and downstream) from localized pressure drops (curves,
valves etc.).
6.3 Protection and Safety Equipment
Refrigeration system
The units are filled with R134a refrigerant fluid of non hazardous type
(group II). Safety device (pressure switch and safety valves) with the
sets below indicated are provided on the discharge and suction line
of each circuit.
Discharge Line
Pressure relief valve 22 bar.
Pressure switch 19.8 bar for HP/RC/BC version,
15.5 bar for CO version.
Suction line
Pressure relief valve 14.5 bar.
Pressure switch 0.5 bar.
Frost Protection for the Chilled Fluid
If the leaving water temperature drops below 4 °C (standard value for
a non-glycol unit) the machine’s antifreeze alarm is activated. If the
circulating fluid is water, before the beginning of the cold season it is
advisable to drain the circuit to prevent water frosting.
If the circuit cannot be drained, it is essential to avoid de-energizing
the unit, so as to permit the activation, when necessary, of the frost
protection.
Compressor protection
Compressors are equipped with a heating element to prevent
oil dilution, which may result in remarkable risks of failure of
compressors.
The windings of the compressors’ motors are provided with a
thermal protection.
An accessory kit for thermal protection (ACB) is available, for any
overcurrent of compressors, which shall be shop-mounted.
