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Esempio NRA 1650 00
3. 1
REFRIGERATING CIRCUIT
Compressors
Hermetic scroll type compressor s
equipped, as standard, with anti-freeze
heater.
The heater is automatically powered when
the unit stops, provided that the unit is
kept under tension. The compressor area
is acoustically insulated. The use of more
than one scroll type compressor allows a
high level of efficiency with partial loads. In
these cases in fact, a variable number of
scroll compressors are working, each at
its own 100% (i.e. maximum efficiency) of
the output power.
Air side heat exchanger
It is made of copper pipes and aluminium
fins locked into place through mechanical
expansion of the pipes. Of the high efficiency
type; furrowed tube and corrugated fins for
heat pump, smooth tube and turbo fins for
cooling only.
Water side heat exchanger
Of the plate type (AISI 316), externally
insulated with closed cell material to
reduce thermal dispersion. Fitted, as
standard, with anti-freeze heater.
Liquid separator
(heat pump only)
Suction from compressor, to protect from
any liquid refrigerant return, flooded starts,
working in the presence of liquid.
Filter drier
Of the mechanical type, made of ceramic
and hygroscopic material, able to hold back
any impurities and traces of humidity in the
refrigerating circuit.
DESCRIPTION OF COMPONENTS
3
Sight glass
For checking the refrigerating gas load and
any humidity in the refrigerating circuit.
Thermostatic valve
The mechanical valve, with outside equali-
ser on the evaporator outlet, modulates the
gas flow to the evaporator on the basis of
the thermal load, in such a way as to ensu-
re the proper degree of overheating of the
intake gas.
Liquid and force gas taps
(cooling-only versions)
They allow the refrigerant to be cut off
during extraordinary maintenance.
Solenoid valve
The valve closes when the compressor
turns off, preventing the flow of refrigerant
gas towards the evaporator.
Reverse cycle valve
(heat pump only)
Inverts the flow of the refrigerant when
there is a change of summer / winter
operation and during the defrosting cycles.
One-way valve
This allows the refrigerant to flow in just
one direction.
Desuperheater (only upon request)
Of the plate type (AISI 316), externally
insulated with closed cell material to reduce
thermal dispersion.
The desuperheater is also available for heat
pump versions, limitedly in the cooling func-
tion. It must be intercepted in the heating
function.
Total recovery (only upon request)
KEY
1 Compressor
2 Exchanger water side
3 Exchanger air side
4 Frame
5 Control keypad
6 Fans
7 Electric panel
Of the plate type (AISI 316), externally
insulated with closed cell material to reduce
thermal dispersion.
NOTE
In heat pumps total recovery is only available
for the "OO versions without hydronic kit"
Liquid accumulation
only for heat pumps, or with total heat
recovery.
It is used in the heat pump or total recovery
versions. Used to keep the refrigerating
gas in a liquid state if the machine, in that
particular working point, has an excess
of it.
3.2
FRAME AND FANS
Fan unit
Screw type, statically and dynamically
balanced. The electric fans are protected
electrically with thermomagnetic switches
and mechanically with metal anti-intrusion
grilles, in accordance with the standard CEI
EN 60335-2-40.
Load-bearing structure
Made of hot-galvanised steel sheet of a
suitable thickness, varnished with polyester
powders able to resist atmospheric agents
over time.
3.3
HYDRAULIC COMPONENTS
Circulation pump
Depending on the characteristics of the
pump chosen, it offers an effective pressure
to overcome the pressure drops in the
system. There is also the possibility to have
a reserve pump.
The stand-by pump that in NRA 800
- 900 - 1000 models is controlled by
5
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