Refrigerating Circuit; Frame And Fans; Hydraulic Components; Safety And Control Components - AERMEC NRA 2000 Manual Tecnico

3. 1

REFRIGERATING CIRCUIT

Compressors
Hermetic scroll type compressors
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
ef ficiency 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.
Sight glass
For checking the refrigerating gas load
and any humidity in the refrigerating
circuit.
Thermostatic valve
The mechanical type valve, with outside
equaliser on the evaporator outlet,
modulates the gas flow to the evaporator
on the basis of the thermal load, in such
a way as to ensure 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
6
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.
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 reserve pump is
manually.
Flow switch 1 per circuit
(only in versions with hydronic unit or
pump/s)
This checks that the water is circulating.
If this is not the case, it shuts down the
unit.
Water filter
Supplied in the "00 versions, mounted
in the versions with hydronic kit"
Allows you to block and eliminate any
impurities in the hydraulic circuits. Inside,
it has a filtering mesh with holes not
greater than one millimetre. It is essential
in order to avoid serious damage to the
plate heat exchanger.
Storage tank
1000 litres for the model 2000, 1200
litres for the remaining models. In
order to reduce the thermal dispersion
and eliminate the phenomenon of the
formation of condensation, it is insulated
with polyurethane material of a suitable
thickness. It is fitted, as standard, with an
anti-freeze heater (down to -20°C outside
temperature, tank water temperature
5°C), commanded by the anti-freeze
probe situated in the tank.
Drain valve
(only in the versions with hydronic unit
or pump(s))
Of the manual type, it discharges any air
pockets. It is intercepted by a stopcock so
that it can be substituted if necessary.
Filling unit
(only in the versions with accumulation
or pump(s))
This has a pressure gauge showing the
pressure in the system.
Two expansion tanks (of 25 litres)
(only in the versions with accumulation
or pump(s))
of the membrane type, with nitrogen pre-
charge.
Hydraulic circuit safety valve
(only in the versions with hydronic unit
or pump(s))
Calibrated at 6 bar and with a discharge
that can be channelled, it intervenes by
discharging the overpressure in the
event of anomalous pressures
NOTE
The hydraulic parallel is only supplied in
the versions with hydronic kit "01-02-03-
04-P1-P2-P3-P4
managed
3.4 SAFETY AND CONTROL
COMPONENTS
Low pressure switch
not present in the heat pump versions.
Of fixed calibration, located on the low
pressure side of the refrigerating circuit, it
stops the operation of the compressor in
the event of anomalous work pressures.
High pressure switch
Of variable calibration, located on the
high pressure side of the refrigerating
circuit, it stops the operation of the
compressor in the event of anomalous
work pressures.