6
EN
i-ACCURATE i-AX - i-AW - i-AD - i-AT - i-AF
i-AX - air cooled
i-AW - water cooled
REFRIGERANT CIRCUIT
All models have a single refrigerant circuit, and in some cases,
depending on the model, two circuits - 1 x ON/OFF + 1 x
INVERTER or 2 x ON/OFF + 1 x INVERTER (mod.130-150).
Each refrigerant circuit includes the compressor and an electronic
thermostatic valve to ensure stable superheat.
A liquid indicator is fitted before the thermostatic valve to show
gas charge. The refrigerant circuit is also fitted with an oil separa-
tor at the compressor discharge to ensure perfect compressor
lubrication, even at minimum speed. A dewatering filter is
installed on the liquid line so as to keep the circuit clean and free
of dirt. The refrigerant circuit features safety pressure switches
for both high and low pressure.
The low pressure switch has automatic reset, while for safety sea-
sons the high pressure switch requires manual reset. The com-
pressor pumps the hot refrigerant gas into the condenser.
The liquid refrigerant then flows to a liquid receiver (fitted with
safety valve) installed on the indoor unit, to ensure a constant
flow of refrigerant to the thermostatic valve and subsequently the
evaporator. Here the liquid refrigerant absorbs the heat from the
environment and changes state, becoming a gas, then returning to
the compressor: the cycle is then repeated.
The units are fitted with scroll compressors that feature non-
return valves to prevent liquid from migrating from the outdoor
condenser during summer, and unwanted refrigerant flow during
start-up.
AIR-COOLED DIRECT EXPANSION UNIT
- VERSION i-AX
The i-AX series units use air as the cooling fluid, and are there-
fore combined with an outdoor air-cooled condenser (supplied
separately). The BASIC version includes the condenser control
function with EC fan speed control in combination with i-BRE
remote condensers. The MODULATING version features speed
control for the fans on the BRE condenser, in this case axial-flow
fans with asynchronous motors, so as to maintain correct refrig-
erant condensing pressure.
The i-AX units are supplied with valves for closing and isolating
the refrigerant circuit and to assist service operations.
A second non-return valve, to be fitted by the installer at the con-
denser outlet on the liquid line, is recommended during operation
in winter, to prevent migration of the refrigerant charge from the
liquid receiver to the outdoor condenser, with consequent low
pressure alarms.
The i-AX units are supplied as standard with EC radial fans in the
standard version.
Outdoor air-cooled condenser
The indoor unit can be connected to different types of BRE (axi-
al-flow fans with asynchronous motor) and i-BRE outdoor con-
densers (axial-flow fans with EC motor), standard or low noise
version, and with special coil treatment.
For more specific information see the manual on the outdoor air-
cooled condensers.
Note 1
: unit and outdoor condensers supplied separately
Note 2
: the indoor unit is delivered charged with nitrogen at
near-atmospheric pressure.
The outdoor condenser, on the other hand, is supplied pres-
surised with dry air (around 3 bars)
Note 3
: the customer is responsible for properly making the
connections between the indoor and outdoor units, as clearly
described in this manual, and for ensuring the required gas and oil
charge, where necessary.
WATER-COOLED DIRECT EXPANSION UNIT
- VERSION i-AW
The i-AW series units use water as the cooling fluid, therefore
each refrigerant circuit is combined with a plate heat exchanger
installed on the unit, suitably sized to ensure minimum water side
pressure drop and consequently reduce the power consumption
of the water pump.
Remember that the units are supplied without the system circu-
lating pump.
The i-AW units are supplied as standard with EC radial fans in the
standard version.
Water-cooled condenser
The units are fitted with an internal braze welded stainless steel
plate heat exchanger.
The units for applications with well water are supplied with a
pressure control valve to manage the condensing pressure.
This circuit works with primary water or with a closed circuit
connected to an outdoor dry cooler or cooling tower.
For “closed” circuits, it’s recommended to use water mixed with
antifreeze to prevent ice from forming in winter and consequently
damaging the system: see the installation manual for the calcula-
tion of the percentage of antifreeze to use.
The BDC (axial-flow fans with asynchronous motor) and i-BDC
Dry Coolers (axial-flow fans with EC motor) are supplied as stan-
dard accessories.
The antifreeze and fluid circulating pump are generally supplied by
other manufacturers.
For “open” circuits mechanical filters must be used to trap impu-
rities and prevent blockage of the braze-welded plate heat
exchanger.
To reduce energy consumption (pump), it’s suggested to use a
valve to close the circuit when the indoor unit is off.
Note 1
: the i-AW water-cooled indoor units come with the
refrigerant circuit completely charged and factory-tested before
delivery.
