CLIMAVENETA accurate ax Installation - User - Maintenance Manual page 5

REFRIGERANT CIRCUIT
All models have a single refrigerant circuit, and in some cases two
circuits.
Each refrigerant circuit includes the compressor and a pressure-
balanced thermostatic valve (or electronic valve) to ensure stable
superheat temperatures. A liquid indicator is fitted before the
thermostatic valve to display the gas charge.
A filter-drier is installed on the liquid line to keep the circuit clean
and free of dirt. The refrigerant circuit is also fitted with high and
low pressure switches.
The low pressure switch has automatic reset, while for safety rea-
sons the high pressure switch has manual reset.
The compressor pumps the hot refrigerant gas into the con-
denser.The liquid refrigerant then flows to a liquid receiver (fitted
with safety valve) installed on the indoor unit, to ensure a con-
stant flow of refrigerant to the thermostatic valve and subse-
quently the evaporator. Here the liquid refrigerant absorbs the
heat from the environment and changes state, becoming a gas,
then returning to the compressor: from this point onwards the
cycle repeats itself.
AIR-COOLED DIRECT EXPANSION UNIT - VERSION
AX
The AX series units use air as the cooling fluid, and are therefore
combined with an outdoor air-cooled condenser (supplied sepa-
rately). The MODULATING version features speed control for
the fans on the condenser, so as to maintain correct refrigerant
condensing pressure. The 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 condenser outlet on the liquid line, is recommend-
ed during operation in winter, to prevent migration of the refrig-
erant charge from the liquid receiver to the outdoor condenser,
with consequent low pressure alarms.
The AX units are supplied as standard with EC radial fans in the
standard version.
Air-cooled condenser, outdoor installation
The indoor unit can be connected to different types of outdoor
condensers, standard or low noise versions, with special treat-
ments on the coils.
For the corresponding information refer to the manual on out-
door air-cooled condensers.
Note 1: the outdoor units and condensers are 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 pressurised with dry air (around 3 bar.)
Note 3: the customer is considered responsible for making the
correct connections between the indoor and outdoor unit, as
clearly indicated in the Installation manual, and for ensuring the gas
and oil charges, where necessary.
AX - air cooled
ACCURATE AX - AW - AD - AT - AF
WATER-COOLED DIRECT EXPANSION UNIT - VER-
SION AW
The 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 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 dry coolers are supplied as an optional accessory, while the
antifreeze and fluid circulating pump are generally supplied by oth-
er 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 AW water-cooled indoor units come with the refrig-
erant circuit completely charged and factory-tested before deliv-
ery.
AW - water cooled
EN 5