31
6.5 - 24 V user power reserve
After all possible options have been connected, the transformer
ensures the availability of a usable 24 VA or 1 A power reserve
for the control circuit on site.
7 - 30WGA UNIT CONNECTIONS
7.1 - Recommendations for the installation of liquid
chillers with remote condenser
The 30WGA units (split units for connection to air-cooled
condensers) have been specially designed to optimise the
operation of split system installations, using air-cooled
condensers as the chiller heat rejection system.
The refrigerant circuit installation of an operational system is
limited to the connection of the air-cooled condenser inlet
and outlet to the 30WGA unit.
The components such as the check valve (in the discharge
line), moisture sight glass and solenoid valves are installed
and wired in the factory.
The lter-drier is supplied with the unit and must be installed
upstream of the solenoid valve on the liquid line.
The Pro-Dialog+ control system of the 30WGA units
incorporates the logic to permit control of the different fan
versions (xed or variable-speed).
To guarantee optimum and reliable performance of the units
it is necessary to comply with the regulations described below,
when these units are connected to remote condensers:
• Size the discharge and liquid line piping according to
the recommendations in the following paragraphs (if
necessary, install a double riser to ensure correct oil
circulation in the refrigerant circuit).
• Select a condenser with an integrated subcooler to obtain
a minimum of 3 K subcooling at the inlet to the expansion
device.
• Install the lter drier supplied with the unit as close as
possible to the liquid line lter drier.
• Install the outside air temperature sensor supplied near
the air-cooled condenser.
For units with remote condenser control (option 154),
the sensor is supplied. The outside air temperature
information is required for correct operation of the
complete system.
Control of the remote air-cooled condenser using option 154
• Connect the fan stages electrically to the control board,
using auxiliary electronic board AUX 1. To assign the
fan stages refer to chapters 14 and 15 with the description
of the analogue and digital inputs and outputs.
• Make the communication bus connection (twisted and
shielded cable type for communication bus RS485)
between the specic electronic AUX 1 board, that must
be integrated in the condenser control box and using
the NRCP master board of the 30WG unit.
• The Pro-Dialog+ control is used to congure the number
of fan stages and the fan type based on the air-cooled
condenser model used in the installation.
• A fan speed controller may is recommended for the rst
fan stage for operation at low ambient temperature at
part load and for condensers with few fans.
ATTENTION: The air-cooled condenser must always be
used with a subcooler. Normally 8 K subcooling at the
condenser outlet is recommended.
7.2 - Piping installation and connection
On all units release the holding charge pressure before
opening the circuit.
Use the various valves and/or remove the safety cap from
the conical Schrader valve supplied. Push in the valve tip to
release the complete system holding charge (nitrogen).
Preparation before unsoldering the liquid and discharge line
plugs:
• Remove all components that may be damaged during
the unsoldering procedure
• Pipe soldering: remove the cores from the conical
Schrader valves near the area, remove the pipe collars,
remove the cladding panels and the metal crossbars.
All these components must be replaced before commissioning
the system.
Componentsberemovedbeforesoldering
• Unsolder the plugs and prepare the pipes for connection.
• Connect the liquid line to the system, install the lter
drier upstream of the unit.
• Make the high-pressure connections (discharge line)
between the unit and the condenser.
• During these operations circulate and inert gas such as
nitrogen in the pipes to prevent the formation of copper
oxyde.
IMPORTANT: The condenser circuit piping must be in
accordance with good practices relating to the static support
and the thermal expansion of copper pipes.
To ensure system vibration control, the collar positions on
the piping in the unit must not be changed. At the outlet of
the refrigerant section there are pipe ange collars. It is
imperative to tighten these collars to prevent vibrations and
possible breaks.
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