Carrier 30WG 080 - 16 - START-UP; 16.1 - Preliminary checks; 16.2 - Actual start-up; 16.3 - Refrigerant charge adjustment

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16.2 - Actual start-up
IMPORTANT
• • Commissioning and start-up of the unit must be
supervised by a qualied refrigeration engineer.
• • Start-up and operating tests must be carried out
with a thermal load applied and water circulating in
the evaporator and condenser.
• • All set-point adjustments and control tests must be
carried out before the unit is started up.
Ensure that all safety devices are operational, especially
that the high pressure switches are switched on and that the
alarms are acknowledged.
For 30WGA units operating with a remote air-cooled
condenser the compressor oil level must be monitored during
the system start-up phase. This is to ensure that the oil charge
of the original compressors is sufcient for the system size
and the piping conguration. Once the oil level has stabilised,
it must not be lower than 1/4 of the oil sight glass level for
the compressors that operate.
16.3 - Refrigerant charge adjustment
IMPORTANT: It is imperative to empty the nitrogen holding
charge from the system and evacuate the system before
beginning to charge refrigerant into the unit. Never charge
refrigerant into the low-pressure side of the unit. While
charging refrigerant ensure that all fans of the outdoor unit
are operating.
With all fans operating add refrigerant until the subcooling
(upstream of the expansion device) is between 4 and 8 K.
To achieve this:
Measure the refrigerant pressure at the level of the service
valve in the liquid line of the 30WGA unit, measure the liquid
line temperature as close as possible to the service valve.
Add charge until the refrigerant passing through the sight
glass is ‘clear’: the refrigerant is now only liquid. Then
complete the charge until the actual subcooling required is
between 4 et 8 K, based on the liquid line pressure drops (lter
drier, solenoid valve, special components and possible liquid
head).
The actual subcooling is equal to the saturated temperature
at the bubble point, minus the liquid line temperature
measured. If the actual subcooling value is higher than 8 K,
(unit outlet) an excess charge is possible. This excess charge
translates to an excessive condensing pressure and increases
the compressor power input.
If adding charge does not result in a clear sight glass and the
condensing pressure rises above the acceptable values, ensure
that the lter drier is not blocked and that one of the solenoid
valves is not partially closed.
Pro-Dialog+ controls the automatic switching of all fan stages,
based on operating time and number of start-ups of the
different stages. This function prevents fan motors from only
running a little or not at all and the shafts seizing up, especially
during periods with a low cooling demand, when the outside
temperature is low. Switching is often specified by the
condenser manufacturers to ensure a long operating life of
the fan motors that are only used a little or not at all in these
particular operating conditions.
16 - START-UP
16.1 - Preliminary checks
• Never be tempted to start the unit without reading fully,
and understanding, the operating instructions and without
having carried out the following pre-start checks:
• Check the chilled water circulation pump operation with
the Quick Test function.
• Check the air handling units and all other equipment
connected to the evaporator. Refer to the manufacturer’s
instructions.
• Check the condensing loop water circulation pump
operation with the Quick Test function (61WG/30WG).
• For units without hydronic module, the water pump
overheat protection devices must be connected in series
with the pump contactor power supply (61WG/30WG/
30WGA).
• Ensure that there are no refrigerant leaks.
• Conrm that all pipe securing bands are tight.
• Conrm the the electrical connections are secure.
• Avoid a long common power wiring connection run
inside the unit close to the control or signal wiring.
• Observe the clearances on each unit side to facilitate
maintenance.
• The unit pipings are not 100% insulated whatever the
options. The insulation only protects against running
condensation.
• To ensure that no condensate can run under the unit, a
condensate pan must be added under the unit that collects
100% of the condensate.
• If work is required in a control box or on the compressor
wiring, the phase order must be veried with a quick
test (refer to the 61WG/30WG/30WGA Pro-Dialog+
Control manual. The compressors cannot support
prolonged operation (>30 seconds) with reversed phases.
• Ensure that the last refrigerant charge made by the
service team corresponds with the charge given on the
name plate - otherwise the operating ranges and the unit
efciency will be impaired. The required tolerance for the
charge is ±2%.
• Do not interchange material with another Carrier unit.
The elements used for this unit are specic to this unit.
Use the specic Carrier component list when ordering
any parts.
• Before start-up ensure that the unit is level (1.5 mm/m).
• Check the operation of the fans in the air-cooled
condensers.
ATTENTION: Use of units in an open loop is forbidden.