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Check the drain connections.
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Ensure that there are no refrigerant leaks.
-
Confirm that the electrical power source agrees with the
unit nameplate rating.
-
Make sure that compressors float freely on the mounting
springs.
WARNING: The compressors are mounted on vibration
isolators. Do not loosen or remove the support mounting bolts.
-
Check for proper fan rotation.
Refrigerant charge
Gas tightness testing and dehydration
50VZ/PZ units are shipped fully charged with refrigerant R-407C
ready for operation. If, when the unit is run, symptoms of loss
of charge (for example, low pressure switch tripping or
abnormally low cooling capacities) are detected, first conduct a
leak test followed, if necessary, by a gas tightness test using
compressed nitrogen. For the latter all refrigerant must be
removed from the circuit. Transfer the refrigerant to a storage
tank and then rinse the circuit. For your information, we are
listing here some precautions that need to be taken into
consideration, when working with these units.
Refrigerant guidelines for R-407C
Refrigerant R-407C consists of a non-azeotropic blend of 23%
of R-32, 25% of R-125 and 52% of R-134a, and is character-
ised by the fact that at the time of the change in state the
temperature of the liquid/vapour mixture is not constant. All
checks must be pressure tests, and the appropriate pressure/
temperature ratio table must be used for the interpretation of
the values.
Leak detection is especially important for units charged with
refigerant R-407C. Depending on whether the leak occurs in
the liquid or the vapour phase, the proportion of the different
components in the mixture remaining in the unit is not the
same.
The following basic guidelines must be observed:
•
Leaks must be repaired immediately by qualified
personnel.
•
Refrigerant must never be discharged to the atmosphere.
•
Use a refrigerant reclaim unit.
•
Any loss of oil from the system during maintenance must
be stopped immediately and the collected oil must by
removed in accordance with applicable regulations
38VZ/PZ and 40PZ units are supplied with a nitrogen holding
charge. This must be removed before soldering the connecting
refrigerant lines to the unit. Once the soldering has been
completed, the complete refrigerant circuit must be evacuated
then the correct quantity of R-407C refrigerant for each system
must be charged.
WARNING: If any brazing is to be done the refrigerant circuit
must be filled with nitrogen. Combustion of refrigerant
produces toxic phosgene gas.
VERY IMPORTANT:
-
Never use the compressor as a vacuum pump.
-
If more refrigerant is needed add gas very slowly via the
suction line. Liquid refrigerant must never be introduced
into the suction line.
-
Do not overcharge with refrigerant.
START-UP
Actual start-up should only be done under the supervision of a
qualified refrigeration mechanic. These units include the
Master Link II electronic control. The operation of the control
is explained in the instructions accompanying each unit.
Initial checks
With the unit in operation, ensure that the values shown on the
high and low pressure gauges are within the normal limits. It is
advisable to simulate unit shutdown due to high and low
pressure, in order to make sure that the pressurestats work
properly. To do so, proceed as follows:
-
High pressure shutdown:
Completely cover the outdoor
air inlet, or disconnect the outdoor fan and motor. The
unit should stop at a pressure of 2844 kPa.
-
Low pressure shutdown
: Cover the indoor air inlet, or dis-
connect the indoor fan and motor. Observe the low pressure
gauge. The unit should stop at a pressure of 265 kPa.
In both cases, after a reasonable time, reset the unit through the
remote control as previously indicated.
Check that the motor and compressor consumptions are
approximately the same as those shown on the unit nameplate.
Consumption data is also given in Table 2.
Refrigerant system description
The refrigerant circuit incorporates the following primary
elements:
-
Refrigerant-air heat exchanger:
made of high quality
copper tubes and pretreated aluminium fins, for extra
corrosion resistance and greater protection than offered by
copper fins.
-
Refrigerant lines:
made completely of high quality
copper.
-
Expansion valve or metering device
.
-
Compressors:
hermetic reciprocating or scroll
compressors depending on model, cooled by suction gas.
They incorporate internal protection.
-
Filter drier and Schrader valves.
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Safety elements:
high, low pressurestat.
-
All units are supplied with the correct refrigerant charge.
-
The split system units are supplied with a nitrogen
holding charge which must be evacuated and replaced
with the right refrigerant charge for the unit size and the
connection lines.
Compressor replacement
When an internal fault occurs, the compressor must be
replaced. This must be done as detailed below:
-
Disconnect the unit from the electrical supply.
-
Remove the panels.