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falls below the setpoint value. Correct
operation can be checked, after about
5 minutes of operation, by removing
the coil from the solenoid valve of the
liquid under the control of the pressure
gauge eventually installed by the user or
installer because it was not supplied by
the factory in the low pressure points.
Verify that the intervention takes place
in correspondence with the calibration
value.
ATTENTION
In the event of failure to intervene at
the calibration value, stop the com-
pressor immediately and check the
cause. The reset of the ALARM is
manual and can only be done when the
pressure falls below the differential
value.
10.2.3 Superheating
Verify the superheating by comparing
the temperature measured with a con-
tact thermometer situated on the com-
pressor intake with the temperature
shown on the pressure gauge (satura-
tion temperature corresponding to the
evaporation pressure).
The difference between these two tem-
peratures gives the value of superhea-
ting.
The optimal value must be above 8°C
.
NOTE
All routine and special maintenance ope-
rations must be carried out exclusively by
qualified personnel.
Before starting any servicing operation
or cleaning, be sure to disconnect the po-
wer supply to the unit.
All appliances are subject to inevitable wear
and tear over time.
Maintenance makes it possible to:
- Maintain the efficiency of the unit
- Reduce the speed of deterioration
- Gather information and data and under-
stand the condition of efficiency of the
unit in order to prevent breakdowns.
It is therefore essential to carry out perio-
dic controls:
• YEARLY
• SPECIAL CASES
Keep a maintenance log on the machine
(not supplied with the unit, the user must
provide for one) that enables you to keep
track of the servicing carried out on the
unit. This makes it easy to organise the
The pressure gauge is not supplied in
the ANR units, therefore we recom-
mend installing one in the respective
pressure point.
10.2.4 Subcooling
Verify the subcooling by comparing the
temperature measured with a contact
thermometer situated on the pipe at the
outlet of the condenser with the tempe-
rature shown on the high pressure gau-
ge (saturation temperature correspon-
ding to the condensation pressure).
The difference between these two tem-
peratures gives the value of subcooling.
The pressure gauge is not supplied in
the ANR units, therefore we recom-
mend installing one in the respective
pressure point.
10.2.5 Pressing line temperature
If the subcooling and superheating va-
lues are normal, the temperature me-
asured in the pressing line pipe at the
compressor outlet must be 30-40°C
greater than the condensation tempe-
rature.
10.3
P R I M I N G / D I S C H A R G I N G
SYSTEM
During the winter period, in the event
of a system pause, the water present
11 MAINTENANCE
work appropriately and facilitates trouble-
shooting on the machine.
In the log, record the date, type of work car-
ried out (routine maintenance, inspection,
or repair), a description of the work, any
measures taken, and so on.
• Yearly checks
Cooling circuit
- Verify the watertight seal of the cooling
circuit, and that the pipes have not been
damaged.
- Perform an acidity test on the oil of the
cooling circuit.
- Verify the operation of the high and low
pressure switches; in the event of poor
operation, replace the switches
- Check the state of incrustation on the
dehydrator filter; if incrusted, replace
the filter.
•
Electrical checks
- Check the condition of the electrical wi-
res and their insulation
- Verify the operation of the resistor of the
in the exchanger can freeze, causing
irreparable damage to the exchanger,
the complete discharge of the cooling
circuits and, at times, damage to the
compressors.
To prevent the danger of freezing, the
following solutions are possible.
Circuit without glycol:
- Complete discharge of the water
from the exchanger at the end of the
season and filling at the beginning of
the subsequent season by means of
a blowdown valve to be installed by
the installer.
- Use of heating resistors of the ex-
changer (accessory).
In this case the resistors must al-
ways be supplied with electrical po-
wer for the entire period of possible
freezing (machine in stand-by)..
Circuit with glycol
- Operation with glycol/water fluid,
with a percentage of glycol chosen
based on the minimum outdoor tem-
perature expected. In this case you
must take into account the different
outputs and absorption of the chiller,
the sizing of the pumps, and the ou-
tput of the terminals.
evaporator and, if present, of the com-
pressor oil pan
•
Mechanical checks
- Check the tightening of the screws on
the fan grilles and on the fan bodies, the
compressors and the electrical box, as
well as the exterior panelling of the unit.
Insufficient fastening can lead to undesi-
red noise and vibrations.
- Check the condition of the structure.
If there are any oxidised parts, treat with
paint suitable to eliminate or reduce oxi-
dation.
•
Hydraulic controls
- Clean the water filter.
- Empty the air from the circuit.
- Verify that the water flow rate to the eva-
porator is constant.
- Verify the thermal insulation of the
hydraulic piping.
- Check the percentage of glycol where ne-
cessary.
45
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