25
14_09. 5641250_01
NRL free cooling 0280-0750 60Hz
EN
15. FUNCTIONING
CHARACTERISTICS
15.1. COOLING SET POINT
(Default defined) = 7°C/44.6°F, ∆t = 5°C/ 10°F
15.2. COMPRESSOR START DELAY
To prevent the compressor start too close to each
other, two functions have been arranged.
- Minimum time from last turn-off 60 seconds.
- Minimum time from last start 300 seconds.
15.3. CIRCULATION PUMP
The electronic board provides an output to manage
the circulation pump.
After the first 10 seconds of the pump operation,
when the water flow rate is running, activate the
function of water flow rate alarm (flow switch).
15.4.
ANTI-FREEZE ALARM
The anti-freeze alarm is active as if the machine is
turned-off or if the machine is in standby mode.
In order to prevent breakage of the plate-type
exchanger due to freezing water contained, the
compressor is locked (if the machine is turned on
under 4° C) and the resistance starts up (if standby
below 5° C). If the temperature detected by the
probe in the exchanger output and in the chiller
input is below +4 ° C.
WARNING
THE ANTI-FREEZE SET TEMPERATURE
CAN BE VARIED ONLY BY AN AUTHORISED
SERVICE CENTRE AND ONLY AFTER
VERIFYING THAT IN THE WATER CIRCUIT
IS AN ANTIFREEZE SOLUTION.
The intervention of this alarm sets the compressor
block and not of the pump, which remains active,
and the resistance starts-up if installed.
For the restoration of the normal functions of the
temperature of the water output have to come back
over +4 ° C, the reset is manual.
WARNING:
AT ANY INTERVENTIONS OF THIS ALARM
IT IS RECOMMENDED TO IMMEDIATELY
CONTACT THE NEAREST TECHNICAL
SERVICE ASSISTANCE
15.5. WATER FLOW RATE ALARM
The GR3 provides the management of a water
flow rate alarm commanded from a flow switch
standardly installed on the machine. This safety type
can occur after the first 10 seconds of operation of
the pump if the water flow rate is not sufficient.
This alarm sets the block of the compressor and the
pump.
WARNING
Inspection, maintenance and possible
repair operations must be carried
out only by an authorised technician
according to the law.
A deficient check/maintenance
operation may result in damage to
things and people.
For machines installed near the sea the
maintenance intervals must be halved.
16. REGULAR MAINTENANCE
Any cleaning operation is forbidden before
disconnecting the unit from the power supply.
Check for voltage before operating.
Periodic maintenance is essential to maintain the
unit in perfect working order under the functional as
well as the energetic aspect.
Therefore it is essential to provide yearly controls
for the:
16.5.1. HYDRAULIC CIRCUIT
CONTROL:
−
Water circuit filling
−
Water filter cleaning
−
Flow switch control
−
Air in the circuit (leaks)
−
That the water flow rate to the evaporator is
always constant
−
The hydraulic piping thermal insulation state
−
Where provided the percentage of glycol
16.5.2. ELECTRIC CIRCUIT
CONTROL:
−
Efficiency of safety devices
−
Electrical power supply
−
Electrical power consumption
−
Connections tightened
−
Function of the compressor housing resistance
16.5.3. CHILLER CIRCUIT
CONTROL:
−
Compressor conditions
−
Efficiency of the plate-type exchanger
resistance
−
Working pressure
−
Loss test for the control of the sealing of the
refrigerant circuit
−
Function of high and low pressure switches
−
Perform the necessary checks on the filter-drier
to verify their efficiency.
16.5.4. MECHANICAL CONTROLS
CONTROL:
−
The screws, compressors and the electric box
of the unit external panelling are properly
tightened. If they are poorly tightened, they
produce abnormal noise and vibrations
−
The structure conditions.
If necessary, treat oxidised parts with paints
suitable for eliminating or reducing oxidation.
17. EXTRAORDINARY
MAINTENANCE
The NRL are loaded with R410A gas and tested
in the factory. In normal conditions, no Technical
Assistance Service operation is needed for the
refrigerant gas check. Along time, however, small
leaks from the joints may be generated. Due to
these leaks, the refrigerant comes out and the
circuit is drained, causing the unit malfunction. In
these cases, the refrigerant leakage points are found
and repaired, and the cooling circuit is recharged,
