Hitecsa EWMIG 236 Manual De Instalación, Uso Y Mantenimiento página 47

The machine can be started by pressing the ON/OFF key on the
keyboard built into the machine. Using the MODE key, select an
operating mode (chiller or heat-pump). Any problems the system
encounters will be immediately shown on the display on the control
keyboard. At start-up, the first device to start in the system is the pump,
which has priority over the rest of the system. During this phase, the
minimum water flow differential pressure switch and the low pressure
switch are ignored for a pre-set time, to prevent variations caused by air
bubbles or turbulence in the water circuit or by pressure fluctuations in
the cooling circuit.
Spending these timings, the final consensus is accepted when the
machine subsequently passed another time security, starts for the first
inverter compressor and only then the fixed speed compressor. This
order is always ignition.
The compressor follows a start-up procedure with controlled
acceleration ramps. After a few minutes you can note that the
compressor will run at a speed of rotation which is proportional to the
thermal load.
IMPORTANT!
In this phase, it must be considered normal that the
flow temperature drops by a few degrees below the
set value, however remaining higher than the anti-
freeze set in the summer cycle.
II.8.3 DECOMMISSIONING
IMPORTANT!
If the unit is not used during the winter period, the
water contained in the system may freeze.
When the machine is out of use for long periods of time, it is necessary
to disconnect it from the mains by opening the master switch. All the
water contained in the circuit must be drained in time. During
installation, consider mixing the water in the circuit with the correct
proportion of ethylene glycol to guarantee protection against freezing
(see Protecting the unit from frost).
II.8.4 RESTART AFTER PROLONGED SHUTDOWN
Before starting up again, make sure that:
there is no air in the hydraulic system (bleed it if required);
water in the heat exchanger is circulating in the required amount.
the air side heat exchanger is well ventilated and clean.
II.9 NATURE AND FREQUENCY OF THE
SCHEDULED CHECKS
DANGER!
Maintenance operations, even if for inspection
purposes only, must be carried out by skilled
technicians, qualified to work on air conditioning
and refrigeration products.
DANGER!
Always use the mains switch to isolate the unit
from the mains before carrying out any
maintenance work on the unit, even if it is for
inspection purposes only. Make sure that no one
supplies power to the machine accidentally; lock
the master switch in zero position.
In order to guarantee that the unit runs regularly and efficiently, it is
necessary to schedule an overall inspection at regular intervals to
prevent malfunctions which could damage the main machine
components.
Every 6 months
Check the gas charge.
Check that there are no gas leaks
Check the power consumption of the unit
Check the operation of the water differential pressure switch
Air bleed from hydraulic system
Check the contactors on the electric panel.
END OF SEASON with unit switched off
Check that the air side heat exchanger is clean.
Draining the water system
Inspect and, if necessary, tighten the electrical contacts and terminals.
SECTION II: INSTALLATION AND MAINTENANCE
II.10 INSTRUCTIONS FOR MAINTENANCE
DANGER!
Maintenance operations, even if for inspection
purposes only, must be carried out by skilled
technicians, qualified to work on air conditioning
and refrigeration products. Use suitable personal
protective equipment (gloves, goggles, etc).
DANGER!
Do not introduce pointed objects through the air
flow and intake grilles.
DANGER!
Always use the mains switch to isolate the unit
from the mains before carrying out any
maintenance work on the unit, even if it is for
inspection purposes only. Make sure that no one
supplies power to the machine accidentally; lock
the master switch in zero position.
DANGER!
In the event cooling or fan circuit component fail or
the refrigerant fluid charge drops, the upper part of
the compressor casing and the discharge line may
reach temperatures close to 150°C for brief periods
of time.
II.10.1 ROUTINE MAINTENANCE
II.10.1.1 Refrigerant circuit
Refrigerant charge check
With the unit off, fit a pressure gauge on the test point on the outlet side
and another on the test point on the inlet side. Start up the unit and
check both pressure readings once they have stabilised.
Check for the absence of refrigerant fluid leaks
With the unit off, check the refrigerant circuit with a suitable leak
detector.
Check that the air side heat exchanger is clean.
With the unit off, observe the air side heat exchanger and, as needed:
remove any foreign bodies from the finned surface which may obstruct
air flow;
remove built-up dust possibly vacuuming it;
wash and brush, gently, with water and gentle brushing;
let it air dry;
keep condensation drain pipes free from any obstructions.
II.10.1.2 Hydraulic circuit
Check the operation of the water differential pressure switch
With the unit running normally, slowly close the shut-off valve on the
unit water inlet pipe. If, during a test phase, the shut-off valve is
completely closed without the differential pressure valve triggering, stop
the unit immediately by pressing ON/OFF on the control panel and
replace the component.
Bleed the air from the water system
Bleeding the air is facilitated by manual valves found inside the unit,
which are accessed by opening the panelling of the technical
compartment
Pre-load pressure of the expansion tank
From the specific loading connection on the expansion tank, you can
verify the pre-load pressure (see Expansion tank technical data).
Draining the water system
The system can be drained from the relief valve on the water inlet pipe.
Make sure the hydraulic circuit is completely emptied by opening all the
manual relief valves inside the unit.
SAFEGUARD THE ENVIRONMENT!
If the system has an antifreeze additive, it must not
be drained freely, because it causes pollution. It
should be collected for possible recycling. The
filling valve must not be opened in the presence of
glycol water.
II.10.1.3 Electrical circuit
The following checks are recommended on the electrical circuit:
check the unit power consumption using a clip-on meter and compare
the reading with the values shown in the technical data table;
with the unit disconnected from the power supply, check and inspect
electrical contacts and terminals for tightness.
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