General Maintenance, Maintenance And Final Recommendations - CIAT EREBA ACCESS T 017 Manual De Instrucciones

12 - GENERAL MAINTENANCE, MAINTENANCE AND FINAL RECOMMENDATIONS

General maintenance
CAUTION: Before starting any servicing or maintenance operation on
the unit, make sure that the power supply has been disconnected.
A current discharge could cause personal injury.
In order to obtain maximum performance from the unit special attention
should be paid to the following points:
- Electrical connections:
The supply voltage should be within the limits indicated in Table II.
Ensure that no faulty contacts exist in the terminal blocks, contactor
boards, etc.
Make sure that all the electrical connections are properly tightened,
and that all the electrical components (contactors, relays, etc) are firmly
secured to the corresponding rails.
Pay special attention to the condition of the connecting cables between
the control elements and the electrical box, and to that of the unit
power supply cable.
They should not be twisted and there should be no slits or notches in
the insulation.
Check that the starting and running consumptions are within the limits
specified in Table II.
- Water connections:
Make sure there are no water leaks from the system. Should the unit
be shutdown for long periods, open the drain valve installed on the
hydraulic module and partially drain the pump and the water pipes
as well as the drain valve on the plate-type exchanger, which must
be installed on the hydraulic circuit. To completely drain the pump,
remove the cap on it. This operation is essential if temperatures are
expected to drop below freezing. If the unit is not drained, the main
switch should remain connected so that the defrost thermostat can
operate. Carefully clean the system water filter.
If the water circuit must be emptied for longer than one month, the
complete circuit must be placed under nitrogen charge to avoid any
risk of corrosion by differential aeration.
- Plate heat exchanger cleaning:
In some applications, for example when very hard water is used, there
is an increased tendency for fouling. The heat exchanger can always
be cleaned by circulating a cleaning fluid.
A weak acid solution should be used (5% phosphoric acid or, if frequently
cleaned 5% oxalic acid), and the cleaning fluid should be pumped
through the exchanger.
The tank installation can be permanent or, alternatively, the connections
can be prepared and, at any given time, a portable cleaning device can
be connected.
To achieve optimum cleaning the acid solution should be circulated at a
minimum of 1.5 times the normal operational flow speed, and preferably
in reverse direction.
The installation should then be flushed with large amounts of water to
totally remove the acid before the system is started up.
Tank installation
Heat exchanger
Cleaning should be done at regular intervals and should never be left
until the unit has become blocked.
The time intervals between cleaning depend on the quality of the water
used, but as a general rule it is advisable to clean it at least once a year.
- Refrigerant circuit:
Ensure that there is no leakage of refrigerant or oil from the compressor.
Check that the high and low side operating pressures are normal.
Check the cleanliness of the refrigerant-water heat exchangers by
checking the pressure drop across them.
The compressors do not require any specific maintenance.
Nevertheless the preventive system maintenance operations prevent
specific compressor problems. The following periodic preventive
maintenance checks are strongly recommended:
• Check the operating conditions (evaporating temperature, condensing
temperature, discharge temperature, heat exchanger temperature
difference). These operating parameters must always be within the
compressor operating range.
• Check that the safety devices are all operational and correctly
controlled.
• Check oil level and quality. If there is a colour change in the sight glass,
check the oil quality. This may include an acidity test, moisture control,
a spectrometric analysis etc.
• Check the leak tightness of the refrigerant circuit.
• Check the compressor motor power input, as well as the voltage
imbalance between phases.
• Check the tightening of all electrical connections.
• Ensure that the compressor is clean and runs correctly; verify that there
is no rust on the compressor shell and no corrosion or oxidation at the
electrical connections and the piping.
ATTENTION: The compressor and piping surface temperatures can in
certain cases exceed 100°C and cause burns. Particular caution is required
during maintenance operations. At the same time, when the compressor
is in operation, the surface temperatures can also be very cold (down to
-15°C for units with a low leaving water temperature), and
can cause frost burns.
- Controls:
Check the operation of all the electrical components, the high pressure
switch and of the high and low pressure transducers and the water, air
and defrost temperature detector.
- Coils:
We recommend, that finned coils are inspected regularly to check the
degree of fouling. This depends on the environment where the unit
is installed, and will be worse in urban and industrial installations and
near trees that shed their leaves.
Recommendations for maintenance and cleaning of round tube plate
fin (RTPF) condenser coils (based on the AFNOR X60-010 standard):
• If the condensers are fouled, clean them gently in a vertical direction,
using a brush.
• Only work on condensers with the fans switched off.
• For this type of operation switch off the HVAC unit if service
considerations allow this.
• Clean condensers guarantee optimal operation of your HVAC unit.
This cleaning is necessary when the condensers begin to become
fouled. The frequency of cleaning depends on the season and location
of the HVAC unit (ventilated, wooded, dusty area, etc.).
- Vibration:
Ensure regularly that the vibration levels remain acceptable and close
to those at the initial unit start-up.
Weak acid solution - Corrosion:
tank
Periodically inspect all valves, fittings and pipes of the refrigerant and
hydraulic circuits to ensure that they do not show any corrosion or any
signs of leaks; also on components coating.
EN - 19 EREBA ACCESS 17 - 40 T/HT
EN