Air Heat Exchanger; Water Heat Exchanger Maintenance; Unit Maintenance; Refrigerant Volume - Riello NXHP Series Installation, Operation And Maintenance Instructions

5 -MAINTENANCE

5.3 - Air heat exchanger

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.
For coil cleaning, two maintenance levels are used:
■ If the air heat exchangers are fouled, clean them gently in a
vertical direction, using a brush.
■ Only work on air heat exchangers with the fans switched off.
■ For this type of operation switch off the HVAC unit if service
considerations allow this.
■ Clean air heat exchangers guarantee optimal operation of your
HVAC unit. This cleaning is necessary when the air heat
exchangers begin to become fouled. The frequency of cleaning
depends on the season and location of the HVAC unit
(ventilated, wooded, dusty area, etc.).
Clean the coil, using appropriate products. We recommend
products for coil cleaning:
■ No. 00PSP000000115A: traditional cleaning method.
CAUTION:
Never use pressurised water without a large diffuser. Do not
use high-pressure cleaners for Cu/Cu and Cu/Al coils.
Concentrated and/or rotating water jets are strictly forbidden.
Never use a fluid with a temperature above 45°C to clean the
air heat exchangers.
Correct and frequent cleaning (approximately every three
months) will prevent most of the corrosion problems.

5.4 - Water heat exchanger maintenance

Check that:
■ The insulating foam is intact and securely in place.
■ The BPHE and piping electric heaters are operating, secure
and correctly positioned.
■ The water-side connections are clean and show no sign of
leakage.
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5.5 - Unit maintenance

CAUTION:
Before any work on the unit ensure that the circuit is isolated
and there is no voltage present. Note that it may take 5 minutes
for the circuit capacitors to fully discharge after isolating the
circuit. After the 5 minutes, check that there are no of the
inverter LED are lit before working on the VFD. Only
appropriately qualified personnel are authorised to work on
the VFD.
In case of any alarm or persistent problem related to the VFD,
contact Service.
The VFDs fitted with NXHP units do not require an insulation test,
even if being replaced; they are systematically verified before
delivery. Moreover, the filtering components installed in the VFD
can falsify the measurement and may even be damaged. If there
is a need to test the insulation of the unit components (fan motors
and pumps, cables, etc.), the VFD must be disconnected at the
power circuit.

5.6 - Refrigerant volume

The unit must be operated in cooling mode to find out, if the unit
charge is correct, by checking the actual subcooling.
Following a small refrigerant leak a loss of refrigerant, compared
to the initial charge will be noticeable in the cooling mode and affect
the subcooling value obtained at the air heat exchanger (condenser)
outlet, but it will not be noticeable in the heating mode.
IMPORTANT:
It is therefore not possible to optimise the refrigerant charge
in the heating mode after a leak. The unit must be operated
in the cooling mode to check, if an additional charge is
required.