Indoor Unit - Hitachi YUTAMPO Series Service Manual

7 Maintenance notes
Maintenance work

7.1.2 Indoor unit

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General procedure
To ensure good operation and reliability of the indoor unit its main parts and field wiring have to be checked periodically.
The following checks have to be done by qualified technicians at least once a year:
1 Cabinet
• Stain: Check for any stain and remove it cleaning if it is the case.
• Fixing screw: Check for any loosened screw or any lost screw. Tighten the loosened screws and replace the lost
screws.
• Insulation material: Check for any peeled thermal insulator on the indoor part of the covers.
2 Water piping connection
• Leakage: Check there are no water leakages neither in the inlet and outlet water connections, nor in the main
water circuit nor the tank connections. Check all the joints, connections and circuit elements.
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N O T E
• If leakage is detected in the inlet/outlet water connections, repair it and remember to replace the gaskets.
• Pay special attention to the water pipe connection placed over the electrical box.
3 Security water valve for DHW:
• Operation: Check the correct operation of the security water valve (pressure relief valve) at the DHW inlet
connection. Remember that this element must ensure that the following functions are pro vided: Pressure
protection, non-return function, shut-off valve, filling and draining.
4 Refrigerant piping connection
• Leakage: Check for the refrigerant leakage at the refrigerant piping connections in the indoor unit. Check the
different connections of the plate heat exchanger.
5 Electrical equipment
• Activation: Check for an abnormal activation of the magnetic contactor, the relay, the PCBs and others.
• Line condition: Pay attention to the working voltage, the working amperage and the working phase balance.
Check for any faulty contact that is caused by the loosened terminal connections, the oxidized contacts, the
foreign matter and other items. Check the electrical insulation resistance.
6 Control device and protection device
• Setting: Do not readjust the setting in the field.
7 Ground wire
• Ground line: Check for the continuity to earth in the main electrical components.
8 Anode
• The Mg anode should be replaced yearly or once its size has been reduced to the half. It may loose its function
for protection against corrosion if this period is exceeded. It is recommended to replace the Mg anode every 1
year depending on the quality of the water.
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Draining of the DHW
1 Switch OFF the main power supply of the indoor unit.
2 Close the main DHW inlet valve (water inlet shut-off valve) in order to avoid the tank filling.
3 Close the shut-off valve of the DHW outlet.
4 Connect a drain hose to the cold water inlet for DHW and lead the other end to the general draining.
5 Open manually the hot water outlet for DHW.
6 Open manually the cold water inlet and wait a long time until all the water has been removed.
7 Lean the unit in order to allow removal of the water remaining inside the tank through the cold water inlet.
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C A U T I O N
When draining the DHW, the leaved water could be hot and could keep in pressure. Perform the draining procedure carefully.
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• When draining the DHW, Check Water Pressure always and keep Open a hot water tap to allow draining without creating a vacuum.
83 SMGB0135 rev.0 - 06/2020
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