Maintenance; General Procedure; Descaling - Hitachi YUTAKI S80 Series Installation And Operation Manual

MAINTENANCE

11 MAINTENANCE

C A U T I O N
All the following operations must be done by a licensed technician.

11.1 GENERAL PROCEDURE

To ensure good operation and reliability of the DHW tank its main
parts and field wiring have to be checked periodically.
C A U T I O N
• All inspections and checks of the DHW tank have to be carried
out by a licensed technician and never by the user itself.
• Before any inspection and check the DHW tank main power
supply has to be switched OFF. In this case, the indoor unit
supply has to be switched OFF.
• Make sure that the outdoor unit main power supply is also
switched OFF before any operation or repair.
The following checks have to be done by qualified technicians at
least once a year:
1 Domestic Hot Water flow and pressure: check that the water
circulation is correct along all the DHW circuit and that there
is no loss of pressure and water flow.

11.2 DESCALING

Water quality and set temperature can affect the scale production
and it can deposit on the heating coil surface of the DHW tank
restricting the heat exchange and the good operation of the unit.
N O T E
Descaling should be necessary periodically at certain intervals
depending on the supplied water quality.
Check the scale level when proceeding maintenance to ensure
reliability of the unit.
50 PMML0291A rev.2 - 09/2014
2 Water leakage: check that there are no water leakages in the
main water circuit. Check all the joints, connections and circuit
elements.
3 Security water valve: check the correct operation of the secu-
rity water valve (pressure relief valve) on the DHW tank water
circuit.
4 Fixing points tightening: check the fixing points of the DHW
tank. In case tank over indoor unit option, check the joints be-
tween the tank and the indoor unit. In case tank beside indoor
unit option, check the DHW tank mounting foots. The tank has
to be always in a vertical position and well fixed to the wall with
the required Wall fixing accessory providing higher stability.
N O T E
All these maintenance operations must be done with appropriate
materials and following this manual.
If necessary, proceed with descaling:
1 Switch OFF the main power supply of the indoor unit.
2 Empty the DHW tank of water as explained in
tion.
3 Proceed with descaling of the heating coil.
4 Ensure that the water quality remains compliant with the
EU council directive 98/83 EC.
Draining sec-