Hitachi YUTAKI S80 R410A Series Installation And Operation Manual page 42


NOTE
• The indoor unit is equipped with an automatic air purger (factory supplied) at the highest
location of the indoor unit. Anyway, if there are higher points in the water installation, air might
be trapped inside water pipes, which could cause system malfunction. In that case, additional air
purgers (field supplied) should be installed to ensure no air enters into the water circuit. The air
vents should be located at points which are easily accessible for servicing.
• The water pressure indicated on the indoor unit manometer may vary depending on the water
temperature (the higher temperature, the higher pressure). Nevertheless, it must remain above
1 bar in order to prevent air from entering the circuit.
• Fill in the circuit with tap water. The water in the heating installation must comply with EN
directive 98/83 EC. Non-sanitary controlled water is not recommended (for example, water from
wells, rivers, lakes, etc.)
• The maximum water pressure is 3 bar (nominal opening pressure of the safety valve). Provide
adequate reduction pressure device in the water circuit to ensure that the maximum pressure is
NOT exceeded.
• For heating floor system, air should be purged by means of an external pump and an open circuit
to prevent the formation of air pockets.
• Check carefully for leaks in the water circuit, connections and circuit elements.
Domestic hot water tank
◆
If a domestic hot water tank has been installed, perform the following operations:
Heating coil circuit
Fill the DHW tank heating coil from the space heating circuit filling in point. Follow the instructions
explained in the "5.3.3.1 Water filling"
!
CAUTION
• Check that the heating coil pipes are correctly connected between indoor unit and tank before
filling the tank's heating coil.
• Ensure the correct water quality of the indoor unit water circuit.
Domestic hot water tank and DHW circuit
1 Open the outlet water taps of the DHW installation one after each other, to expel all the air
from inside the water circuit.
2 Open the main DHW inlet valve in order to fill the tank. If there is a shut-down valve installed in
the DHW outlet, open it to allow circulation through the DHW installation.
3 When water begins to flow from the outlet water taps of the DHW installation, close all these
taps.
4 Finally, close the main DHW inlet valve when the pressure reaches approximately 6 bars.
PMEN0648 rev.0 - 03/2023
chapter to correctly perform the operation.
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