Hitachi YUTAKI M Bedienungsanleitung Seite 33

6 Remove as much air from inside the water circuit as possible through the air purger and other
air vents in the installation (fan coils, radiators...).
7 Start the air purge procedure test. There are two modes (Manual or Automatic) which helps in
case of installations with heating and DHW operation:
a. Manual: Start and stop the unit manually using the unit controller (Run/Stop button) and
also using the DSW4 pin 2 of the PCB1 (ON: Forced to derive to DHW coil; OFF: Forced to
derive to space heating).
b. Automatic: Select the air purge function using the user controller. When the automatic
air purge function is running, the pump speed and the position of the 3-way valve (space
heating or DHW) are automatically changed:
Water pump
ON
DHW 3-way valve
OFF
8 If a little quantity of air is still remaining in the water circuit, it should be removed by the
manual air purger of the unit during the first hours of operation. Once the air in the installation
has been removed, a reduction of water pressure in the circuit is very likely to occur. Therefore,
additional water should be filled until water pressure returns to an approximate level of 1.8 bar.

NOTE
• The unit is equipped with a manual air purger (factory supplied) at the highest location of the
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 manometer may vary depending on the water temperature
(the higher temperature, the higher pressure).
• 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.) (See
• 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.
PMEN0647 rev.0 - 11/2023
"5.4.9 Water quality" section).
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