Hitachi YUTAKI M RASM-3WF2E Installation And Operation Manual page 31

5.3.8 Water filling
1 Check that a water check valve (field supplied) with a shut-off valve (field supplied) is connected
to the water filling point (water inlet connection) for filling the space heating hydraulic circuit
(see "5.1 Outdoor Unit Draining
2 Make sure all the valves are open (water inlet/outlet shut-off valves and the rest of valves of the
space heating installation components).
3 Ensure that the air purgers of the unit and installation work correctly.
4 Connect a drain pipe to the safety valve and make sure that it is correctly connected to the
general draining system. The safety valve is later used as an air purging device during the water
filling procedure.
5 Fill the space heating circuit with water until the pressure displayed on the manometer reaches
approximately 26.1 psi (1.8 bar).

NOTE
While the system is being filled with water, it is highly recommended to operate the safety valve
manually so as to help with the air purging procedure.
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 26.1 psi
(1.8 bar).
PMEN0657 rev.0 - 02/2024
Operation").
Repeat...
Seconds
Repeat...
Seconds
30
5