Giatsu WD2N8B Serie Manuel De L'utilisateur Et D'installation page 89

Before continuing installation of the unit, check the following:
The maximum water pressure ≤ 3 bar.
The maximum water temperature ≤ 70°C according to safety device setting.
Always use materials that are compatible with the water used in the system and with the materials used in the unit.
Ensure that components installed in the field piping can withstand the water pressure and temperature.
Drain taps must be provided at all low points of the system to permit complete drainage of the circuit during maintenance.
Air vents must be provided at all high points of the system. The vents should be located at points that are easily accessible
for service. An automatic air purge valve is provided inside the unit. Check that this air purge valve is not tightened so that
automatic release of air in the water circuit is possible.
9.3.2 Water volume and sizing expansion vessels
The units are equipped with an expansion vessel of 5L that has a default pre-pressure of 1.5 bar. To assure proper operation
of the unit, the pre-pressure of the expansion vessel might need to be adjusted.
1) Check that the total water volume in the installation, excluding the internal water volume of the unit, is at least 40L.
In most applications this minimum water volume will be satisfactory.
In critical processes or in rooms with a high heat load though, extra water might be required.
When circulation in each space heating loop is controlled by remotely controlled valves, it is important that this
minimum water volume is kept even if all the valves are closed.
2) Expansion vessel volume must fit the total water system volume.
3) To size the expansion for the heating and cooling circuit.
The expansion vessel volume can follow the figure below:
25
20
15
10
5
0
0 50
NOTE
100 150 200
System water volume (L)
24
250 300 350 400