When using open system on the FLOW line following elements are to be installed: safety
pipework for the open expansion vessel, boiler valve. On the RETURN line come safety return line of
the open expansion vessel, boiler valve and circulation pump valves.
Open expansion vessel is connected to the hot-water distribution pipes (FLOW and RETURN)
as shown on Figure – with an additional OVERFLOW pipe output plus CIRCULATION pipe (to prevent
freeze during winter months).
Please note that no additional items shall be connected to the open expansion vessel – espe-
cially not valves.
The size of expansion vessel is deducted from the following equation:
V
= 0
,
07
V
water
(
l
)
V
water
(
l
)
is the water volume in the entire installation. Diameter for the pipework of the expansion vessle
line should be round 25 mm.
Open expansion vessel is to be positioned vertically above the highest heating element.
6
Mixing valve
The use of a mixing valve unit mounted on the return line of the boiler is OBLIGATORY.
13
