Description of functioning
t e c h n i c a l
9
Expansion vessel:
(Part number MCB2005)
The expansion vessel is a hermetically closed receptacle with two chambers separa-
ted by an SBR membrane. One chamber contains nitrogen (air) and the other is fi lled
with the water from the heating circuit. It has a capacity of 7 litres.
The function of the expansion vessel is to absorb the increase in volume of the hea-
ting circuit water when it is heated up.
The amount of
expansion by the
expansion vessel depends on the temperatu-
re selected by the
user
for the heating circuit
,
and on the total volume
of the heating
circuit.
Automatic bypass:
The bypass is located inside the hydraulic unit. It joins the heating outlet and return.
It is
preset
, only opening when the pressure between the bypass
inlet and outlet exceed
0.3 b
Its purpose is to assist when there is a large loss of load in the circuit and the pump
consequently has diffi culty in moving the water. When the bypass opens, an amount
of water which was fl owing towards the radiators is made to circulate directly to the
return pipe, thus making the work of the pump easier.
Central heating low p
ressure switch:
(Part number FCB1480)
This indicates the pressure inside the heating circuit
is correct. If the pressure is under 0,5 bar the switch
opens and the boiler
locks out (F3)
The expansion vessel pressure is 1 bar
, with zero pressure in
the heating circuit
I
FCB1480
8
