Primary Circuit Flow Switch; Function; Checks; Removal - Biasi Activ A 25C Service Manual

12

Primary circuit flow switch

12.1

Function

The Primary circuit flow switch (A in Fig. 12.1) function
is to check the presence of water in the primary hy-
draulic circuit and that the pressure is above the mini-
mum.
D
Fig. 12.1
This device is connected to the main electronic control
p.c.b. and if, it does not activate the control board will
indicate that a fault condition (see section 4.1 of this
manual) has occurred.
12.2

Checks

Warning: isolate the boiler from the mains
electricity supply before removing any
covering or component.
Electrical check
n
It is possible to verify the general operation of the switch
by measuring the electric resistance between the con-
tacts C. and N.O. of the switch.
1 Measure the electrical resistance between the
tabs marked C. and N.O. (Fig. 12.2).
The contact must close (resistance zero) with c.h.
pressure of 0,35 bar or higher.
30
A
N.O.
Fig. 12.2
12.3

Removal

Warning: isolate the boiler from the mains
electricity supply before removing any
covering or component.
1 Remove the front and right hand side panels of
the case, turn off the flow and return isolation
valves and empty the primary circuit.
2 Remove the fixing spring B (Fig. 12.3) and re-
move the primary circuit pressure switch A.
Disconnect the connectors C (Fig. 12.3).
3
C
A
B
Fig. 12.3
4 Reassemble the primary circuit pressure switch
in reverse order of removal.
Warning: to lubricate the O-- ring gaskets
exclusively use a silicone base grease
compatible to be in contact with foods and
approved by the local water Authorities.
13 Expansion vessel and pressure
gauge
13.1 Function
The Expansion vessel (D in Fig. 12.1) function is to
allow for the volume expansion of the c.h. circuit water
due to the temperature rise.
13.2 Checks
1 Turn off the flow and return isolation valves and
empty the primary circuit of the boiler.
C