Primary Circuit Flow Switch; Function; Checks; Removal - Biasi RIVA ADVANCE HE M110B.24SM/C Service Manual

12

primary circuit flOw switch

12 .1 function

The Primary circuit flow switch (A in Figure 12.1) function is to
detect water flow rate through the primary hydraulic circuit of the
boiler.
b
figure 12 .1
This hydraulic/membrane operated electrical micro-switch device
will control the functioning of the ignition control circuit, providing
there is an adequate quantity and flow of water in the primary cir-
cuit. Any failure of the pump or obstructions in the primary circuit,
whilst in either c.h. or d.h.w. modes, will not allow the device to
operate.
This device is connected to the electronic control p.c.b. and if,
after the pump operates, it does not activate within 20 seconds
the control board will indicate that a fault condition (see section
"Operation lights" page 21) has occurred.

12 .2 checks

warning: isolate the boiler from the mains electrici-
ty supply before removing any covering or compo-
nent .
Electrical check
It is possible to verify the general operation of the switch by
measuring the electric resistance between the contacts C and
N.O. of the switch.
1 Measure the electrical resistance between the tabs marked C
and N.O. (Figure 12.2).
The contact must close (resistance zero) with c.h. pressure of
0,35 bar or higher.
- 32 -
Primary circuit flow switch
a
n .O .
figure 12 .2

12 .3 removal

warning: isolate the boiler from the mains electrici-
ty supply before removing any covering or compo-
nent .
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 D (Figure 12.3) and remove the pri-
mary circuit pressure switch E.
3 Disconnect the connectors.
e
d
figure 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 con-
tact with foods and approved by the local water au-
thorities .
c