Primary Circuit Flow Switch; Function; Checks; Removal - QHT RIVA FP Service Instructions Manual

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Third Part
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Primary Circuit Flow Switch

1) Function

2) Checks

3) Removal

1 Function
The Primary circuit flow switch (A in Figure 1)
function is to detect water flow rate through the
primary hydraulic circuit of the boiler.
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 circuit. Any failure of the pump or
obstructions in the primary circuit 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 30 seconds the control board will
indicate that a fault condition has occurred.
RIVA FP SERVICE MANUAL – REV A
(edition-0106)
Figure 1
2 Checks
Warning: Isolate the boiler from the mains
A Mechanical function
1) Remove the front panel of the case.
2) Start and stop the boiler.
3) Looking through the switch box verify the
position of the shaft B referring to Figure 2.
A
Boiler OFF
B 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) Remove the switch as explained in next
section.
2) Measure the electrical resistance between the
tabs marked C. and N.O. (Figure 3). The
contact must be normally open.
3) Operate the switch by hand and verify that the
contact is now closed.
3 Removal
Warning: Isolate the boiler from the mains
A Removal of the switch
1) Remove the front panel of the case.
2) Remove the fork C (Figure 4).
3) Open the box D (Figure 4) and disconnect the
switch.
Primary Circuit Flow Switch
electricity supply before removing any
covering or component.
B
Figure 2
C
N.O.
do not use
Figure 3
electricity supply before removing
any covering or component.
Boiler ON
9-1