Full Sequence Ignition Device; Function; Checks - Biasi RIVA COMPACT M90E.24S Service Manual

10

Full sequence ignition device

10.1

Function

The Full sequence ignition device used on the boiler
carries out the following fundamental functions:
does a sequence of operations (ignition cycle)
f
which lead to the ignition of the gas at the burner
checks the presence of the flame during the en-
f
tire period in which it is activated
supplies the fan and checks its functioning by
f
means of the signal coming from the air pressure
switch.
The Full sequence ignition device is supplied by the
electronic control p.c.b. when the ignition of the burner
is requested.
The Full sequence ignition device has a safety function
and any incorrect interventions or tampering can result
in conditions of dangerous functioning of the boiler.
The Full sequence ignition device can lock the function-
ing of the boiler (lock state) and stop its functioning up
to the resetting intervention. The lock is signalled by the
lighting of the lock ---out signal lamp and the device can
be reset only by using the boiler reset button placed on
the control panel fascia.
Some components which are connected to the device
can activate the lock state. The causes of a lock state
could be:
The intervention of the safety thermostat (over-
f
heat of the primary circuit).
A fault on gas supply
f
Faulty ignition (faulty ignition electrodes, their wir-
f
ing or connection).
Faulty flame detection (faulty detection electrode,
f
its wiring or connection).
Gas injectors blocked
f
Faulty modulation gas valve (faulty on---off oper-
f
ators or not electrically supplied).
Faulty Full sequence ignition device.
f
Other components like the air pressure switch can tem-
porarily stop the ignition of the burner but allow its igni-
tion when the cause of the intervention has stopped.
Fig. 41 shows the sequence of the operations that are
carried out at the start of every ignition cycle and during
normal functioning.
10.2

Checks

Lock sequence
n
Start the boiler until the burner is ignited.
24
With the burner firing, interrupt the gas supply. The Full
sequence ignition device must carry out a complete
ignition cycle and then stop.
By turning the boiler on and off by means of the function
switch the device must not unlock and the burner must
not turn on.
Fan functioning device
n
With the boiler operating and the burner on, open the
negative pressure test point of the Venturi device.
At the moment of opening the burner must turn off.
10.3
Removal
Warning: isolate the boiler from the mains
electricity supply before removing any
covering or component.
1 Gain access to the parts located inside the con-
trol panel as explained in the section 2.3 of this
manual.
2 Remove all the wiring connected to the Full se-
quence ignition device.
To disconnect the connectors A, delicately flex the
hook present on one side of each socket
(Fig. 40).
3 Unscrew the two screws B that hold the Full se-
quence ignition device on the panel and remove
the component.
A
Fig. 40
4 Re---assemble the Full sequence ignition device
following the removal procedures in the reverse
order.
B
B
A