Checks; Ignition And Detection Electrodes; Function; Removal - Biasi GARDA M90F.24S Service Manual

16

Ignition and detection electrodes

16.1

Function

Three electrodes are fitted near the front part of the
burner. The ignition sparks take place between the me-
tallic edges of the ignition electrodes over the central
ramp of the burner during the ignition sequence.
The third electrode is the detection electrode and it de-
tects the presence of the flame.
Fig. 63 shows the electrodes configuration on the mo-
dels M90F.24S, M90F.24SR, M90F.28S, M90F.28SR.
Fig. 64 shows the electrodes configuration on the
model M90F.32S
Ignition
Female
Fig. 63
Detection
Male
Female
Fig. 64
30
Detection
Male
Ignition
16.2

Checks

Check the position of the electrode edges
n
Warning: isolate the boiler from the mains
electricity supply before removing any
covering or component.
1 Remove all the case panels, the sealed chamber
lid and the combustion chamber lid.
2 Check for the correct distance between the me-
tallic edges of the ignition electrodes (see
Fig. 65).
Ignition
Fig. 65
3 Check the integrity of the detection electrode and
ensure that its metallic edge is correctly placed
over the ramp of the burner.
Check the connection wires.
n
Warning: isolate the boiler from the mains
electricity supply before removing any
covering or component.
1 Remove all the case panels, the sealed chamber
lid and the combustion chamber lid.
2 Check for the integrity of the insulation of wires
which connect the electrodes to the ignition de-
vice.
16.3

Removal

Warning: isolate the boiler from the mains
electricity supply before removing any
covering or component.
1 Remove all the case panels, the sealed chamber
lid and the combustion chamber lid.
2 Disconnect the electrode wires from the full se-
quence ignition device.
3 Remove the burner by unscrewing the four
screws placed at the right and left sides of the
burner.
3b For models M90F.28S, M90F.28SR and M90F.32S
remove also the plate C (see Fig. 68 on page 32).
4 Unscrew the screws A (Fig. 66) which hold the
electrodes to the burner.
Two screws are used on the models M90F.24S,
M90F.24SR, M90F.28S, M90F.28SR.
Three screws, one for each electrode, are used
on the model M90F.32S.
4 mm