Supplied By www.heating spares.co Tel. 0161 620 6677
21
DOMINA PLUS F 24 - 30 E
FERELLA EXTRA F 24 - 30 MEL
Version - 09.2002
2.4 Burner unit
Operation
The burner unit comprises a manifold and 12/16 nozzles (depending on the capacity), the burner mount,
electrodes and the burner assembly.
Manifold - nozzles
The valve sends gas at a suitable pressure to the manifold, which homogeneously
distributes the gas to the single burner stages at the nozzles. It is secured
directly to the burner mount. Its positioning must be exact since it affects the air/
gas mixture. In addition, the threaded holes forming the seat of the nozzles must
be aligned with the respective Venturi tube of the burner. If it were not so, the air/
gas mixture would be wrong and there would be poor combustion with an unstable
flame. The nozzles are made of brass and machined extremely precisely for their
dimensions. There is a seal between the nozzles and the manifold.
Ignition electrode
The ignition electrode is made of a metal alloy (Kanthal) that withstands high
temperatures and oxidation. Its base is composed of a ceramic composite of
glazed alumina whose purpose is to protect and electrically insulate it. Once the
ignition procedure begins, the card powers the electrode with a pulsating voltage
of a few kV, a series of electrical discharges is set off between the electrode and
the head of the burner (set at a distance of 3.5 mm). Clearly, these sparks are
the trigger for the air-gas mixture. It is important for the distance between the
electrode and the burner head to be 3
¸
4 mm and the discharge to be made at
the centre.
Checks
If there is no discharge:
·
Check whether the boiler shuts down, in which case check the
connection of the electrode to the card or whether it discharges at
other points; if necessary, check the safety thermostat and the card.
·
If the boiler does not shut down and the fan keeps on working,
check the air pressure switch.
·
If there is a discharge, but no ignition and after 10 seconds the
boiler shuts down, check the gas valve and, if necessary, the
card.
·
If there is a discharge and then a flame, but the boiler still shuts
down after 10 seconds, check the detection electrode and its
connection.
3.5
±0.5
