baltur BGN LX series Betriebsanleitung Seite 40

22) In case of UV photoelectric cell, after at least one minute from ignition extract the photoelectric cell from its hous-
ing. When the UV photoelectric cell is extracted from its housing, it cannot "see" the ultraviolet radiation emitted by
the flame and thus, the relevant relay de-energises. The burner immediately shuts down in "lock".
A light greasiness strongly affects the passage of ultraviolet beams through the UV photoelectric cell bulb, thus
preventing the internal photosensitive element from receiving the necessary radiation for a correct operation. If
the bulb is dirty with light oil, heavy oil, etc., clean it accurately. Note that a simple finger contact can cause a light
greasiness, sufficient to impair the UV photoelectric cell operation. The UV photoelectric cell does not "see"
daylight or the light of a common candle. A possible sensibility check can be made with a flame (lighter, candle) or
with the electrical discharge occurring between the electrodes of a common ignition transformer.
To ensure a correct operation, the UV photoelectric cell current value must be sufficiently stable, and must not
decrease below the minimum value required for the specific control box. Said value is shown in the wiring dia-
gram. It may be necessary to experimentally search the best position by making the body containing the photo-
electric cell slide (axial or rotation movement) with respect to the fixing clamp.
23) Check the efficiency of the boiler thermostats or pressure switches (their start must shut down the burner).
AIR REGULATION ON COMBUSTION HEAD (See dr. n° 0002933310)
Warning: When, as in this case, the burner is provided with gas valves model MB-VEF.., DMV-VEF.., by moving the
air regulation device on the combustion head there automatically and unavoidably occurs a gas output
variation (see chapter Valve operation principle, model MB-VEF.., DMV-VEF..).
The combustion head is equipped with a regulation device, so as to open or close the air passage between disk and
head. By closing the passage, it is thus possible to obtain a high pressure upstream of the disk also for low flow rates.
The high air speed and turbulence allows a better penetration of the same into the fuel and therefore, an excellent
mixture and flame stability. It may be necessary to have a high air pressure upstream of the disk, so as to prevent
flame pulses. This condition is indispensable when the burner operates on pressurised combustion chamber and/or
with high heating load. From what said above it is evident that the device closing the air on the combustion head must
be set to such position as to always obtain, behind the disk, a very high air pressure value. It is advisable to regulate
so as to have such air closure on the head as to require the opening of the air damper regulating the flow of the burner
ventilator suction. Of course, this condition must only occur when the burner is operating at the maximum desired
output. In practice, the regulation must start with the device that closes the air on the combustion head in an interme-
diate position, igniting the burner for an indicative regulation as explained above.
When the maximum desired output is reached, correct the position of the device closing the air on the combustion
head by moving it forwards or backwards so as to have a suitable air flow for the output, with suction air regulation
damper sensibly open (see dr. n° 0002933310).
N.B. To facilitate the combustion head regulation, see table (dr. n° 0002933200)
When reducing the air passage on the combustion head, avoid closing it completely, which may cause an
excessive heating of the head with a consequent quick deterioration. Perfectly adjust to central position with
respect to the disk. Note that if not perfectly centred with respect to the disk may cause a wrong combustion
and an excessive head heating, with a consequent quick deterioration. The check is carried out by looking
through the inspection hole on the rear side of the burner. Afterwards, tighten the screws locking the position of the air
regulation device on the combustion head.
N.B. Check that ignition is regular because if the controller has been moved forward, the output air speed could be so
high as to make ignition difficult. In such a case, it is necessary to move backwards, degree by degree, the
regulator until reaching the position in which the ignition is regular and accept this new position as definitive.
We still remind you that it is preferable, for the small flame, to limit the air quantity to the minimum indispensable
to have a safe ignition even in the most demanding case.
MAINTENANCE
The burner does not need special maintenance. However, it is advisable to check that the gas filter is clean. It may
also be necessary to clean the combustion head. In this case, dismantle the components of the mouth.
Be careful when assembling again, so as to prevent the electrodes from to earth or in short circuit.
Also check that the ignition electrode spark only occurs between the same and the drilled plate disk.
EN
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