baltur GI 1000 Serie Mode D'emploi page 48

UV CELL
Detection of the pilot flame is effected by a UV cell: the following information should be born in mind.
Even slight greasiness will compromise passage of the UV rays through the UV photocell bulb, thus prevent-
ing the sensitive device inside it receiving the quantity of radiation needed for correct operation. If the bulb is
smeared with light oil, heavy oil, etc. it must be cleaned thoroughly. Note that even gentle contact with fingers
can leave a slight film of grease which is sufficient to compromise proper UV photocell operation.
The UV cell does not "see" daylight or the light emitted by a common bulb.
A sensitivity check can be carried out using a flame (lighter, candle) or the spark generated between the
electrodes of a common ignition transformer. To ensure proper operation the UV cell current must be suffi-
ciently stable and must not drop below the minimum required by the specific control box. It may be neces-
sary to try different positions in order to find the best one: do this by shifting (axial or rotary shift) the body that
contains the photocell with respect to the attachment strap. The check is effected by connecting a micro-
ammeter (with suitable scale), in series, to one of the two UV photocell connection wires; it is, of course,
necessary to observe polarity ( + and - ). The cell current needed to ensure proper control box operation is
given on the wiring diagram.
17) When the burner is working at "minimum" adjust the air to the quantity needed to ensure good combustion.
Turn the adjuster screws in or out at the point of contact with the lever that transmits combustion air
regulation damper movement. The quantity of air at "minimum" should be a little scarce so as to ensure
perfect ignition even under the most demanding circumstances.
18) After adjusting the air for the "minimum" turn the modulation switches to position "MAN" and to position "MAX".
19) The modulation motor starts moving: wait for the disk (on which the adjuster screws are fitted) to sweep through
an angle of about 12° (this corresponds to the space taken up by three screws) and then stop modulation by
turning the switch back to position "0". Run a visual check on the flame and, if necessary, regulate combustion
air as described in point 17. Then check combustion using the appropriate instruments and, if necessary, correct
the adjustment previously made by way of visual check. The above-described operation must be repeated by
proceeding progressively (by advancing the disk about 12° at a time) and, each time, modifying, where neces-
sary, the fuel-air ratio throughout the entire modulation range. It is necessary to make sure that fuel feed pro-
gression occurs gradually and that maximum fuel flow occurs at the end of the modulation range. This condition
is necessary for attainment of smooth, gradual modulation. If necessary modify the position of the fuel control
screws to obtain that specified above. Note that maximum flow is attained when return pressure is about 2 - 3
bar less than delivery pressure (generally 20 - 22 bar). A correct air-fuel ratio should give a carbon dioxide (CO
value that increases as fuel flow increases: as a rough guide, it should be at least 10% at minimum flow and
reach an optimum of about 13 % at maximum flow.
It is inadvisable to exceed a CO
possibly leading to a significant increase in smoke number owing to unavoidable causes (changes in atmos-
pheric pressure, small dust deposits in the fan air ducts etc.). The resulting smoke (i.e. fume) number is closely
linked to the type of fuel used (latest regulations indicate n° 6 on the Bacharach scale as a maximum).
it is advisable, if possible, to keep the smoke number below n° 6 on the Bacharach scale even if the CO
could, as a consequence, be slightly lower. Reduced opacity (i.e. a lower smoke number) soils the boiler less
and the average efficiency of the latter is normally higher even if CO
achieve proper adjustment system water must be up to normal working temperature and that the burner must
have been working for at least fifteen minutes. In the absence of proper instrumentation use fume colour as a
guide. We recommend that adjustment be effected so as to obtain a light orange flame; avoid red flames with
smoke and white flames with an exaggerated excess of air.
20) Now check that modulation works properly in automatic mode. Turn the AUT - O - MAN switch to "AUT" and the
MIN - O - MAX switch to "O". The modulation system is now on and under the exclusive automatic control of the
boiler probe. It is not normally necessary to act on the internal adjusters of the "RWF 40" power regulator;
however, the relevant instructions are contained in the pamphlet.
figure of 13% so as to prevent operation with a rather limited excess of air,
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levels are slightly lower. Remember that to
2
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2
value
2