baltur GI 1000 DSPN-D, Instructions Manual

Page: 48 / 76

48
ENGLISH
15) Close burner switch “S1” and the main switch. The elements contained in the fuel preheaters are thus turned
on. Switching on of the elements is signalled by the relative control panel indicator lights.
The contactor coils on elements “KR1” and “KR2” are powered via contacts “Y1” and “Y2” of the “MS 30”
electronic temperature regulator (where applicable) or the regulator thermostat. The burner still does not start
because minimum thermostat consensus is absent (i.e. the fuel in the preheater is not hot enough).
NOTE Do not turn on the elements with the tank empty as doing so could damage them.
16) The minimum thermostat closes its contact (i.e. comes on) when the temperature in the preheater reaches its
setting value. Tripping of the minimum thermostat immediately causes switching on of the burner control box
(as long as boiler safety thermostats/pressure switches are closed).
With the burner control box now on the burner ignition sequence begins. The programme includes simultane-
ous pre-ventilation and pre-circulation, with low pressure hot oil, throughout the burner fuel circuit.
Burner ignition is as described in the previous chapter, “Description of Operation”; the burner is ignited at its
minimum.
NOTE: To adjust the gas pilot flame proceed as follows:
- disconnect the wire from terminal n° 18 of the LFL... control box to prevent the electromagnet being
switched on.
- disconnect the wire from terminal n° 17 of the LFL... control box (intermittent pilot) and connect it to
terminal n° 18 (pilot always on).
- ignite the burner, adjust the quantity of gas and air for the pilot flame and check for proper ignition
several times.
- when adjustment is over restore the original connections.
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 necessary 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 modu-
lation 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 necessary, the fuel-air ratio throughout the entire modulation range. It is necessary to make
sure that fuel feed progression occurs gradually and that maximum fuel flow occurs at the end of the modu-
lation 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 (CO2) 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 CO2 figure of 13% so as to prevent operation with a rather limited excess of air,
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 CO2
value could, as a consequence, be slightly lower. Reduced opacity (i.e. a lower smoke number) soils the boiler