baltur GI 350 DSPN, Maintenance, Use And Installation Manual

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18) When the burner is operating at “minimum”, proceed with
regulating the air to the air to the quantity considered
necessary to ensure efficient combustion. Tighten more
or loosen more the adjusting screws in corresponden -
ce to the point of contact, with the lever which transmits
the movement to the combustion air regulation shutter.
It is preferable that the quantity of air for the “minimum” is
slightly reduced, in order to ensure a soft ignition even in the
most critical conditions.
19) After having regulated the air for the “minimum”, put the modu -
lation switches in the “MAN” (manual) and “MAX” (maximum)
positions.
20) The modulation motor starts moving; wait until the disk on which
the regulating screws have been fitted, has reached an angle
of about 12° (this corresponds to the space taken up by three
screws), stop the modulation motor and return the switch to the
“O” position. Carry out a visual control of the flame and proceed,
if necessary, with regulating the combustion air by operating
as described in point 18. Subsequently, control combustion
with the appropriate instruments and modify, if necessary,
the previous regulation carried out by visual control only. The
operation described above should be repeated progressively
(by moving forwards the disk by about 12° at a time) and
modifying every time, if necessary, the fuel/air ratio during the
entire modulation run. Make sure that the increase in fuel
delivery occurs gradually and that maximum delivery is reached
at the end of the modulation run. This is necessary in order to
ensure that modulation functions with good graduality.
The positions of the screws that commend the fuel may need
to be modified in order to obtain the graduality required. Maxi -
mum delivery is obtained when the return pressure is about 2
÷ 3 bar less that the delivery pressure (normally 20 ÷ 22 bar).
For a correct air/fuel ratio, the percentage of Carbon Dioxide
(CO
2
) should increase with the increase in delivery (about a
minimum of 10% at minimum delivery to a maximum of 13%
at maximum delivery. We advise against exceeding 13% of the
CO
2
to avoid operating with a rather limited excess of air which
would cause a considerable increase in smoke opacity due
to unavoidable circumstances (a variation in the atmospheric
pressure; presence of dust particles in the fan’s air ducts,
etc.). Smoke opacity depends on the type of fuel utilized (the
most recent provisions indicate that it should not exceed N° 6
of the Bacharach Scale). We advise, if possible, maintaining
smoke opacity below N° 6 of the Bacharach Scale even if, as a
consequence, the CO
2
value is slightly lower. The lower smoke
opacity dirties the boiler less and therefore its average yield is
normally higher even when the CO
2
value is slightly inferior. It
should be remembered that, in order to regulate properly, the
water in the system should be at the right temperature and the
burner should have been operating for at least 15 minutes. If
the appropriate instruments are not available, judgement can be
based on the colour of the flame. We advise regulating in such
a way as to obtain a flame bright orange in colour. Avoid a red
flame with smoke in it, or a white flame with an exaggerated
excess of air. After having checked the air/fuel regulation, tighten
the locking screws of the adjustable screws.
21) Control that the modulation motor functions automatically by
putting the AUT - O - MAN switch in the “AUT” position and the
MIN - O - MAX switch in the “O” position. In this way, modula -
tion is activated exclusively by the automatic command of the
boiler’s probe, if the burner a GI....MNM (modulating) version,
or on the command of the thermostat or pressure switch of the
2nd stage, if the burner is a GI....DSPN (two stage progressive)
version. (See Chapter “Electronic Potentiality Regulator RWF
40 for the modulating version). Normally, it is not necessary
to alter the internal settings of the Potentiality Regulator RWF
40 . However, the relative instructions are contained in the
appropriate chapter.
22) Check that regulation of the pre-heater’s thermostat does not
cause any defects (bad ignition, smoke presence, formation
of gas in the pre-heater, etc.). If necessary, higher or lower
these values keeping in mind that the thermostat should
be regulated at a temperature of about 15 ÷ 20° C higher
than that at which the minimum thermostat is regulated. The
minimum thermostat must close at the minimum temperature
indispensable in order to obtain good atomisation (viscosity
at the nozzle should not exceed 2° E).For further information,
see the Viscosity-Temperature Diagram with to the type of oil
used.
REGULATION OF THE COMBUSTION HEAD AND
FLAME DISK
The burner is equipped with a combustion head which can be
regulated (by moving it backwards or forwards) in such a way as
to close more or open more the air passage between the disk and
the head. By throttling the passage, it is possible to achieve high
pressure upstream the disk, and therefore high velocity and air
turbulence for low inputs as well. High velocity and air turbulence
ensure better penetration in the fuel and are therefore an optimum
mixture and allow the burner to operate with good flame stability.
High air pressure, upstream the disk, might be necessary in order
to avoid flame pulsations, and it is considered practically indispen -
sable when the burner is operating with a pressurized furnace and/
or high thermal load. It is evident from above, that the position of
the device which regulates the air on the combustion head should
be put in such a position as to always obtain a decidedly high air
pressure value behind the disk. It is advisable to regulate in such
a way as to achieve a throttling of the air between the disk and the
head; this will necessitate a considerable opening of the air shutter
which regulates the flow to the burner’s fan suction.
Obviously these adjustments should be carried out when the burner
is operating at maximum delivery desired.
In practice, commence regulating with the combustion head in
an intermediate position, start up the burner and make a first
adjustment as previously described. When maximum delivery
desired has been reached, proceed with correcting the position of
the combustion head; move it backwards and forwards in such a
way as to obtain an air flow suitable for the fuel delivery with the
air regulation in suction considerably open. If the combustion head
is pushed forwards (which causes a reduction in the air passage
between the head and the disk), avoid closing it completely. When
regulating the combustion head, proceed with centering it perfectly