baltur GI MIST 350 DSPGM, Инструкция

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0006080103 ed2005/10
DESCRIPTION OF TWO STAGE PROGRESSIVE OPERATIONS WITH NATURAL GAS
(See N° 0002910611)
Control box &
relative
Programmer
LFL 1.333
Cyclic relay
Safety Time
in seconds
3
Pre-Ventilation
Time with shut-
ter open
in seconds
31,5
Pre-ignition
Time
in seconds
6
Post-ignition
Time
in seconds
3
Time between
1st fl ame & Start of
Modulation
in seconds
12
This is referred to as a 2-stage progressive operation because the passage from the 1
st
fl ame to the 2
nd
fl ame
(from the minimum rate to the maximum pre-established rate) takes place gradually.
The amount of combustion air and fuel delivery are increased very gradually and this ensure stabilization of the
gas feed network pressure. The fi eld of variation in fl ow obtainable is from 1 to 1/3. The burner is fi tted with an
end-of-the-run switch (a micro-switch) which stops the burner starting up if the fl ow regulator is not in the minimum
position. Before ignition, a pre-ventilation of the combustion chamber occurs (according to Regulations) with air
open. At the end of the ventilation phase, if the air ventilation pressure switch has measured suffi cient pressure,
the ignition transformer will be connected and, after the ignition (pilot) valves and the safety valve will open.
Gas reaches the combustion head, mixes with air supplied by the fan, and is ignited.
Delivery is regulated by the fl ow regulator incorporated in the ignition fl ame (pilot) valve.
The ignition transformer is disconnected after the ignition fl ame and safety valves are inserted.
The burner is now operating with the ignition fl ame (pilot) only.
Flame presence is detected by a relative control device (ionization probe immersed in the fl ame, or UV cell).
The relay programmer passes the “shut down” position and gives voltage to the servomotor which regulates the
delivery (gas/air); the burner is now operating at minimum output.
If the boiler thermostat (or pressure switch) of the 2
nd
stage allows it (regulated at a temperature or pressure
value superior to that existing in the boiler), the servomotor which regulates the gas/air delivery starts turning and
determines a gradual increase in the gas delivery and in the relative combustion air until it reaches the maximum
delivery value at which the burner has been regulated.
N.B. The “V” cam of the servomotor regulating air/gas delivery (see BT 8562/1) inserts almost immediately
the principle gas valve, which in turn opens completely. Gas delivery is not determined by the principle
valve but by the position of the gas delivery regulation valve (see BT 8814).
The burner remains in the maximum delivery position until the temperature or pressure reaches the limit set for
the intervention of the boiler thermostat (or pressure switch) of the 2
nd
stage and makes the servomotor regulating
gas/air delivery rotate in the opposite sense of direction.
Thus gas delivery and the relative combustion air are gradually reduced until they reach minimum value.
Even with delivery at a minimum, if the limit (temperature or pressure) at which the shut down device (thermostat
or pressure switch) has been regulated is reached, the burner will be brought to a standstill. When the tempe-
rature or pressure drops below the intervention limit set on the shut down device, the burner will start up again,
according to the programme previously described.
During normal operations, the boiler thermostat/pressure switch of the 2
nd
stage fi tted to the boiler detects the
variations requested and automatically proceeds with adapting the fuel and combustion air delivery by inserting
the servomotor which regulates delivery (gas-air). This will rotate in such a way as to obtain an increase or a
decrease. With this manoeuvre, the gas/air delivery regulating system try to equilibrate the quantity of heat sup-
plied to the boiler with that which the boiler gives to be utilized.
If the fl ame does not appear the control box goes to “shut down” (the burner stops completely and the relative
indicator light is turned on).
To unblock the control box, press the appropriate push button.