baltur BT 40 MG Instrucciones De Uso página 27

BURNER FEED SYSTEM
Fuel must be fed to the burner pump by a suitable feed circuit equipped with an auxiliary pump. The latter may, in
turn, be fit with a pressure regulator operating within the 0.2÷1 bar range (see 0002901120) In this case the
pressure of the fuel fed to the burner pump (0.2÷1 bar) should not fluctuate in any way whether the burner is off or
when the burner is operating at maximum fuel flow. Normally this circuit can be prepared without a pressure
regulator following the outline diagram shown in drawing BT 8666/3.
The feed circuit must be prepared according to our drawings 0002901120 or BT 8666/3. The diameter of the pipes
depends on their length and on the capacity of the pump used. The arranged layout only indicates what is required
to ensure proper function. See the specific publications for the provisions which must be followed in order to
comply with Italian law no. 615 (antismog), circular no. 73 issued by the Italian Ministry of the interior on 29/07/71
and any other regulations required by the local Fire Department.
DESCRIPTION OF HOW THE MODULATING BURNER OPERATES
(see diagram no. 0002900900)
Trip the general circuit breaker on the burner control panel. If the thermostats (regulation and safety) give the go-
ahead, the power reaches the control box which turns on the motor. The motor then activates the blower which
cleans out the combustion chamber with air. At the same time, the fuel pump is started up, circulating fuel through
the ducts to eliminate any gas bubbles. The control box then proceeds with the ignition program whereby the
ignition transformer cuts in, thus powering the electrodes with high voltage electricity. The high voltage running
between the electrodes causes electrical sparking used to ignite the fuel-air mixture. After the ignition sparking has
been running for 2.5 seconds the control box powers the solenoid valve opening it to feed fuel to the nozzles. The
fuel reaches the nozzles at a pressure of 20÷21 bar; passing through the nozzle the fuel is atomized and enters the
combustion chamber. As soon as the atomized fuel passes through the nozzle it is ignited by the spark running
between the electrodes.
Control box and Safety delay
Its programmer
(in seconds)
LAL 1.25
5
Cyclical relay
The return oil pressure, which determines the flow into the furnace, is regulated by the return pressure regulator.
For the ignition flow (minimum flow) this is approximately 3÷4 bar. The presence of a flame is detected by a
photoresistance. The servomotor regulating flow of the fuel/air mixture simultaneously controls the increase in
both the fuel and air flows. An increase in light oil flow is determined by a variable section disk. Rotating this disk
causes the return pressure regulation spring to be further compressed, thus increasing the return pressure.
An increase in the return pressure translates into increased fuel flow.
An increase in the fuel flow must be counterbalanced by a corresponding increase in the combustion air flow. This
is achieved during initial regulation by manipulating the screws varying the profile of the disk controlling the
combustion air flow. The flow of fuel, and the simultaneous flow of combustion air, is increased up to the maximum
value (at the return pressure regulator the light oil pressure is 9-10 bar if the pump pressure is 20÷21 bar).
The flow of fuel and air remain at maximum values until the temperature in the boiler (or the pressure if it is a
steam boiler) approaches the value set on the electronic modulation unit. This unit inverts the servomotor regulating
the fuel/air flow, thus gradually reducing the flow of fuel, and subsequently of the combustion air, to the minimum
values. If the maximum temperature (or pressure if it is a steam boiler) is reached even when fuel and air flows are
at minimum, the thermostat (or pressure switch if it is a steam boiler) will cut in when its set point has been
reached, thus locking out the burner. Lowering the temperature (or pressure if it is a steam boiler) below the set
point for the lockout device will ignite the burner once more, as described above.
During normal operation, the modulation probe automatically perceives any changes in boiler capacity and signals
the flow regulation servomotor to adjust the flow of the fuel/air mixture. In this manner the fuel/air flow regulation
system reaches a point of equilibrium, i.e. the proper fuel/air flow rate required for the amount of heat the boiler is
required to produce. lf for any reason the flame goes out while the unit is running, the photoresistance immediately
cuts in (delay time 1 second) thus cutting off the relay power supply. This automatically trips the solenoid valve
which cuts off the flow of fuel to the nozzle and the unit is locked out. lf the program is interrupted for any reason
whatsoever (i.e. power supply failure, manual intervention, thermostat trip, etc.) during the prewashing stage, the
programmer returns to the starting position and automatically repeats the burner ignition phase once more.
Control box specifications
Preventilation and oil Pre-ignition
precirculation times
(in seconds) (in seconds)
22,5
< 25 >
Post-ignition
(in seconds)
2,5 5
ENGLISH
Lapse between of 1° flame
and modulation
(in seconds)
15