baltur TBML 50 ME Installation, Use And Maintenance Instruction Manual page 64

ENGLISH
DESCRIPTION OF OPERATION WITH
LIQUID FUEL
FURTHER INSTRUCTIONS TO START A MIXED BURNER
It is not advisable to have too large a burner for the boiler for
heating and for hot water as the burner may work for long periods
with a single flame, making the boiler work at lower than required
output; as a result of this the combustion products (fumes) emerge
at too low a temperature (at about 180°C in the case of heavy
oil and 130°C with diesel fuel), causing soot to build up at the
chimney outlet.
In addition, when the boiler is working at lower output than that
indicated by the technicians, it is likely that acidic condensate and
soot will form in the boiler with the result that it will quickly corrode
and get clogged up.
When the two-flame burner is installed on a water boiler for hea-
ting use, it must be connected so that it works normally with both
flames, completely stopping without passing to the first flame
when the preset temperature is reached.
To obtain this operating condition, do not install the second flame
thermostat and make a direct connection (bridge) between the re-
spective four pole plug terminals.
In this way only the burner's capacity to switch on at low rate is
used for a gentle ignition, which is essential for boilers with a pres-
surised combustion chamber and also very useful for normal boi-
lers with depression combustion chamber. The burner (start/stop)
command is subject to the usual operating or safety thermostats.
With main switch -1 in the "on" position, close the switch -2 if the
thermostats are closed, the command and control equipment star-
ts its operation.
The motor turns the fan that carries out an air wash of the combu-
stion chamber and, at the same time, the fuel pump that causes
circulation in the ducts, expelling any gas bubbles through the re-
turn valve. This pre-washing phase ends with the opening of the
operating solenoid valves that makes it possible for the fuel, at a
pressure of 12 bar, to reach the nozzle and enter the combustion
chamber finely atomised.As soon as the atomized fuel exits the
nozzle, it is set on fire by the spark present between the electro-
des since the start of the motor.
During first stage ignition, the air gate is held in the adjusted posi-
tion on the special air adjustment servomotor cam.
If the flame appears regularly, after the safety time foreseen by
the device, it starts the air regulation servomotor that moves to the
second stage position. During the transition from the first to the se-
cond stage, the equipment activates the solenoid valve (normally
closed) of the second stage.
The opening of the second flame valve allows the diesel oil, at a
pressure of 12 bar, to reach the second nozzle and the burner to
operate at full capacity.
Once the flame appears in the combustion chamber, the burner
is controlled and commanded by the flame control equipment and
by the thermostats.
The control equipment follows the program and switches the igni-
tion transformer off. When the temperature or the pressure in the
boiler reaches that set by the thermostat or pressure switch, the
latter stops the burner.
Subsequently, if the temperature of pressure decreases below the
lower thermostat or pressure switch threshold value, the burner
will switch on again.
If, for any reason, the flame fails during operation, after just one
second the flame control device cuts off the power supply to the
relay, causing the deactivation of the solenoid valves which inter-
cept the fuel flow to the nozzles.
The equipment will shut-down automatically.
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