baltur BT 17 SPN, Manual Instructions For Use

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DESCRIPTION OF OPERATION WITH FUEL OIL –
PRESSURE DROP
(See diagram)
Close the switch on the burner to activate the remote control on the
resistances if the thermostat gives its consent.
Voltage reaches the thermostat, which commands the remote re-
sistance control through the boiler thermostat(s), so the switch on
these thermostats must also be closed.
Through the boiler thermostat, the resistance control prevents fuel
oil from boiling when the appliance is not in operation and wasting
electricity. The resistances turned on in this way will heat fuel oil in
the preheater tank. When the oil reaches a sufficient temperature,
the minimum thermostat will close and, if the other thermostats
(regulation and safety) give their consent, current will reach the
appliance, which will turn on the devices making up the boiler in
accordance with the established programme.
The burner motor comes on at the same time as the ignition tran-
sformer motor. The motor starts the fan rotating, which provides
pre-ventilation with air in the combustion chamber and, at the same
time, the pump causes hot oil to circulate in the pipes, expelling
cold oil and any gas through the return.
This “pre-washing” and pre-ventilating stage lasts 25 seconds and
ends when electrovalve n°1 closes (it is open in the resting posi-
tion), interrupting free release of oil to the tank.
When the electrovalve closes, pressure increases in the delivery
pipes. When pressure reaches a value of 12.5 bar, it opens the
mechanical valve on the pulveriser assembly and oil reaches the
nozzles, coming out of it finely pulverised.
Pressure is stabilised at around 20 bar, because this is the value
the pressure control on the first flame is set to. As soon as the pul-
verised oil comes out of the nozzle, it is burnt by the spark at the
electrodes, which is already present as soon as the motor starts
up. When the 1st flame is being ignited, the air gate is kept in the
position it is set to, which depends on the quantity of fuel burnt, by
the return spring.
If the flame appears as usual, it overcomes the locked position, the
ignition transformer goes off and electrovalve n. 2 comes on, inter-
cepting the oil flow through the pressure control for the 1st flame.
The pressure control for the 1st flame is thus excluded, and pres-
sure increases up to the value to which the pump’s built-in pressu-
re regulation is set (27 bar).
A pressure of 27 bar also acts on the piston regulating the air con-
trol. The piston moves to the end of its travel, opening the air con-
trol farther. The travel of the piston controlling the air control may
be adjusted using the “limit switch” screw provided.
When the appliance is operating at a pressure of 27 bar, it is at its
maximum flow rate.
NOTE: The choice of nozzle must be made on the basis of total de-
sired flow rate, taking into account the flow rates corresponding
to an operating pressure of 25 bar with load loss (p = 2 bar) due
to the antigas valve installed on the pre-heater filter.
It follows from the above, however, that when the burner is opera-
ting with the first flame only, the fuel supplied to the nozzle corre-
sponds to the values shown in the table at 18 bar, because this is
the pressure the nozzle is subject to.
As soon as the flame appears in the combustion chamber the bur-
ner is commanded and controlled by the photoresistances and the
thermostats.
When the temperature or pressure in the boiler reaches the value
the operating thermostat or pressure switch is set to, it is triggered
and causes the burner to shut down.
After this, when temperature or pressure drops below the value at
which the thermostat or pressure switch is closed again, the burner
will come on again.
If the flame disappears during operation for some reason, the pho-
toresistance acts immediately (within one second) to interrupt the
power supply to the relay, causing it to open and turn off washing
electrovalve n. 1, which opens and rapidly releases the pressure
in the tank, intercepting the spray of pulverised oil caused by the
automatic closing of the valve on the pulveriser assembly. If the
burner shuts down (no flame during operation), the ignition phase
is automatically repeated, and if the flame comes back on normally
the burner will resume operation, while if it does not (unusual flame
or no flame at all) the appliance will automatically shut down.
If the programme is interrupted (no voltage, manual intervention,
thermostat tripped, etc..) during pre-washing and is later put back
on (voltage comes back, manual intervention, thermostat tripped,
etc..), the programmer returns to the starting position and the entire
burner ignition phase is repeated automatically. During burner ope-
ration resistances are turned on or off by the adjustment thermo-
stat, as required; the signal for turning on the resistances is given
by the yellow light on the burner.