baltur BT 180 DSG, Instruction

Page: 9 / 29

9
ANCILLARY PUMP (see BT 8666/2)
In some cases (excessive distance or difference in level) it is necessary to install a “loop-type” supply system with an
ancillary pump, which dispenses with the connection of the burner pump directly to the tank.
In this case the ancillary pump can be put into operation when the burner is started up and cut-off when the latter
stops.
The electric wiring of the ancillary pump is made by connecting the coil (220 V) which controls the pump remote
control switch to terminals “N” (equipment terminal board) and “L1” (downstream the motor remote control switch).
It is important to comply strictly with the previsions set forth here below:
- The ancillary pump should be installed as near as possible to the fuel to be sucked.
- Its head should meet the requirements of subject system.
- We recommend a delivery rate equal to at least that of the burner pump.
- Connection pipes should be sized to cope with the delivery rate of the ancillary pump.
- Always avoid to electrically connect the ancillary pump directly to the remote control switch of the burner motor.
DESCRIPTION OF OPERATIONS (see diagram)
By closing the switch on the burner, and if the thermostats (control and safety) allow it, current flow to the control box and
activate the motor and the ignition transformer.
The motor will start up the fan which will carry out a pre-ventilation with air from the combustion chamber and simultane-
ously the pump which will drive oil through the pipes and expel any gas bubbles through the return pipe.
During the pre-ventilation phase the combustion air shutter is activated by its motor and opens in the 2nd flame position
(pre-ventilation with air open). Subsequently, the air shutter returns to the 1st flame position for ignition.
This “pre-washing” cases when electrovalve no. 1 closes (open in the rest position) and this interrupts the free discharge
of oil towards the cistern. When electrovalve no. 1 closes, an increase in pressure in the delivery pipes follows.
When the light oil pressure reaches 7 bar, the mechanical valve which can be found in the atomizer unit opens allowing
oil to reach the 1st flame nozzle and come out of it into the combustion chamber finely atomized. The pressure
stabilises at about 10 bar because the 1st flame pressure regulator has been set at this value. As soon as atomized
oil comes out of the nozzle, it is ignited by the spark between electrodes which has been present since the motor started
up. If the flame appears regularly, the programmer passes over the “shut down” position and inserts the motor which
activates the combustion air shutter and puts it in the 2nd flame position.
While this is happening, an adjustable cam activated by the same motor, closes the electrical contact which takes
voltage to electrovalve no. 2 which intercepts the flow of oil through the 1st flame pressure regulator. The 1st flame
pressure regulator is excluded in this way and the pressure increase until it reaches the value at which the pressure
regulator incorporated in the pump has been set (16 bar). The 16 bar pressure also acts on the mechanical valve
which, up to a pressure value of 13 bar, prevents the fuel from flowing to the second nozzle. This valve is opened in this
way by the pressure, and the second nozzle also starts operating. The 16 bar, pressure now acts on the two nozzles.
When the unit is working at a pressure of 16 bar, it is operating at maximum capacity.
Note:
From the above outline it is evident that the choice of nozzles with respect to the desired total
burner output (2 nozzles in operation) should be made taking into account the delivery rates corresponding to the
light oil 16 bar, operating pressure. It should be noted, however, that when the burner operates only with the 1st
flame, the delivery rate of the first nozzle corresponds to the values given in the 10 bar, pressure table because
the pressure regulator for the 1st flame is set at this value. Obviously, it is possible to change the ratio between
the 1st and 2nd flame within a wide range by replacing the nozzles. However, it should be remembered that for
efficient operations the fuel supply for the 1st flame should not be less than the minimum burner output (shown
on the name-plate) for each specific model. A smaller output could make ignition difficult, and combustion with
the 1st flame only might not be satisfactory. From the moment the flame appears in the combustion chamber,
the burner is controlled and monitored by the photoresistant cell and thermostats, the programmer continues its
cycle and disconnects the ignition transformer; consequently the burner is “on” and operating at full rating. If
the programme is interrupted (voltage failure, manual operation, thermostat tripping, etc.) during the pre-washing
phase, the programmer will return to its original position and automatically repeat the whole burner start-up
cycle. When the temperature or pressure reaches the value preset on the thermostat or operating pressure
switch, its tripping will cause the burner to stop. The burner will resume its operation automatically when the
temperature or pressure value falls by the required amount. In case of flame failure during operations, the
photoresistant cell will trip immediately (1 second) and stop current to the relay which then opens and conse-
quently disconnects the washing electrovalve. This in turn rapidly discharges the existing pressure and the jet
of atomized oil is cut off by the automatic closure of the atomizing unit valve as soon as the pressure drops below
7 bar. In this case, the start-up cycle is repeated automatically and if the flame ignites normally again, the burner
will also resume its normal operations. If there is a poor flame or no flame at all, the unit goes automatically to
“shut down”.