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Start-up, calibration and operation of the burner
5
5.11 Steady state operation
Burner without modulating operation kit
Once the start-up cycle is completed, the servomotor command
moves on to the thermostat/pressure switch TR that controls the
pressure or the temperature in the boiler.
If the temperature or the pressure is low (so the thermostat/
pressure switch TR is closed), the burner progressively
increases the output as far as the MAX value (point "P9").
If the temperature or the pressure increases as far as the
opening of the thermostat/pressure switch TR, the burner
progressively reduces the output as far as the MIN value
(point "P1"). And so on.
The burner switches off when the request for heat is lower
than the heat supplied by the burner at MIN output. The ther-
mostat/pressure switch TL opens and the control box carries
out the switching off phase (see Ch. 5.7). The air damper
closes completely to reduce heat losses to a minimum.
Burner with modulating operation kit
See the handbook enclosed with the adjuster.
5.12 Ignition failure
If the burner does not switch on, there is a lockout within 3 s of
the electrical supply reaching the gas valve.
It may be that the gas does not arrive at the combustion head
within the safety time of 3 s.
In this case increase gas ignition delivery.
The arrival of the gas at the pipe coupling is shown on the
pressure gauge of Fig. 36.
5.13
Burner flame goes out during operation
If the flame accidentally goes out during operation, the control
box carries out a recycle (i.e. it repeats the start-up phase once,
and makes a further ignition attempt).
If the flame is still absent, the control box goes into lockout.
5.14 Stopping of the burner
The burner can be stopped by:
intervening on the disconnecting switch of the electrical sup-
ply line, located on the boiler panel;
removing the hood and working on the switch 1-0 of
Fig. 26;
removing the transparent protection that covers the Operator
Panel, after loosening the relative screw, and using the panel
itself according to ìManual lockout procedure".
5.15 Measuring the ionisation current
The burner is fitted with an ionisation system to check that a
flame is present.
The minimum current for control box operation is 4 μA. The
operator panel visualises "30%" (see Parameters list, param-
eter no. 954).
The burner provides a much higher current, so controls are
not normally required.
However, if it is necessary to measure the ionisation current,
disconnect the plug-socket on the ionisation probe cable and
insert a direct current microammeter with a base scale of
100 μA - see Fig. 35.
20005963
Carefully check the polarities!
5.16 Checking the air and gas pressure on the com-
bustion head
Checking
gas pressure
+ _
Checking
air pressure
5.17 Final checks (with burner operating)
Open the thermostat/pressure switch TL:
Open the thermostat/pressure switch TS:
the burner must stop
Rotate the maximum gas pressure switch knob to the mini-
mum end-of-scale position.
Rotate the air pressure switch knob to the maximum end-of-
scale position.
the burner must stop in lockout
Switch off the burner and disconnect the voltage.
Disconnect the minimum gas pressure switch connector.
the burner must not start
Disconnect the ionisation probe wire.
The burner must stop in lockout due to ignition failure
Make sure that the mechanical locking systems on the differ-
ent adjustment devices are fully tightened.
33
GB
Fig. 35
D8750
+
_
Fig. 36
D8751
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