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5.10
Final adjustment of the pressure switches
5.10.1 Air pressure switch
Adjust the air pressure switch after performing all other burner
adjustments with the air pressure switch set to the start of the
scale (Fig. 31).
With the burner operating at MAX. output, increase adjustment
pressure by slowly turning the relative knob clockwise until the
burner locks out.
Then turn the knob counter-clockwise by about 20% of the set
point and repeat burner start-up to ensure that it is correct.
If the burner locks out again, turn the knob slightly anticlockwise.
In conformity with current standards, the air
pressure switch must prevent the CO in the flue
gases exceeding 1% (10,000 ppm).
ATTENTION
5.10.2 Maximum gas pressure switch
Adjust the maximum gas pressure switch (Fig. 32) after making
all other burner adjustments with the maximum gas pressure
switch set to the end of the scale.
To calibrate the maximum gas pressure switch, open the tap and
then connect a pressure gauge to its pressure test point.
The maximum gas pressure switch must be regulated to a value
no higher than 30% of the measurement read on the gauge when
the burner is working at maximum output.
After making the adjustment, remove the pressure gauge and
close the tap.
5.10.3 Minimum gas pressure switch
Adjust the minimum gas pressure switch after performing all the
other burner adjustments with the pressure switch set to the start
of the scale (Fig. 33).
With the burner operating at maximum output, increase the
adjustment pressure by slowly turning the relevant knob
clockwise until the burner stops.
Then turn the knob anticlockwise by 0.2 kPa (2 mbar) and repeat
the burner start-up to ensure it is operating regularly. If the burner
locks out again, turn the knob anticlockwise again by 0.1 kPa (1
mbar).
1 kPa = 10 mbar
ATTENTION
5.10.4 Minimum oil pressure switch
The minimum oil pressure switch is calibrated in the factory at 16-
18 bar. If the oil pressure falls below this value in the delivery line,
the pressure switch stops the burner.
The burner restarts automatically if the pressure goes above bar
value set after the burner starts.
5.10.5 Maximum oil pressure switch
The maximum oil pressure switch is calibrated in the factory at 4-
5 bar. If the oil pressure in the return line goes above this value,
the pressure switch stops the burner in a lockout.
To adjust the pressure switches, use a tool to operate the adjust-
ment screw (Fig. 34).
20169350
Start-up, calibration and operation of the burner
D3854
D3856
20079898
30
GB
Fig. 31
PA
20183681
PGM
Fig. 32
Fig. 33
D3855
Fig. 34
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