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5.8
Pressure switches setting
Air pressure switch
Adjust the air pressure switch after having performed all other burner adjustments with
the air pressure switch set to the start of the scale (Fig. 23).
With the burner operating at max. output, increase adjustment pressure by slowly turn-
ing the relative knob clockwise until the burner locks out. Then turn the knob anti-clock-
wise by about 20% of the set point and repeat burner starting to ensure it is correct.
If the burner locks out again, turn the knob anticlockvise a little bit more.
Attention: as a rule, the air pressure switch must limit the CO in the fumes to less than
1% (10,000 ppm). To check this, insert a combustion analyser into the chimney, slowly
close the fan suction inlet (for example with cardboard) and check that the burner locks
out, before the CO in the fumes exceeds 1%.
Maximum gas pressure switch
Adjust the maximum gas pressure switch after having performed all other burner adjust-
ments with the maximum gas pressure switch set to the end of the scale (Fig. 24).
With the burner operating at MAX output, reduce the adjustment pressure by slowly turn-
ing the adjustment knob anticlockwise until the burner locks out.
Then turn the knob clockwise by 2 mbar and repeat burner firing.
If the burner locks out again, turn the knob again clockwise by 1 mbar.
Minimum gas pressure switch
Adjust the minimum gas pressure switch after having performed all the other burner ad-
justments with the pressure switch set at the start of the scale (Fig. 25).
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 anti-clockwise by 2 mbar and repeat burner starting to ensure it is uni-
form.
If the burner locks out again, turn the knob anti-clockwise again by 1 mbar.
Final checks
Before leaving the plant:
- Ensure the adjustment and safety devices work correctly.
- Check all the mechanical blocking systems on the adjustment devices are tightly closed.
20
5
CHAPTER
Preparation for start up
D2215
Fig. 23
D2213
Fig. 24
D2214
Fig. 25
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