6.9
Pressure switch adjustment
6.9.1
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. 25). With the burner operating at MAX. output, in-
crease adjustment pressure by slowly turning the relative knob
clockwise until the burner locks out. Then turn the knob anti-
clockwise by about 20% of the set point and repeat burner start-
ing to ensure it is correct. If the burner locks out again, turn the
knob anti-clockwise a little bit more.
In conformity with current standards, the air pres-
sure switch must prevent the CO in the flue gases
exceeding 1% (10,000 ppm).
WARNING
6.9.2
Maximum gas pressure switch
Adjust the maximum gas pressure switch after having performed
all the other burner adjustments with the maximum gas pressure
switch set at the end of the scale (Fig. 26). With the burner oper-
ating at MAX output, reduce the adjustment pressure by slowly
turning the adjustment knob anticlockwise until the burner locks
out. Turn the knob clockwise by 0.2 (2 mbar) and repeat the start-
up of the burner.
If the burner locks out again, turn the knob again clockwise by 0.1
kPa (1 mbar).
6.9.3
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. 27).
With the burner operating at maximum output, increase adjust-
ment pressure by slowly turning the relative knob clockwise until
the burner locks out. Then turn the knob anticlockwise by 0.2 (2
mbar) and repeat burner start-up to ensure it is operating regular-
ly. If the burner locks out again, turn the knob again anticlockwise
by 0.1 kPa (1 mbar).
1 kPa = 10 mbar
WARNING
20136081
Start-up, calibration and operation of the burner
26
GB
D3854
Fig. 25
D3856
Fig. 26
D3855
Fig. 27