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6.6
Pressure switch adjustment
6.6.1
Air pressure switch - check CO
Adjust the air pressure switch after performing all other burner
adjustments with the air pressure switch set to the start of the
scale (Fig. 29).
With the burner working at MIN output, insert a combustion
analyser in the stack, slowly close the suction inlet of the fan (for
example, with a piece of cardboard) until the CO value does not
exceed 100 ppm.
Slowly turn the appropriate knob clockwise until the burner goes
into lockout.
Check the indication of the arrow pointing upwards on the gradu-
ated scale.
Turn the knob clockwise again, until the value shown on the grad-
uated scale corresponds with the arrow pointing downwards, and
so recovering the hysteresis of the pressure switch (shown by the
white mark on a blue background, between the two arrows). Now
check the correct start-up of the burner.
If the burner locks out again, turn the knob anticlockwise a little
bit more.
6.6.2
Maximum gas pressure switch
Adjust the maximum gas pressure switch after performing all oth-
er burner adjustments with the maximum gas pressure switch set
to the end of the scale (Fig. 30).
With the burner operating at maximum output, lower the adjust-
ment pressure by slowly turning the relative knob anticlockwise
until the burner locks out.
Now turn the knob clockwise by 2 mbar and repeat the start-up of
the burner.
If the burner locks out again, turn the knob clockwise again by 1
mbar.
6.6.3
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. 31).
With the burner operating at maximum output, increase adjust-
ment pressure by slowly turning the relative knob clockwise until
the burner stops.
Now turn the knob anticlockwise by 2 mbar and repeat burner
start-up to ensure it is uniform.
If the burner locks out again, turn the knob anticlockwise again by
1 mbar.
6.6.4
PVP pressure switch kit
Adjust the pressure switch for the leak detection control (PVP kit)
(Fig. 32) according to the instructions supplied with the kit.
Start-up, calibration and operation of the burner
27
GB
D3854
D3856
D3855
D3855
Fig. 29
Fig. 30
Fig. 31
Fig. 32
20062132
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