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6.10
Pressure switch adjustment
6.10.1 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. 35).
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.
6.10.2 Maximum gas pressure switch
Adjust the maximum gas pressure switch (Fig. 36) 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.
6.10.3 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. 37).
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 0,2 kPa (2 mbar) and repeat
burner start-up to ensure it is uniform.
If the burner locks out again, turn the knob anticlockwise again by
0,1 kPa (1 mbar).
1 kPa = 10 mbar
WARNING
6.10.4 PVP pressure switch kit
Adjust the pressure switch for the leak detection control (PVP kit)
(Fig. 38) according to the instructions supplied with the kit.
Start-up, calibration and operation of the burner
D3856
33
GB
D3854
PA
PGM
D3855
D3855
Fig. 35
20181543
Fig. 36
Fig. 37
Fig. 38
20061317
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