5.12
Pressure switch adjustment
5.12.1 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. 35).
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 about 20% of the adjusted
value and check the burner starts up correctly. 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
5.12.2 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. 36).
With the burner operating at MAX output, reduce the adjustment
pressure by slowly turning the adjustment knob anticlockwise un-
til the burner locks out.
Turn the knob clockwise by 0.2 kPa (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).
5.12.3 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 locks out. 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
WARNING
5.12.4 Oil pressure switch
Check that the oil pressure switches have intervened correctly.
Turn the adjustment screw (Fig. 38) to check that the pressure
switches have intervened. The check should be carried out by in-
dividually varying the calibration of each pressure switch.
Decreasing the maximum calibration of the oil pressure switch,
the burner should go into lockout. Increasing the minimum cali-
bration of the oil pressure switch, the burner should not start.
While the minimum oil pressure switch must be calibrated to ap-
prox. 16-18 bar.
With the control carried out, restore the factory setting of the max-
imum oil pressure switch to approx. 4-5 bar.
Any other pressure values should be adjusted to the burner out-
put.
Start-up, calibration and operation of the burner
31
GB
D3854
Fig. 35
D3856
Fig. 36
D3855
Fig. 37
20079898
Fig. 38
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