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6.9
Final adjustment of the pressure switches
6.9.1
Air pressure switch
Adjust the air pressure switch (Fig. 34) after performing all other
burner adjustments with the air pressure switch set to the start of
the scale.
With the burner operating at minimum output, insert a combus-
tion 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
Start-up, calibration and operation of the burner
20096442
on the graduated 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 anti-clockwise a little bit more. During
these operations it may be useful to measure the air pressure
with a pressure gauge.
The connection of the pressure gauge is shown in Fig. 34. The
standard configuration is that with the air pressure switch con-
nected in absolute mode. Note the presence of a "T" connection,
not supplied.
D3951
Connection of the pressure gauge with
the pressure switch in absolute mode
37
GB
Fig. 34
20182250
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