Riello 20032946 - Air Pressure Switch - CO Check; Minimum Gas Pressure Switch; Combustion Checks

29
20033283
GB
Start-up, calibration and operation of the burner
7.7.4 Air pressure switch - CO check
Adjust the air pressure switch after having performed all other
burner adjustments with the air pressure switch set to the start of
the scale (Fig. 36).
With the burner operating in 1
st
stage, increase adjustment pres-
sure 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 starting to ensure it is correct.
If the burner locks out again, turn the knob anti-clockwise a little
bit more.
The air pressure switch may operate in "differential" operation in
two pipe system. If a negative pressure in the combustion cham-
ber during pre-purging prevents the air pressure switch from
switching, switching may be obtained by fitting a second pipe be-
tween the air pressure switch and the suction inlet of the fan. In
such a manner the air pressure switch operates as differential
pressure switch.
7.7.5 Minimum gas pressure switch
Adjust the minimum gas pressure switch after having performed
all the other burner adjustments with the pressure switch set at
the start of the scale (Fig. 36).
With the burner operating in 2nd stage, increase adjustment
pressure by slowly turning the relative knob clockwise until the
burner locks out.
Then turn the knob anti-clockwise by 0.2 kPa (2 mbar) and repeat
burner starting to ensure it is uniform.
If the burner locks out again, turn the knob anti-clockwise again
by 0.1 kPa (1 mbar).
7.8 Combustion checks
CO
2
It is better to set the burner with CO
2
not higher than 10% (gas
with Pci 8,600 kcal/m
3
).
In this way avoiding a loss of calibration setting (for example draft
variation) that could cause combustion with little air and the pro-
duction of CO.
CO
It must be not higher than 100 mg/kWh.
WARNING
As a rule, the air pressure switch must limit the CO
in the fumes to less than 1% (10,000 ppm).
To check this, insert a combustion analyser into
the chimney, slowly close the fan suction inlet (for
example with cardboard) and check that the burn-
er locks out, before the CO in the fumes exceeds
1%.
Fig. 36
D521
WARNING
The use of the air pressure switch with differential
operation is allowed only in industrial applications
and where rules enable the air pressure switch to
control only fan operation without any reference to
CO limit.
WARNING
1 kPa = 10 mbar
Fig. 37
D896