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6.7
Pressure switch adjustment
6.7.1
Air pressure switch - check CO
Adjust the air pressure switch (Fig. 27) after performing all other
burner adjustments with the air pressure switch set to the start of
the scale.
With the burner operating at MIN output, increase adjustment
pressure by slowly turning the relative knob clockwise until the
burner locks out.
Then turn the knob anticlockwise by about 20% of the set point
and repeat burner start-up to ensure it is correct.
If the burner locks out again, turn the knob anticlockwise a little
bit more.
In conformity with the standard, the air pressure
switch must prevent the air pressure falling below
80% of the adjusted value and the CO in the flue
gases exceeding 1% (10,000 ppm).
WARNING
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%.
On RS 810/M BLU burners the air pressure switch is fitted in an
"absolute" mode, that is, connected only to the pressure test point
"+" 22) (Fig. 4 on page 11).
6.7.2
Maximum gas pressure switch
Adjust the maximum gas pressure switch (Fig. 28) 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.
6.7.3
Minimum gas pressure switch
The purpose of the minimum gas pressure switch is to prevent
the burner from operating in an unsuitable way due to too low gas
pressure.
Adjust the minimum gas pressure switch (Fig. 29) after having
adjusted the burner, the gas valves and the gas train stabiliser.
With the burner operating at maximum output:
–
install a pressure gauge downstream of the gas train stabili-
ser (for example at the gas pressure test point on the burner
combustion head);
–
choke slowly the manual gas cock until the pressure gauge
detects a decrease in the pressure read of about 0.1 kPa
(1 mbar). In this phase, verify the CO value which must
always be less than 100 mg/kWh (93 ppm).
–
Increase the adjustment of the gas pressure switch until it in-
tervenes, causing the burner shutdown;
–
remove the pressure gauge and close the cock of the gas
pressure test point used for the measurement;
–
open completely the manual gas cock.
20160598
Start-up, calibration and operation of the burner
D3856
1 kPa = 10 mbar
WARNING
26
GB
Fig. 27
D3854
PA
20181543
PGM
Fig. 28
Fig. 29
D3855
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