Pressure Switch Adjustment; Air Pressure Switch; Maximum Gas Pressure Switch - Riello GAS 3 P/M Installation, Use And Maintenance Instructions

6.7

Pressure switch adjustment

6.7.1

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. 30).
With the burner operating in 1st stage, increase adjustment
pressure by slowly turning the relevant 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 that it is correct.
If the burner locks out again, turn the knob slightly anticlockwise.
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
ATTENTION
example with cardboard) and check that the
burner locks out, before the CO in the fumes
exceeds 1%.
The incorporated air pressure switch can work in a 'differential'
mode if connected with two pipes. If a strong depression in the
combustion chamber during the pre-purging phase does not
allow the air pressure switch to switch, this can be obtained by
applying a second tube between the air pressure switch and the
suction inlet of the fan. In this way, the pressure switch will work
in differential mode.
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
ATTENTION
CO limit.
6.7.2

Maximum gas pressure switch

Adjust the maximum gas pressure switch (Fig. 31) 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.
20159111
Start-up, calibration and operation of the burner
D3854
Fig. 30
D3856
32 GB
PA
20181543
PGM
Fig. 31