Riello RS 50 - 6.6 Pressure switch adjustment; 6.6.1 Air pressure switch; 6.6.2 Gas minimum pressure switch; 6.6.3 Flame presence check

27
20144599
GB
Start-up, calibration and operation of the burner
6.6 Pressure switch adjustment
6.6.1 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. 27).
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 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 slightly anticlockwise.
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.
6.6.2 Gas minimum 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. 28).
With the burner operating in 2nd stage, increase adjustment
pressure by slowly turning the relevant knob clockwise until the
burner stops.
Then turn the knob anticlockwise by 0.2 kPa (2 mbar) and repeat
burner start-up to ensure it is operating regularly.
If the burner locks out again, turn the knob again anticlockwise by
0.1 kPa (1 mbar).
6.6.3 Flame presence check
The burner is fitted with an ionisation system to check that a
flame is present. The minimum current required for the control
box operation is 5 A. The burner supplies a significantly higher
current value, so that no check is usually needed. However, if it
is necessary to measure the ionisation current, disconnect the
plug-socket 8)(Fig. 4 on page 12) on the ionisation probe cable
and insert a direct current microammeter with a base scale of 100
A. Carefully check polarities.
ATTENTION
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
burner locks out, before the CO in the fumes
exceeds 1%.
ATTENTION
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.
Fig. 27
D521
ATTENTION
1 kPa = 10 mbar
Fig. 28
D896
Fig. 29
D3023