Air Pressure Switch; Minimum Gas Pressure Switch; Flame Presence Check - Riello RS 34 MZ Installation, Use And Maintenance Instructions

AIR PRESSURE SWITCH

(A)

MINIMUM GAS PRESSURE SWITCH

(B)
(C)
1)
2)
D3951
D3855
µA
4 - AIR PRESSURE SWITCH (A)
Adjust the air pressure switch after having per-
formed all other burner adjustments with the air
pressure switch set to the start of the scale (A).
With the burner operating in 1st stage, increase
adjustment pressure by slowly turning the rela-
tive knob clockwise until the burner locks out.
Then turn the knob anticlockwise 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.
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%.
The air pressure switch may operate in "differ-
ential" operation if connected to two pipes. If a
negative pressure in the combustion chamber
D3842
during pre-purging prevents the air pressure
switch from switching, switching may be
obtained by fitting a second pipe between the air
pressure switch and the suction inlet of the fan.
In such a manner the air pressure switch oper-
ates as differential pressure switch.
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 opera-
tion without any reference to CO limit.
5 - MINIMUM GAS PRESSURE SWITCH (B)
Adjust the minimum gas pressure switch after
having performed all the other burner adjust-
ments with the pressure switch set at the start of
the scale (B).
With the burner operating in 2nd stage, increase
adjustment pressure by slowly turning the rela-
tive knob clockwise until the burner locks out.
Then turn the knob anticlockwise by 2 mbar and
repeat burner starting to ensure it is uniform.
If the burner locks out again, turn the knob anti-
clockwise again by 1 mbar.
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FLAME PRESENT CHECK (C)
The burner is fitted with an ionisation system
which ensures that a flame is present. The mini-
RMG
mum current for control box operation is 6 μA.
The burner provides a much higher current, so
that controls are not normally required. How-
ever, if it is necessary to measure the ionisation
current, disconnect the plug-socket 24)(A)p.4 on
D3843
the ionisation probe cable and insert a direct
current microammeter with a base scale of
100 μA. Carefully check polarities!
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