Air Pressure Switch; Minimum Gas Pressure Switch; Flame Present Check - Riello RS 70 Instrucciones De Instalación, Funcionamiento Y Mantenimiento

AIR PRESSURE SWITCH 14)(A)p. 3
(A)
MIN GAS PRESSURE SWITCH 7)(B)p. 8
(B)
(C)
5 - 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 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.
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%.
D521
The air pressure switch may operate in "differ-
ential" operation in two pipe system. If a nega-
tive pressure in the combustion chamber during
pre-purging prevents the air pressure switch
from switching, switching may be obtained by fit-
ting a second pipe between the air pressure
switch and the suction inlet of the fan. In such a
manner the air pressure switch operates as dif-
ferenzial pressure switch.
Warning
The use of the air pressure switch with differen-
tial operation is allowed only in industrial appli-
cations and where rules enable the air pressure
switch to control only fan operation without any
reference to CO limit.
6 - 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).
D896
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 anti-clockwise by 2 mbar
and repeat burner starting to ensure it is uni-
form.
If the burner locks out again, turn the knob anti-
clockwise again by 1 mbar.
FLAME PRESENT CHECK (C)
The burner is fitted with an ionisation system
which ensures that a flame is present. The mini-
mum current for plant operation is 5 µA.
The burner provides a much higher current, so
D3023
that controls are not normally required. How-
ever, if it is necessary to measure the ionisation
current, disconnect the plug-socket 8)(A)p.3 on
the ionisation probe cable and insert a direct
current microamperometer with a base scale of
100 µA.
Carefully check polarities!
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