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The gas/air control is set in the factory such that the
combustion is optimal for the gas type used. The gas type (natural gas
or LPG) for which the boiler is adjusted is indicated on the data plate
under the boiler. The boiler may not be implemented if the gas used
deviates form that which is indicated on the data plate. The boiler may
optionally be converted to another gas type using a conversion set.
For the correct gas restriction ring, see the table below.
Table 1: Gas restriction rings
Boiler type
Xtreme
Insert
number
Gas category
Natural gas
G20
20 mbar
LPG
G31
30 & 50 mbar
Gas restriction ring number
24 528 392 315
30 500 450 370
36 500 450 370
By default, the boiler is set to natural gas G20.
A proper operation of the gas air control can be established
by measuring the flue gases directly above the boiler using an
analyser probe of a flue gas analyser. The measurement takes
place at high and minimum output (for this, see §8.10.1 and
§8.10.2). Any deviation can be corrected solely at minimum
output by setting the gas valve anew (see §8.10.3).
IMPORTANT
► Inspection of the gas/air control must be
done with opened casing.
► The measurement must be performed
based on O
2
; in other words, the flue
gas analyser must have an O
2
sensor.
Conversion of the measured O
2
measurement value in the flue gas analyser
to a CO
2
measurement value is allowed.
► The deviation of the flue gas analyser may
be a maximum of ± 0.3% (based on O
2
).
► A reliable check and adjustment is only
safeguarded if no extreme vacuum is
present in the flue connection opposite the
installation location. This also includes a
natural draught (wind), for example.
► A deviation at maximum output cannot
be corrected by adjusting the gas valve. In
that case, the boiler must be meticulously
inspected for gas density and correctness
of components used (especially the gas
restriction ring and the fan including
venturi).
► When replacing components and/or
converting to another gas type, the
operation of the gas air control must
always be inspected.
8.9 Gas/air control
IMPORTANT
► Work on gas supply pipe components
as well as the adjustment of the gas
air control must be performed by an
authorised installer.
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