Intergas Heating Ltd 38
10.8 Gas-Air ratio control
The gas air ration control of the boiler is set to the correct value in the factory and does not need to
be adjusted. The gas type of the boiler on which the boiler has been set is noted on the data plate.
The boiler is only to be used in combination with this gas type.
When necessary the boiler can be converted to another gas type using the appropriate conversion
set. See the table below for the correct gas ring.
Table 1, inserts and associated gas rings per boiler type.
Model
Insert
number
Gas category
Natural gas
G20
20 mBar
Propane 3P
G31
37 mBar
Gas ring
HRE 24/18 471 505 410
HRE 28/24 406 600 480
HRE 36/30 362 655 525
HRE 36/40 362 655 525
The correct setting of the Gas-Air ratio can be checked by measuring the flue gases using a
calibrated O
2
measuring device. The measurement must be performed first at maximum power
and thereafter on the minumum power.(see § 10.9.1 and § 10.9.2). For reference reasons the
tables below contain O
2
and CO
2
values.
When the CO
2
or O
2
value is incorrect only the setting on minumum power can be adjusted
(see § 10.9.3 ) by changing the setting of the gas valve.
Important
• During the CO
2
or O
2
check the front casing of the boiler needs to
be removed.
• The deviation of the O
2
analyser must be restricted to +/- 0.3%
• A reliable measurement is only guaranteed when no extreme
vacuum in the flue pipe is present (i.e. draft due to hard wind).
• A deviation at maximum power can not be adjusted with the gas
valve setting. When the value measured at maximum power is
without the prescribed range the boiler has to be checked on gas
tightness and usage of the correct components, in particular the
gas ring and the fan.
• When replacing parts or converting the boiler to another gas type
the correct functioning of the gas air ration always has to be
checked.
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