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00BNO9061-L
VARMAX -
Installation, Use and Maintenance
7.8. Setting the gas valve
This VARMAX boiler has been adjusted in the factory to operate with group
H natural gas (type G20) with inlet gas pressure of 20 mbar.
!
WARNING:
Any work on adjusting the gas valve must be performed by a quali
fi
ed
professional.
The valve must be adjusted with the boiler working at maximum and minimum
pressure. To do this, use the operating "Manual operating" mode (see § 3.3.4
of the NAVISTEM B3000 boiler command table instructions), which makes it
possible to switch directly to the minimum or maximum value (0% or 100%).
7.8.1.
For models 120 and 140
Start the burner up at maximum power.
Using the combustion analyser, measure the rate
of CO
2
in the
fl
ue-gases in the
fl
ue outlet (see
fi
gure 39).
Check the CO
2
value at Maximum power and, if
necessary, manipulate the valve's gas throughput
adjustment screw to obtain CO
2
values between
8.8% and 9.2% or between 10,4% and 10,8%
(G31).
Move to Minimum power and check that the CO
2
value is between 8.3% and 8.7% (G20) or between
9,8% and 10,2% (G31). If necessary, adjust the
Offset regulator by removing the stopper using a
fl
at screwdriver and adjust the screw with a Philips
screwdriver.
If changing the setting while on minimum power,
switch back to Maximum power and check the CO
2
value again. Repeat until both values conform.
Go back to standard operating mode.
fi
gure 40 - VARMAX gas valve models 120 and 140
Offset
regulator
Gas throughput
adjustment
screw
Air relay pipe
connection points
U0501967-#
