baltur BTG 20 LX Notice D'instructions page 54

S
ETTING THE PRESSURE
E
The pressure – adjustment unit is factory set.
N
Settings should then be adapted on site to suit
the needs of the system.
G
The MB-VEF B01 modulating valve works by automatically incre-
asing the gas supply if the air supply increases and automatically
L
reducing the gas supply in the event of a reduction in the air
supply. For this reason, the supply of gas at burner "minimum" and
I
"maximum" should only be regulated by adjusting combustion air
"minimum" and "maximum". This is basically achieved by setting
S
the two "cams" that regulate the minimum and maximum of the air
H
adjustment servomotor. Keeping this principle in mind, we recom-
mend adopting the following procedure for adjusting the burner.
Switch on and keep the burner at modulation minimum (modulating
valve open to minimum), check the content of CO2, or O2 and CO in
the flue gas and if necessary use adjuster screw "N" to correct the
gas/air ratio that is obtained by parallel displacement of performance
curves (see diagram).
NB: In order to reduce the amount of air compared to gas and thus
increase the percentage of CO2, move adjuster screw 'N" towards
positive values (+). In order to increase the amount of air compared
to gas and thus reduce the percentage of CO2, move adjuster screw
'N" towards negative values (-). Take the burner to modulation
maximum, measure the content of CO2 or O2 and CO in the flue
gas and if necessary use adjuster screw "V" to correct the ratio
previously set until an optimum reading is obtained.
NB: In order to reduce the amount of air compared to gas and thus
increase the percentage of C02, move adjuster screw "V" towards
higher ratios. In order to increase the amount of air compared to gas
and thus reduce the % of CO2, move adjuster screw "V" towards
lower ratios (see diagram). Once maximum modulation has been
set, return to the minimum position and check the adjustments
previously carried out. If necessary, correct "0" point again with
adjuster screw "N"
NB: When a parallel change to the performance curve has been
required in order to obtain good CO2 or O2 values at low loads
(modulation at minimum), it is necessary to recheck the setting of
the gas/air ratio and alter if required using adjuster screw "V".
A d j u s t e r s c r e w s
and gas/air ratio "V"
WARNING: It can clearly be seen from that stated above
that the change in burner air pressure obtained by using the
device controlling the flow of air to the combustion head (by
varying the air flow area) automatically and inevitably causes
a change to the gas supply.
–
ADJUSTMENT UNIT
- z e r o p o i n t
Seat for 2.5 mm hollow exagon
key.
Example: By reducing the air flow area between head and
disk, an increase is obtained in burner air pressure and a
reduction in the combustion chamber air supply. As a result,
the MB-VEF B01 gas valve detects the increase in pressure
and increases the gas supply, thus meaning that correction
(reduction) of the gas supply becomes essential using the
relative devices fitted to the valve.
" N "
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0006080937_2010/03