21
Setting the startup gas flow rate
To adjust the gas flow rate at the startup, proceed as follows:
-
slacken screw A (Fig. 8) in measuring nozzle. Connect pressure gauge.
-
Set to the minimum the pressure regulator by turning adjustment screw B (Fig. 8) anticlockwise .
-
Turn the burner on.
-
Adjust the flame during the startup phase by means of the bypass C (see Fig. 8 n. 10). Turning clockwise the gas flow decreases,
turning counterclockwise the gas flow increases. Do not exceed in the start flow, otherwise the stabiliser B (Fig. 8) will be ineffica-
cious.
-
Go on adjusting the gas flow rate (unscrewing
C
) until hte flame lights up. Then do not act on
C
anymore and see next paragraph.
NOTE:
The adjustment screw
C
for the start flow restrictor is closed (factory setting). The start flow can be set by opening the restrictor
up to approx. 80% of the main gas flow rate.
Setting the gas flow rate
Act on the pressure regulator to achieve the desired gas flow rate, by means of the Adjustment screw B (Fig. 8): turn the screw
clockwise to increase the flow rate, turn counter-clockwise to decrease it.
Adjusting the maximum flow rate valve
The adjustment screw D for the main flow restrictor is completely open (factory setting): do not change its position. Once the adju-
smetns are accomplished, close screw A (Fig. 8) in the measuring nozzle..
The air flow rate can be adjusted by means of the
V
screw. The air damper position is shown on the graduated indes
I
, where “0” refe-
res to the totally closed postion.
Fig. 10
Double-stage burners
1
Before starting the burner up, set the slow opening. To set the slow opening, remove cover
T
, reverse it upside down and use it as
a tool to rotate screw
VR
. Clockwise rotation reduces start flow rate, anticlockwise rotation increases it. Do not use a screwdriver
on the screw
VR
!
Note:
the screw
VSB
must be removed only in case of replacemente of the coil.
2
startup the burner by turning its main switch
A
to on: if the burner locks (LED
B
on in the control panel) press the RESET button (
C
)
on the control panel..
3
the burner lights in low flame stage;
4
drive the burner to high flame stage, by means fo the thermostat
TAB
.
5
acting on the pressure stabiliser of the valves group, adjust the
gas flow rate in the high flame stage
as to meet the values
requested by the boiler/utilisation: the pressure governor is adjusted by operating the screw
VS
located under the cover
C
. By
screwing down the pressure is increased and by unscrewing it is reduced.
The valve is adjusted by means of the
RP
regulator after
On completion of work on the MBC, perform a gas proving test.
ATTENTION:
in case of start-up failure, increase the gas flow rate according to the procedure quoted below.
I
V
C
