19
Double-stage burners
Air damper position is set by means of the actuator cams both in low and high flame. As for the setting, refer to the next
table.
During the first setting, set the cam III between the cams I and II. Then, passing from the low to the high flame stage, or
viceversa, change the setting according to the flame composition: if cam III is too near to the low flame position (cam II),
flue gas can take place, because there is more fuel than air; if cam III is too near to high flame (cam I), the flame could fade
because of too much air. The graduated index, connected to the actuator, shows the opening angle of the air damper
Berger STA Siemens SQN72
Note:
to move the cams use:
Berger STA: the cams adjustement must be performed by means of a screwdriver acting on the VS screw placed
inside the cam.
Siemens SQN72: provided with key for cams I and IV, with scerws for the other cams.
The Berger actuator is not provided with the manual control for the air damper. The Siemens actuator is provided with
AUTO/MAN mode (see pictures above).
Berger STA
Siemens SQN72
High flame position
I I
(red)
Stand by, ignition and Low flame position
II II
(blue)
EVG2 opening
III IV
(black)
Combustion head adjustment
To adjust the combustion head position, and consequently the burner output, proceed as follows:
1. remove the burner cover, unscrewing the fixing screws;
2. by means of a screwdriver, turn counterclockwise to move towards the combustion head (picture below) or clockwise to
move the head backwards (picture below). The ID index shows how much the head moves.
”All-backwards” position
”All-forwards” position
ATTENTION: Once the adjustements are accomplished, check that the factory-set values are observed (Tab. 3-
page 22). If it was necessary to change that values according to the utilisation, make a note of them in the Tab.
3-page 22, as for the maintenance operations.