Unigas C85A Manual Of Installation - Use - Maintenance page 28

PART III: OPERATION
Double-stage burners
drive the burner to the low flame stage by means of the TAB thermostat;

To change the gas flow rate in order to get an efficient combustion, slacken the nut DB and adjust the opening angle of the gas

butterfly valve by rotating the screw TG (clockwise rotation increases gas flow, anticlockwise rotation decreases it). The slot on the
butterfly valve shaft shows the opening degree of the valve regardingthe horizontal axis. Don't act on DE nuts.
NOTE: At the end of settings, make sure the locking screws RA and DB are fully tightened.
Now adjust the pressure switches.

If it is necessary to change the burner output in the low flame stage, move the low flame cam: the low flame position matches the

ignition position. As far as burners fitted with Dungs MBC gas valves, the low flame cam does not match the ignition cam position,
that is why it must be set at about 30° more than the ignition cam.
Turn the burner off and then start it up again. If the adjustment is not correct, repeat the previous steps.

Berger STA6 B 3.41 (high-low flame burners)
MV
ST2
ST1
ST0
For DUNGS MB-DLE / Siemens VGD gas valves
High flame position (set to 90°)
Low flame and ignition position
Stand-by position (set to 0°)
Not used
Berger STA12: a key is provided to move the cams.
Siemens SQN72: a key is provided to move cams I and IV, the other cams can be moved by means of screws.
On the BERGER STA12B3.41 actuator, the manual air damper control is not provided. On the Siemens actuator the AUTO/MAN mode
is provided (see picture).
Fig. 5
Siemens SQN72.2A4Axx (high-low flame burners)
IV
III
II
I
Actuator camsBerger
STA
ST2
ST1
ST0
MV
28
DE
TG
Siemens SQN72
I (red)
III (orange)
II (blue)
IV (black)
DB
AUTO/MAN