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Start-up, calibration and operation of the burner
6.7 Servomotor adjustment
The servomotor (Fig. 30) adjusts the air damper.
Do not alter, for now, the factory setting for the 4 levers; A grad-
uated label with 4 coloured sectors shows the intervention point
of the levers.
It has 4 levers:
To sum up, the intervention of the levers should occur in the fol-
lowing order:
1st Blue lever
2nd Orange lever
3rd Black lever
4th Red lever
BLUE LEVER:
Adjusts the position of the air damper with the
burner stopped: air damper closed.
ORANGE LEVER:
Adjusts the position of the air damper with the
burner operating in the 1st stage.
RED LEVER:
Adjusts the position of the air damper with the
burner operating in the 2nd stage.
BLACK LEVER:
Determines when the 2nd stage gas valve
opens.
It should always intervene before (just slightly)
the red lever and after the orange lever.
It should never intervene with the black lever,
to avoid the risk that the gas valves opens for
nothing.
It should never intervene immediately after the
orange lever, to avoid combustion without air.
To get closer to the time of the opening of the
gas valve in the position of the 2nd stage
damper, turn the black lever to the left; to
move further away from the time of the open-
ing, turn the lever to the right.
Fig. 30
D728
BLACK
RED
ORANGE
BLUE
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