11
SERVOMOTOR (A)
The servomotor, by means of connection mech-
anisms, simultaneously regulates air pressure
and delivery and the flow of fuel in use.
It features adjustable cams that operate as
many switches.
Cam
1
:
blue
Limits servomotor travel to 0° position. With the
burner off, the air damper is fully closed.
Cam
2
:
orange
Adjusts the position of the air damper to 1
st
stage or pre-purging (factory set to 30° position).
Cam
3
:
red
Adjusts air damper travel or 2
nd
stage operation
without exceeding 90° (factory set to 90° posi-
tion).
Cam
4
:
black
Determines how early 2
nd
-stage valve is
switched on.
WARNING
Under no circumstances should
the
BLUE
cam be moved to the
right, beyond the air damper
closing position.
Under no circumstances should the
RED
cam be moved to the left beyond 90°.
SERVOMOTOR
D3958
4
3
2
1
