
PART III: OPERATION
33
Progressive burners
Once the procedure till step 8 described on paragraph “Adjustment procedure” on page 31, is accomplished, go on as follows:
9
set the low flame cam matching the high flame cam;
10 set the
TAB
thermostat to the minimum in order that the actuator moves progressively towards the low flame position;
The manual air damper control is not provided on these actuators. The adjustments must be carried out acting manually on the cams.
11 move the low flame cam to the minimum to move the actuator towards the low flame until the two bearings find the adjusting screw
that refers to the lower position: screw
V
to increase the rate, unscrew to decrease.
12 Move again the low flame cam towards the minimum to meet the next screw on the adjusting cam and repeat the previous step; go
on this way as to reach the desired low flame point.
13 Now adjust the pressure switches.
14 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.
15 Turn the burner off and then start it up again. If the adjustment is not correct, repeat the previous steps.
Fully modulating burners
To adjust the fully-modulating burners, use the
S3
switch on the burner control panel (see next picture), instead of the
TAB
thermostat
as described on the previous paragraphs about the progressive burners. Go on adjusting the burner as described before, paying atten-
tion to use the CMF switch intead of
TAB
.
The
S3
position sets the oprating stages: to drive the burner to the high-flame stage, set S3=MAX; to drive it to the low-flame stage, set
S3=MIN.
To move the adjusting cam set S3=MIN or MAX and then S3=MAN.
VF
SC
SV
ID
V
SV
Gas butterfly valve clo
s
ed
Gas butterfly valve open
S3
S3 = MAN stop at the current position
S3 = MAX high flame operation
S3 = MIN low flame operation
S3 = AUTO automatic operation
SQM40
.265 CSW
Actuator cams
MAN-AUTO
I
High flame
II
Stand-by
III
Low flame - gas
-
-
VI
Ignition - gas
X3
X2
X1