Combustion Air Adjustment; Maximum Output; Minimum Output; Intermediate Outputs - Riello DB 4 LSM C13 Installation, Use And Maintenance Instructions

5.10

Combustion air adjustment

The fuel/combustion synchronization is made by means of a ser-
vomotor connected to two variable profile cams, which act on the
outlet air damper 1) (Fig. 35) and the gas damper 2)(Fig. 35) and,
using special levers, on the combustion head.
It is advisable, to reduce the loss and for a wide calibration field,
to adjust the servomotor to the maximum of the output used, the
nearest possible to the maximum opening (130°).
On the gas butterfly valve, fuel step according to the burner out-
put required, with servomotor completely open, is carried out by
the pressure stabiliser placed on the train.
The values in the Tab. K can be useful as reference for a good
calibration of the fuel.

5.10.1 Maximum output

Adjust the servomotor to the maximum opening so that the air
dampers are completely open.

5.10.2 Minimum output

Min output must be selected within the firing rate range shown on
pag. 9.
Turn the "output reduction" selector (on the boiler main panel)
and keep it turned towards "-" until the servomotor has closed
the air damper and the gas butterfly valve is at 35° (adjustment
made in the factory).
Air adjustment
Progressively adjust the end profile of cam 1) (Fig. 32) by turning
the cam adjustment screws 2)(Fig. 32).
It is preferable not to turn the first screw since this is used to set
the air damper to its fully closed position.

5.10.3 Intermediate outputs

After adjusting the maximum and minimum output of the burner,
carry out air and gas adjustment on several intermediate posi-
tions of the servomotor.
Passing from one position to the next is attained by keeping the
selector pressed on the symbol "+ / -" (on the boiler main panel).
For better adjustment repeatability, take care to stop the rotation
of the cam unit when the upper bearing that slides on the profile
4)(Fig. 32) is aligned with one of the adjustment screws
2)(Fig. 32).
Screw or unscrew the pre-set screw 2)(Fig. 32) to increase or de-
crease the air output so as to adjust it to the corresponding gas
output.
After output adjustment (maximum, minimum and
intermediate), it is important to lock all the air ad-
justment screws 2)(Fig. 32) by the locking screws
WARNING 3)(Fig. 32) so as to avoid possible movements
from the position of air - gas calibration.
Start-up, calibration and operation of the burner
EN 676
Theoretical max
GAS CO
2
0 % O
2
G 20 11.7
G 25 11.5
G 30 14.0
G 31 13.7
EN 267
Theoretical max CO
0 % O
2
15.2
2
31 GB
Air excess
Max. output.
 1.2
CO % Calibration
2
 = 1.2  = 1.3
9.7 9.0
9.5 8.8
11.6 10.7
11.4 10.5
Air excess
Max. output.
 1.2
CO % Calibration
2
2
 = 1.2  = 1.3
12.6 11.5
1
Min. output
 1.3
CO
mg/kWh
 100
 100
 100
 100
Min. output
 1.3
CO
mg/kWh
 100
Tab. K
20146734
Fig. 35
20146011