Burner Calibration; Firing Output; Maximum Output; Minimum Output - Riello RS 28/M Installation, Use And Maintenance Instructions

5.5

Burner calibration

The optimum calibration of the burner requires an analysis of the
flue gases at the boiler outlet.
Adjust successively:
1 - First firing output
2 - Max. burner output
3 - Min. burner output
4 - Intermediate outputs between low and high fire
5 - Air pressure switch
6 - Minimum gas pressure switch
5.5.1

Firing output

Pilot adjustment has been illustrated on page 16.
5.5.2

Maximum output

The maximum output of the burner must be set within the firing rate
range shown on page 8.
In the above instructions we left the burner running in MIN. output
operation. Now press switch 2)(Fig. 30, page 26) "increase output"
and keep it pressed until the servomotor has opened the air damp-
er and the gas butterfly valve to 90°.
Gas calibration
Measure the gas delivery at the meter.
A guideline indication can be calculated from the table on page 6,
simply read off the gas pressure on the U-type manometer, see
Fig. 28, and follow the instructions on page 19.
– If delivery needs to be reduced, reduce outlet gas pressure
and, if it is already very low, slightly close adjustment valve.
– If delivery needs to be increased, increase outlet gas pressure.
Adjusting air delivery
Progressively adjust the end profile of cam 3)(Fig. 31) by turning
the cam adjustment screws as they appear through the access
opening 5)(Fig. 31).
– Turn the screws clockwise to increase air delivery.
– Turn the screws counter-clockwise to reduce air delivery.
Key
1 Servomotor
2 Lever, push to engage, push to release
3 Adjustable profile cam
4 Cam profile adjustment screws
5 Opening for access to screws 4)
6 Index for graduated sector 7)
7 Graduated sector for gas butterfly valve
Start-up, calibration and operation of the burner
D2267
Fig. 31
27
5.5.3

Minimum output

Minimum output must be selected within the firing rate range
shown on page 8.
Press switch 2)(Fig. 30, page 26) "output reduction" until the servo-
motor has closed the air damper and the gas butterfly valve to 15°
(factory set adjustment).
Adjusting gas delivery
Measure the delivery of gas from the gas meter.
– If this value is to be reduced, decrease the angle of orange cam
(Fig. 29, page 26) slightly by proceeding a little at a time until
the angle is changed from 15° to 13° or 11°....
– If it has to be increased press the switch "output
increase" 2)(Fig. 30, page 26) (i.e. open the gas butterfly valve
by 10-15°), increase the orange cam angle (Fig. 29, page 26)
with small successive movements, i.e. take it from angle 15° to
17° - 19°.... Then press the switch "output decrease" until the
servomotor is taken to the minimum opening position and
measure the gas delivery.
NOTE:
The servomotor follows the adjustment of cam only when the
cam angle is reduced. If it is necessary to increase the cam an-
gle, first increase the servomotor angle with the switch "out-
put increase", then increase the orange cam angle, and at the
end bring the servomotor back to the MIN output position with
the switch "output decrease".
Adjustment of air delivery
Progressively adjust the starting profile of cam 3)(Fig. 31) by turn-
ing the screws working through the access hole 5)(Fig. 31).
5.5.4

Intermediate outputs

Adjustment of gas delivery
No adjustment of gas delivery is required.
Adjustment of air delivery
With the switch 1)(Fig. 30, page 26) move in intermediate outputs
and set the variable profile cam 3) by turning the screws 4).
– If the burner operation is low-high it is sufficient to set only min-
imum and maximum firing rates
– If the burner operation is modulating, all the points of modula-
tion should be adjusted.
When the adjustment is complete, release the servomotor and
manually check there is no binding of the cam.
GB
20154169