Table of Contents
Advertisement
5.7
Burner firing
Having completed the checks indicated in the previous heading,
the pilot of the burner should fire.
If the motor starts but the flame does not appear and the flame
safeguard goes into lock-out, reset and wait for a new firing at-
tempt.
Pilot adjustment has been illustrated on page 18.
5.8
Burner calibration
The optimum calibration of the burner requires an analysis of the
flue gases at the boiler outlet.
Adjust successively:
firing output
Maximum burner output
Minimum burner output
Intermediate outputs between low and high fire
Air pressure switch
Minimum gas pressure switch
Maximum gas pressure switch
5.8.1
Firing output
Pilot adjustment has been illustrated on page 18.
5.8.2
Maximum burner output
Maximum output of the burner must be set within the "Firing rates"
range shown at page 10. In the above instructions we left the burn-
er running in MIN. output operation.
Move the selector 1)(Fig. 38, page 29) in manual position.
Move the selector 2)(Fig. 38, page 29) in position (+) (increase
output) and keep it until the servomotor has opened the air
damper and the gas butterfly valve to 90°.
Gas Calibration
Measure the gas delivery at the meter.
A guideline indication can be calculated from the Tab. G, page 21,
simply read off the gas pressure on the manometer (Fig. 34), and
follow the instructions at page 21.
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 4)(Fig. 43) by turning
the cam adjustment screws as they appear through the access
opening 6).
Turn the screws clockwise to increase air delivery.
Turn the screws counter-clockwise to reduce air delivery.
5.8.3
Minimum burner output
Minimum output must be selected within the "Firing rates" range
shown at page 10.
Move the selector 1)(Fig. 38, page 29) in manual position.
Move the selector 2)(Fig. 38, page 29) in position (-) (reduc-
tion output) until the servomotor has closed the air damper
and the gas butterfly valve to 15° (factory set adjustment).
Start-up, calibration and operation of the burner
31
Having adjusted the pilot, reconnect the main valve
and ignite the main flame; it might require several
attempts to purge the air from the gas lines or to ad-
just the valve with little gas.
WARNING
Once the burner has fired, now proceed with calibration operations.
Adjusting gas delivery
Measure the delivery of gas from the gas meter.
If this value is to be reduced, decrease the angle of black cam
slightly by proceeding a little at a time until the angle is
changed from 15° to 13° or 11°....
Move the selector 1)(Fig. 38, page 29) in manual position.
If it has to be increased move the selector 2)(Fig. 38, page 29)
in position (+) (increase output) (i.e. open the gas butterfly
valve by 10-15°), increase the cam black angle with small suc-
cessive movements, i.e. take it from angle 15° to 17° - 19°....
(Refer to paragraph "Cams adjustment" on page 29).
Move the selector 2)(Fig. 38, page 29) in position (-) (reduc-
tion output) until the servomotor is taken to the minimum
opening position and measure the gas delivery.
The servomotor follows the adjustment of cam only
when the cam angle is reduced.
If it is necessary to increase the cam angle, first in-
WARNING
crease the servomotor angle with the switch "output
increase", then increase the black cam angle, and
at the end bring the servomotor back to the MIN out-
put position with the switch "output decrease".
Adjustment of air delivery
Progressively adjust the starting profile of cam 4)(Fig. 43) by turn-
ing the screws working through the access hole 6).
1
Key
1
Servomotor
2
Graduated sector for gas butterfly valve
3
Index for graduated sector 2
4
Adjustable profile cam
5
Adjustment screws for cam starting profile
6
Adjustment fixing screws
7
Adjustment screws for cam and profile
8
Cam
GB
20162481
3
2
5
8
4
7
6
Fig. 43
20160778
Advertisement
Table of Contents
