20190369
26
GB
Start-up, calibration and operation of the burner
5.6.2
2nd stage burner output
2nd stage output of the burner must be set within the firing rate
Fig. 2 on page 9.
In the above instructions we left the burner running in 1st stage
operation. Now set switch 2)(Fig. 28) to the 2nd stage position:
the servomotor will open, simultaneously, the air damper and the
gas butterfly valve to 90°.
Adjustment of gas delivery
Measure the delivery of gas from the gas meter.
A guideline indication can be calculated from the Tab. F on
page 20, simply read off the gas pressure on the manometer
Fig. 26 on page 24, and follow the
–
If delivery needs to be reduced, diminish outlet gas pressure
and, if it is already very low, slightly close adjustment valve
VR.
–
If delivery needs to be increased, increase outlet gas
pressure.
Adjustment of air delivery
Progressively adjust the end profile of cam 4)(Fig. 29) by turning
the cam adjustment screws as they appear through the access
opening 6)(Fig. 29).
–
Lock the screws to increase air delivery.
–
Loose the screws to reduce air delivery.
1
Servomotor
2
Cam 4 engaged/
disengaged
3
Cam cover
4
Variable profile cam
5
Screws for adjusting the adjustable profile
6
Slit to access the screws 5)
7
Index of graduated sector 8)
8
Gas butterfly valve graduated sector
5.6.3
1st stage burner output
Burner power in 1st stage operation must be selected within the
firing rate range Fig. 2 on page 9.
Set the switch 2)(Fig. 28) to the 1st stage position: the servomo-
tor 1)(Fig. 30) will close the air damper and, at the same time,
closes the gas butterfly valve down to 15°, i.e. down to the origi-
nal factory setting.
Adjustment of gas delivery
Measure the delivery of gas from the gas meter.
–
If this value is to be reduced, decrease the angle of cam St1
(Fig. 30) slightly by proceeding a little at a time until the angle
is changed from 15° to 13° or 11°....
–
If it is necessary to increase it, move to 2nd stage operation
by altering the setting of switch 2)(Fig. 28) and increase the
angle of cam St1, proceeding a little at a time until the angle
is changed from 15° to 17° - 19°....
At this point return to 1st stage operation and measure gas
delivery.
NOTE:
The servomotor follows the adjustment of cam St1 only
when the angle is reduced. If, however the angle must be
increased, switch to 2nd stage operation, increase the angle
and then return to 1st stage operation to check the effect of
the adjustment.
If you increase the angle of St1 while the burner is operating
in 1st stage, lockout will result.
In order to adjust cam St1, remove press-fit cover 1)(Fig. 30),
extract the relevant key 2)(Fig. 30), from inside, and fit it into the
keyway in cam St1.
Adjustment of air delivery
Progressively adjust the starting profile of cam 4)(Fig. 29) by
turning the screws working through the access hole 6)(Fig. 29).
It is preferable not to turn the first screw since this is used to set
the air damper to its fully-closed position.
5.6.4
Intermediate outputs
Adjustment of gas delivery
No adjustment of gas delivery is required.
Adjustment of air delivery
Switch off the burner using switch 1)(Fig. 28), disengage the
variable profile cam, set the servomotor shaft slot 2)(Fig. 29) to a
vertical position and turn the central screws of the cam so that the
cam offers a progressive gradient.
Try turning the cam back and forth by hand a few times until the
movement is completely smooth with no signs of sticking.
Do not alter the position of the screws at each end of the cam
track, which have already been adjusted for 1st and 2nd stage air
damper control.
NOTE:
Once you have finished adjusting 2nd stage - 1st stage -
intermediate outputs, check firing once again: noise
emission at this stage must be identical to the following
stage of operation. If you notice any sign of pulsation,
reduce the firing stage delivery.
Fig. 29
D518
Fig. 30
D520