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5.5
Burner calibration - light oil operation
It is advisable to first set the burner for opera-
tion on oil and then for gas.
Turn burner off prior to switching fuels.
WARNING
5.5.1
Firing
Set the AZL (Display) in the manual position.
During the first firing, and the change from low to high fire, there is
a momentary lowering of the fuel pressure caused by the filling of
the high fire nozzle tubing.
This lowering of the fuel pressure can cause the burner to lock-out.
5.5.2
Operation
The optimum calibration of the burner requires an analysis of the
flue gases at the boiler outlet and adjustments at the following
points:
Low and high fire nozzles
See the information listed on page 20.
Combustion head
The adjustment of the combustion head already carried out
(page 26) need not be altered unless the high fire input of the burn-
er is changed.
5.6
Burner calibration - gas oparation
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
5.6.1
Minimum gas pressure switch
Adjust the minimum gas pressure switch after having performed all
the other burner adjustments with the pressure switch set at the
start of the scale (Fig. 32).
With the burner operating at high fire, increase adjustment pres-
sure by slowly turning the relative dial clockwise until the burner
locks out.
Then turn the dial anti-clockwise by 0.8" WC and repeat burner
starting to ensure it is uniform.
If the burner locks out again, turn the dial anti-clockwise again by
0.4" WC.
Start-up, calibration and operation of the burner
Pump pressure
174 PSI: this is the pressure calibrated in the factory which is usu-
ally sufficient for most purposes.
Sometimes, this pressure must be adjusted to:
145 PSI: in order to reduce fuel delivery.
This adjustment is possible only if the surrounding tem-
perature remains above 0 °C;
203 PSI: in order to increase fuel delivery or to ensure firings
even at temperatures of less than 0 °C.
In order to adjust pump pressure, use the screw 5)(Fig. 17).
Low fire fan air damper
Keep the burner operating at low fire.
The fan air damper is adjusted by moving the servomotor to drive
from the air/fuel ratio.
High fire fan air damper
Increase output and keep it pressed until the high fire position.
The fan air damper is adjusted by moving the servomotor to drive
from the air/fuel ratio.
Store the two points of low fire/high fire.
5.5.3
Minimum oil pressure switch
The minimum oil pressure switch 26)(Fig. 2 at page 8) is factory set
to 145 PSI (10 bar).
If the oil pressure goes below this value, the pressure switch stops
the burner.
29
GB
D9290
Fig. 32
20027066
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