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7.3.2
Operation
The optimum calibration of the burner requires an analysis of the
flue gases at the boiler outlet and interventions on the following
points.
st
nd
1
and 2
stage nozzles
See the information listed on page 16.
Combustion head
The adjustment of the combustion head already carried out
(page 27) need not be altered unless the 2
burner is changed.
7.4
Adjustment before first firing (gas operation)
Adjustment of the combustion head has been illustrated on
page 27.
In addition, the following adjustments must also be made:
open manual valves up-line from the gas train.
Adjust the minimum gas pressure switch to the start of the
scale (Fig. 35).
Adjust the maximum gas pressure switch to the start of the
scale (Fig. 36).
Adjust the air pressure switch to the zero position of the
scale (Fig. 37).
Purge the air from the gas line.
Continue to purge the air (we recommend using a plastic
tube routed outside the building) until gas is smelt.
Fit a U-type manometer (Fig. 38) to the gas pressure test
point on the sleeve.
The manometer readings are used to calculate the MAX.
burner power using the Tab. N at page 23.
Connect two lamps or testers to the two gas line solenoid
valves VR and VS to check the exact moment at which volt-
age is supplied.
This operation is unnecessary if each of the two solenoid
valves is equipped with a pilot light that signals voltage pass-
ing through.
Before starting up the burner it is good practice to adjust the gas
train so that ignition takes place in conditions of maximum safety,
i.e. with gas delivery at the minimum.
D896
20034985
Start-up, calibration and operation of the burner
nd
stage delivery of the
Fig. 35
Pump pressure
12 bar: this is the pressure calibrated in the factory which is
usually sufficient for most purposes.
Sometimes, this pressure must be adjusted to:
10 bar: in order to reduce fuel delivery.
This adjustment is possible only if the surrounding tem-
perature remains above 0°C.
14 bar: 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. 21 at page 21).
st
nd
1
and 2
stage fan air gate valve
See adjustments of "Servomotor" on page 18.
28
GB
D66
D521
Fig. 36
Fig. 37
D1180
Fig. 38
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