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Start-up, calibration and operation of the burner
5
5.3
Burner start-up
Feed electricity to the burner via the disconnecting switch on the
boiler panel.
Close the thermostats/pressure switches and turn the switch of
Fig. 28 to position "1".
Make sure that the lamps or testers connected to
the solenoids, or indicator lights on the solenoids
themselves, show that no voltage is present. If volt-
age is present, stop the burner immediately and
DANGER
check the electrical wiring.
Carry out the "Start-up procedure", as described on page 30.
5.4
Final calibration of the pressure switches
Air pressure switch
Adjust the air pressure switch after having performed all other
burner adjustments with the air pressure switch set to the start
of the scale (Fig. 29).
With the burner working at MIN output, insert a combustion
analyser in the stack, slowly close the suction inlet of the fan
(for example, with a piece of cardboard) until the CO value
does not exceed 100 ppm.
Slowly turn the appropriate knob clockwise until the burner
goes into lockout.
Check the indication of the arrow pointing upwards on the grad-
uated scale (Fig. 29).
Turn the knob clockwise again, until the value shown on the
graduated scale corresponds with the arrow pointing down-
wards, and so recovering the hysteresis of the pressure switch
(shown by the white mark on a blue background, between the
two arrows).
Now check the correct start-up of the burner.
If the burner locks out again, turn the knob slightly anticlock-
wise.
During these operations it may be useful to measure the air
pressure with a pressure gauge.
The connection of the pressure gauge is shown in Fig. 29.
The standard configuration is that with the air pressure switch
connected in absolute mode. Note the presence of a "T" con-
nection, not supplied.
In certain applications in strong depression situations, the con-
nection of the pressure switch does not allow it to change over.
In this case it is necessary to connect the pressure switch in dif-
ferential mode, applying a second tube between the air pres-
sure switch and the fan suction line mouth. In this case also,
the pressure gauge must be connected in differential mode, as
shown in Fig. 29.
20022445
D3951
+
_
Connecting the
pressure gauge
with the pressure
switch in abso-
lute mode
21
GB
0
1
D8049
+
D8153
Connecting the
pressure gauge
with the pressure
switch in differen-
tial mode
Fig. 28
_
Fig. 29
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