ADJUSTING THE MINIMUM POWER
After burner regulation at maximum power, restore the burner to
minimum power. Press the switch on the connector (4) towards the
minimum without varying the adjustment of the gas valve already per
-
formed.
•
Regulate the minimum power gas flow rate to the required value
using the regulation cam for servomotor minimum output. (See
Servomotor cam regulation).
•
If necessary, correct the combustion air supply adjusting the
screw(s) (12).
•
Check the combustion parameters in the 1st stage with appropriate
instruments (C02 max= 10%, O2 min=3%, CO max=0,1%)
ADJUSTING THE FLOW RATE FOR IGNITION
•
Once regulation of minimum flame has been carried out, the burner
needs to be switched off and check that ignition occurs properly. If
necessary, it is possible to optimise burner regulation during igni
-
tion, proceeding as follows:
-
Regulate the gas flow rate upon ignition, using the cam IV (see
Servomotor cam regulation). It is usually advisable to set cam
IV at a slightly higher angle than the first stage cam III.
-
If necessary, correct the combustion air supply adjusting the
screw(s) (11).
CAUTION / WARNINGS
Check that the ignition takes place properly. If the passage
between the head and the disk is closed, the speed of the (air/
fuel) mix may be so high that ignition is difficult. Open the gas
valve speed regulator (if fitted) bit by bit to a position in which
ignition takes place correctly, and accept this as the final po
-
sition.
The air pressure switch stops the equipment operation if air pressure
is not at the expected value.
The pressure switch must therefore be adjusted so that it is triggered
to close the NO (normally open) contact when the air pressure in the
burner reaches a particular value.
If the air pressure switch does not detect a pressure greater than that
calibrated, the equipment runs through its cycle but does not switch
on the ignition transformer and does not open the gas valves and so
the burner “locks-out”.
To unlock the burner, press the special push button and return the
pressure switch regulator to a value sufficient for measuring an air
pressure slightly below the actual air pressure detected in minimum
output operation.
Release the burner and check that it starts up correctly.
Adjust the setting of the pressure switch to a level slightly below the
actual air pressure detected in first stage operation. Release the bur
-
ner and check that it starts up correctly.
The gas pressure control switches (minimum and maximum) prevent
the burner from operating when gas pressure does not lie between
the expected range.
The minimum value pressure switch makes use of the NO (normally
open) contact which is closed when the pressure switch detects a
pressure higher than its own setting.
The maximum pressure switch uses the NC (normally closed) contact
that is closed when the pressure switch detects a pressure lower than
the value it is set to.
Adjustment of minimum and maximum pressure values on the pres
-
sure switches must be performed when testing the burner, on the
basis of the pressure measured in each case.
The triggering (opening of the circuit) of any of the pressure switches
when the burner is running (flame on) locks out the burner immedia
-
tely.
When first switching on the burner it is essential to check that they
work properly.
•
Check for the triggering of the ionisation electrode by disconnecting
the jumper between terminals 30 and 31 on the printed circuit bo
-
ard and start the burner.
The equipment must run through its cycle completely and, three se-
conds after the ignition flame has formed, “lock-out”.
•
Check the efficiency of the thermostats or boiler pressure switches
(they should shut down the burner when triggered).
IMPORTANT
Once the adjusting operations are completed, visually check
that the thin plate on which the bearing acts has a progressive
profile.
Using the special instruments, check also that throughout the
entire burner operating range, the combustion parameters are
not too far from optimal values.
ENGLISH
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