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MINIMUM OUTPUT REGULATION
After regulation of the burner at maximum output, return the burner
to minimum output. Press the switch on the connector -4 towards the
minimum without varying the already performed regulation of the gas
valve.
• Regulate the minimum output gas flow rate to the required value
by using the servomotor's cam for minimum output regulation. (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 the minimum output 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 ignition, 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 / WARNING
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
position.
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 contact (normally open) 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”.
Reset the burner by pressing the appropriate button and readjust the
pressure switch to a sufficient value to detect an air pressure value
slightly lower than the actual pressure detected at the minimum
operating output.
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. Reset the burner
and check that it starts up correctly.
The gas pressure switches (minimum and maximum) prevent
the burner from operating when gas pressure is not 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 makes use of the NC (normally closed)
contact which is closed when the pressure switch detects a pressure
lower than its own setting.
Adjustment of minimum and maximum pressure values on the
pressure 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) causes the burner to stop
immediately.
It is essential to check that the burner is functioning correctly at the
time of the first ignition.
• Check the triggering of the ionisation electrode by disconnecting
the jumper between terminals 30 and 31 on the printed circuit
board and switching on the burner.
The equipment must run through its cycle completely and, three
seconds after the ignition flame has formed, “lock-out”.
• Check for the efficiency of the thermostats or boiler pressure
switches (they should shut down the burner when triggered).
IMPORTANT
Once the adjusting operations are complete, make sure that
the sheet on which the bearing operates has a progressive
profile.
Using the appropriate instruments check also that, in the entire
work range of the burner, the combustion parameters do not
move too much away from the optimal values.
Summary of Contents for TBG 120 MC
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