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7) Put the burner in the second stage and check if the regula-
tions carried out in point 6 have determined a variation in the
combustion parameters as a result of the regulations imposed
previously for the second stage. If necesary correct the combu-
rent air supply operating as described in point 5-a The gas
flow regulation cam in the second stage of the
servomotor must be positioned at 90°.
8) The air pressure switch is there to prevent the opening of the
gas valves if the air pressure is not at the required level. The
pressure switch must therefore be adjusted to intervene in
closing contact when the air pressure in the burner reaches
a sufficient value. If the air pressure switch does not reach
pressures above those calibrated, the unit will carry out
its cycle but will not switch on the ignition transformer and
will not open the gas valves so the burner will shut down.
To ensure correct working of the air pressure switch you must,
with the burner on and with the first flame only, increase the regu-
lation until it is triggered and immediately "locks-out" the burner.
Release the burner by pushing the appropriate button and
readjust the pressure switch until preventilation air pressure is
detected at sufficient level as the existing air pressure detected
during the preventilation stage.
9)
The control pressure switches for the gas (minimum) are to
prevent the working of the burner when the pressure of the
gas is not as provided for. It is clear from the specific function
of the pressure switches that the control pressure switch for
minimum pressure must make use of the contact that is closed
when the pressure switch detects pressure greater than that
for which it is regulated. The adjustment of the minimum gas
pressure switch must therefore be carried out when the burner
is started up, in accordance with the pressure that is found at
the time. The triggering (i.e. the opening of the circuit) of any
of the pressure switches when the burner is running (flame on)
causes the burner to stop immediately. When first switching
on the burner it is essential to check the correct working of the
pressure switch.
10) Check the triggering of the flame detector (ionisation electrode).
Open the connector in the ionization electrode lead and switch
on the burner. The equipment must run through its cycle com-
pletely and, three seconds after the ignition flame has formed,
"lock-out". This check must also be carried out when the burner
is already on. By opening the connector, the equipment must
immediately go into its "lock-out" action.
11) Check that the boiler thermostats or pressure switches are
operating correctly (they must cause the boiler to shut down
when they intervene).
Equipment and
Safety time
programmer
s
LME 22.331A2
3
LME 21.430A2
3
Preventila-
Pre-
Post-
tion time
ignition
ignition
s
s
30
2
40
2
12 / 20
0006081426_201203
12) Having finished regulation tighten the nuts (1), (3) and (3a) and
switch off the burner, It is recommended to stop the closing cam
of the air shutter (0002936210) in a position that guarantees
complete closing of the air shutter when the burner is switched
off.
To guarantee the safe functioning of the burner, it is advis-
!
able to tighten nuts (1), (3) and (3a) with the aid of a wrench
or counterwrench.
Check that the ignition takes place properly. In the
!
event that the mixer is too far forward, it may hap-
pen that the speed of the delivery air is so high that
ignition is difficult. If this happens, move the regula-
tor back bit by bit to a position in which ignition takes
place correctly, and accept this as the final position.
Remember that with a small flame, it is bet-
ter to limit the amount of air to the amount
strictly indispensable to ensure safe ignition
even in the most difficult cases.
IONIZATION CURRENT
Minimum current required to enable the unit to work is 3 µA for
LME 2.
The burner provides a significantly higher current and therefore
does not normally require any checks at all. Should however, the
ionisation current need to be measured a microammeter must be
connected in series to the ionization electrode lead by opening the
connector "C" as illustrated in the figure.
Time between open-
ing of 1st flame valve
and 2nd flame valve
s
s
2
11
2
11
Air shut-
Air shut-
ter opening
ter closing
stroke time
stroke time
s
s
12
12
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