NATURAL GAS STARTING UP AND
REGULATION
In order to proceed with ignition, if the burner is three-phase, check
that the motor rotation direction is correct. If not already done so
at the moment of connecting the burner to the gas pipeline, it's
indispensable to carry a purge of the air contained in the pipeline. As
a precaution, special care should be taken and doors and windows
should be opened. As a precaution, special care should be taken
and doors and windows should be opened. When the characteristic
odour of gas can be smelled, close the cut-off cock. Wait until gas
has dispersed, then reconnect the burner to the gas pipeline. Then
proceed as follows:
•
Make sure that the discharge of combustion products can take
place freely (chimney lock-gates should be open) and that there
is water in the boiler.
•
Set the air adjustment gate to the position that is presume
to be required. To do this, slacken fastening screw "C" (see
0002934112) and set index "B" in the desired position using
screw "A".
•
Operate the regulators incorporated in the safety and operating
valve in such a way as to obtain the gas delivery presumed
necessary.
Refer to the last pages for a specific description of the
operations necessary for regulating gas delivery according
to the type of valve the burner is fitted with.
•
Give current to the burner by opening the main switch. The
burner is therefore activated and carries out the pre-ventilation
phase. If the air pressure exceeds the value at which the
air pressure switch has been set, the ignition transformer
will be connected and, subsequently, the gas valves (safety
and operating) will be inserted. The valves open completely
and the gas delivery is limited to the position at which the flow
regulator incorporated in the main operating valve has been
manually regulated. Upon first switching on, repeated "lock
outs" may occur due to:
- The gas pipeline has not been adequately purged of air and
therefore the quantity of gas is not sufficient to allow for a
stable flame.
- A "shut down" with flame presence could be caused by flame
instability in the ionisation zone, due to and incorrect air/gas
ratio. This can be solved by changing the amount of air and/or
gas supplied, so as to find the right ratio. This problem could
also be caused by an incorrect distribution of air/gas in the
combustion head. This can be solved with the combustion
head adjustment device by further closing or opening the air
passage between the combustion head and gas diffuser. See
chapter "Regulation of the combustion head".
- It could happen that the ionisation current is help up by the
current discharged from the ignition transformer (the two
currents have to run the same course on the burner's "earth")
and so the burner goes to "shut down" due to insufficient
ionisation. This can be solved by inverting the input (230
V side) of the ignition transformer (the places of the two
wires that give voltage to the transformer are exchanged).
A shut down with flame presence could also be caused by
the burner's casing not being properly "grounded". We must
point out that the minimum value of the ionisation current to
ensure the working of the control box is shown in the electrical
diagram; normally the ionisation current is decidedly higher. To
check the ionisation current, connect a microammeter with an
adequate scale "in series" to the ionisation circuit. The cable
of the ionisation electrode is equipped with a connector (see
circuit diagram) to facilitate the micro-ammeter connection.
The high isolation wire that comes from the electrode must be
inserted to the negative (sign -) of the microammeter.
•
With the burner on, adapt delivery to the desired value (methane
gas = 8550 kcal/m
second one exactly one minute after the first one. The difference
between the two readings should be multiplied by sixty in order
to obtain the flow per hour (60 minutes). This output can be
modified by operating the special regulator incorporated in the
valve (see the last pages for a description of how to regulate
the valves).
•
Check that combustion occurs correctly by using the appropriate
instruments (CO
= 0.1%).
•
After regulation, turn the burner off and on again several times
to check that ignition occurs correctly.
•
When the burner has started up it is necessary to check as
previously shown, the gas delivery and the combustion with
the appropriate instruments. When the results are known, if
necessary proceed with varying the gas delivery and relative
combustion air in order to adapt delivery to that required for the
specific case (boiler potentiality). It's also necessary to check if
the CO
and CO values are adequate (CO
2
for methane gas and CO = 0.1%).
•
Control the efficiency of the safety and "shut down" devices of air
pressure switch, gas pressure switch and thermostats (detach
the ionisation electrode cable).
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0006080876_201403
) by reading the meter. Take two readings, the
3
max= about 10% for natural gas - CO max.
2
max. = about 10%
2