grandimpianti S250-320/40 EA Mode D'emploi page 27

- Maximum-power burner tune-up
(Qmax)
- Minimum-power burner tune-up
(Qmin)
- Maximum-power adjustment check and
relevant correction
- Machine cold start-up and flame control
under operation.
Every single step is described below in
order for the burner to be adjusted perfectly,
and specifically for the gas families that the
equipment can be used with.
Step 1 Maximum power burner tune-up
Open the door closing the right flank and
find the gas-adjustment valve unit: it looks
like the one appearing on the figure.
Valve description:
1) ½" gas inlet: ensure that the pressure
meets the value established for the gas
family to be used.
2) Connection for the pressure meter to
read the pressure on the gas line. Closed by
a safety screw that can be twisted off to read
the pressure: THIS SCREW MUST
ABSOLUTELY BE PUT BACK IN PLACE
AFTER THE MEASUREMENT.
3) Connection for the pressure meter to
read burner pressure. Closed by a safety
screw: THIS SCREW
ABSOLUTELY BE PUT BACK IN PLACE
AFTER VALVE ADJUSTMENT. This is
factory-adjusted and requires no further
actions.
4) Offset adjustment screw (minimum
setting), located under an aluminium cap;
it is to be used to adjust the air/gas rate at the
minimum setting.
5) Throttle to be used to adjust the air/gas
rate at the maximum setting.
Using an adequate tool, turn screw 5
clockwise until it is tight.
All along the rest of the procedure the screw
will have to be loosened (i.e. turned
clockwise) by steps of
- ½ a turn for second-family gas (G20/
G25)
- ¼ of a turn for third-family gas (G30/
G31)
When in this condition and with the machine
at ambient temperature, ensure that the
ignition spark is there through the peephole
and start the machine. Then set the burner
to maximum power by selecting
MAXIMUM from the password-protected
adjustment menu.
While in this setting, repeat ignition
attempts with increasing amounts of gas by
turning the screw as indicated for the
relevant gas family, until the machine
ignites.
When the machine is on, observe
combustion values and check the CO2
released at the exit of the heat exchanger:
this is the value that will determine burner
adjustment.
The device may take a few seconds to read
a stable and real combustion value; it is
advisable to allow a few seconds for the
value to become stable and only then proceed
to adjust the burner as needed.
The CO2 combustion values must fall into
the ranges appearing on the table of page
91, depending on the relevant gas category:
If values differ from those indicated, turn
adjustment screw 5 on the figure to make
the mixture richer or poorer as needed.
Remember that the mixture becomes poorer
when the screw is turned clockwise, which
decreases the CO2 value accordingly.
Conversely,
counterclockwise causes the mixture to
become richer.
It is advisable to adjust by using very small
movements and to allow the measuring
device a few seconds for it to read a steady
combustion value.
Adjust gradually until the desired
combustion value is met.
Then proceed to step 2: minimum-power
combustion tune-up.
Step 2 Minimum-power burner tune-up
Burner adjustment at minimum power is
done by selecting MINIMUM operation in
the adjustment menu and then checking the
combustion value with reference to the
values provided for the various gas types on
MUST
the table of page 91. Again, allow a few
seconds for the measuring device to read a
stable value.
f the CO2 value differs from the indicated
range, modify the air/gas rate at minimum
power.
To adjust the air/gas rate, remove the
aluminium cap on the gas valve - which is
marked 4 on the figure - and uncover the
plastic adjustment screw.
Using the appropriate tool, turn the
adjustment screw slightly until the
combustion value indicated for the relevant
gas family is met.
When the adjustment is made, put the
aluminium cap back onto the screw and
ensure that combustion is good.
Once the burner has been tuned up at
minimum power, check combustion values
at the maximum power setting again, as
this could have been affected by the
minimum-power tune-up.
turning the screw
25
Step 3 Maximum-power adjustment
check
Select MAXIMUM power from the
Adjustment menu. Check that combustion
values at maximum power still meet those
indicated for the relevant gas family (cfr.
step 1). If the values have gone out of the
prescribed range, repeat maximum-power
tune-up as described on step 1. Then proceed
to step 4.
Step 4 Check under normal use conditions
Once the burner has been tuned up, turn the
machine off, wait for it to cool to ambient
temperature and only then check that it
goes on and operates properly under normal
use conditions.
The heating should go on easily and it
should give out no unusual noise. By looking
into the peephole, check that the flame is
blue, spread out and uniform on the entire
surface of the burner with no gaps.
IMPORTANT
If tune-up procedures take long and the
diathermic oil heats up beyond 200°C, the
burner will go off automatically and it will
not be possible to finalise the tune-up until
the machine has cooled down.
If burner ignition is difficult or noisy, or if
it fails even after performing the tune-up
steps, it may be necessary to check it and
clean it up, replacing the ignition electrodes
or the flame controller.
Ensure that all the heating-unit components,
i.e. fan, gas leading line, diaphragms,
electrodes and burner, are in good working
order and clean.
Ensure that the flue gas pipe is clean.
Combustion control is mandatory every
time the machine is installed or the heating
unit/burner unit is serviced.
Combustion adjustment is also mandatory
every time the machine is converted to a gas
type other than the one the machine was
factory tuned-up for.
CAUTION!
Only qualified and authorised personnel is
allowed to perform combustion tune-up.
Combustion values need to be checked every
time the machine is installed.
When the machine is started up for the first
time or after a long operation break, it will
be necessary to turn it on repeatedly, until
the gas flows into the valve and fills the
entire line.
CAUTION!
Gas-heated appliances cannot be installed
in premises housing dry-cleaners, as
burnt fuel could react with the chemicals
used for dry-cleaning and produce
substances that may be toxic for man and
corrosive for materials.