Riello 20162652, Installation, Use And Maintenance Instructions

Page: 35 / 60

33 20162733 GB
Start-up, calibration and operation of the burner
6.5 Air / fuel adjustment
Air/fuel synchronisation is carried out with the relevant air and
gas servomotors by logging a calibration curve by using the elec-
tronic cam.
It is advisable, to reduce the loss and for a wide calibration field,
to adjust the servomotors to the maximum of the output used, the
nearest possible to the maximum opening (90°).
The choking of the air, taking into account the maximum combus-
tion output, takes place by varying the adjustment of the combus-
tion head (see “Combustion head adjustment” on page 22).
On the gas butterfly valve, the fuel step according to the burner
output required, with servomotor completely open, is carried out
by the pressure stabiliser on the gas train.
6.5.1 Air adjustment for maximum output

Adjust the servomotor to maximum opening (nearly 90°) so
that the air butterfly valves are entirely open.
6.5.2 Air/fuel adjustment and output modulation
system
The air/gas regulator and output modulation system equipping
RS/EV series burners performs a number of integrated functions
to optimise burner function, in both individual installations and in
combination with other units (e.g. double furnace boiler or multi-
ple heat generators in parallel).
The basic system functions control:
1
The dosage of the air and fuel through positioning using
direct servocommands of the relevant valves eliminating the
possible play in the calibration systems with mechanical
cam lever mechanisms, used on traditional modulating
burners.
2 The modulation of the burner output in accordance with the
load required by the system, with maintenance of the pres-
sure or temperature of the boiler at the operating values set.
3 The sequence (cascade adjustment) of more than one
boiler through the suitable connection of the various units
and the activation of the internal software of the individual
systems (option).
Further interfaces and communication functions with computers,
for remote control or integration in central supervision systems
are available on the basis of the configuration of the system.
6.5.3 Burner adjustment
The optimum adjustment of the burner requires an analysis of
flue gases at the boiler outlet.
Adjust in sequence:
1 - Output upon ignition
2 - MAX output
3 - MIN output
4 - Intermediate outputs between Min. and Max.
5 - Air pressure switch
6 - Maximum gas pressure switch
7 - Minimum gas pressure switch
6.5.4 Output upon ignition
Ignition must occur at a lower output than the max. operation out-
put. Regulations provide that the ignition output of this burner
must be equal to or less than 1/3 of the MAX operation output.
Example:
MAX operation output of 600 kW.
The ignition output must be equal to or less than 200 kW with
ts = 3s
In order to measure the ignition output:

disconnect the plug-socket on the ionisation probe cable
(the burner will fire and then go into lockout after the safety
time has elapsed);

perform 10 consecutive ignitions with lockouts;

on the meter, read the quantity of gas burned:
This quantity must be equal to, or lower than, the quantity
given by the formula, for ts = 3s:
Vg volume supplied in ignitions carried out (Sm
3
)
Qa ignition delivery (Sm
3
/h)
n number of ignitions (10)
ts safety time (sec)
Example for gas G20 (9.45 kWh/Sm
3
):
ignition output 200 kW corresponding to
After 10 ignitions with their lockouts, the delivery indicated on the
meter must be equal to or less than:
Air adjustment
The adjustment of the air is carried out by changing the angle of
the air damper changing the degrees of the air servomotor inside
the electronic cam programme.
6.5.5 Maximum output
The MAX output must be set within the firing rate (Fig. 2 on
page 11).
Adjustment of gas delivery
Measure the gas delivery on the gas meter.
As an indicative guide just read the gas pressure on the pressure
gauge (shown in Fig. 29 on page 37) and follow the instructions
given on page 27.
–
If it is necessary to reduce it, lower the output gas pressure
via the pressure adjuster located beneath the gas valve.
– If delivery needs to be increased, increase the adjuster outlet
gas pressure.
Air adjustment
If necessary vary the degrees of the air servomotor.
6.5.6 Minimum output
The MIN output must be set within the firing rate (Fig. 2 on
page 11).
WARNING
The first start up and every further internal setting
operation of the adjustment system or the expan-
sion of the base functions require access by
means of password and are to be carried out by
service personnel who are especially trained for
the internal programming of the instrument and
the specific application created with this burner.
Vg =
3600
Qa (max. burner delivery) x n x ts
9.45
200
= 21.16 Sm
3
/h
Vg =
3600
21.16 x 10 x 3
= 0,176 Sm
3