Burner Ignition; Burner Adjustment; Ignition Output; Output In 2Nd Stage - Riello RS 70 Installation, Use And Maintenance Instructions

6.4

Burner ignition

The burner should light after having performed the above steps.
If the motor starts but the flame does not appear and the control
box goes into lockout, reset and wait for a new ignition attempt.
If ignition is still not achieved, it may be that gas is not reaching
the combustion head within the safety time period of 3 seconds;
In this case increase gas ignition delivery.
The arrival of gas at the sleeve is indicated by the U-type manom-
eter (Fig. 24).
6.5

Burner adjustment

The optimum adjustment of the burner requires an analysis of
flue gases at the boiler outlet.
Adjust in sequence:
1 Burner output in 2nd stage
2 Burner output in 1st stage
3

Ignition output

4 Air pressure switch
5 Minimum gas pressure switch
6.5.1 Ignition output
According to EN 676:
Burners with MAX output up to 120 kW
Ignition can occur at the maximum operation output level. Exam-
ple:
• max. operation output: 120 kW
• max. ignition output:
Burners with MAX output above 120 kW
Ignition must occur at a lower output than the max. operation out-
put.
If ignition output does not exceed 120 kW, no calculations are re-
quired. If ignition output exceeds 120 kW, the regulatory standard
sets that the value be defined according to the control box safety
time "ts":
– for "ts" = 2s, ignition output must be equal to or lower than 1/
2 of max. operation output;
– for "ts" = 3s, ignition output must be equal to or less than 1/3
of the max. operation output.
Example:
MAX operation output of 600 kW.
Ignition output must be equal to or lower than:
• 300 kW con ts = 2s
• 200 kW con ts = 3s
In order to measure the ignition output:
– Remove the UV sensor 29)(Fig. 4 on page 12)(the burner
comes on and goes into lockout after the safety time).
– Perform 10 ignitions with consecutive lockouts.
– Read the quantity of gas burned on the meter. This quantity
must be equal to or lower than the quantity given by the for-
mula:
Start-up, calibration and operation of the burner
120 kW
In the event that the burner locks-out again, refer to chapter
"Faults - Possible causes - Solutions" on page 34.
In the event the burner stops, in order to prevent
any damage to the installation, do not unblock the
burner more than twice in a row. If the burner
locks out for a third time, contact the customer
WARNING
service.
In the event there are further lockouts or faults
with the burner, the maintenance interventions
must only be carried out by qualified, authorised
personnel, in accordance with the contents of this
DANGER
manual and in compliance with the standards and
regulations of current laws.
Once the burner has fired, now proceed with global calibration
operations.
Example for G 20 gas (10 kWh/Nm
Max operation output, 600 kW
corresponding to 60 Nm
After 10 ignitions with their lockouts, the delivery indicated on the
meter must be equal to or less than:
6.5.2

Output in 2nd stage

The output in the 2nd stage must be selected from within the fir-
ing rate range shown on page 10.
In the above description, we left the burner running, operating in
the 1st stage. Turn switch 2)(Fig. 25) to the 2nd stage position:
The servomotor will open the air damper and, at the same time,
also the gas butterfly valve opens at 90.
Adjustment of gas delivery
Measure the gas delivery on the gas meter.
A rough indication can be obtained from the tables on page 5, just
read the gas pressure on the U-shaped pressure gauge, see Fig.
24 on page 24), and follow the instructions on page 20.
If delivery needs to be reduced, diminish outlet gas pressure; if it
is already very low, slightly close the VR adjustment valve.
If delivery needs to be increased, increase outlet gas pressure.
25 GB
3
(max. burner delivery)
Nm /h
360
3
):
3
/h.
3
60 : 360 = 0.166 Nm .
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