Burner Calibration; Determination Of Output Upon Firing (Minimum); 2Nd Stage Burner Output - Riello RS 34 MZ Installation, Use And Maintenance Instructions

Burner off
Burner on
(A)
1 2
1st stage
2nd stage

BURNER CALIBRATION

The optimum calibration of the burner requires
an analysis of the flue gases at the boiler outlet.
Adjust successively:

1 - 2nd stage burner output

2 - 1st stage burner output
3 - Intermediate outputs
4 - Air pressure switch
5 - Minimum gas pressure switch
D469
DETERMINATION OF OUTPUT UPON FIR-
ING (MINIMUM)
According to EN 676 Regulation
Burners with max. output up to 120 kW
Firing can be performed at the maximum opera-
tion output level. Example:
• max. operation output
• max. firing output
Burners with max. output above 120 kW
Firing must be performed at a lower output than
the max. operation output.
If the firing output does not exceed 120 kW, no
calculations are required. If firing output
exceeds 120 kW, the regulation prescribes that
the value be defined according to the control
box safety time "ts":
for "ts" = 3s, firing output must be equal to, or
lower than, 1/3 of max. operation output.
Example
MAX operation output of 450 kW.
The firing output must be equal to, or less than,
150 kW with ts = 3s
In order to measure the firing output:
- disconnect the plug-socket 24)(A)p.4 on the
ionisation probe cable (the burner will fire and
then go into lockout after the safety time has
elapsed).
- Perform 10 firings 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 formula, for ts = 3s:
Vg =
Vg: volume supplied upon firings carried out
3
(Sm
Qa: firing output (Sm
n: number of firings (10)
ts: safety time (sec)
Example for gas G 20 (9.45 kWh/Sm
firing output 150 kW
corresponding to 15.87 Sm
After 10 firings with lockout, the output indicated
on the meter must be equal to, or less than:
Vg =
1 - 2ND STAGE BURNER OUTPUT
2nd stage output of the burner must be set
within the firing rate range shown on page 5.
In the above instructions we left the burner run-
ning in 1st stage operation. Now set switch 2)(A)
to the 2nd stage position: the servomotor will
open, simultaneously, the air damper and the
gas butterfly valve to 90°.
Adjustment of gas delivery
Measure the delivery of gas from the gas meter.
A guideline indication can be calculated from the
tables on page 6, simply read off the gas pres-
sure on the manometer, see fig.(C) on page 10,
and follow the instructions on page 6.
- If delivery needs to be reduced, diminish out-
let gas pressure and, if it is already very low,
slightly close adjustment valve VR.
- If delivery needs to be increased, increase
outlet gas pressure.
11
: 120 kW
: 120 kW
Qa (max. burner output) x n x ts
3600
)
3
/h)
3
/h.
15.87 x 10 x 3
= 0.132 Sm
3600
3
):
3