Burner Adjustment; Ignition Output; Preliminary Calibrations, If Necessary - Riello GAS 3 P/M Installation, Use And Maintenance Instructions

6.6

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 - Preliminary calibrations, if necessary

3 - MAX output
4 - MIN output
5 - Intermediate outputs between Min. and Max.
6 - Air pressure switch
7 - Maximum gas pressure switch
8 - Minimum gas pressure switch
6.6.1

Ignition output

According to EN 676 standard:
Burners with MAX output up to 120 kW
Ignition can occur at the maximum operation output level.
Example:
– Max. operation output: 120 kW
– Max. ignition output: 120 kW
Burners with MAX output above 120 kW
Ignition must be performed at a lower output than the max.
operation output.
If ignition output does not exceed 120 kW, no calculations are
required. 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 lower than
1/3 of max. operation output.
Example:
MAX operation output of 600 kW.
Ignition output must be equal to or lower than:
– 300 kW with ts = 2 s.;
– 200 kW with ts = 3 s.
In order to measure the ignition output:
– Disconnect the plug - socket 5)(Fig. 6 a pag. 14) on the
ionisation probe cable (the burner will fire and then go into
lockout after the safety time has elapsed).
– 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 formula ( for ts = 3)
3
/h (max. burner delivery)
Nm
Example:
3
for G 20 gas (10 kWh/Nm
Max. operation output: 600 kW corresponding to 60 Nm
After 10 ignitions with a lockout, the delivery indicated on the
meter must be equal to or lower than: 60: 360 = 0.166 Nm
Start-up, calibration and operation of the burner
360
):
6.6.2 Preliminary calibrations, if necessary
They concern the arm (Fig. 27) of the gas butterfly valve, the tie-
rod (Fig. 26) controlling the arm (Fig. 27) and the tie-rod
7)(Fig. 28 a pag. 30) controlling the air damper.
Their calibration depends on the MIN and MAX outputs required
for the burner operation.
 The burner is factory set for a MIN-MAX output ratio of 1:3 -
1:4. The articulated coupling 1)(Fig. 26) controlling the arm
(Fig. 27) of the gas butterfly valve is positioned at 90°. In this
way the gas butterfly valve turns by 90° when the cam
2)(Fig. 28 a pag. 30) covers the whole angle of 130° (A)
(Fig. 29 a
approximately 1:2, the articulated coupling 1)(Fig. 26) must
be moved from 90° hole to 60° hole (Fig. 27), with the burner
off. In this case the gas butterfly valve turns by 60° when the
cam 2)(Fig. 28 a pag. 30) covers the whole angle of 130° (B)
(Fig. 29 a pag. 30).
 If the 1- 2 ratio falls within the highest output range (e.g. 40-
80% of the MAX burner output), it is necessary, apart from
moving the articulated coupling from 90° to 60°, to shorten
the tie-rod (Fig. 26) and rotate the working angle of the gas
butterfly valve so that the maximum opening is 90°: from 0 -
60°(Fig. 29 a pag. 30) to 30 - 90°(Fig. 29 a pag. 30). In this
case the gas butterfly valve remains partially open, index at
about 30°, with the burner in stand-by mode.
To shorten the tie-rod, proceed as follows, with the burner off:
– Disengage the articulated coupling 1)(Fig. 26) from the arm
(Fig. 27).
– Loosen the nuts 3)(Fig. 26).
– Tighten the hexagon 2) by a few turns.
– Lock the nut 3).
– Reconnect the articulated coupling 1)(Fig. 26) to the arm
(Fig. 27).
3
/h.
 If the 1- 2 ratio falls within the lowest output range (e.g. 25-
50% of the MAX burner output), lengthen the tie-rod
3
7)(Fig. 28 a pag. 30) controlling the air damper. In this way, a
too curved cam profile can be avoided.
With the burner off, proceed as follows (Fig. 28 a pag. 30):
– Disengage the articulated coupling 4) from the lever 8).
– Loosen the nut 6).
– Loosen the hexagon 5) by a few turns.
– Lock the nut 6).
29 GB
D120
pag. 30). When the MIN-MAX
D74
Fig. 26
Fig. 27
ratio is
20159111