Burner Ignition; Air/Fuel Adjustment; Procedures For Setting The Burner - Riello 20122858 Installation, Use And Maintenance Instructions

6.6

Burner ignition

The burner should light after having performed the above steps.
If after completing the starting cycle the flame does not appear
and the control box goes into lockout, reset it 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.
6.7

Air/fuel adjustment

Fuel/combustion air is synchronized by means of a servomotor
that, connected to a variable-profile cam, operates the outlet air
dampers and, by means of suitable linkage, the combustion head
and gas butterfly valve.
To reduce pressure loss and to have a wider adjustment range,
it is best to set the servomotor to the maximum output used, as
near to maximum opening (130°) as possible.
On the gas butterfly valve, the fuel's partial setting adjustment
based on required output, with the servomotor fully open, is made
by using the pressure stabilizer on the train.
When setting the air/fuel ratio for the gas burners, the air and gas
variable profile cams must be used, Fig. 22.
6.7.1

Procedures for setting the burner

Turn the AUTO / MAN selection switch on the control panel to
MAN (manual). Turn the burner on.
If it does not ignite, it could mean that the gas does not reach the
combustion head within the safety time period of 3 s.
In this case increase the ignition gas delivery level.
When the burner ignites, it can be completely set and adjusted.
Maximum output
Maximum output should be selected from the firing rates, see
Fig. 3.
Max. gas adjustment
Slowly increase the output, checking it does not exceed the max-
imum gas delivery, taking the servomotor to 130° and make the
first maximum setting to the air cam.
At this point, adjust the pressure regulator to reach the maximum
delivery required with the gas butterfly valves completely open
(90°), or turn the screws 2)(Fig. 22) on the gas cam profile and/or
the gas train adjustment valve.
Max. air adjustment
Vary the final profile of the air cam by turning the screws 2)
(Fig. 22).
Do not turn just one screw, but turn those nearby as well, so that
the cam curve is progressive.
Minimum output
Min. gas adjustment
Using the manual switch, go to the minimum run (factory setting
20°). Change the gas cam profile by turning the screws 2).
Min. air adjustment
Change the initial air cam profile by turning the screws 2) on the
variable profile air cam.
Take care not to change the final parts of the profile of the cam
that regulates the air damper at maximum delivery, as previously
set.
20118862
Start-up, calibration and operation of the burner
The arrival of gas at the pipe coupling is evidenced by the U-
shaped pressure gauge (Fig. 20) or else with the aid of a digital
pressure gauge placed on the pressure test point under the cou-
pling.
If further burner lockouts occur, refer to the "Reset procedure" in
the equipment manual supplied. with the boiler's main panel.
Once the burner has fired, now proceed with global calibration
operations.
Key (Fig. 22)
1 Cam
2 Adjustment screws
3 Fixing screws
4 Variable profile
Intermediate output levels
Turn the manual switch to the intermediate levels.
The air/gas ratio is adjusted by turning the respective screws to
vary the air and gas cam profiles.
Take care not to change the final parts of the air and gas cam pro-
files, as previously set.
When adjustment is complete, block the transversal screws on
the variable profile cam.
24 GB
1 2
3
D1499
Fig. 22
4