Intermediate Outputs; Final Adjustment Of The Pressure Switches; Air Pressure Switch - Riello RS 68/M BLU Installation, Use And Maintenance Instructions

6.5.5

Intermediate outputs

Adjustment of gas delivery
No adjustment is required
Air adjustment
After adjusting the maximum and minimum output of the burner,
carry out air adjustment on higher intermediate positions of the
servomotor.
The passage from one position to the next one is obtained by
pressing the button 2) on the symbol (+) or (-) (Fig. 29 on
page 26). Press button 2)(Fig. 29 on page 26) "Output increase"
briefly so that the servomotor rotates by about 20°, see
servomotor graduated index Fig. 31 and air damper graduated
index 5)(Fig. 30 on page 27).
Screw or unscrew the screw 5) of the mechanical cam (Fig. 30 on
page 27) to increase or decrease the gas output so as to adjust
it to the corresponding air output, to obtain optimal combustion.
Proceed in the same way with the other screws.
Take care that the cam profile variation is
progressive.
ATTENTION
6.6

Final adjustment of the pressure switches

6.6.1

Air pressure switch

Adjust the air pressure switch after performing all other burner
adjustments with the air pressure switch set to the start of the
scale (Fig. 32).
With the burner operating in 1st stage, increase adjustment
pressure by slowly turning the relevant knob clockwise until the
burner locks out.
Then turn the knob anticlockwise by about 20% of the set point
and repeat burner start-up to ensure that it is correct.
If the burner locks out again, turn the knob slightly anticlockwise.
In conformity with current standards, the air
pressure switch must prevent the CO in the flue
gases exceeding 1% (10,000 ppm).
To check this, insert a combustion analyser into
ATTENTION
the chimney, slowly close the fan suction inlet (for
example with cardboard) and check that the
burner locks out, before the CO in the fumes
exceeds 1%.
The incorporated air pressure switch can work in a 'differential'
mode if connected with two pipes.
If a strong depression in the combustion chamber during the pre-
purging phase does not allow the air pressure switch to switch,
this can be obtained by applying a second tube between the air
pressure switch and the suction inlet of the fan.
In this way, the pressure switch will work in differential mode.
The use of the air pressure switch with differential
operation is only allowed in industrial applications
and where standards enable the air pressure
switch to control only fan operation, without any
ATTENTION
reference to CO limit.
20168422
Start-up, calibration and operation of the burner
Switch off the burner using switch 1)(Fig. 29), OFF position,
release the mechanical cam 4)(Fig. 30) to separate the gears of
the servomotor, pressing and moving downwards button
3)(Fig. 31), then manually rotate the mechanical cam I)(Fig. 31)
backwards and forwards a few times to check that the movement
is smooth and without any hindrance.
It is recommended that the mechanical cam
5)(Fig. 30 on page 27) be bound again to the
servomotor by shifting button 3)(Fig. 31) upwards.
ATTENTION
As far as is possible, try not to move those screws at the ends of
the mechanical cam that were previously adjusted for the
opening of the gas butterfly valve to MAX and MIN output.
NOTE:
Once "MAX - MIN - INTERMEDIATE" outputs have been
adjusted, recheck the ignition: its noise must be equal to the
one of the following operation.
If you notice any sign of pulsations, reduce the ignition
stage delivery.
D3854
28 GB
Fig. 32