Pressure Switch Adjustment; Air Pressure Switch; Maximum Gas Pressure Switch - Riello RS 64/M MZ Installation, Use And Maintenance Instructions

6.6

Pressure switch adjustment

6.6.1

Air pressure switch

The air pressure switch can be connected in differential mode,
see 1)(Fig. 32), i.e. it is under pressure either by the depression
or pressure generated by the fan. In this way the burner can
operate even in combustion chambers in depression and with
high modulation ratios: MIN / MAX outputs upt to 1/6.
In this case the air pressure switch needs no adjustment and its
function is limited to controlling fan operation.
The use of the air pressure switch with differential
operation is allowed only in industrial applications
and where rules enable the air pressure switch to
control only fan operation without any reference to
ATTENTION
CO limit.
In civil applications the pipe from the fan air inlet
should be removed, see 2)(Fig. 32), and adjust
the pressure switch as follows.
Air pressure switch connected as in 2)(Fig. 32):
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 at MIN output, increase adjustment
pressure by slowly turning the relative 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.
as a rule, the air pressure switch must limit the CO
in the fumes to less than 1% (10,000 ppm). To
check this, insert a combustion analyser into the
chimney, slowly close the fan suction inlet (for
ATTENTION
example with cardboard) and check that the
burner locks out, before the CO in the fumes
exceeds 1%.
D3854
20169372
Start-up, calibration and operation of the burner
1)
2)
D794
Fig. 32
6.6.2

Maximum gas pressure switch

Adjust the maximum gas pressure switch (Fig. 33) after making
all other burner adjustments with the maximum gas pressure
switch set to the end of the scale.
To calibrate the maximum gas pressure switch, open the tap and
then connect a pressure gauge to its pressure test point.
The maximum gas pressure switch must be regulated to a value
no higher than 30% of the measurement read on the gauge when
the burner is working at maximum output.
After making the adjustment, remove the pressure gauge and
close the tap.
D3856
28 GB
PA
20181543
PGM
Fig. 33