Final Calibration Of The Pressure Switches; Air Pressure Switch; Maximum Gas Pressure Switch - Riello RS 190/M Installation, Use And Maintenance Instructions

5.6

Final calibration of the pressure switches

5.6.1

Air pressure switch

Adjust the air pressure switch after having performed all other burn-
er adjustments with the air pressure switch set to the start of the
scale (Fig. 39).
With the burner operating at minimum output, increase adjustment
pressure by slowly turning the relative dial clockwise until the burn-
er locks out.
Then turn the dial anti-clockwise by about 20% of the set point and
repeat burner starting to ensure it is correct.
If the burner locks out again, turn the dial anti-clockwise a little bit
more.
During these operations it may be useful to measure the air pres-
sure with a pressure gauge.
The connection of the pressure gauge is shown in Fig. 40.
The standard configuration is that with the air pressure switch con-
nected in absolute mode.
Note the presence of a "T" connection, not supplied.
The air pressure switch may operate in "differential" operation in
two pipe system.
If a negative pressure in the combustion chamber during pre-purg-
ing prevents the air pressure switch from switching, switching may
be obtained by fitting a second pipe between the air pressure
switch and the suction inlet of the fan. In such a manner the air
pressure switch operates as differential pressure switch.
5.6.2

Maximum gas pressure switch

Adjust the maximum gas pressure switch (Fig. 41) 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.
Start-up, calibration and operation of the burner
29
D3854
D3856
GB
Fig. 39
20161112
Fig. 40
PA
20181543
PGM
Fig. 41
20160742