Final Calibration Of The Pressure Switches; Air Pressure Switch; High Oil Pressure Switch - Riello RL 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. 41).
With the burner operating at min. output, increase adjustment pres-
sure by slowly turning the relative dial clockwise until the burner
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.
As a rule, the air pressure switch must prevent the
formation of CO. To check this, insert a combustion
analyser into the chimney, slowly close the fan suc-
tion inlet (for example with cardboard) and check
WARNING
that the burner locks out, before the CO in the
fumes exceeds 400 ppm.
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. 42.
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

High oil pressure switch

The high oil pressure switch is factory set to 43.5 PSI (3 bar).
If the oil pressure goes above this value in the return piping, the
pressure switch stops the burner.
Burner starts again automatically if the pressure goes down under
43.5 PSI (3 bar) after burner shut down.
If a loop circuit with Px pressure feeds the burner, the pressure
switch should be adjusted to Px + 43.5 PSI.
For the adjustment, see (Fig. 43).
Start-up, calibration and operation of the burner
29
D11134
+
D10627
GB
Fig. 41
D3854
Fig. 42
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-
Fig. 43
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