Unigas RX90 Installation Manual page 38

Calibration of minimum gas pressure switch
As for the gas pressure switch calibration, proceed as follows:
Be sure that the filter is clean.

Remove the transparent plastic cap.

While the burner is operating at the maximum output, test the gas pressure on the pressure port of the minimum gas pressure

switch.
Slowly close the manual cutoff valve (placed upstream the pressure switch, see gas train installation diagram), until the detected

pressure is reduced by 50%. Pay attention that the CO value in the flue gas does not increase: if the CO values are higher than the
limits laid down by law, slowly open the cutoff valve as to get values lower than these limits.
Check that the burner is operating correctly.

Clockwise turn the pressure switch adjusting ring nut (as to increase the pressure value) until the burner stops.

Slowly fully open the manual cutoff valve.

Refit the transparent plastic cover on the pressure switch.

Adjusting the high gas pressure switch (when provided)
To calibrate the high pressure switch, proceed as follows according to its mounting position:
1 remove the pressure switch plastic cover;
2 if the maximum pressure switch is mounted upstreaam the gas valves: measure the gas pressure in the network, when flame is off;
by means of the adjusting ring nut VR, set the value read, increased by the 30%.
3 if the maximum pressure switch is mounted downstream the "gas governor-gas valves" group and upstream the butterfly valve:
light the burner, adjust it according to the procedure in the previous paragrph. Then, measure the gas pressure at the operating
flow rate, downstream the "gas governor-gas valves" group and upstream the butterfly valve; by means of the adjusting ring nut
VR, set the value read on step 2, increased by the 30%;
4 replace the plastic cover.
PGCP Gas leakage pressure switch (witn Siemens LDU burner control/Siemens LMV Burner Management
System)
remove the pressure switch plastic cover;

adjust the PGCP pressure switch to the same value set for the minimum gas pressure switch;

replace the plastic cover.

38