Riello 46662X Installation, Use And Maintenance Instructions page 34

4.2 Wiring diagrams
D9227
PA Air pressure switch
PGM Max.gas pressure switch
SM Servomotor
TA Ignition transformer
12
VP1 Pilot valve
VP2 Pilot valve
UV UV cell
XP1 24 pole socket
4
CHAPTER Fuel supply
XS1 24 pin plug
XTB Burner earth
XT1 Burner terminal strip
Fig. 13