This manual provides detailed information on the Riello 40 GS20 TYPE 556T1 CODE 3755613 gas burner, including its technical specifications, structure, accessories, installation method, combustion range, applicable boilers, gas pressure and burner output relationship, gas supply piping, electrode position, circuit connection diagram, burner start timing diagram, damper adjustment, burner head adjustment, combustion condition check, ion probe current, air pressure switch, burner start fault phenomenon and its cause.