While you wait for answers, we may have found some information which could help you.
Success
Message
Riello 40 Burner problem?
How to increase air supply to Riello RDB Burner?
Burner not working ?
how can i mend my riello burner rdb1 483t50?
My riello burner lights for about 12sec and then locks out?
Bleed a boiler?
riello 40 starts, runs fine then stops. ?
Oil not reaching burner?
Bleeding it after oil ran out?
My Riello 40 loses it prime ?
can you fix the pump on a riello40?
Fan Cage Making noise on a Riello 40 FS?