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