While you wait for answers, we may have found some information which could help you.
Click here for Saunier Duval Buttonsaunier duval boiler problem?
How to repair F4 code?
Saunier Duval Isofast condens F35E....nothing working?
Saunier Duval timeclock not working?
I have a Saunier Duval Isotwin condens F 35 E with hot water No heating?
isotwin condens f 35 e service menu codes?