While you wait for answers, we may have found some information which could help you.
Click here for Pilot Saunier DuvalI have a Saunier Duval Isotwin condens F 35 E with hot water No heating?
saunier duval sd620f?
Saunier Duval F35E auto-vents down to code 21 in minutes?
saunier Duval is over pressurising when the heating is on. ?
Saunier Duval timeclock not working?
Saunier Duval Isofast condens F35E....nothing working?