why does f9 keeping flashing on my boiler, what does it mean?
my boiler is a saunier duval and it is not working at all. not the hot water or central heating. F9 keeps flashing. what does that mean and how can i fix it?
F9 depending on exact model of SD boiler you have generally indicates fault on water pressure sensor.
Check in your manual for the boiler, there will be a list of fault codes
