Saunier Duval SD 623?

Hi all,

I have a Daunier Duval SD 623 that last night stopped providing any hot water or heating.

Leading up to the fault, I turned the heating on, and after approx. 5 mins there was a screeching sound from the unit, there was then steam escaping from the unit for another approx 1 min. The pilot light then went out.

I have tried to re-light the boiler, and I can get the pilot to stay alight. However, the boiler will not fire when I turn a hot tap on.

The pressure guage appears to be reading zero.

I assume a seal of some sort has given, but otherwise would welcome any thoughts on what might be wrong and the whether this is something that is likely to be easily fixed.

Many Thanks