Boiler banging noises

[Chrisw0410]

Got back from a week visiting family over Xmas and our boiler has now started making banging and grinding noises.

It’s a British Gas 330 which is a Glow Worm boiler.

 

[John.g]

Is the boiler pressure ~ 1.0/1.5bar if a sealed system or is there water in the feed & expansion cistern if open vented?.