If you have been following the thread entitled "Baxi Bermuda boiler problems and leaks" you will know that I have been trying to help 'Bawser' make sense of his system.
One of the photos which he uploaded
Does anyone have any clue as to what this cylinder is? The only thing I can think of is to wonder whether he has the equivalent of a Primatic cylinder - but with the bit which allows limited mixing of primary and secondary circuits in order to fill the primary being implemented externally. Is this likely/possible - or has anyone got a better explanation?