Sorry guys had to fly out .
I installed the cylinder around 6/7 years ago , old lady sadly died . New guy moves in , no hot water , I opens the cupboard and sees this load of *****. Multibloc, tundish , ex valve fed from all directions , cylinder header tank overflow disconnected etc etc . The guy said the plumbers he got in to do his bathroom did this to the cylinder lol .
I said it was wrong , he's had a word with his plumbers and they say its correct and I am wrong ..
So there you go lol