Expansion tank?

[Madrab]

We find out tonight that the cylinder we bought is for a pressurised system

Who fitted it? It should have been spotted at that point. I assume it has been vented?

When you have the boiler on calling for HW do both flow and return to the cylinder coil heat up? Did your plumber not check that the new tank was heating up properly? I'd get him back in TBH

 

[pip2223]

Thanks for reply. It's not really his fault as it was meant to be a straight swap of a leaking cylinder for a new one. The boiler is a multifuel stove and it is vented. It was too late and too warm last weekend to fire it up. It filled and there were no leaks and we checked the immersion heater was working ok. We bought the cylinder and went for the same size and description that was on the old cylinder.