What certification etc does a thermal store need?

[dnb]

I am considering an out of the box idea at the moment but before I go too far I need to know about certification requirements.

 

What certification etc does a thermal store tank need. (Just the tank. Leave any immersion heaters, accessories etc aside for the moment)

Let's assume it is designed to be vented so it isn't a pressure vessel and that we would expect the usual ISO and CE markings as appropriate.

 

Thanks

[PeterW]

None.