RIMS along the lines of Speidel Braumeister

[Kev888]

how formable are they?
the entry would have to be at right angles to the wall so it would have to go straight across then bend around I make that roughly 7 foot

They're pretty easy to form. They suggest that you use a mini pipe bender for sharp curves, so you'd probably be looking at a minimum internal radius of say around 25mm or something like that. For larger bends you can bend them by hand, though I found that to keep it looking even you have to wrap it around something really. IIRC you aren't supposed to bend them towards the very ends, though.

When I finally get around to a build like this, I'd like to to take the tails out through the bottom of the boiler rather than the sides. I reckon the minimum external radius for the downward curve would be around 30mm or so, so the element should conceptually be able to sit reasonably close to the bottom (which for my intended design would be important, probably less so for a true braumeister clone). Unfortunately though, in practice the straight glands protrude inwards perhaps another inch before the element can begin to bend, so if I'm to do that I'll have to devise a way to seal the element as it passes through (or at least closer to) the boiler base.

Cheers
kev