Rad pipes chased outside??

AJake135 · Jan 4, 2022

Hi all,

Background situation… I’ve refit our new bathroom from scratch, re-located toilet waste, all new plumbing for wastes and supplies within floorboards etc and new shower valve pipe work etc chased in to internal wall.

So I have had to do a lot of research, and I’ve muddled along ok so far…

I have a hurdle though, I’ve now got a wall hung rad to install, that wasn’t in the original plans. Plumbing is there ish for it…

Only thing is that I don’t want 2 long pipes going down the wall and I don’t fancy pulling the tiles I’ve already laid on that wall to chase them in internally.

It’s on an external wall. What I was going to do, was exit the rad pipes at floor level (boxed in) chase them in up the OUTSIDE wall then come back in where the bottom of the rad is.

So I know the need for insulation, I was going to chase them in quite deep, then fill around with expanding foam, then finish the external surface how it was.

Would this be ok to do like this?

If not I need some suggestions etc lol

Thank you in advance 🙂

Ric2013 · Jan 4, 2022

Expanding foam only has a k value around 0,035 so is little better than fibreglass if my memory serves me correctly. I'd be seriously concerned that the cold bridge effect of laying them in external brickwork would create a serious frost risk if you ever go on holiday (though I suppose you could add glycol to your primary water), and I think as far as Part L of the Building Regulations are concerned, this would be considered a waste of energy.

What if you run them externally, and then insulate the complete outside wall, thus securing them safely on the warm side of your new thermal envelope? Alternatively, run them to the opposite bottom ends of your new radiator, perhaps in chrome pipe - would it really look that bad? If the pipes come from above, can you not run them down to below floor level via an adjacent room and perhaps chase them into an internal wall or the inner skin of an external wall somewhere where you don't have tiles?