Is pipe-in-pipe worth the bother?

[cjard]

i see that a roll of speedfit 15mm pipe is, for example, 50 quid. I see one can also buy a dedicated flexible conduit through which one can thread said pipe for 40 quid. Or one can buy it prethreaded for 120 quid. Apparently installing it in conduit makes replacing easier, because in theory you can pull a new section of pipe through as you pull out the old leaking pipe. the conduit should also capture water and prevent damage to the structure while indicating which pipe is leaking

So I'm now curious, what is the likelihood of these pipes actually leakig? I don't see it likely that they will just burst so is there any point in putting the conduit in?
Perhaps it's for reasons such as forgetting whre it is in the wall, and not being detectable to a metal stud detector like a copper pipe would be, pounding a picture hook nail through it?

I reckon I'll use 100m of pipe in my build, so should I throw the extra 80 quid in and run the conduit?

Tanks

 

[Dean744PiN5]

Pipe in pipe is a good method, but buy it already "pre-threaded" as trying to feed the pipe through seperate conduit is a fooking nightmare.

Also it is a easy way to comply with regs as no fittings can be buried in the floor and all pipes must be accessible / removable, the only way to achieve this is with purpose made ducts that are accessible (which is a real faff) or pipe in pipe with no hidden joints, for a complete peace of mind system.

 

[Burnerman]

+1 and Speedfit coils have a bloody mind of their own
John

 

[Dean744PiN5]

here's a system i installed recently using pipe in pipe

20150729_181653

• Dean744PiN5
• 11 Nov 2015

 

[Dan Robinson]

Must remember to bill for that

 

[simond]

We always use pipe in pipe for water, both hot and cold. For CH it isn't strictly necessary.

We use bend 90 deg pipe stiffening formers to avoid joints under the screed, to turn out the pipe vertically, because joints are the one weakness of plastic pipe. There's no way I'm leaving a plastic joint under a screeded underfloor heated tiled kitchen, I just know what will happen and it will be down to me. No joints-no leaks.