Pipes in concrete floor

[grabshell]

I am repositioning some downstairs radiators and have a couple of questions i am a little unsure of.

I have channelled the floor along the wall to the new rad position. Can i use plastic pipe and speedfit/polyplumb fittings to new rad position, bearing in mind the pipe and fittings will be covered over in concrete screed. Or is it best to use copper to match existing?

There is a small amount of water left in existing pipes after draining. if i was to use copper pipe to new rad, will water in pipe affect the solder joint?

Any suggestions appreciated

 

[ChrisR]

You can't solder wet pipes reliably. Vac/blow the water out.

Don't let concrete touch copper at all. Use flexible or rigid duct for the pipes, and pay particular attention to the parts eg where it comes up to the rads. Cover very well in Denso Tape (petrolatum covered sticky stuff).

I would never put a pushfit connection anywhere inaccessible.

 

[grabshell]

thanks ChrisR. What happens when concrete touches copper pipes? the existing pipes have been under concrete for 40 odd years. can i expect a problem?
Also, where can i get Denso Tape and duct for 15mm pipes? Would wrapping the pipes in insulation be ok instead?

 

[gas4you]

Eventually the concrete can eat through them. I think its the lime in the concrete or something. You could always use tubular hair felt around the pipes and let it extend out of floor until concrete sets then trim back.