I've just fitted a rad in the new conservatory and buried the copper pipes in screed. However i have been told this is not a good idea. How serious is it? Do i need to dig up the cred around the pipes and protect them with something? thanks.
Yes you do. Concrete in direct contact with copper pipes will corrode them.
The choices are to wrap the pipes in Denso tape which is a kind of greasy and sticky cloth tape, or to replace the pipes with plastic sleeved ones.
Its not best practice, but its not a big problem. Millions of us have copper direct in concrete, and it isnt causing Noah's floods yet. Its simply that now we know better we can sleeve or wrap pipes first and avoid that remote chance of a leak.
NT
Thanks for the reply guys. I guess i wish i had remained in ignorance, but now that i know.... Anyway, since posting, i've dug up almost all of the bit required - luckily it wasn't that hard after a couple of weeks - and i'll do the job properly. One of the pitfalls of an anal personality i guess :-)
You also need to allow space for pipes to expand when they get hot. In a large school building some years back, they had to dig up all the central heating pipes after the first time they switched the heating on. They all buckled and split in the concrete. Thermal insulation around the pipes usually has enough give in it for this, unless you have any very long runs.
We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember snipped-for-privacy@hotmail.com saying something like:
They'll leak in 30 years time. Will you still be around to give a toss?
Get some insulation at least!
If you've just used 15mm copper pipes then just sleave them in 22mm plastic, or even copper, pipe. It allows for expansion and also keeps the acid in the cement away from the 15mm copper. Calum Sabey (NewArk Traditional Kitchens 01556 690544)
and also keeps
How very odd! My recollections from school chemistry lessons would be that concrete was an alkali, and that copper is immune to any reaction with it. I think any problems would only be due to the use of something like flyash in the concrete.
http://64.90.169.191/applications/plumbing/techcorner/problem_embedding_copper_concrete.htmlJulian.
Copper will corrode in the presence of damp concrete..but in dry screed you have many many years before any deterioration happens.
http://64.90.169.191/applications/plumbing/techcorner/problem_embedding_copper_concrete.html>
IIRC what the reaction is that the copper slowly oxides to cuprous oxide in teh air, whicvh will normally form a stable surface film that prevents further oxidation. Water and alkali makes for a soluble and porous copper salt of some sort, which doesn't protect in the same way. copper hydroxide? .
If you don't protect them the concrete eats them away.
A friend of mine when he moved into a house near me in 1994 (built 1974) kept on getting a "damp stain" on the lounge carpet. Anyway ripped carpet up and there was a large damp area on concrete floor. Carefully chiselled out and found two copper central heating pipes and one copper gas pipe that fed/came from the back boiler. The gas pipe was wrapped in a sticky cloth tape (Denzo tape ?) but the two copper pipes hot out and cold return to the radiators where just embedded in the concrete. Both these pipes had tiny pin prick holes all along their length very slowly leaking water causing the damp patch. He simply replaced the runs under the floot, this time putting the copper pipe in a plastic pipes (Hep2O ?) and problem solved.
Your remembering your chemistry almost correctly, but for aluminium, not copper. Al behaves as you say ; copper is comparatively unreactive. What caused me horrible problems with copper pipes that a previous owner had covered in a concrete-based screed was that they supported the screed into the hole (going through a load-bearing wall) on chicken wire. One little bit of chicken wire touching the copper and ... within a year of me moving in, a nice fountain of mains-pressure water playing across the back of the bath. Learning domestic plumbing under those conditions is not nice.
Well there is no doubt that copper in screed does go funny...probably in the presence of damp..so what IS the reaction that causes it?
I have a feeling its not the reaction of copper and cement but reaction of the copper impurities and cement thats the issue. This is why you get pinhole leaks in the cemented copper pipes (see my other post) as opposed to the copper pipe being completely dissolved away in the the cement. Also a lot was due to poor quality copper pipes in the 70's and 80's that cuased this issue. This is probably why modern high quality copper pipes can be embedded in cement as one poster suggested. Mind you if you are laying pipes in cement it is relatively trivial to place them in 22mm plastic just to be sure.
Well, copper isn't completely inert. It's a lot less reactive than aluminium, but not completely inert. If there's some iron (or aluminium, or almost any other metal) in the vicinity that can form an electrochemical circuit, then you'd get some sort of oxidation reactions going on. Copper salts aren't particularly mobile in alkaline conditions, because the hydroxide isn't very soluble. The obvious thing to do is to keep your pipes out of contact with the concrete. Plastic slip-on lagging did the job perfectly well for me, and I was going to use it anyway. Two birds, one stone.
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