CPVC v. Copper

13 years ago

I have a very short question but I will try to give as much background info as possible. We are renovating our home in north central florida. It is a 1987 currently fitted with all copper piping. We decided to install an instant hot water heater - and we were convinced to put it outside. I think that was a mistake but that is for a different thread. Anyway, the plumbers used CPVC. They really didn't ask us if we had a preference, they just did it. This was run outside and through the attic. The supply lines eventually run down into the concrete slab in the kitchen. We need to move these a few inches in order to make the new oven fit (it was originally installed all messed up and they worked around it with cabinetry - we are essentially moving some pipes about 3" so that they are inside the wall where they come out of the slab). So they are using CPVC here also, which will be covered in concrete tomorrow morning. and our oven and cabinets placed on top of flooring (wood).

My unprofessional inclination would have been to just stick to one kind of piping in the house. Now it might be too late, but maybe not. There is still plenty of more work to do (re-hooking up sinks and stuff) and I can still decide on what goes in there, at the very minimum. But once the concrete is poured there is no going back.

Does anyone want to weigh in on whether we should switch back to copper or keep going with CPVC? My main concerns are: health reasons, fear of cracking due to weather, fear of releasing chemicals or breaking due to heat in the attic, fear of cracking under the concrete, fear of bad joints leaking under the concrete.

I feel like we really messed up by not researching this earlier, we just sort of took the advice of our plumbers.

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Comments (4)

ladoladi
Original Author
13 years ago
oh I just want to be clear also that the CPVC / copper interconnect will be underneath the concrete slab, under our gas range.
maryland_irisman
13 years ago
Briefly, you shouldn't be concerned with using plastic. In today's world, copper is very expensive. I prefer using copper because the job goes faster and the end user can use the water right away without waiting for the curing process as is required with CPVC.

The content in cement has a tendency to eat copper over time. I think the CPVC would be fine at that location and you shouldn't see a problem as long as the transition from copper to CPVC is secure and leak free.

CPVC is supposed to be impervious to heat and not prone to introducing plastic type toxins into the water. What I have noticed with CPVC over time....When I've used the CPVC cutter in the past on new CPVC, it would be a nice smooth cut. When I have done work on a point where CPVC has been there for 5 years or more, the cut was different. Instead of a smooth slice through, the pipe appeared brittle and would snap when the blade was half way through. After truing the cut and using the normal CPVC prep with new fittings, it doesn't seem to make any difference. The CPVC is expected to expand and contract as is copper. With copper, the stress would be more inclined to effect the soldered joints. With plastic, the gluing process is supposed to meld the joint which would have virtually no more impact from stress than the rest of the tubing. The CPVC must be secured by brackets in a specific way and frequency to hold it in place and still allow for expansion and contraction.

50 years from now we should see what the application of CPVC produces. Poly plastic was supposed to be so great when it first came out. It's not allowed for potable water in homes here.
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asolo
13 years ago
I'm no pro but I'm not sure I would be comfortable with that transition-point encased in concrete.
alan_s_thefirst
13 years ago
All plastics get brittle with age. I prefer copper but the concrete corrosion question is a good one, but if it's approved for it, it shouldn't be too bad.

I think PEX will come back to haunt us later on, as IT gets brittle, but I do think it's a clever system with a lot of advantages - but I don't know if it's worse in the hands of a DIY-er since the crimping seems to be a bit of an art. You don't set fire to your house joining it, though.