CPVC/PVC plumbing questions

RogerT · 2010-09-15T16:08:12+00:00

I am running new plumbing lines in the basement of a 3-unit apartment building that I own. The purpose of the re-plumbing is to separate out the water service for each unit. All of the existing plumbing is copper. The hot and cold copper lines that go to each individual apartment are easily accessible in the basement, so separating out the water service for each apartment will be easy because all I will need to do is tie into the copper lines for each apartment in the ceiling of the basement.I don't want to use copper, and I think I am probably not going to go with PEX. My plan right now is to use CPVC pipe and fittings for all of the new plumbing and to tie that into the existing copper lines for each apartment.One question I have is whether to use all CPVC, or use CPVC for the hot water lines and PVC for the cold water lines. My inclination is to use all CPVC rather than try to save a few bucks on materials by using PVC for the cold water lines. Does that make sense? Is there any reason NOT to just use all CPVC instead of trying to use both CPVC and PVC, other than the cost of materials?I also have questions about how to connect the CPVC to the existing copper lines. I can easily solder female threaded adapters to the ends of the existing copper lines and use male threaded CPVC adapters to make the connections. But, I think there may be a problem with doing that for hot water connections due to possible variations in expansion of the two materials and, therefore, possible future leaks at the connections. I have seen the Sharkbite and Watts push-on connection adapters but they make me nervous in terms of how secure the connections would be. And, I believe there are copper to CPVC adapters that either screw onto, or get soldered to (I am not sure about that), the copper and then are glued to the CPVC pipe.I would appreciate any thoughts or suggestions on how to best make the connections from the CPVC to the existing copper.And, any thoughts, suggestions,...

Sep 15, 2010 25 Replies

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RogerT 15 years ago

I was originally planning on using PEX. But, in this case, I decided against it.

The way the layout is set up, it turns out that it wouldn't make sense to try to do manifolds and a home-run type of setup. One reason is that the existing plumbing goes up through the walls etc. to each apartment and it wouldn't be practical to try to do new home runs to each fixture.

It also turns out that the cold water coming into the property is in the front of the building and the utility room where the 3 hot water heaters and

3 boiler/furnaces are located is in the back of the building. And, all of the fixtures for each apartment are in the middle. So, rather than running the supply from the front to the back, and putting in 6 manifolds there (3 hot and 3 cold) for home runs, I decided to use a more traditional plumbing layout.

And, another reason for not using PEX is that there are some sharp turns required in a space where PEX bends would not fit. And, if I did the PEX with fittings etc. to make the turns, the cost of all of that would be a lot more than just using CPVC pipe and CPVC fittings.

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RogerT 15 years ago

Thanks everyone. Final update -- we finished the project last night using all CPVC pipe and fittings plus the transition adapters to connect the CPVC to the existing copper. It worked out great and now the water is completely separated out for each apartment unit as planned.

I am REALLY appreciative of those who pointed out that the code no longer allows for PVC for cold water distribution within the dewlling, and that CPVC is now required for both cold and hot distribution lines. So, we went with all CPVC and we used the one-step yellow no-cleaning-solvent-required type of CPVC glue.

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KC 15 years ago

I had some sticks of CPVC left over from a project about 10 years ago. They were stored inside my shop. When I went to use them for another project this week, I found that they had turned brittle, to the point that PVC cutters would shatter them rather than cut thru them. Don't know what this says about installed CPVC other than I hope I never have to splice into an older install.

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HerHusband 15 years ago

Were your pipes exposed to sunlight? If I remember correctly, CPVC does not have UV protection, which would probably cause the pipe to break down in sunlight. (Grey PVC conduit does have UV protection).

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jamesgangnc 15 years ago

I agree. Sounds like it was exposed to uv. I have cpvc in my lake house. It's 8 years old and it cuts fine.

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Harry K 15 years ago

Mine is around 25-30 years old, no problems.

Harry K

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