Replacing old cast iron water lines


Old 03-11-14, 03:30 PM
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Replacing old cast iron water lines

i am going to be helping a friend replace old water lines with pvc/cpvc. I know that CPVC shouyld be used for the hot wate lines. Should we use pvc for all the cold water lines or just go ahead and use the cpvc for both hot and cold. These lines will be ran in a basement so there is plenty of room. I considered PEX but the friend wants to go with the cpvc/pvc
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Old 03-11-14, 10:24 PM
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First off, the only cast iron water piping that haws been installed in about the last 100 years is buried utility company piping. The piping in residences has been galvanized steel.

I would try my hardest to convince the friend to go with PEX. CPVC gets really brittle with age and that makes it subject to breakage with the slightest jar. Even the expansion and contraction that occurs from the hot water flowing can cause a stress failure if allowances for the movement is not considered.
Old 03-12-14, 05:39 AM
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Pex will also expand instead of cracking if it ever froze instead of cracking like CPVC.
You can make longer runs with no fittings.
Faster to install.
And no, PVC should not be used for supply's, only waste and vent lines.
Old 03-12-14, 05:47 AM
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I've seen all the lines run with the same material. I assume mainly because you don't need to buy two identical sets of fittings and pipe and run the risk of mixing them up.

I have to second Furd's comment. I can't figure out why anyone would install CPVC these days, especially in a northern climate with the possibility of pipes freezing. A retrofit installation of CPVC will have a lot of joints with each joint being a potential leak point. CPVC is very susceptible to damage from freezing. It can shatter or break if hit or bumped too hard, and it just gets worse with age.

I would pick PEX as a superior piping method especially for a re-plumb. It's flexible so it can easily be snaked around existing house framing, ducting, electrical and drain lines. It's flexible nature also allows you to feed it into joist bay and run it through existing holes. CPVC might require you to cut the pipe into little nibblets to get the rigid sections up into joists. PEX can make long runs without fittings so there are less potential leak points and flow is improved. And finally, PEX is highly tolerant of freezing.
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