Cut out a CPVC valve and replaced with a PEX-A valve today. I could barely get the last connection on. What did I do wrong?

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JHCL1990

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So what I had to do was cut a stretch of CPVC pipe above and below the valve, then I had to glue in CPVC x PEX-A adapters, then attach the PEX-A pipe to the adapters and new valve. Thing is, when I was attaching the last (PEX) connection, I had to separate the pipes enough to slip the PEX pipe onto the fitting and it required me to pull the entire stretch of pipe sideways. So far, everything SEEMS good, but I was pretty concerned when doing this because I was thinking I could damage/break the pipe--especially considering it's CPVC (except for the small stretch I replaced with PEX-A).

This is essentially what happened to me (except the connection I had to make was PEX-A):


Is there any better way to do this, or is it just a risk you have to take? I know there are repair couplings for PVC, but I don't know of anything like that for CPVC or PEX...
 

JohnCT

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I had to separate the pipes enough to slip the PEX pipe onto the fitting and it required me to pull the entire stretch of pipe sideways.

You could safely heat PEX A with a heat gun, and as long as you don't scorch it, heat it until it becomes transparent. At that point, it's as flexible as silicone.

The other thing you could have done is to use a CPVC slip coupling and not used PEX at all.

John
 

wwhitney

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Is there any better way to do this?
If you are dealing with, say, a 14" length of exposed straight pipe, fixed at both ends, with the rest of the run inaccessible (or maybe fixed by tees), then that is a difficult problem. Some options that haven't been mentioned so far would be to use one or two unions (troublesome) or a left/right coupling (not sure if those are made for potable water). The Sharkbite repair coupling would be the simplest solution.

But if you have access to a longer run of piping, you can make your job easier by replacing a longer length. Particular if one end goes to an elbow, then you can replace the elbow as well, and the new makeup should be pretty straight forward.

Cheers, Wayne
 

JHCL1990

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You could safely heat PEX A with a heat gun, and as long as you don't scorch it, heat it until it becomes transparent. At that point, it's as flexible as silicone.

The other thing you could have done is to use a CPVC slip coupling and not used PEX at all.

Johno
Could heating the PEX like that mess up the expansion? In this case I would have had to heat up the pipe until it was soft enough to bend, then use the expansion tool on the end to insert it into the fitting.
 

JohnCT

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Could heating the PEX like that mess up the expansion? In this case I would have had to heat up the pipe until it was soft enough to bend, then use the expansion tool on the end to insert it into the fitting.

I was referring to heating the pipe in the middle of the run, not the whole pipe - once it's heated to the point of being transparent, it's a flexible as a wet noodle. So if you have a short stiff run of PEX A that you can't flex to fit between two rigid connections, you can heat the A (again, don't scorch) and while it's still transparent, expand the fitting end of the A as usual and connect. The heated middle section will "solidify" in a couple of minutes after you made the connection at the end.


John
 

JHCL1990

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I was referring to heating the pipe in the middle of the run, not the whole pipe - once it's heated to the point of being transparent, it's a flexible as a wet noodle. So if you have a short stiff run of PEX A that you can't flex to fit between two rigid connections, you can heat the A (again, don't scorch) and while it's still transparent, expand the fitting end of the A as usual and connect. The heated middle section will "solidify" in a couple of minutes after you made the connection at the end.


John
I see--thanks!
 

John Gayewski

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I think you did it right. Muscle the pex into submission. You can even kink the pex A. After it's kinked you can heat it and it returns to its shape.
 
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