Just changed out the main supply line valve in my house, and it ended up slipping the same day. Thankfully, it did not come apart. I took it apart and reinstalled, and it's holding for now, but I am wondering what would be recommended for a permanent fix in the this situation. One end is 3/4" copper and the other end (coming from the street) looks like 3/4" PEX, and I used compression couplings on both ends. On my first try, I didn't have blocking, and did not tighten the compression fittings as tight as they could be. It held OK at first, but probably slipped when we had laundry and shower going at the same time. I would attach a photo, if I could figure out how to do it.

Did you use a stainless steel insert on the pex side of the compression fitting?

I would sweat a brass pex adapter onto the copper and crimp the pex to it.

depending on the type of compression coupling you used, it probably stated that it CANNOT resist "axial movement", in other words it can slip apart if the pipes are not restrained somehow.

Here's a few photos of the repair:



Lower connection:



Upper connection:





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Author: JLNY (NY):

"Did you use a stainless steel insert on the pex side of the compression fitting?"
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No, no insert. I'm thinking, since you're asking, I should have added one.

Author: hj (AZ):

"depending on the type of compression coupling you used, it probably stated that it CANNOT resist "axial movement", in other words it can slip apart if the pipes are not restrained somehow."
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You're right on. When it slipped, the CVPC slipped mostly out of the upper connection, and the PEX bowed toward the blocking you see in the photos.

Author: North Carolina Plumber (NC):

"I would sweat a brass pex adapter onto the copper and crimp the pex to it."
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I'd prefer not to have to buy a crimper kit, for this one job. Would a Sharkbite coupling work with PEX on one side and copper other?

Yes, just be sure to use the supplied stiffener inside the pex pipe.

The PVC pipe and valves may not pass inspection if you have to have it inspected. Why not use regular valves made for for PEX ?

1) PVC compression couplings must NEVER be used inside walls.

2) PVC compression couplings must NEVER be used inside a house.

To me from your pictures so far this is a disaster waiting to happen and I wonder that when you have a blowout and massive flooding if your insurance company would even pay since I can't imagine any code anywhere in the U.S. allowing what you are currently showing.



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"Author: vic (CA)

1) PVC compression couplings must NEVER be used inside walls.

2) PVC compression couplings must NEVER be used inside a house.

To me from your pictures so far this is a disaster waiting to happen and I wonder that when you have a blowout and massive flooding if your insurance company would even pay since I can't imagine any code anywhere in the U.S. allowing what you are currently showing."

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That's what was there when I bought the place, and it held for at least the 5 1/2 years I've been here (and without any blocking). Only reason I changed it all out, was because the shutoff valve wasn't closing all the way. But thanks for your input. Really trying to gain insight on permanent fix options.



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Here's the final state:





No more potential inspection failure, or disaster waiting to happen.





Thanks for everyone's comments.



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