Cu to PVC

What the best way to connect Cu plumbing to a PVC supply line. Pipe is 3/4 inch.
Ive fixed this a couple of time and had it professionally done but the screw together joint made of a threaded male PVC adapter and CU male threaded adapter eventually leaks. I am thinking I have an expansion issue here and I am going to try to make an expansion jiont using a loop of flexible copper to connect the two.
Any other opinions are welcome and appreciated.
Thanx Jimmie
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A real plumbing store might have Fernco fittings that size.
If its CPVC, then these things are the nuts. http://www.rd.com/18255/article18255.html Some of the Borg stores carry them. If it is PVC & I were in your shoes I'd be tempted to look for a PVC to CPVC adapter- then use the CPVC fittings.
Jim
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I've used "Male" PVC adapters threaded into "Female" metal adapters (brass, copper, galv, etc.), with a little teflon tape, and they've always held up well for me. Just don't use "Female" plastic adapters (PVC, CPVC, etc.). They tend to crack open along the seam.
In any case, my preference is to use the adapters that have a rubber gasket in the middle. Kind of like a union, with a brass piece on one side and a CPVC piece on the other. I've seen these with threaded brass or sweated copper fittings on the metal side, but don't know if I've seen a plain PVC version or not.
Anthony
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A Sharkbite fitting.
R
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PVC male adaptor > brass coupler > copper male adaptor. Or substitute a union for the coupler.
s

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I have a few feet of Teflon chemical transfer hose (unused). Im going to put barbs on the PVC and Cu and connect them together with the hose. I know this will make a good connection and if there is a problem with expansion and contraction it will take care of that too.
Jimmie
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Elaborate on what you mean by barbs, then on how you are going to put barbs on the PVC and copper. Out of curiousity, did you look into the Sharkbite fitting?
R
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wrote in message

They have them in HD for Cu and PVC.
Sharkbite doesnt work with regular old PVC. At least thats my understanding.
I really like the chemical transfer hose. Its a little pricey at over $5.00 a ft the last I bought but its great for repairs and last forever. I still have a few ft left so it's spent money
Jimmie
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I just wanted to clarify what you meant and make sure you weren't doing something wacky.

Actually, they do work with PVC. Why their specs list only CPVC, I don't know, but as long as the PVC conforms to CTS there's not a problem. If you're a by-the-book guy, you could use all purpose primer and cement to glue on a coupling and piece of CPVC to transition so you could use a Sharkbite. I'm not saying you should, but you could.

Well, the stuff you have on hand is 'free', but you still have to buy and install the barbed fittings you mentioned and you'll have four potential leakage points instead of two.
It's weird how this one joint has been such a problem over the years. Even if there's a fair amount of expansion going on, repairing one joint five times is highly unusual.
R
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wrote in message

Yes very weird. I think its because the actual cause of the problem has never been addressed. I have no direct proof that this is an expansion/contraction problem but its the only thing I can think of that is left. The PVC comes up through a concrete slab from the well, then transistions to Cu then on to 2 (hot and cold) whole house filters. I think its because there is just no wiggle room in the pipe and its pulling loose at the weakest point.
Also to use the Sharkbite I would have to cut off a few inches of PVC and Cu and then add pipe back on to at least one of them to be able to clean things up enough to use the sharkbite. With the hose all I need to do is cut back far enough to get a place I can glue/solder on the barbs
I dont know how you figure I will have 4 leakage points. Ive never had a PVC glued joint or sweated Cu joint that I made leak on me in my life. I wish I could say the same for the combination of the two.
One thing I have learned about threading metal in to PVC is to run a tap into the PVC and use pipe dope instead of PTFE tape.
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and a copper adapter with a female thread. Threading a copper male fitting into a PVC female adapter is likely to either split the PVC female adapter or to leak and is not permitted by some codes/inspectors. Tape or sealer can reduce the possibility of leaking.
Don Young
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Even simpler for us shameless DIY-ers is to use a rubber coupling that has a mechanical pipe-clamp at each end and doesn't care if the pipe is copper or plastic. This works for the big pipes, too, for the black iron problems.
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supply
Jimmie
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Don, that what I got now and eventually it leaks. I think its due to expansion and contraction pulling and pushing on the PVC/Cu joint.
The house wasw built in 74 and I know it has started leaking at least 5 time since 1990. My wife says it been a regular problem since the house was built. Its in a utility room and doesnt leak bad enough to cause any damage as long as you can monitor it.
Jimmie
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Well, I got down to Fl this week and fixed the plumbing using my hose connection. The water had been off all winter and the plumbing was at room temp which Friday was about 85F. After the repair I checked the distance between the hose clamps on each end of the hose then turned on the water. After leting the water run for a few minutes I checked the distance again and the clamps had moved apart by almost an 1/8 of an inch. This is making me feel very warm and fuzzy that my diagnosis was right. Even if I was dead wrong about why I dont think I will ever have another problem with this connection
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