Re: Compression supply valves are dripping
Posted by Gary Slusser on March 15, 2003 at 21:39:18:
In response to Re: Compression supply valves are dripping
: I'm no expert, but the book "The Complete Guide To Home Plumbing" in the Black & Decker series says that compression fittings are not recommended with type L rigid copper (page 44). Compression fittings can be used with type M rigid copper and type L & K flexible copper. If you are using rigid type L copper, this may explain why they leak. Rigid type L does not bend enough for the compression fitting to work.

: : I replumbed my house about 15 months ago using "L" grade copper. Under the sinks I used supply valves with compression fittings (to the 1/2" copper). Since then at least half of those valves have dripped at one time or another at the 1/2" compression fitting. None of the 150 or so sweat joints have failed.

: : When one does leak I first try tightening - if that doesn't work I remove it and reinstall it and that usually works - at least for awhile.

: : Is it possible that these valves are just crap? I got them at Menards. I'm now ready to go to sweated valves.

: : I hate to have to cut-off any of the pipe stubs - is it possible/advisable to sweat new valves in place without removing the compression ring (that is - sweat the valve on the pipe stub that extends past the compression ring)?

: : Thoughts?

I've used many brass comppression fittings and many are on L copper and none have ever leaked. I think the main cause of leaks is thinking that they have to be tightened REAL tight or they'll leak, and over tightening causes leaks. If you try to take the fitting off and the ring doesn't want to, IMO the fitting was overtightened.

If one is leaking you must shut off the water and relieve the pressure before attempting to tighten the fitting, and only tighten it about a quarter to half turn and see if it continues to leak. If it does repeat the process until it doesn't. That's how I install them and it's always worked for me. I've only had one call for a leak in over 10 years. No dope or tape either.

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