Compression fittings for copper water supply line?

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  • Gator95
    Established Member
    • Jan 2008
    • 322
    • Atlanta GA
    • Ridgid 3660

    Compression fittings for copper water supply line?

    Quick question: how reliable and non-leaky are compression fittings for shut-off valves? I've heard different things from different people. This would be for installing three shutoff valves for a toilet and the hot and cold sink water supply.

    The supply copper pipe is coming out of the wall, current 30YO supply valves are soldered on to it. Once I cut the old valves off, I'd be kinda close to the drywall. Is there a significantly higher chance of a leak using compression fittings here rather than soldered on fittings? Talking about the type where you put the nut on the copper pipe first, then put the compressible copper sleeve on the pipe, and screw the nut into the rest of the fitting, trapping and compressing the copper sleeve.
  • cgallery
    Veteran Member
    • Sep 2004
    • 4503
    • Milwaukee, WI
    • BT3K

    #2
    I had a plumber handle the shutoffs on my toilet and sink when I did that bathroom. He used German-made shutoffs with compression fittings. They were very high-quality, 1/4-turn units that don't look like the type that will fall apart the first time I need to use them.

    But I was (and am) concerned about the compression connection. I think solder would be more reliable, but he was somewhat dismissive of that concern. I will be interested in what others say on this topic.

    Comment

    • Hellrazor
      Veteran Member
      • Dec 2003
      • 2091
      • Abyss, PA
      • Ridgid R4512

      #3
      If done properly they will be fine.

      Comment

      • JeffG78
        Established Member
        • Jan 2007
        • 385
        • Northville, Michigan - a Detroit suburb
        • BT3100

        #4
        I learned a valuable lesson while using compression fittings several years ago.

        I was plumbing a double bowl vanity and was using 3/8" soft copper with various compression fittings. Between the two sinks, I had about 20 elbow, T and sink connections to make. I had used compression fittings many times before that with great success, but I could NOT get these to stop leaking. I tried everything I could think of, but one joint or another would leak either right away or within a day or two. I decided to go to an old neighborhood hardware store across town and look around for different supplies. I wasn't sure what I would find, but I set off to the store. Once there, everything looked just like what I had been using. Finally, I explained the problem to the guy behind the counter and he stopped me before I could even finish. He laughed and said that he knew I bought my copper at HD. After I nodded my head up and down, he said that HD copper is famous for being thinner than spec and will not seal properly with compression fittings. I bought a box of ferrules and a roll of copper from him and replaced everything I had done. Immediately, I could tell they were going together better and I have had zero leaks after over five years.

        So, compression fittings are fine as long as you buy quality copper pipe and tighten the nuts properly.

        Comment

        • Charlie R
          Forum Newbie
          • Jun 2007
          • 90

          #5
          I've always been able to seal a leaking compression fitting with Permatex #2 sealer. It's black, sticky, and non hardening. Comes in a small tube at hardware or automotive stores. Keep it off your fingers as it is hard to get off. When reopening a tube where the cap won't turn (sealed shut) heat the cap with a match and loosen it with a pliers as the cap gets too hot to hold. The stuff lasts forever and works every time. It also comes in a hard setting formulation (#1).

          Comment

          • LinuxRandal
            Veteran Member
            • Feb 2005
            • 4889
            • Independence, MO, USA.
            • bt3100

            #6
            I've had mixed luck with compression fittings. I bought some that I found had a burl on the ferral, and they didn't seat right. On the other hand, for vertical lines that are next to impossible for the bread/solder trick, I think they are great.


            That said, I have had mulitple people rave to me about the new fittings that just snap/lock on. I don't know what they are called, but they are about $6 a fitting for non shutoff ones, but they supposably have shut off ones.
            She couldn't tell the difference between the escape pod, and the bathroom. We had to go back for her.........................Twice.

            Comment

            • Mr__Bill
              Veteran Member
              • May 2007
              • 2096
              • Tacoma, WA
              • BT3000

              #7
              My question is, why not just heat the current shutoff and remove it from the pipe and solder a new on on?

              One of the things with compression fittings is that pipe that it's going on must be perfectly round with no scratches, flats or other imperfections that will make the compression ring fail to seat on the pipe. When the ring properly seats and seals the fitting is very reliable and easy to take apart if necessary and then put back together with just wrenches.

              Bill,

              Comment

              • cabinetman
                Gone but not Forgotten RIP
                • Jun 2006
                • 15218
                • So. Florida
                • Delta

                #8
                My suggestion is to heat and remove the soldered on fitting. That will give you as much pipe as there is there to work with. Abrade the old pipe smooth. Wipe the pipe clean. The fitting should be placed on a good section. The brass ferrule should slip snugly on the old pipe. As you tighten up the compression, go very slowly. Leaks can be caused by over tightening. I usually get them snug, and keep giving a quarter turn or so until it stops leaking.
                .

                Comment

                • chrisk
                  Forum Newbie
                  • Jan 2008
                  • 61
                  • Mankato, MN
                  • Craftsman Professional 21829

                  #9
                  I've had good luck with compression fittings. None of the fixtures in my house had shutoffs when I bought it, so I put at least ten of compression, 1/4 turn shutoffs on last summer doing various renovations.

                  Many of the same things that would cause a leaky compression fitting (bent pipe, rough/dirty metal, burs,etc.) would also cause as much if not more of an issue with soldering. Plus you have to look at how comfortable you are with soldering, especially in a tight space. I only solder fittings like elbows, tees, and such.

                  Comment

                  • chopnhack
                    Veteran Member
                    • Oct 2006
                    • 3779
                    • Florida
                    • Ryobi BT3100

                    #10
                    Never a problem, but do as C-man said and save the pipe.
                    I think in straight lines, but dream in curves

                    Comment

                    • master53yoda
                      Established Member
                      • Oct 2008
                      • 456
                      • Spokane Washington
                      • bt 3000 2 of them and a shopsmith ( but not for the tablesaw part)

                      #11
                      only thing I do with compression fittings that know one has brought up is use a little mineral or olive oil on the nut, this goes for flare fittings as well.

                      Good luck
                      Art

                      If you don't want to know, Don't ask

                      If I could come back as anyone one in history, It would be the man I could have been and wasn't....

                      Comment

                      • DaveStL
                        Established Member
                        • Jan 2006
                        • 100
                        • St Louis, MO, USA.
                        • Jet 10: Xacta RT

                        #12
                        Compression Fittings

                        The 1/4-turn valves should be more reliable, but they're typically straight-through, not right-angle. Also, something to remember about compression fittings is they distort the pipe and if you need to replace them you must cut the pipe back, so if you're already near the wall and you have a problem w/ this install or later, it will be a much bigger deal to fix.

                        What I've done is solder on an ell and a piece of "L" gauge pipe (thicher than the "M" many folks use these days, and thus better for compression fittings), then put on the 1/4-turn valve w/ compression fitting. IIRC, the valve was 5/8 compression by 3/8 compression, so the braided hose to the fixture connected right up to the valve. Even if the compression joint needs replacing later, all of the pipe stub at the wall is still there.

                        Dave

                        Comment

                        • Russianwolf
                          Veteran Member
                          • Jan 2004
                          • 3152
                          • Martinsburg, WV, USA.
                          • One of them there Toy saws

                          #13
                          I had to do an emergency repair in the shop yesterday. The pipe for one of the yard spigots bust such that when I opened the valve it started spraying and closing the valve didn't stop it.

                          I bought everything needed to cap the line (temp fix) for less than $25 including a small propane torch. It is not difficult at all to solder/unsolder copper lines. If you have a space issue, try to squeeze a piece of cement board or metal sheeting between the fitting and the wall and you should be fine while you do it.

                          don't forget to buy flux if you do decide to solder it. the flux make the solder draw into the joint regardless if it has to go up or down.
                          Mike
                          Lakota's Dad

                          If at first you don't succeed, deny you were trying in the first place.

                          Comment

                          • RayintheUK
                            Veteran Member
                            • Sep 2003
                            • 1792
                            • Crowborough, East Sussex, United Kingdom.
                            • Ryobi BT3000

                            #14
                            I've always used "Water Hawk" on compression fittings and only ever nipped them up just enough so that they don't leak. That way, if you've got to dis-assemble, you can re-tighten a little more on re-assembly, as you've still got some compression left in the olive. Most others I've seen tighten the nuts as though they're trying to cap Mount Vesuvius!

                            Ray
                            Did I offend you? Click here.

                            Comment

                            • Richard in Smithville
                              Veteran Member
                              • Oct 2006
                              • 3014
                              • On the TARDIS
                              • BT 3100

                              #15
                              If there is still any question about how reliable a compression fitting is.....FIL use to work for the water dept and they used big comp fittings on the mains.
                              From the "deep south" part of Canada

                              Richard in Smithville

                              http://richardspensandthings.blogspot.com/

                              Comment

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