Repiping PB to PEX from slab to fixture... details?

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by miamicanes, Mar 8, 2013.

  1. miamicanes

    miamicanes New Member

    Messages:
    103
    Location:
    Pembroke Pines, FL
    Tomorrow, I'm planning to replace the polybutylene pipes for 3 fixtures. At the moment, the PB emerges from the slab parallel to a steel marker conduit (about 1/2" away), connects to another run of PB via a plastic fitting (whose replacement is the main purpose of tomorrow's project), then the second piece of PB gets unceremoniously bent, runs through the wall, and ends up crimped to a plastic valve.

    I'm looking for suggestions as to the best specific way to get from the slab-PB to the fixture. Keep in mind that I have high intelligence, but terrible dexterity and zero experience with anything besides Sharkbite (however, the Sharkbite fittings elsewhere in the house have been in place now for more than 2 years, with zero leakage).

    As a practical matter, all new piping has to be PEX. Well, ok... copper might be negotiable, but I'd have to use Sharkbite push fittings because soldering is out of the question, and compression fittings that have to be "tight enough... but not TOO tight" scare the bejesus out of me

    Decision 1: crimped copper rings, or pinched stainless-steel clamps (both presumably Sharkbite, both from Home Depot).

    I'm leaning towards clamps, simply because the PB (after I cut away the old plastic fitting) will be shorter than the steel marker conduit that's literally a half-inch away, and I really don't think there will be room TO crimp. The fact that clamping involves pinching the ring shut from the front seems to make it an easy decision.

    Why not Sharkbite push fittings? Because I'm ultimately going to be replacing about 20-30 plastic couplings and fittings in my quest (Qest? Ok, bad pun...) to abolish all the above-slab PB from my house (or at least, all the crimped plastic connectors/fittings, and accessible pipe runs as the opportunity presents itself over the next couple of years... bathroom now, kitchen later). Behind the kitchen wall, there's a manifold with at least 8 connections. AFAIK, there's no such thing as a 100%-Sharkbite manifold, and at some point I'm going to HAVE to crimp/clamp at least the manifold, so I might as well get the tool now and save ~25-50% on all the connectors in the meantime.

    possible complication: The Sharkbite PB-PEX adapter includes a black and a copper crimp ring. Can I toss both in the trash (or a box for future hoarding), and use stainless steel clamps instead? Or is there some technical reason why I'd HAVE to crimp the PB end?

    Decision 2: PB-PEX adapter to valve.

    Idea #1: PEX through right-angle plastic mounting bracket that maintains precise curvature and gives me a hole I can use to screw the bracket to a stud and somewhat immobilize the bracket, the out a hole in the wall & through the escutcheon, then directly clamped onto the back of a right-angle valve.

    Idea #2: ~4 inches of PEX to a Sharkbite copper rough-in tube. Copper tube through the wall and escutcheon, terminating at a push-on Copper-CPVC-PEX right-angle valve.

    Idea #3: ~4 inches of PEX up to a Sharkbite 1/2" FIP mount that's bolted to a stud, with 1/2" 3-4"steel pipe screwed into the Sharkbite FIP mount, through the wall and escutcheon, and terminating at a valve screwed onto the ~3-4" pipe.

    Idea #3 seems to be the most mechanically-solid, but I still have nightmares remembering how hard it was to get the pipes and valves screwed together tightly enough to not leak when I plumbed the master bath this way a couple of years ago. To be honest, I still don't completely trust them to never, ever leak a single drop, and I probably never will. This is also the most expensive option (with brushed nickel-like stainless steel pipe and valve, it'll cost me at least $50-100 more than the other two options by the time I'm done with the sink and toilet). I still remember seeing the plumber I hired 2 weeks ago to fix my original PB leak turn pale when he saw the antiqued-brass ones I used in the master bath & say, "Jesus Christ, those are expensive pipes and valves. You really didn't have to go that far overboard".

    Idea #1 pretty much replicates the current setup, but with PEX instead of PB.

    Idea #2 is basically the compromise between the cheapest and most expensive extremes, but would also cost me about $10-15 more per valve to do than idea #1, and I'm doing 3 valves tomorrow (1 toilet, 2 sink). If I'm going to spend $30-50 more, I'd like to feel like there was at least some meaningful reason for doing so. If I do #3, at least I'll have nice-looking brushed nickel-finish stainless steel pipes sticking out of the wall and terminating at similarly-pretty valves. If I do #2, it's going to look almost as cheap as #1, but cost almost as much as #3.

    (I'm going to go lay out the parts I have now and take some pics to illustrate this with)

    Attached Files:

    Last edited: Mar 8, 2013
  2. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,134
    Location:
    New England
    #3, don't use steel! If you go this route, use a brass nipple otherwise down the line, you'll be cursing when the water starts to show up and make rust stains on things. Soldering isn't really all that bad. For probably $10 in extra fittings and some sections of pipe, you can practice a bit to get the feel of it. You can use compression fittings on pex, but you need to either pick one up in a package for pex, or pick up the SS ferrules that reinforce the pipe so you can compress the ring. It's pretty hard to over tighten a compression fitting...it certainly can be done, but it isn't catastrophic, it just means that you can't reuse that bit of pipe since you will put a crimp in it. All of the valves also come with a crimp barb for pex on them if you decide to go that route. If a compression fitting is tight enough, you won't be able to turn it or pull it off. If it's too loose, it will leak. There's room in between. There is also a system to crimp copper, but the tool is fairly expensive. You use special fittings.

    [​IMG]

    The gray end of the Sharbite if for PB
    Last edited by a moderator: Nov 1, 2013
  3. miamicanes

    miamicanes New Member

    Messages:
    103
    Location:
    Pembroke Pines, FL
    Is there any specific advantage to traditional compression fittings vs push-on (when using copper), besides the fact that they're a buck or two cheaper than Sharkbite push-on friction fittings?

    I have to admit that I really dread the thought of option #3. I had a HORRIBLE time 2 years ago getting the pipes and valves screwed together tightly enough to not leak. Even after wrapping the threads with Teflon tape & tightening them so hard I managed to scratch the antiqued brass finish on one of them through two layers of bath towels with the wrench's teeth (and was afraid I was going to end up bending the valve or worse), I still saw 2 or 3 drops of water bead up on them at various times during the first month or so after I installed them. I haven't seen it happen since then, but I'll probably never trust them completely because of that.

    Getting to the more urgent issue for tomorrow morning, is there any problem with tossing the black and copper ring that comes with the PB-PEX adapter fitting, and using Sharkbite clamp rings instead?

    Attached Files:

  4. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,815
    Location:
    Cave Creek, Arizona
    As you can see, there are different fittings and clamps for PB and PEX. You need a PB to PEX coupling, (which that one MAY be but it does not seem to be specific about that), AND the two different rings that come with it to make the transition.
  5. miamicanes

    miamicanes New Member

    Messages:
    103
    Location:
    Pembroke Pines, FL
    The fitting is definitely for joining PB to PEX.. the package is hard to read, but you can sort of make out the "1/2" x 1/2" PB Polybutylene Adapter" printed on it in the last pic I posted (next to the clamping tool).

    I can't think of any blatant technical reason why clamps shouldn't work for both the PB and PEX end (it looks like the clamps ratchet closed a tiny bit at a time, so even if the PB crimp ring is a slightly-different diameter than the PEX crimp ring, the clamp should be able to accommodate both), as long as the brass fitting itself takes the PB's slightly larger interior diameter into account... but as far as I can tell, the manufacturer is officially silent on the topic.

    The only thing I can sort of think of is that clamps *might* be applied under higher pressure & might stress out the PB more... but then again, for all I know, maybe the crimped rings stress it out more.

    Truth be told, I'd actually prefer to use the push-on friction fittings for most of the pb-pex attachments, but unfortunately most of the PB is ALSO covered with splattered-on polyurethane insulation, so there's literally no way I could give the fitting a smooth, flawless, smooth and clean surface to grip without pulling out sandpaper & probably making matters worse.
  6. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,815
    Location:
    Cave Creek, Arizona
    The same tool crimps both PEX and pb, which is why the metals are different thicknesses. I saw that it was a "pb adapter" but was not sure if the meant it was a "Pex to pb" adapter.
  7. miamicanes

    miamicanes New Member

    Messages:
    103
    Location:
    Pembroke Pines, FL
    ^^^ Right, but I'm not talking about CRIMPING. I'm talking about using the OTHER tool/method sold by Home Depot, which consists of little ratcheting rings with a slightly different tool that appears to pinch them together from one side (see my last pic for the specific tool and rings I'm talking about).

    From last night's research, here's what I learned (feel free to disagree):

    * All of Sharkbite's non-friction-grip products are just rebranded products from others. Apparently, the clamps are from a company named "Otiker"

    * Clamp pluses: easier to install when working room is limited, less likely to suffer from corrosion than brass crimp rings, and in theory, less that can actually go wrong with the installation itself.

    * Clamp minuses: Installing them is a matter of experience and faith, because there's no equivalent to crimp rings' "go/no-go" gauges. For DIY, this means it's basically "faith-based plumbing". On the other hand, so are push-on friction fittings.

    ----------------------

    Revisiting the matter of mechanical stress on valve stubs, I'm totally delighted right now, because I tripped over a product that's available from Lowe's and seems to solve the problem perfectly: PexRite 701 stub-out clamps (http://www.holdrite.com/products/pex_supports/pexrite/701). Finally. I knew *somebody* had to make something to properly secure PEX and copper stub-outs so they don't just limply hang out of the wall the way the original PB ones did :)
  8. hj

    hj Moderator & Master Plumber Staff Member

    Messages:
    26,815
    Location:
    Cave Creek, Arizona
    we call those "cinch" rings and they would NOT be suitable for the pb side of the connection. The "holdrites" are ONE way to do it but NOT the way I, or many plumbers, would so it. There was NO reason why the pb had to "limply hang out of the wall" either, other than a lazy, cheap, or incompetent, (possibly all three), installer put them in.
    Last edited: Mar 10, 2013
  9. miamicanes

    miamicanes New Member

    Messages:
    103
    Location:
    Pembroke Pines, FL
    Do you happen to know why they (the clamp-on Sharkbite-rebranded-Oetiker rings) wouldn't be suitable for the polybutylene side of the connection?

    Here's the thing... I have two realistic options I'm aware of, neither of which is perfect:

    1. Use the clamps on both the PB and PEX ends of the adapter.

    2. Use Sharkbite push-on fittings... but remember, the outside surface of the pipe has splattered-on polyurethane foam insulation that I'll never be able to completely remove (at least, not without sandpaper, which would probably make matters worse). In all honesty, if a bit of crusted-on foam on the exterior is no big deal, the push-on fittings are my preferred option for the PB-PEX adapters, just because it seems like they'd put the least possible stress on the PB that remains, and hopefully avoid causing future leaks due to stress fractures at the crimp/clamp point.

    Even if I went out and bought a crimping tool so I could crimp the black ring onto the PB end instead of using a clamp, the PB is roughly a 4-inch stub poking out of the concrete, literally 1/4" away from a 1/2" steel electrical conduit that was apparently put there for support or positioning. The only way I'll be able to get a crimping tool into there is if I cut down the steel stub next to it, and there's a good chance that I'll end up nicking the PB with the hacksaw blade along the way. Well, OK, I'm sure I could try bending the PB, but I'm trying to stress it out as little as possible.
    Last edited: Mar 12, 2013
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