Pex bending

Discussion in 'General Plumbing Help' started by edee_em, May 22, 2019.

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  1. May 22, 2019 #1

    edee_em

    edee_em

    edee_em

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    I understand that the maximum bending radius for 1/2" pex is 5". In my plan for a project, I want to run pex from a shutoff valve and then have it double back to supply a spigot outside (the copper supply is not in the ideal location). This would all happen within a joist bay of about 14 1/2". Typing it out is leading me to think it might be too tight given the joists are 2x8" and a 5" radius means a diameter of 10". Regardless, I'm wondering if anyone has had any experience turning pex back in tight spots and if there are other solutions my limited experience is hiding from me. I am aware of one solution to use 90* connectors but I want to create the fewest connection points at the least cost. That would be the last resort (if not maybe the only resort). Thanks
     
  2. May 23, 2019 #2

    FishScreener

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    Post a picture of what your doing. I can’t picture what you’re trying to accomplish. So, I can’t help you get there.
     
  3. May 23, 2019 #3

    edee_em

    edee_em

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    pex.png
    No photo. Hope this answers any questions (side view)
     
    Last edited: May 23, 2019
  4. May 23, 2019 #4

    TomFOhio

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    If your concerned about bending it and kinking it you could use one of these pex 90 degree brackets. pex bend.png
     
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  5. May 23, 2019 #5

    Mikey

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    You're mostly right, but 5" is the minimum bending radius, not the maximum. Your sketch doesn't show dimensions, but it looks like there's plenty of room to make the bend(s) required. I would use the brackets.
     
  6. May 23, 2019 #6

    edee_em

    edee_em

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    I meant "minimum" in that the maximum you can bend it is 5". For example, I wouldn't be able to bend it to a 3" radius. Did I get that right? The joists are 2x8" and the joist bay I'm concerned about is 14 1/2" wide. About those turn brackets, would one do it or would you need another to turn it back around? Maybe it's time to sweat some copper!!
     
  7. May 23, 2019 #7

    TomFOhio

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    Look online at pex 90 degree brackets. Maybe there are some closer ones.
     
  8. May 23, 2019 #8

    Mikey

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    You've got it right. Bending 180° as much as is allowed (5" radius) results in a U-shaped pipe with an inside dimension of 10" along the parallel section; adding 1 1/4" for the pipe diameter on both legs gives 11 1/4", so this bent pipe will fit in between the 2 joists with 3 1/4" to spare. Looked at another way, you could run the pipe down one joist, bend it 180° and run it back along the other joist, and your bend radius would be 6 5/8", well above the minimum allowed. Don't sweat it :).
     
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  9. May 24, 2019 #9

    Geofd

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    im wondering if you could put the section of pex you want to bend in hot water let it sit then bend it around something round close to the radius???you need not sure if that is even a method that could be used
     
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  10. May 24, 2019 #10

    Diehard

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    Clipboard01.jpg
     
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  11. May 24, 2019 #11

    FishScreener

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    You can add nineties. So, I’m not sure why you have a problem.
     
  12. May 24, 2019 #12

    Diehard

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    OP had said, "I am aware of one solution to use 90* connectors but I want to create the fewest connection points at the least cost."
    I say just try to do whatever he's trying to do(I still don't have a good picture of the problem). If it's a no go then throw a 90 in there.
     
  13. May 24, 2019 #13

    WyrTwister

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    Were it me , I would consider building a manifold w/ an outlet to each " device " .

    Wyr
    God bless
     
  14. May 24, 2019 #14

    Diehard

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    He appears to be talking about one device.
     
  15. May 24, 2019 #15

    WyrTwister

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    Sorry . :-(

    Wyr
    God bless
     
  16. May 25, 2019 #16

    edee_em

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    You don't like my artwork Diehard???;) Or by "picture" do you mean understanding of what I'm trying to do?
    I have been reading quite a bit from you experienced types and many say 90s slow the flow. I would need 2 90s essentially back to back to create the 180 turn to get the pipe going in the direction I need to the outside hose bib. I could use a 180 return bend 1/2" fitting but I haven't found one locally, as of yet. That's why I wanted to see if a full piece of pex could be used here as that would eliminate the 90s. You feel differently about the effect of 90s?
     
  17. May 25, 2019 #17

    Mikey

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    If you Google something like "flow restriction through 90 degree elbow" you'll find millions of references. This has been studied to death, but I think (caveat: I'm no expert) the bottom line is: at the flows and pressures we deal with in residential plumbing, you won't see much difference. But clearly the radius does matter, so the larger you can make the radius, the better.
     
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  18. May 25, 2019 #18

    chiraldude

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    If you really want maximum flow just go to 3/4 pipe instead. You could put a bunch of 90's in and not notice any restriction in flow.
     
  19. May 25, 2019 #19

    edee_em

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    Would going to 3/4" make a difference when entire house is 1/2" (to fixtures) and in the last two feet as is the case here to my garage spigot?
     
  20. May 25, 2019 #20

    chiraldude

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    What you are saying is that you have no choice but to tap into 1/2" pipe for this run to the garage? You are correct that the 1/2" pipe will limit the flow but a long run of 3/4 would have better flow that 1/2. However, it remains to be seen whether you would notice the difference at the spigot.
    What are you trying to accomplish? Do you know what the maximum flow rate of your house is? If your supply can only give you 3.5 gpm, you can't get 4 gpm at the spigot no matter what size of pipe you use. What is the pressure of your supply? That also plays into what the max flow out the spigot can be, just as much as pipe diameter.
     

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