Help with PEX pipe sizing

Discussion in 'Plumbing Forum, Professional & DIY Advice' started by LesP, May 10, 2011.

  1. LesP

    LesP New Member

    Messages:
    3
    Location:
    PNW
    Hoping you smart folks can help me plan my plumbing upgrade correctly. I am planning to use Uponor Wirsbo PEX and EP (plastic) fittings.

    I have attached a diagram of the remodeled kitchen, laundry, and hose bib that will need new supply lines. The line currently supplying the whole house is 3/4" galvanized steel and the fixture branches (everything past the water heater) are 1/2".

    Eventually I will be swapping out all the galvanized pipe for PEX but for now I am just working on the kitchen and laundry. Should the new PEX trunks be 3/4" reducing down to 1/2" at the Tee supplying the fixture? Or should I just use 1/2" pipe throughout?

    These lines will be running in the floor joist bays so I will have to make both horizontal and vertical turns. When is it appropriate to bend the PEX and when is it necessary to install an elbow?

    At the fixture, is it better to use a copper stub ell or the Wirsbo drop ear bend support? (I don't have much experience sweating copper!)

    Thanks in advance for your help!

    Attached Files:

  2. Terry

    Terry Administrator Staff Member

    Messages:
    15,443
    Location:
    Bothell, Washington
    No more then two plumbing fixtures on 1/2" is a good rule.

    An ice maker doesn't count as one, it uses so little water.
  3. jadnashua

    jadnashua Retired Defense Industry Engineer xxx

    Messages:
    22,353
    Location:
    New England
    Each type of tubing will list the minimum radius bend it can support. The larger the tubing, the larger the radius. Usually, the bend supports will provide you with a neater corner at about the minimum radius without kinking. One of the beauties of pex is that it does bend, and you can minimize the fittings required. So, go with that. They do make preformed stubouts with a pex fitting, so no soldering required. It does work best if you use the support bars, and the stubout is soldered to that. Makes for a neat, strong supply for your shutoffs and supplies to the fixture.
  4. LesP

    LesP New Member

    Messages:
    3
    Location:
    PNW
    PEX plan

    Thanks for the quick input. Here's my new plan, with more details. Please let me know if I have the pipe size and fittings right. FYI: the distance to the furthest fixture is about 30 ft away.

    I thought about using Uponor's remote manifolds but for so few fixtures it didn't seem to be helpful. Any thoughts to the contrary?

    Thanks again! Layout3.jpg
  5. LesP

    LesP New Member

    Messages:
    3
    Location:
    PNW
    Bueller? Bueller?
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