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Newbie PEX manifold questions...

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  • Newbie PEX manifold questions...

    Plumbing Pros,

    So this summer we bought a big fixer-upper of a house. I'm pretty good with traditional sweated copper, but given the modern price and all the rave reviews I read about PEX, I'm thinking it's PEX all the way as I re-plumb the 4 1/2 baths of this 100 year old house. Looks like there has been some fixes over the years (all the supply is now copper for the most part, and parts of the DWV system here and there are PVC although come copper and cast iron too. That's just a bit of background, here are my real questions...

    1) PEX manifold
    I have what looks like a 1" copper supply coming into my basement. My plan is to tee off of that to a 1" handmade "loop" type PEX manifold with approximately 8 3/4" PEX outlets, each feeding one of the bathrooms, then kitchen, laundry, and an extra for future. I'm under the impression that if I'm planning out using 3/4" PEX outputs, then 1" PEX manifold would be ideal? I realize it could be overkill, but no reason not to right? Even if the supply line were 3/4" COPPER, would it make sense to use the 1" PEX (since the 3/4" PEX has a smaller I.D.?)

    2) 3/4 Feed to each bathroom
    On our previous house, I had a 3/4" copper feed supplying the master bathroom which had a multi-head shower (3), jetted tub, as well as sink and toilet. It seemed ample, but now because of the reduced thickness of 3/4" PEX over copper, I'm a bit concerned. I'm guessing with today's water "sipping" valves, 3/4" PEX supply will be plenty anyway - is that true? I'm planning on running the 3/4 lines up from the manifold mentioned above and either putting in remote manifolds, or just teeing off with 1/2 PEX to sinks/toilet/etc - probably keeping 3/4" PEX going to the thermostatic valve of any multi-head show. Will 3/4" PEX be adequate?

    3) Elevation.
    2 of the 4.5 bathrooms in this house are on the 3rd floor - ceilings are probably about 10' high, so it's a good 30' or so from mid-basement to mid-3rd floor. How much will that effect pressure/volume?

    4) PEX IS good right?
    My wife has concerns about compression rings popping, leaks in walls, etc. I myself don't think that's likely if they are crimped properly and pressure tested, but I'm a creature of habit and a lot of me is thinking of still going with copper - but I also like to use the latest and greatest. If you guys were restoring 100 year old house with new supply.. what would you use?

    Thank you all in advance - I know this is a lot, but having a professional thought or two will be invaluable.



  • #2
    Re: Newbie PEX manifold questions...

    Every 2.31' you rise you will have a pressure drop of one psi, pex is good because its quick and easy to install. If your comfortable doing it in copper its bye far the better of the two. I would defineyly consider just running one hot supply pipe with a recirculation line back to your domestic hot water supply aka hot water tank ect.. copper is a lot more money but the money you save bye doing yourself it probally evins out. Goodlyck Sean


    • #3
      Re: Newbie PEX manifold questions...

      Things I will be doing in my house:

      - use 1" from water source to all supply stops and faucet valves. Stop down to size needed at the valve.

      - run full lengths to each area with sweeping bends (less joints, less pressure drop) from a master spool

      - use a pex-al-pex type of pipe, it holds bends better and has better UV protection

      - for the recirculation lines also use one complete length. pex doesnt wear with constant flow, but fittings do.

      probably overkill, but it would make me happy and I know that any future updates would have the proper volume.

      p.s. for a well system I would install a constant pressure pump, rather than a standard 40-60 system

      ... it was plumbed by Ray Charles and his helper Stevie Wonder


      • #4
        Re: Newbie PEX manifold questions...

        I read about rats seem to like chewing on PEX tubing, also romax and armadilloes ))) very surprising to me


        • #5
          Re: Newbie PEX manifold questions...

          Yah and cedarbugs.....


          • #6
            Re: Newbie PEX manifold questions...

            Originally posted by gibsonhandyman View Post
            I read about rats seem to like chewing on PEX tubing, also romax and armadilloes ))) very surprising to me
            Thats no fault of the pex. Buy a couple cans of spray foam and a doberman.


            • #7
              Re: Newbie PEX manifold questions...

              PEX is the way to go these days. But you need to buy expensive good quality product like Pextech or Rifeng, don't go for cheap tubing.
              It is more convenient and quick to install PEX rather than the traditional copper pipes, they easily bend and the best part of it - you don't need a huge truck to transport it to your house. Most of them will fit your every day vehicle's trunk, actually, buying them online with delivery is even better.
              The company I work for installs PEX for about 3 years. So far so good, no complaints.

              As for the rat and mice problem, just get yourself a cat, meow