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radiant heat riser pipe type pex vs L copper

keyote
keyote Member Posts: 659
It would be much easier to connect my newly installed manifold to a riser now. its three floors down to the future boiler so the 1" O2 heating pex I already have is tempting vs a lot of 1" L copper, but i worry about the restriction of those pex fittings. The ID seems to reduce them a full copper size. i suppose i could buy 1 1/4 pex and still be cheaper but i bet a 1/14 pex x 1 npt is a tough find. am i over thinking this.
Also if anyone has anything to say about the appropriate designs software im thinking there hydronics designs studio is what ive been looking for not sure if i neeed the pro or can get away with the free demo for my one house.

Comments

  • hot_rod
    hot_rod Member Posts: 14,836
    what kind of flow rates are you looking to move to the manifold?

    Here is a chart showing tube carrying capacity.

    Typically pex can be used with fewer fittings than copper with some planning. But no doubt the tube and fittings is more restrictive than copper.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Ironman
    Ironman Member Posts: 6,400
    What kind, or brand, of 1" pex do you now have?

    Look closely at the chart that HR posted. You'll notice that 1" pex-Al-pex has almost the exact capacity as 1" copper. You can bend it with a bender and eliminate a lot of fittings. You can also get compression fittings for it if you don't have the press tool.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • keyote
    keyote Member Posts: 659
    I have the expander and the crimp and the clamp tools seems everytime i use pex for something i must use a different system for some reason lol.
    problem is im not sure of flow yet kind of lost faith in the guy that was to design the sytem which is why i asked about that software.
    I did do some calcs and figured the worst case scenario at 30mbth on the longest 230' loop would be 1.4 gph, there's four loops now total 775' serving 1100 sf top floor. and two futures capped on the manifold to serve another 400sf. PH. So i suppose my worst case scenario is 9gph w futures included which 1" pex doesnt cut it. and since im nor designed yet i want to build to a worst worst case. turns out 1 1/4" pex is actually more expensive for a hundred foot roll than copper so copper it must be.
  • hot_rod
    hot_rod Member Posts: 14,836
    I ran regular 1" pex across my shop from a wood fired boiler to storage, best I can get is 7 gpm with an Alpha on speed 3. a couple ball valves, no other fittings about an 80' circuit. I'm replacing it with copper as we speak :)

    I like Fostapex, but I believe the OD is the same as regular pex? It's not really a pex al pex, just regular pex with extra outer layers. And only insert fittings are available, so you take a hit on every connection.
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • SWEI
    SWEI Member Posts: 7,356
    I'm curious, since I would expect something like 100' of developed length for that run, but clearly I must be wrong. Was that a one way measurement?

    3.85 FPS seems reasonable from a design standpoint, and 6-ish feet of head depending on the water temp.

    Grundfos curves indicate more like 11 feet of head there at 7 GPM.

    We typically spec PEX below 8-9 GPM and Aquatherm SDR11 on higher flow circuits.
  • keyote
    keyote Member Posts: 659
    @hotrod well seems like the charts are correct then. i bought 300' of viega o2 pex because i needed to add/move some temp radiators to lower floors while renovating and thought i had carefully determined it could be used for the uponor sprinkler system as well- wrong their sprinkler head fittings only work with the $300 expander tool although you can use regular tees and elbows with clamps etc, so i have a bunch of the heat pex left.a couple hundred dollars wont kill me at this point. thanks everyone.