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PEX - Copper pipe and T's vs Manifolds

hr Member Posts: 6,106
we use manifolds that extend the length of the home, in some cases. The reverse return method will help balance that flow issue, if all loops are the same length.

This article explains the how and whys.


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  • RLYable Handyguy
    RLYable Handyguy Member Posts: 7
    Using Copper pipe and T's as PEX radiant Manifold

    I want to Keep my Radiant loops of 1/2" PEX equal in length... to keep balanced flowrates without requiring flow regulating valves... but that means T-ing off of a 30-40foot length of 3/4" or 1" copper supply where each loop starts (4-6 foot increments between T's) .. how much will the flowrate vary between the Loops T-ing off at the beginning of the copper supply... and the last loop 40feet away... 6-8 loops/T's later...?
    Knowing that larger diameter pipe has less effect on head... I dunno how much of an issue this is in my case

    Did that make sense?
  • ALH_4
    ALH_4 Member Posts: 1,790
    Common Supply

    We frequently design systems that way. be careful in finished ceilings, because you cannot isolate each loop to determine where a leak may be if the flooring guy hits a tube. With a crawlspace, it's not really an issue. Just shorten the radiant loops as you get farther from the circulator. How much you shorten them requires some hydraulic analysis.

  • Ron Schroeder_3
    Ron Schroeder_3 Member Posts: 254
    Your question makes sense, your approach does not

    IMHO unless your time has no value, unless you get a better discount on copper pipe and fittings than I do, unless acetylene is free, unless, unless, unless...

    Consider using any one of the wonderful manufactured manifolds to connect your heating tubing, please. Not only are they designed to do the job, they are quick to install, they are convenient in that flow control and loop isolation and provision for thermostatic actuators are included, but they are also warranteed.

    Why would you not want flow regulating valves? These things are a great way to regulate differing temperatures in a building without the need for zone controls. Unless you have no walls in your proposed building you will only come to realize that you wished for better post occupancy temperature control when you realize that you cannot achieve it. Ask me how I know.

    If you want the soldering practise, if you need the experience of working with a displacement cutter (don't forget to ream each cut end), if you want insulating practise, in other words, if your time has no value, build your own.

    Please do not forget the cost of purchasing and installing isolation valves for each loop, flow balancing valves (not ball valves) for each loop, some means for zone control, mechanical/compression type connectors (not crimp rings) for each loop unless you are also the service guy, and a proper jig to build this monster header on.

    IMHO this is not the place to save money.
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