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pex/oxygen diffusion

How serious is the problem of oxygen diffusion through pex tubing? I have some installed pex I am thinking of trying to replace with hepex but I am wondering if this is really necessary?


  • Ironman
    Ironman Member Posts: 6,686
    We really need more info. Such as:
    1. What type of heat source do you have?
    2. Are there iron or steel components in the system?
    3. Is it an open or closed loop?
    4. Is there glycol in the system?
    5. What type off emitters do you have?

    It can be quite serious under the right/wrong circumstances.
    Bob Boan
    You can choose to do what you want, but you cannot choose the consequences.
  • hot_rod
    hot_rod Member Posts: 15,367
    Time and temperature.

    We had failures within 2 years on the high operating temperature systems, mainly baseboard running 180F. That included PB, rubber and pex systems.

    Lower temperatures = slower ingress.

    Here is a system I connected, against my better judgement :) for a former Heatway employee, that lasted about 12 years, before serious failures. Although he did get a boatload of the class action money :)

    Roll the dice.

    Chemical treatment with an O2 scavenger inhibitor is another option, but treatment doses will be needed occasionally.

    Or separate the piping, from steel and iron with a HX and all non ferrous components on the tube side. Stainless bodied circs, radiant exp tanks that are lined, etc.

    Weigh the pros and cons of each "fix"
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • deadhead
    deadhead Member Posts: 2
    Thanks! This is, or will be. a closed loop system with a new boiler and pumps. I am shooting for a low temp system with a condensing boiler. Looks like I can save on the parts if I pull out and replace the pex with hepex. So I will see how much trouble this will be. Again, thanks for your comments!
  • Canucker
    Canucker Member Posts: 704
    Unless you're going to use non ferrous materials in your new system, spend the little extra for barrier tubing. It will give you peace of mind. I had aquapex installed in my system, by my former installer, and when i replaced it all with hepex, i found that every sq inch of aquapex tubing was covered with a layer of rust sludge. It wasn't enough to block the flow but it was the cause of my flow sensors sticking periodically until the system was flushed out.(It was filthy) I had it installed for 2 heating seasons.
    You can have it good, fast or cheap. Pick two