I'm looking at a home built in the 80's with hydronic radiant in-floor heating embedded in concrete slab. I've never seen this type of hydronic tubing before. I'm pretty sure that the attached photo shows the manifold where the copper piping from the boiler transitions to rubber in-floor tubing. There were several sets of manifolds like this - each associated with a different part of the house. I couldn't follow the copper pipes to be 100% sure that they are connected to the boiler. The rubber is quite soft and stretchy. I was wondering if anyone knew the manufacturer's name or the name of this type of system so I could research it. Or if anyone has any first-hand experience regarding it's reliability, that would be great.

I am starting to find some references out there (but none testify as to it's reliability):

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    The fact it is stretchy likely means no O2 barrier. The lack of crimp rings or deformation from barbed fittings is disconcerting to me. I'd be leery of any hydronic system where the materials used and level of insulation was not documented anywhere.
    – bcworkz
    Apr 30, 2013 at 22:56
  • @bcworkz O2 barrier seems to be important for only polyethylene tubing? esp when metallic connectors are used. My best guess is that these loops are unreinforced EPDM which has a pretty good track record unless exposed to organics. I'm not too worried about the manifolds lack of crimps/barbs since they are accessible and replaceable. My primary concern is longevity and reliability of the of the tubing itself.
    – Paul
    May 1, 2013 at 0:30
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    First it is really cool - just outside the box. Second - glad it isn't in my house.
    – DMoore
    May 1, 2013 at 5:18
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    Hi Paul - AFAIK the O2 barrier is for protection of other system components. I would not expect EPDM to be any less O2 permeable than any other flexible material. Otherwise, EPDM is good stuff, it's still widely used in a variety of applications. There are other factors though, such as consistency of manufacture, that can compromise an otherwise excellent material. Another concern is it appears this tubing is on the small side for heating use, there could be issues with it being choked with sediment. If the system has been operating properly for this long, it may be fine.
    – bcworkz
    May 1, 2013 at 22:09

2 Answers 2


It looks like Onix tubing, but installed incorrectly. If it is Onix then it does have an O2 barrier. It should be installed with special reusable crimp rings

If it is Onix, the material is very reliable (when installed correctly).


The crimps are important; if this were my unit I'd install a ball valve leading to each zone so you can give different floor zones different amounts of heat for each area.


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