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PEX vs Onix for Radiant Heat in a Floor

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  • Transcript

    LESLIE: Now we’ve got Olen in North Carolina on the line who needs some help with a radiant floor-system project. Tell us what you’re working on. Are you doing this yourself?

    OLEN: Yeah, I am a do-it-yourselfer kind of guy and I’m going to just do the rough end of the tubing myself. I’m going to leave the pumps and whatnot to the professionals. But it’s sort of smart to let the – to have somebody to do the hard stuff for you. But I figure I can do the tubing myself.

    And my question regards the choice between PEX and Onix tubing and about cost-effectiveness.

    TOM: OK.

    OLEN: And which one is more appropriate for my region? I’m in North Carolina.

    LESLIE: Well, what type of subfloor are you working with?

    OLEN: I’m going to be working on my existing, open floor joists and 16-inch centers, so I’ve got plenty of space under there to staple up either the aluminum plates or to put up the rubberized Onix material.

    LESLIE: Mm-hmm. And what’s going to be your flooring?

    OLEN: Above it, I will have a hardwood floor and in some areas, I’m going to be putting down the cement board and tile on top.

    LESLIE: OK. Now, when you’re dealing with radiant flooring with hardwood, you have to make sure that the certain type of hardwood you buy is appropriate for radiant. And it depends on the way the graining is cut. And I forget exactly what it’s called but you have to make sure you buy the correct type of grain: the way the piece of flooring for the wood itself is cut. Otherwise, you’re going to get a lot of shifting and movement just due to the nature of the heating.

    OLEN: Right. I hear that the PEX tends to cause a little bit more expansion and contraction in the tubing itself. And my floor is actually existing pine floor; it’s only a certain area where I’ll be putting in the cement board and the tile.

    TOM: Well, look, I think that either product, as long as it’s installed consistent with the manufacturer’s instructions, is going to be fine. PEX is really the more common, known product for this and we’ve seen it in many, many houses. PEX stands for cross-linked polyethylene. Onix is cross-linked EPDM, so it’s another formulation for a radiant-tubing product.

    Personally, I would use PEX only because it seems to have the history. I know that Onix was used a lot on outdoor applications for snow melting and that sort of thing. But because it’s inside the house and because it’s got such a great reputation, I would use PEX. And I have seen PEX become very, very indestructible when it comes to its ability to work with all sorts of conditions inside the house.

    In fact, I saw a demonstration once. One thing that’s cool about PEX is the memory that it has. You can heat this stuff and stretch it to twice its length and let it go and it goes back to its original shape. So it retains its original shape.

    So it’s a pretty impressive product and I think it’s got the history. And that’s what I think I would trust if I was going to go radiant in my house.

    OLEN: OK. Well, thank you.

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