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Seeking insulated PEX recommendations for hydronic heating/cooling

WilliamLi | Posted in Mechanicals on

So after discussions about the relative costs of labour for different tasks in my electric retrofit, I’m starting to swing back around to ATW rather than mini-split, as with a monoblock design we can avoid refrigerant line runs altogether.  Even though the equipment cost is a bit higher, as we run the numbers, it’s starting to look like ATW may win out overall with a faster, less-disruptive install (just like John Siegenthaler says!)

The leading contender right now has us installing home-run PEX lines to a combination of ductless slim wall-mount hydronic fan-coil air handlers to handle both heating and cooling, and a few replacement wall-mount low-temp radiators for the rooms where I need just a bit more oomph in the winter but don’t need to worry about cooling in the summer.

Design temperatures will be 7C (45F) for cooling, and probably 50C (120F) for heating.  Most runs will be around 30-50 ft, heading into 1/” NPT on the air handlers.  Each air handler or radiator will need 2 pipes — 1 outgoing, 1 incoming.  The PEX will ideally run through wall cavities where possible, but in small soffits where it’s not.

I’ve been looking for a good solution for insulating these runs, both to avoid heat loss as well as to prevent condensation during cooling.  I’ve found solutions such as Uponor Ecoflex with 2 PEX pipes embedded in foam, but these seem primarily oriented towards outdoor (buried or not) runs, and also seem fairly bulky.  I’ve also seen solar-oriented solutions with pairs of steel pipe wrapped in EPDM.  There’s also single-pipe solutions such as Cool-Fit from GFPS.  And of course, there’s good old fashioned 6′ segments of pipe insulation (rubber or foam) as well as pipe wrap.  However, I’m leery of the manual approach both from an anti-condensation point of view as well as labour.

Do you folks have any recommendations for pre-insulated PEX which would be suitable or have any comments about this?

Thank you all in advance for your help.

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  1. matthew25 | | #1

    Wirsbo hePEX is oxygen barrier and comes in pre-insulated spools. I don’t think the stand Uponor AquaPEX is oxygen barrier.

  2. Expert Member
    BILL WICHERS | | #2

    All the dual-run, and most single-run, pre-insulated PEX systems I'm familiar with have been targeted at underground use, as you mentioned, and are primarily used by the outdoor wood boiler people, and sometimes to extend hydronic heat loops out to remote buildings (barns, sheds, workshops, etc.). You do NOT want to use "wrap pipe" for those, which has a sort of reflectix-like bubble wrap wrapped around the PEX lines. Those are prone to failure. The type using a sprayfoam-like foam inside of a corrugated tube is much better.

    Both of those systems are very bulky and stiff though, and I wouldn't try to use either indoors. Even with outdoor/indoor transitions of those, common practice is to expose a foot or two of the internal PEX lines at the end, right where the aseembly enters a structure, and then couple on "regular" PEX runs for the interior portion of the run. Regular pipe insulation is normally used on those single lines.

    On every commerical project I've done, pipe insulation is always installed AFTER the line goes up. Usually this is with a pre-formed rigid fiberglass pipe insulation, that comes in split sections that are put around the pipe and then secured in place with a matching white tape. You can get various fittings to wrap the insulation around 90s and tees too, to keep a clean-looking final assembly. This material is available in several thicknesses, but you have to get it at commercial supply houses. Note that this stuff is pretty rigid, so it's not going to follow PEX around a radius bend the way PEX is commonly run -- you'd need to make your "bend" using a PEX 90 degree fitting, then use the insulation and 90 degree insulation piece instead.

    The poly foam or rubber foam insulation sections you can get from the box stores are much more flexible, and will probably work better for you here if your PEX makes sweeping bends. Note that the rubber foam is a little better R value, and I think is also rated for slightly higher temperatures from the poly foam stuff. The rigid fiberglass stuff I mentioned can take a LOT of heat, and is often used on steam pipes.


  3. jberks | | #3

    I've always toyed with the idea of getting uponor preinsulated tubing.

    I absolutely hate the split foam insulation. Full round Rubber foam insulation from supply houses are better, but still hate the process/labour to get the boxes of insulation tubes and guess your length of run and find the space to do it and sleeve them on your tubing and tape all the transitions as you uncoil.

    You will want preinsulated hepex, because it has the oxygen barrier and cheaper because it's for HVAC (non-potable). The dual tube you're talking about only comes min 1" tubes. You didn't mention your tube sizing, but I dont think you'll be running 1" lines, but tell me if I'm wrong because I've yet to do or see monobloc hydronic fancoil system in the wild.

    The materials for the preinsulated tubing is roughly 1.5x the cost (based on pricing from If I'm doing a new build where I'd be doing a lot of insulated tubing, it's a no brainer as it'll save a bunch of labour.

    Last I checked I couldn't get this in Canada without a whole bunch of hassle. But thing may have changed by now.


    1. WilliamLi | | #4

      Thanks Jamie. Yes, it’s 1/2” for the hydronic runs. I’ll work with my installer and see if he can his hands on this. It’s not a huge job, but trading materials dollars for labour hours really helps.

  4. user-6349239 | | #5

    Any updates on how this is progressing? I'm also trying to design an ATW system for cooling and heating, and seem to have hit a wall with finding insulated pex suppliers. Are the uponor products open cell or closed cell insulation? If the former, will you need a vapor barrier as well?

    The only other North American supplier of insulated pex for cooling applications I've come across so far is Messana, which I think is open cell with a vapor barrier. I haven't tried to get prices yet, but I think it's much more than uponor 1/2" insulated pex.

    I'm worried this may be what derails my ATW ambitions. Please do share where you land on this.

    1. WilliamLi | | #6

      The project is still in the works, currently held up at the electrical utility phase for upgrading the service to the house.
      I did some pricing for what will turn out to be 3/4” (rather than 1/2”) pex. Materials-wise, it looks to be quite a bit more expensive for the pre-insulated stuff vs site-integrated insulation. Not quite sure yet which way we’ll go in this, as the reduction in labour of hooking up plumbing vs building ducting is a significant part of the tilt towards ATW.
      In the meantime, yet another Siegenthaler article put me on to 2-pipe rather than home run for the ductless fan coil units, which has not quite halved the amount of pipe we need as well as reduced installation labour yet again. 2-pipe also has a minor effect on reducing the size of chase I need to build afterwards, as this is a retrofit project.
      I found an online uponor price book for Canada I’ll try to find the link for and post later. There are a variety of insulation thicknesses available, depending on the pipe diameter.

      1. user-6349239 | | #9

        At least in the states, Messana appears to be cheaper than Uponor. However I believe they only have a 1/2 pex option. sells the Messana pex, but their website appears to be down at the moment.

        I may order samples and see if I can source pre-insulated PEX directly from China. It is still up in the air, but it is frustrating that this appears to be an unexpectedly expensive aspect of the system.

        I need to get further in my design to see what makes sense regarding pex and system layout. I may combine elements of a home-run and two-pipe system to limit costs here.

        Are you working with an experienced hydronic planner or designer? I'm in the front range of Colorado and I haven't found anyone yet in my area who would be open to trying different products or approaches. Which has left me to track down Siegenthaler's textbook and do a lot of internet research (but there may be more firms I could reach out to as well).

        Any concerns about the fittings in the wall with the tees/diverter valves you'll be using in the 2 pipe system? Home-run feels like a no-brainer when its the cost of PEX alone, but the insulation for cooling really changes the math.

        1. WilliamLi | | #10

          Hi 6349239,
          I found this URL for Uponor by Googling "uponor insulated pex price canada":

          It looks like there is at least the existence of different insulation thicknesses for various PEX diameters, but if you look at the pricing and compare vs. PEX + separate insulation, the pre-integrated stuff is unexpectedly much more expensive (as opposed to somewhat more expensive), but YMMV depending on what you need.
          I'm currently doing most of the legwork myself, with the heat pump company providing the engineering on the central part of the system.
          Another recent Q&A thread, now makes me nervous about sourcing the TRVs required for a 2-pipe system...

  5. spraggins | | #7

    @WilliamLi, which article are you referring to concerning the 2 pipe vs home run?

    1. WilliamLi | | #8

      Spraggins, I was looking for piping layouts and found this:
      When I got to the end was when I realized it was a John Siegenthaler article.

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