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PEX vs. Copper vs. Rubber Hose

Kevin_in_Denver_2
Kevin_in_Denver_2 Member Posts: 588
in Solar
Many of us have concluded that PEX can fail in a solar collector loop, and should not be used.



Some folks like the corrugated stainless, but it is too expensive.



Does anyone use hose like Duroflex? <a href="http://www.rsci.com/duro-flex-multi-purpose-hose-5821.html">http://www.rsci.com/duro-flex-multi-purpose-hose-5821.html</a>



I've been testing it to stagnation temperatures and pressures, i.e., 320F and 150psi, with no failures.



It is easier to use and cheaper than soft copper. I also like the fact that it is freeze tolerant, just in case you have a recirculation system with a control failure.



It isn't rated for potable service, does anyone know of a hose that is?
Superinsulated Passive solar house, Buderus in floor backup heat by Mark Eatherton, 3KW grid-tied PV system, various solar thermal experiments

Comments

  • hot_rod
    hot_rod Member Posts: 22,121
    how long

    have you been testing it under conditions above it's listing? I would not risk a tube that is not tested and listed by the manufacturer for the temperatures you are considering. A typical flat plate collector stagnates at about 345F or so. Evac tube probably much higher.



    In many cases the collector will be under stagnation conditions for extended periods, vacation homes, oversized DHW arrays, etc.



    The exterior of the hose would need to be able to withstand the conditions it is exposed to also.



    But the old Lennox solar collectors were connected together with a green colored silicone rubber hose with stainless clamps. i have seen that connector last 15 years in my area. I suspect silicone rubber hose would be a bit $$. I have bought 12" sections to repair and reinstall Lennox collectors, it makes copper look cheap :)





    Steel pipe, especially the lighter wall like schedule 20 or the Wheatland MegaThread are a price point option.



    If the new steel press fittings, that Viega has introduced, get a high temperature o-ring that could be a slick & quick installation.



    The stainless flex is usually a dual tube with wire and, depending on the brand, a 400F insulation. Consider the labor cost savings of not needing to sweat, thread or crimp and the price is not all that far out of range. Especially with labor rates of $100, 200 and higher.



    hr
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Kevin_in_Denver_2
    Kevin_in_Denver_2 Member Posts: 588
    Fishing two preinsulated pipes?

    HR,



    Thanks for the review of what's available. I'm looking into the steel pipe.



    In retrofit AND new construction, running the collector loop is a matter of fishing pipes around obstacles and through walls, etc. So it's always baffled me that anyone would think that process could be easier with two fat preinsulated pipes that are attached to each other.



    I generally don't even want to make such a large penetration in an exterior wall, due to air leakage and even structural issues. Even if you make the big hole, it can really be tough fishing a double pipe through and on to where it wants to go.



    I keep the hose at least six feet away from the panels. I'm using stainless braided hose for direct attachment to the panels. http://www.grainger.com/Grainger/HOSE-MASTER-Flexible-Metal-Hose-6MP28?Pid=search



    I've found similar stuff for about $2/ft, to get the Duroflex at least 6 feet away from the panels.
    Superinsulated Passive solar house, Buderus in floor backup heat by Mark Eatherton, 3KW grid-tied PV system, various solar thermal experiments
  • Mark Eatherton
    Mark Eatherton Member Posts: 5,853
    Is oxygen barrier necessary?

    Because you won't have it with hose. Even the hose that is supposed to have an O2 barrier doesn't work very well...



    ME
    It's not so much a case of "You got what you paid for", as it is a matter of "You DIDN'T get what you DIDN'T pay for, and you're NOT going to get what you thought you were in the way of comfort". Borrowed from Heatboy.
  • Kevin_in_Denver_2
    Kevin_in_Denver_2 Member Posts: 588
    O2 Barrier not required

    My test system is direct with recirculation freeze protection.
    Superinsulated Passive solar house, Buderus in floor backup heat by Mark Eatherton, 3KW grid-tied PV system, various solar thermal experiments
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