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Defective PEX solar hot water tubing

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  • Defective PEX solar hot water tubing

    Since I just joined this group, I wanted to post a warning in case anyone had the same experience. Years ago I purchased hundreds of feet of Pex-Al-Pex 1" insulated tubing conduit from Brent Industries, or dba Outdoorfurnance supply. I had 6 breaks in the conduit over a 3 year period. Brent was nice enough to replace the entire conduit for free, but the aggravation of finding a leak in a 250 feet line was not easy, especially with the conduit in 5 layers of insulation. I have a trick if you ever find yourself in this scenario. So if you find your conduit breaking, this could be from the same batch. The new conduit they sent seems fine.

  • #2
    First it is not conduit, it is plastic tubing and does not meet any code standards, Thus why it cannot be used or approved by any AHJ in any stationary application. Can only be used in RV's and Mobile Homes in Trailer Trash Parks where no one cares if a pipe breaks and floods everything or leaks gas and blows up.
    MSEE, PE

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    • #3
      Sunking...When Pex is placed in a conduit, it is called conduit. Here is definition of conduit. https://www.google.com/search?client...-1-d&q=conduit

      The piping for a Closed solar hot water systems does not to meet any code, only any heat ex-changers used and food grade type glycol.

      I was trying to help others who may experience leaks, don't look for things to pick on.

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      • #4
        PEX is generally not rated for exterior use, as it has zero resistance to UV light. Even sitting outside a couple days it will have enough solar UV exposure to ruin it and the failure is not likely to show up for years. But once exposed, it will fail.
        chlorine degradation is also beginning to appear , and even the printing on the exterior of the pipe, has been eating away at the PEX causing failures.

        Egad ! I've got pex in my place, and all the plumbers think it's the cats meow.
        Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
        || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
        || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

        solar: http://tinyurl.com/LMR-Solar
        gen: http://tinyurl.com/LMR-Lister

        Comment


        • #5
          Originally posted by parobolic View Post
          Sunking...When Pex is placed in a conduit, it is called conduit. Here is definition of conduit. https://www.google.com/search?client...-1-d&q=conduit

          The piping for a Closed solar hot water systems does not to meet any code, only any heat ex-changers used and food grade type glycol.

          I was trying to help others who may experience leaks, don't look for things to pick on.
          When used in the context of conveying fluids, a conduit is usually thought of as an open channel.

          Well, maybe the piping for your system "does not to meet" (sic) any code, or maybe it needs meet a code but doesn't, and so is in code violation. Hard to tell from your text. Maybe your area has no plumbing codes for solar domestic water heating systems. However, mine sure does as do many others have codes for systems that are associated with potable water systems. You might want to think about changing that statement to read something like " My jurisdiction does not require solar domestic hot water supply systems to meet any code requirements...", or some such language. BTW, your jurisdiction amy also have building codes that address the construction requirements for a system that are separate form sanitary or health/safety considerations.

          On definitions: Crosslinked polyethylene tubing in an open channel has a technical name: PEX in a ditch. When not in a ditch PEX is usually called (plastic) tubing. When it's insulated PEX, it's usually called insulated plastic tubing.

          Tubing is defined similar to pipe: Stuff that's longer than it is wide that usually has a round cross section with a concentric round hole in the middle of that cross section that's concentric with the outside of the tube. At least that's what I learned in engineering school.

          BTW, depending on the tubing layout, and if the leaks were at the PEX joints, which can be pretty leak prone and not always easy to get right, especially when the service is at elevated temps., thermal expansion may have been part of the problems you had. Also, Pex may/may not be OK w/an AHJ depending on the application and the mindset of the AHJ. Among other things, it may not be a good idea to have PEX near a water tank. The highest temp./pressure rating I know of for PEX is the excessive pressure and temperature rating capability for SOME TYPES of PEX - that is, 210 F. at 150 PSIG, making it suitable for use with most common pressure relief valves which usually (but not always) carry that 210F, 150 PGIG set to operate/lift point. That's per ASTM F876 - the ASTM spec for PEX.

          However, not all jurisdictions will allow PEX for potable systems and/or systems operating at elevated temps./pressures, and for what are IMO anyway, good reasons.

          Not that I expect anyone cares, but to me PEX is just another example of one of the ways we're going in the toilet. It's a B.S. cheap out way to make things more dangerous and less reliable. Some uses, maybe, but pretty limited. Use PEX, expect a cheaper job up front and expect problems that will cost more down the road. I'd never use it on anything more than an HVAC condensate drain and only then if I could see it and easily get at it.

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          • #6
            I'm not a plumber but pex has one advantage. Less prone to bust from freezing. The term conduit is used every day by electricians when wire is in a pipe they are call is conduit. This is not an open situation. Anyway my failure was a factory defect. The seams opened. Thousands of us use pex in conduit with no failure. As per code. The only code here is a safe form of glycol and a double wall heat exchanger.

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            • #7
              I agree pex should never be near a heat source. My system has an auto shut off tso the heated water in the pipe never exceeds 180f.

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              • #8
                Originally posted by parobolic View Post
                I'm not a plumber but pex has one advantage. Less prone to bust from freezing. The term conduit is used every day by electricians when wire is in a pipe they are call is conduit. This is not an open situation. Anyway my failure was a factory defect. The seams opened. Thousands of us use pex in conduit with no failure. As per code. The only code here is a safe form of glycol and a double wall heat exchanger.
                Pex has a few advantages. One of then is some different and perhaps better tolerance to freeze damage. Note tolerance - not fail safe protection.

                In the opinion of a lot of folks whose opinions I respect, the disadvantages of PEX outweigh the advantages, with one of the disadvantages being that people ignorant of the consequences of what they are doing can use PEX and get into trouble more easily than those who do plumbing and piping work/system design for a living.

                In that sense, PEX is a mistake enabling system.

                Just my $0.02.

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                • #9
                  Around this area, PEX is used in 90% of all new homes and rehabs, and almost 100% for all solar outdoor trenching, when encased in a conduit and insulated. Standard roll poly pipe for transporting drinking water to our homes is also used almost 100% in the world for the past 40 or more years, not in conduit. Im not an expert but that is a lot of statistics. But I started this thread to report defective pex in case any one else had that problem.

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                  • #10
                    Thanks, parobolic . After many years of using copper pipe in my remodeling projects, I have started to use PEX. I dont have any thermal solar. I started using it for recirc lines for long runs back to my water heater.
                    I also recently bought some purple PEX that I am planning in using for low pressure recycled grey water and rain water to flush toilets.
                    Last edited by Ampster; 03-27-2019, 12:50 PM.

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                    • #11
                      I have made the name of this thread less ambiguous
                      Defective PEX solar hot water tubing
                      Powerfab top of pole PV mount (2) | Listeroid 6/1 w/st5 gen head | XW6048 inverter/chgr | Iota 48V/15A charger | Morningstar 60A MPPT | 48V, 800A NiFe Battery (in series)| 15, Evergreen 205w "12V" PV array on pole | Midnight ePanel | Grundfos 10 SO5-9 with 3 wire Franklin Electric motor (1/2hp 240V 1ph ) on a timer for 3 hr noontime run - Runs off PV ||
                      || Midnight Classic 200 | 10, Evergreen 200w in a 160VOC array ||
                      || VEC1093 12V Charger | Maha C401 aa/aaa Charger | SureSine | Sunsaver MPPT 15A

                      solar: http://tinyurl.com/LMR-Solar
                      gen: http://tinyurl.com/LMR-Lister

                      Comment

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