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  • Best Insulation

    I have 2" of insulation space behind the new copper tube absorber plate I am purchasing to install in an old panel, what's the best insulation material for those two inches?

  • #2
    Vermiculite is about the best after that is urethane. I have a 2 inch layer of urethane on my walls and roof.
    4400w, Midnite Classic 150 charge-controller.

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    • #3
      Insulation that doesn't outgas and collect/fog on the backside of the collector. Urethane is pretty impervious to mois. either from leaks or condensation and so may be OK if the temps. don't get high enough for outgassing and may be unstable at high stagnation temps. I used Johns Manville fiberglass made for thermal collector applications w/out the binders that cause the outgassing which will kill performance.b. It worked fine, but I'm not sure it's still made. o. Just make sure the box is tight enough to prevent leaks. I'm not sure loose fill would be a good idea as it will settle and allow voids, probably at the top portions of a tilted collector.

      Bottom line: Insulation material needs to be dimensionally stable, vermin and moisture proof, non combustible, and free of VOC emissions. If you can keep the insulation dry, I'd still use fiberglass made for collectors. Your biggest enemies will be moisture and outgassing.

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      • #4
        Melamine foam sheets (Basotect) are used by some solar collector manufactures for that exact application. It is rated to 350 F continuous and is known for low outgassing, extremely light weight and plenum rated fire properties. If you know about Magic Eraser sponges then you know this foam already.

        Here is some data for you. Full disclosure. I work for this company. We've sold Basotect foam products for over 30 years.
        http://www.techlite.com/product/sheet-stock/


        Dave W. Gilbert AZ
        6.63kW grid-tie owner

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        • #5
          Originally posted by azdave View Post
          Melamine foam sheets (Basotect) are used by some solar collector manufactures for that exact application. It is rated to 350 F continuous and is known for low outgassing, extremely light weight and plenum rated fire properties. If you know about Magic Eraser sponges then you know this foam already.

          Here is some data for you. Full disclosure. I work for this company. We've sold Basotect foam products for over 30 years.
          http://www.techlite.com/product/sheet-stock/

          FWIW, looks fit for purpose to me.

          Dave: R value of something like 3 or so at probable working temps ?

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          • #6
            Originally posted by J.P.M. View Post

            Dave: R-value of something like 3 or so at probable working temps ?
            I don't have a graph with me here but I know it is roughly R-4 per inch at 75F and R-2.2 at 300F.

            We mostly sell Basotect as pipe insulation to the biopharma industry because of how safe it is to use around food and drugs manufacturing areas. Most foams people try to use in solar collectors work fine under operational temperatures but can't survive stagnation temperatures.

            Dave W. Gilbert AZ
            6.63kW grid-tie owner

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