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A \"super\" heat transfer plate (hr)

ALH_4 Member Posts: 1,790
I am intimately familiar with that product. ;-) The U-bends are pretty cool. This could turn into a nice above the floor product. I hope this is the breakthrough that the aluminum channel needs.


  • hot_rod
    hot_rod Member Posts: 22,103
    I've just started testing

    this material as a possible heat transfer plate for radiant.

    The best metallic conductors rate a thermal conductivity of silver 429, copper 401, gold 317, aluminum 237.
    This material rates as high as 1950! And very low thermal expansion, which is good.

    Forms easily, this actually has a peel and stick back. Possibly a fraction of the cost of aluminum!

    Here is a thermal image from below and above 3/4" plywood. With extruded aluminum plates on the right.

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream

  • Those pictures don't lie!!! Can you give any clue to the nature of the substance? "Peel-and-stick" backing makes me think it's some sort of plastic or composite, but I've sure never heard of a plastic with such high conduction.

    Perhaps some sort of plastic/metal/ceramic composite?
  • ALH_4
    ALH_4 Member Posts: 1,790

    I assume those thermal conductivity units are all W/m-K? I am all ears!
  • Dave_4
    Dave_4 Member Posts: 1,405
    thermal spreader

    Hmm... is it Graphite? I've used it often as a thermal interface material in process heaters. X-Y thermal conductivity is many times greater than it is through its thickness. Heat energy 'spreads' as a result. I bet you're on to something with this.

  • Ah, they got a hold of you, eh? Saw some mutterrings a while back...

    very cool!! If anyone wanted to send me one or two of those I'd love to see them!!

    Looks like transfer through the floor isn't as strong as the extruded, but if it's a fraction of the cost and allows for larger coverage areas, I bet the smaller per inch transfer rate is more than offset by the more inches that get the weaker rate! That's very cool.

    Any feedback on "installability" of the mystery material? Brittle, breakable, contact to the subfloor consistently tight?

  • Actually, I see you said it's peel and stick.. I don't know how I'd feel about that long term.. any thoughts?
  • ALH_4
    ALH_4 Member Posts: 1,790
    Peel 'n' Stick

    Now I'm even more curious. My thoughts on peel and stick is that I would still shoot a few staples just to be sure it didn't fall off in 10 years. Good luck finding flat, smooth, clean subfloor. What if you slip and completely misalign it with the adjacent piece and it's stuck forever? How about a liquid adhesive that would improve contact between the "plate" the subfloor and still allow some fine tuning of the positioning of the plate during installation?

  • For all we know, the adhesive might be partly responsible for the extremely high rate of conduction--nearly perfect continuous contact sure couldn't hurt--especially if the adhesive used is itself highly conductive.

    I have a feeling that the "peel and stick" bears only superficial resemblance to things like floor tiles using PSA (pressure-sensitive adhesive).

  • Perhaps, but even if it's a perfect bond, it's only bonding to a surface layer of wood. I'm not sure I trust that to resist expansion stress for the life of a building without penetrating fasteners at first blush anyway...

  • Again we're HIGHLY speculating here, but I had similar reservations about "Liquid Nails". I still don't use it very often, but I have tested it and even without mechanical attachment it will hold furring strips to dirty and/or painted walls/ceilings made of wood or masonary.
  • hot_rod
    hot_rod Member Posts: 22,103
    Yes it is graphite

    designed specfically for lateral heat spread. This company can special build the sheets and align the "flakes" for best purpose.

    I did shoot a staple around the tube every foot. And some small swing hammer staples around the perimeter of the mat.

    I need to crank the temperature to test the adhesive. The graphite is good to 3000K.

    Graphite is used in a lot of electronics to rid components of heat. Also in the nuclear industry. Available in most every country with S Korea and Austria the biggest exporters.

    It needs some more testing, maybe a winters worth of heating, but I am satisfied so far.

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream

  • Interesting.

    Instead of adhesive, a couple of thin "wings" of wood would give compression and something for a screw or staple to hold. Just a thought, of course.

    This is cool.. are you allowed to take a visible light picture?
  • EtienneHancock
    EtienneHancock Member Posts: 18
    graphite sandwich

    I like the idea of sandwiching the graphite in place mechanically rather than relying on adhesives. The material's compressibility makes it good for taking up the irregularities associated with imperfect surface finishes- in my particular day job case of heating in a vacuum- such that good, consistent heat transfer occurs between the 'plate' and the floor. I would not expect an adhesive to hold up year after year in that kind of environment.

    It's pretty neat to see this type of stuff (esoteric materials, etc.) migrating into such things as home heating systems. Keep up the good work, guys.
  • zeke
    zeke Member Posts: 223

    I don't believe any of this socalled super conductive mystery material. Who is the mystery1h0 Mfr and who tested this magic stuff?

    Sounds like solid snake oil to me. Anytime anyone comes up with a material that is 5 times better than silver, I will make a large wager that it just aint so.
  • tim smith
    tim smith Member Posts: 2,752
    Interesting link to thermal conductivity description & chart


    Supports the info hotrod said about comparison of thermal conductivity.
  • Richard Miller_3
    Richard Miller_3 Member Posts: 61

    I can tell you ain't no "true believer".
  • Leo G_101
    Leo G_101 Member Posts: 87
    Oh Great!

    well I guess we better start hoarding pencils now! Just can't bring myself to paying 5 bucks for an HB-2! :)

    Leo G

  • With such high conduction won't you have to use shorter than normal loops and/or larger tube and/or higher flow to keep delta-t and "evenness" of heat across the floor within reason?

  • Check out the picture. Once through finish floor, it would appear to emit less per square inch than extruded plates (I assume because of the highly directional nature of the conduction these guys are all talking about).

    So it can get to the ends of the mat really well, but it's not better at "turning" into the subfloor. However, it does allow for very consistent output over a wide area, which we can't do with aluminum without significant expense...

  • Hard to judge, but it sure looks to me like the average temperature of the area covered by the carbon conductor is significantly higher than the other.

    If I get time in the next few days I should be able to convert the image to a bitmap and determine the actual average temps by examining each pixel and comparing to the reference.

  • that would be awesome. In fact, I would love to know what tools you are using to do that, because I have plans for myself later on.... photoshop?

  • Yes, convert to a bitmap in Photoshop. Then divide into separate images. Then (using the "key") determine what pixel color corresponds with what temperature.

    Then examine the images pixel-by-pixel to find the average temp.

    At least in theory it should work. I just have to dig out the books so I can strip out the .bmp header info from the files.
  • Zeke, the eternal optomist....

    from MISSOURI...

    Or as Dan would say, "The Straw that stirs"

    All in good jest:-)

  • Chris P.
    Chris P. Member Posts: 3
    Temp plot

    It's been a long time since I've done image processing, so consider this strictly an amateur attempt. I used Matlab to map each pixel according to the temperature scale and plotted the temperature across a section perpendicular to the plates. I'll try to extract some average temps - it is tricky because of the camera angle - I have to play around with rotating seperate sections to get a square section I can use for each plate.

    If I can figure out how to do that, I'll post the average temps for each. Hot Rod, what is the tube spacing? That would give me a reference to scale to.
  • Weezbo
    Weezbo Member Posts: 6,232
    I would give the material a go...

    here in this neck of the woods i can do experiments with it that would cost mega dollars to do else where.

    Often our work is in accomplished a less than ideal environment. While carbon (Adhesives) bonds readily after about 30 below F to other carbon vs say (silicon ), many things tend to not preform as advertised...
  • Chris P.
    Chris P. Member Posts: 3
    Average Temps

    Turns out the average temp is really close between the two - I got 91.8 for the "super plate" and 91.1 for the two extruded plates (including the gap in the middle). I'd say this was plus or minus half a degree or so depending on the exact area I avaraged, but the graphite plate seemed to have about a .5-.7 degree advantage consistently.

    One other factor that I haven't adjusted for is the perspective in the picture due to the camera angle. It looks as if the "heated area" of the graphite plate is a bit wider than that of the pair of extruded plates. If that is true then for a fair comparison I should enlarge the area I used for the extruded plates which will decrease their average temp a bit.
  • ALH_4
    ALH_4 Member Posts: 1,790

    Impressive analysis considering the information you were given. By that measure, and considering the cost is expected to be less, this appears to be superior to aluminum plates. However, the devil may be in the details.

  • Thanks! I didn't get time today to analyze the bitmaps, but will try in the next few days. I have a lot of wood to break down and actually have some good help so need to use it while it's here.
  • Gordy
    Gordy Member Posts: 9,546
    Gauge of super plate

    HR just wondering the gauge of the superplate?
    Is it thinner than a light weight plate, or are you experimenting with various thickness?

    Seems to me the peel n stick would be superb for an over the top sandwich application. Any noise issues with the pex in it?

  • hot_rod
    hot_rod Member Posts: 22,103
    Same thickness

    as the heavy extruded aluminum. I actually used a U-fin and some 1/2 od copper to form the shape. It sticks very well to the smooth pex tube. Once stuck it de-lams trying to remove it. The first sample has stick-um on one side and a clear film on the opposite side to keep it mess free.

    I doubt the tube or the plate would make any noise. It if fairly flexible, like thick gasket material, and a low thermal expansion factor.

    This company can do just about anything you might imagine. Vary the graphite "cooking" process for different effects, either up and down or lateral heat spread, vary the thicknes, backings, cover sheet and material. They could even laminate a stiff plastic if need be.

    I think the potential is great. I think it would make an excellent solar absorber plate also. Better thermal performance, no corrossion, great color, less cost, etc, etc.

    So much to do so little time :)

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Tim Doran_4
    Tim Doran_4 Member Posts: 138

    A smart ex-Uponor engineer named Steve Redford was talking about this stuff four or five years ago. He wanted to extrude a plate from thermoplastic using waste pex as a filler and them laminate a graphite sheet to it for transfer. He never got any traction with it. Cool Stuff!

    Tim D.

    To Learn More About This Professional, Click Here to Visit Their Ad in "Find A Professional"
  • Kevin_in_Denver_2
    Kevin_in_Denver_2 Member Posts: 588
    Absorber Plate

    Do you think the stickum would hold up to the stagnation temps. of a glazed collector? (350F)
    Superinsulated Passive solar house, Buderus in floor backup heat by Mark Eatherton, 3KW grid-tied PV system, various solar thermal experiments
  • hot_rod
    hot_rod Member Posts: 22,103
    good point Kevin

    I need to research the adhesive on this product. I have found some thermal conductive adhesives with continous duty at 600F. I'll bet something is available out there. Or mold the tube right in with the layers??

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • zeke
    zeke Member Posts: 223
    True test

    OK. so if this mystery stuff is so good, where is the data that supports improved heat transfer to the room above? I am skeptical about this because the heat transfer to the room has to not only be from lateral conduction but also conduction normal to the surface. As others have pointed out the thermal conductivity of this "anisotropic" material is poor in that direction and so the overall thermal efficacy of the system remains questionable to me.

    Has the mfr or anyone done testing that demonstrates the overall heat transfer to the ambient?
  • hot_rod
    hot_rod Member Posts: 22,103

    all good questions. We are just starting to do all the testing for applications in the radiant heating use.

    It is neither mystery or miracle stuff. basic graphite. www.graphtech.com has a lot more techinical info at their site.

    The material I am messing with is 400W/mK. They also make a 500, and that 1000 plus number I mentioned above is in fact possible, at a cost :)

    I doubt this use would require that "super" of a material.

    Really we are looking for a less expensive equal or better product to do radiant installs with. I feel this product could be more user friendly as far as installation, not subjected to the high aluminum cost and extrusion costs. Eliminate thermal expansion noises, and possibly offer a better temperature spread across the entire floor surface as the pics clearly show.

    We are just starting to look at the possibilities, and get some contractor input, be patient.

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
  • Kevin_in_Denver_2
    Kevin_in_Denver_2 Member Posts: 588

    Unglazed collectors have the potential to look like roofing (good) instead of like a solar panel (not as good).

    If you add stick-on PV, you get a hybrid panel, which I think has a lot of potential, since you collect excess electricity all summer and send it back to the grid.
    Superinsulated Passive solar house, Buderus in floor backup heat by Mark Eatherton, 3KW grid-tied PV system, various solar thermal experiments

  • I think the infrared shots and the ad hoc analysis done on them here in this thread would show that square inch to square inch, it's NOT better than aluminum, but that you can cover a lot more square inches for less cost it sounds, for a better OVERALL output.

    That's a lot better than laboratory testing for establishing that the concept itself is sound at least. Or, at least it's more understandable without a degree....
  • Kal Row
    Kal Row Member Posts: 1,520
    hot rod: did you get this from the people...

    displaying at the rpa show?, they had liquid cristal sheets attached to it, to show the eveness of it, but they did not have an actual product to sell, other than graphite sheets made to order in 1000sq yd qantities
  • Mike T., Swampeast MO
    Mike T., Swampeast MO Member Posts: 6,928
    Avg. [floor] Surface Temps

    Didn't conduct exactly as above, but as best as I can estimate for the same coverage width, the "super" plates average about 92.5F and the extruded plates about 91F.

    Looks like ambient temp in the thermographs was at least 83F


    Assuming 83F ambient then the "super" plates were 92.5 - 83 = 9.5F above ambient

    and the extruded plates were 91 - 83 = 8F above ambient.


    Now assuming 2 btu/hr sq.ft. output per degree of temp difference between surface and ambient air:

    "Super" plates 19.5 btu/hr sq.ft.

    Extruded plates 16 btu/hr sq.ft.


    About 21% output increase!!!!

  • hot_rod
    hot_rod Member Posts: 22,103
    Hi Kal

    yes these samplae are from the folks at the RPA show. I met them and offered to do some contractor level testing and give them application ideas and thoughts. No more.

    As I research this company I find they do have a patent filed for graphite heat transfer relating to radiant heat. At this point several manufactures of radiant have expressed a sincere interest in the technology and product.

    Time will tell if it makes it to the market. I'm privy to some exciting possibilities that this product offers above and beyond aluminum.

    This very thing is what keeps radiant and hydronics fun and interesting for me.

    Better transfer products 1 watt circulators, ECM circs, 90% gas fired appliances, unique solar devices being introduced and invented. There is nothing BUT opportunity in this field of ours.

    hot rod

    hot rod
    Bob "hot rod" Rohr
    trainer for Caleffi NA
    Living the hydronic dream
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