Geothermal HDPE pipe

Discussion in 'Geothermal Loops' started by DavidCraig, Aug 4, 2012.

  1. DavidCraig

    DavidCraig Member

    There seems to be several types: PE 3408/3608, PE 3408/4710, PE 4710

    What makes Geothermal pipe different than, say, "Home Depot" SDR 11 HDPE pipe?

    Better thermal properties? Durability (life)?
     
  2. AMI Contracting

    AMI Contracting A nice Van Morrison song Industry Professional Forum Leader

    I run a lot of pool heater gas lines and trench a lot of 11/4". Recently I took a bunch of tails to my loop contractors to butt-fusion them together. In looking at the warm-up time I couldn't help noticing gas pipe took less time than the geo pipe (indicating a thinner or less dense wall).
    Ergo our geo pipe is actually heartier than the pipe gas companies use to to deliver their product!

    That said, there is no single "geo pipe" or source to purchase it from. Folks have used a variety of metals and plastics. Nor is thermal conductivity a huge concern in selecting pipe (as the earth itself conveys heat rather slowly).

    The single biggest advantage of the SDR 11 HDPE is durability.
     
    Last edited: Aug 6, 2012
  3. Palace GeoThermal

    Palace GeoThermal Well-Known Member Industry Professional Forum Leader

    Very astute observation :D :D

    Geo pipe is HDPE , Where gas pipe MDPE.
     
  4. DavidCraig

    DavidCraig Member

    Well, for more fun I called a manufacturer and asked.

    Basically the resins used for Geothermal HDPE vs other HDPE is the same. It is the "Geothermal" print line that is different. This is for the benefit of inspectors.
     
  5. GCI

    GCI Member

  6. DavidCraig

    DavidCraig Member

    Yes it is important that there be an actual reliable definition. Again, I looked at one manufacturer specs on Geothermal pipe, drinking water pipe, and irrigation pipe - they read much the same - and why not... But I had wondered it the thermal properties for Geothermal resins would be better. As for lifespan, have keep reading that ground loops should be good for 50 to 75 to 100 years.


    Otherwise, thanks for the link ... I can almost understand what it says, lol.

    And it answers many questions about the standard practices of loop layout. For example, it seemed to me that it would be better to have all water sent to the field on one end, then collected on the other. With ground latencies (28-45 days) it might perform slightly better. But then how would you test each loop if the ends are 500' apart? It would be possible but labor costs would increase running back and forth with another 500' "test" roll.

    Or when it says that "All loops will be pressure tested ...", does is mean complete loop systems?


    It was a surprise to see that "stab-type fittings" are acceptable for pipe joining. The local water department has been using them on 1" HDPE lines to homes, but it would seem that heat fused joints could last longer.

    Lots of good info...
     
    Last edited: Aug 7, 2012
  7. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    We tried SDR 13.5 in horizontal loopfield, which have a thinner wall, thinking about better heat transfer, and no need for 160 psi pressure rating. Unfortunately they kink much easier, so we are back to SDR 11. Just FYI
     
  8. docjenser

    docjenser Well-Known Member Industry Professional Forum Leader

    We tried SDR 13.5 in horizontal loopfield, which have a thinner wall, thinking about better heat transfer, and no need for 160 psi pressure rating. Unfortunately they kink much easier, so we are back to SDR 11. Just FYI
     
  9. Kogashuko

    Kogashuko Member

    Since shipping is a concern of mine and I can find this locally for a decent price what about this N-12? Provided it doesnt come with holes in it for irrigation purposes?

    Advanced Drainage Systems 3/4 in. x 300 ft. IPS 100 PSI UTY Poly Pipe-75100300 at The Home Depot
     

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