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GAHT Greenhouse

Discussion in 'Gardening On Your Homestead' started by CrealCritter, Jan 21, 2019.

  1. Jan 21, 2019
    CrealCritter

    CrealCritter Super Self-Sufficient

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    Very interesting (Ground Air Heat Transfer) for a greenhouse. Assuming you can excavate and backfill 5' depth (backhoe/skidsteer) the pipe and fan is fairly inexpensive. It's kind of like a very simplistic non-technical geo thermal heat/cooling pump.



    Anyone here have one?
     
  2. Jan 21, 2019
    Mini Horses

    Mini Horses Super Self-Sufficient

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    Don't have one -- or any other type. But the concept makes some sense.
     
  3. Jan 21, 2019
    Lazy Gardener

    Lazy Gardener Almost Self-Reliant

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    There are various methods of doing this. The one I've seen most often involves a deep trench outside the green house. The plan is for it to draw cool air from below frost level up into the green house, where natural convection then moves the hot air out through vents at the top.

    I need to get some sort of ventilation installed in my greenhouse to make it functional. I'd like to consider something as simple as a fan installed in the window at the north end.
     
  4. Jan 21, 2019
    CrealCritter

    CrealCritter Super Self-Sufficient

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    My son buying his underground house has caused me to research.

    Heat rises to putting on the ceiling doesn't do as much good as if it were lower. Maybe the inlet should be higher than the outlet, but irregardless it's easy and cheap to adjust the inlet / outlet heights. But the whole idea behind the GHAT system is to satablize the temperature in the greenhouse to an acceptable range. Mainly 45 to 75 degrees irregardless of the air temperature outside the greenhouse.

    For example, let's say in Kansas City, the underground temperature at 5 feet is 55. In summer, the air temperature can reach 100, and in winter as low as 20, but underground temperature at 5 feet is still 55. It's not that hard to get that constant temperature out of the ground so you could heat in winter and cool in summer to an acceptable temperature range.

    Hope that makes sense
     
  5. Jan 21, 2019
    CrealCritter

    CrealCritter Super Self-Sufficient

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    Here's an introduction to GHAT in a greenhouse senerio.

    IMG_20190121_121537903.jpg
    IMG_20190121_121551475.jpg

    IMG_20190121_121557999.jpg
     
  6. Jan 21, 2019
    frustratedearthmother

    frustratedearthmother Sustainability Master

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    It's pretty cool. I don't really need a greenhouse. What I'd really love is a screen house. Just to keep the bugs off of my 'maters!
     
  7. Jan 21, 2019
    Lazy Gardener

    Lazy Gardener Almost Self-Reliant

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    Yes, that makes sense. And, if I had earth moving equipment, or money to hire someone, I would do that. But, since I live in an area that is more rock than soil, lots of clay, and during the spring, the water table sits 6" below the soil surface, that won't be happening here. Thus, the cheaper approach of installing a fan, and rolling up the bottom sides of the greenhouse as soon as we are experiencing predictable frost free nights.
     
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  8. Jan 22, 2019
    cabinguy

    cabinguy Lovin' The Homestead

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    I always thought a pit greenhouse would be a great concept
     
  9. Jan 26, 2019
    CrealCritter

    CrealCritter Super Self-Sufficient

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    It would if you could keep the water out of it so it wouldn't become a swimming pool. Good drain tile system with sump pumps should work well.
     
  10. Jan 26, 2019
    Lazy Gardener

    Lazy Gardener Almost Self-Reliant

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    I'd not want to be depedent on electricity to run a sump pump. B/C flooding conditions often go hand in hand with electricity outages.
     

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