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Posts: 37
Reply with quote  #11 
Hi, JoeK,  someone in the UK is doing a little article about the dripwall delta. (In a print magazine).   I have also mentioned something that I think you suggested.  A cold frame with a solar panel driving a computer fan that cycles the air down into some drain rock under the plants.  That keeps the heat in, but without overheating the air in the late afternoon and killing the plants (because the soil, water and drainrock absorbs the heat)  and it cycles the water too.  Anyway, if you want to be credited with the idea, (I think it is neat anyway!)  let me know and I will pass your name, etc on to the editor.  And if you want his details, to go direct, I can do that too.  Thanks Brian.     
Originally Posted by JoeK
Ok I did a little thinking and drew a mockup that just might work. I think this might be all you need, but if you replaced the simple chimney pipe with a more efficient collector you could likely increase the "draw" quite a bit. The collector would just have to be designed so the intake draws cool dry air coming out of the ground and then as it's heated air should rise unobstructed until it exits out the top. It might be possible to take advantage of the rear (North) interior wall of the frame itself and modify it into a large flat collector. Could work very well actually and not really impinge on the growing space. This is sounding like a very good refinement if your willing to do a little more work.  It's already in my head, Back to the drawing board. This one piece,black pipe design is about the most simple, basic "collector" you could make.
Thermosiphon Coldframe.jpg 

I suspect that even a slight airflow would yield a significant advantage over a "plain" cold frame, but more is certainly better. For reference in active systems target flow is at least 5 times the volume of air enclosed, per hour. Up to 10 exchanges per hour has shown significant increase in heat transfer though. That means recycling the entire volume of air in the system every 6 minutes. And of course in an active system you would reverse the direction of airflow and use your fan to push hot/moist air down underground from the elevated pipe, allowing cool air to exit near the plant/soil level. Use the fan to push through the system, not pull, as positive pressure in the underground section will increase the transfer of moisture, heat, and air, into the soil.


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Posts: 283
Reply with quote  #12 
Well done to Gaiatechnician and Joek.

Posts: 135
Reply with quote  #13 
Wow, thanks gaiatech, but I could hardly claim credit for those ideas. People have been using earth sheltered heat mass to buffer temp swings since we first took shelter in a cave. Many "refined" versions of this concept can be found across the ages of history on proably every continent. I believe the Romans had it going full on with vented stone floors. Someone probably hooked up a small solar fan to a buried pipe many years before I even heard the term "thermal mass", let alone Subterranean Heating and Cooling System.  I learned about this idea from Jerome Ostentowski @ CRMPI.org, who along with John Cruickshank(RIP) of sunnyjohn.com, began developing this system for greenhouse climate control +-30yrs ago.  The system I installed is directly taken from their design. Jerome refers to it as a "climate battery". I put a link to his website and credited him in my thread over in the greenhouse forum. He thanked me for those actions so I would suggest you send his info along or contact him, jerome@crmpi.org. As far as I know He and John were pioneers in SHCS greenhouse design, Michael Thompson of eco systems design is a licensed architect who has been working closely with Jerome for at least a couple decades, though I don't know if he got on board when the ship set sail or not. He was very helpful in my design as well.  I don't doubt that this concept was developed in more than one place before the magical internet made it so easy to know what was happening on the other side of the globe...

I suppose I did just draw up that picture for a passive thermosiphon to draw air through the subsoil, which as far as I know I just made up...I started a drawing to show how i would improve the flow with more absorber area by making the whole Nwall of the frame a passive "collector" of sorts. I'm having some trouble getting it to look good, but I'll throw it up later. Gotta try and get some more siding up before the snow hits...

Posts: 37
Reply with quote  #14 
The editor emailed me and said something is definitely going in his next edition. (I think it will include both systems). And just now I forwarded Joeks post to the editor so he could have more detail.  I did something for him years ago and from that experience,  I know he will put it in his own words.   I have to admit that outside of this thread, there is practically zero interest in the dripwall.   Seems that the only things that approve are the plants.   I met an interesting guy recently who told me it would not work because evaporation would cool the water too much.  (He was unconcerned that the water had warmed by up to 15 C on the way down). I believe most people think like that,  if something is new, evidence is meaningless to them.  Look at Joek's post.  The thing where the air is blown underground in a greenhouse has been around for 30 years!  I heard of it about a year ago but Joek is the first person to actually explain it.  Anyways, thanks for the  banter.  I will post more info when I get it.  I don't know the print schedule for the magazine.  Hopefully I will get a complimentary copy.
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