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Dirt Cheap Solar Geo Thermal Greenhouse Heating & Cooling  RSS feed

 
Paul Ladendorf
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My goal has been to build a greenhouse that doesn't freeze in the winter here near Chicago so I've been researching different options. I decided on and finished the installation of a solar geo thermal heating and cooling system a few weeks ago and have been testing since then. It really needs to be tested for a whole year before I will be confident to recommend the system but initial test results are very promising. https://www.youtube.com/watch?v=dxVGm9elZjk
 
Kelly Smith
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Location: In a rain shadow - Fremont County, Southern CO
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sounds similar to a company that makes geodesic grow houses here in CO - but they also include a small water tank to hold heat also.

http://www.growingspaces.com/

cool!
let us know how it works / post pictures when you build it
 
Zenais Buck
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Location: PNW
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I really like this! I have been wondering how to do geothermal inexpensively for an off-grid greenhouse. Your video was very clear and simple. Thank you so much!
 
Terry Ruth
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Paul, thanks for sharing that. I have some questions.

Where did you get the ground temp graph?

Do you have a pic of how you mounted the fan to the tube?

I would think if efficient DC motors PV tied no inverter that would very efficent and as you said intake to minisplits even better. If fresh outdoor air along with indoor could be tee' d in at the intake it could be a heat recovery ventilator using the ground temps vs heat xchanger like plastics they use in air-to-air HRV's/ERV's.
 
Paul Ladendorf
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Terry Ruth wrote:

Where did you get the ground temp graph?


I don't remember. But I've seen lots of them and they don't seem to agree.

Terry Ruth wrote: Do you have a pic of how you mounted the fan to the tube?


I have two fans and since the tubes were slightly different sizes (they came from different manufacturers) on one I was able to just use a 6" hose clamp and duct tape to seal it. The other one I used a rubber plumbing adapter boot and duct tape. I'm still not sure how to get an air tight seal without duct tape.

Terry Ruth wrote: I would think if efficient DC motors PV tied no inverter that would very efficent and as you said intake to minisplits even better. If fresh outdoor air along with indoor could be tee' d in at the intake it could be a heat recovery ventilator using the ground temps vs heat xchanger like plastics they use in air-to-air HRV's/ERV's.


Great ideas. I've got a very tight house and really would like to install an HRV especially because I heat with wood. Unfortunately PV sucks out here. In the winter we can go weeks without a sunny day so even if I could find a really efficient fan to run this system (50 watts?), it would cost a small fortune for a PV system.

On another note, this system will not cool a greenhouse by itself. There's just way too much heat gain on a sunny day. Vents or an exhaust fan would be absolutely necessary.

There are still so many unknowns with this system but I like what I've seen so far.
 
Terry Ruth
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Thanks, seems like the trick is looking at your local ground temps guesstimating how long a run at what depth, what CFM out the fan would get out to the building. Seems like if your doing a basement might as well run the lines next to the french drain lines, when it rains the drain lines may help transfer some heat? Then run some test with fans. Run them in a wall to a nice register. This seems like a good concept just needs some developing. And it's fairly cheap!

Aluminum transfer better than plastic but corrode. Then put nasty stuff in the air. I wonder how natural ceramic or concrete lined ductile iron drain pipe would perform? If it can be found. From what I read the biggest issues with these earth tubes in condensation and mold. Perhaps not a big deal for a greenhouse.
 
darren summerson
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Interesting stuff!

I am constructing a greenhouse from bare earth up with something similar, and found this thread looking for info.

So thought I'd share my thinking, as I'm not far enough gone to have any stats. The green house will be 5mx11m, (sorry I'm a brit living in Sweden - I've had feet conditioned out of me) and the usual pitched roof, so roughly 2.5m high. I have 100m of 4" plastic drainage pipe, going into the ground, in loops of 15m or there abouts. Fans, I'm going to trial small fans such those for computers, but not sure if they have the push or draw to change the air volume 5 times per hour. Inside I'm going to partition it, so winter heating will be limited to roughly a third of the summer volume.

Power, I already have some old batteries and have invested in a 100w panel, which as some have said will be struggling in peak winter to keep the power demands of a fan system going.

I imagine that unless you throw some serious money at this kind of system, there will be a month or two in winter when it struggles to work and stay warm, the opposite with cooling in summer. So conventional venting may be needed and some kind of heating too.

There seems to be so much logic in this kind of system, but so little hard data available too.
 
Paul Ladendorf
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darren summerson wrote:Interesting stuff!
I imagine that unless you throw some serious money at this kind of system, there will be a month or two in winter when it struggles to work and stay warm, the opposite with cooling in summer. So conventional venting may be needed and some kind of heating too.


Not sure what your definition of "warm" is but I'm just trying to keep my gh from freezing. I agree that some supplemental heat will probably be needed for at least a month or so in my Chicago climate. The real question in my mind is how fast the ground will cool off in the winter to where there is not enough heat to extract from it to make a difference (or will it?) and how long it will take to warm back up. Maybe it will be useless until the following heating season (fall).

darren summerson wrote:There seems to be so much logic in this kind of system, but so little hard data available too.


Exactly what I've found. There is one company I've been talking to (I bought their e-book/report) that makes all kinds of outrageous claims about this type of system without anything whatsoever to back them up so be careful.

There are some knowledgeable and very helpful people out there though such as Marc over at http://ceresgh.com. Depending on how things work out with my test gh, I will work with them on my next install.

Good luck.
 
darren summerson
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[quote=Paul LadendorfNot sure what your definition of "warm" is but I'm just trying to keep my gh from freezing. I agree that some supplemental heat will probably be needed for at least a month or so in my Chicago climate.
.

warm? I guess for Dec/ Jan, hoping for 10 degrees C so plants will hang in there! perhaps in Nov and Feb slightly more sunlight so a little warmer. I imagine the climate here isn't vastly different to there, a few months every winter where it will remain permanently below zero, decent snow cover and frost penetrating fairly deep in the ground. I am putting my pipes around a metre down, where lack of bed rock will allow.

I imagine the lack of data is down to the huge number of variables, but I don't intend to buy any plans etc.. I just going to go for it, over engineering where possible, without extreme expenditure.

 
Rose Gardener
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Terry Ruth wrote:Thanks, seems like the trick is looking at your local ground temps guesstimating how long a run at what depth, what CFM out the fan would get out to the building. Seems like if your doing a basement might as well run the lines next to the french drain lines, when it rains the drain lines may help transfer some heat? Then run some test with fans. Run them in a wall to a nice register. This seems like a good concept just needs some developing. And it's fairly cheap!

Aluminum transfer better than plastic but corrode. Then put nasty stuff in the air. I wonder how natural ceramic or concrete lined ductile iron drain pipe would perform? If it can be found. From what I read the biggest issues with these earth tubes in condensation and mold. Perhaps not a big deal for a greenhouse.


I am all excited about this idea, until the condensation and mold part. We are talking about very long tubes that one wouldn't be able to see or inspect. When warm air enter the colder underground environment, no doubt condensation will happen, are there ways to over this? With condensation, mold is just a matter of time, isn't it?

 
darren summerson
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Rose Gardener wrote:
Terry Ruth wrote: With condensation, mold is just a matter of time, isn't it?



mine isn't up and running yet, so I can't confirm my theory, or what I've read on it.

But, the pipes I'm using are drainage pipe 3", which are perforated and water runs through easily. I'm burying them with a little clean gravel above and below, so any water will drain out. Also thinking about the angle so I literally don't drain the ground and cause the water to flow back towards the greenhouse. The only solid pipe I'm using is from the ceiling height to ground level of the air intake pipes in side the greenhouse, as I want to extract the warmest air from the top, however in winter logically you want the coldest air from ground level, I'm yet to find a solution here, other than a half way house of a mid height pipe.

In summer with the air cooling there should be water draining out of the pipes into the gravel, in winter when I hope the air to be warming, potentially the air will pick up any moisture in the pipe.
 
Erik Krieg
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I think as long as you slope your pipes or bore holes in there bottom then there should be no mold in a plastic line. I've been a plumber for over a decade and stick cameras down a lot of sewer lines. Never seen mold in a plastic sewer line. Pvc if sloped right looks almost new after 20 years of sewer sludge
 
Heather Ahrens
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Location: NW Nebraska
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Paul,
I thought you may find this interesting?
http://greenhouseinthesnow.com/
 
I've got no option but to sell you all for scientific experiments. Or a tiny ad:
Video of all the permaculture design course and appropriate technology course (about 177 hours)
https://permies.com/wiki/65386/paul-wheaton/digital-market/Video-PDC-ATC-hours-HD
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