Subterranean Heating and Cooling Systems

[soil]

I want to add one of these to my greenhouse, I know a guy who has some in his two GH and said they are awesome. id love for my GH for be a good 70 year around.

https://www.sunnyjohn.com/indexpages/shcs.htm

[DoubleDogFarm]

Soil,

I find this heating / cooling system very interesting. My first question would be, will it work in the dreary, grey skies of the Pacific Northwest's long winters?

I could see it working in the spring when the sun finally shows.

Eric

[soil]

yes that's the best part! it uses the thermal mass of the soil. in a short sense, you take the hot/warm summer days and cool your greenhouse with the cool earth through the phase change, hot air goes in and cool comes out. meanwhile your storing that heat underground. then come winter its the opposite, cool air goes in, the phase change is the opposite way it happens in summer and warmer air comes out. you set the thermostats to a controller and tell it when to come on at which low and which high. one system does both.

I'm gathering materials now to convert our smaller greenhouse.

my friend told me his mentor had bananas growing year around in Colorado at nearly 7000ft.

[DoubleDogFarm]

Soil,

I need to do more research.

The part I don't quite understand is we have no sun to charge the soil during the day, in the winter. If we dig down deep enough, we get a constant 54 degrees year around.

The cooling part is very easy to understand. Running hot 100 degree air temperatures through a large cool moist earth filter.

How do we get running 40 degree air temperature through a luck warm 54 degree moist earth filter and get heat to grow year around. You would think the average is 47 degrees?

I will also add, do they mention the short day light hours. is there artificial light involved?

Eric

[soil]

The part I don't quite understand is we have no sun to charge the soil during the day, in the winter. If we dig down deep enough, we get a constant 54 degrees year around.

its all about the phase change, read that website good, a few times over if you have to. when I was first told about the system I thought it had to go with the relative stable temp underground, but it doesn't. you essentially "charge" the warmth underground in the summer while replacing it with cool as you get the idea, and then use all that stored heat all winter. in the winter you use up that warmth and replace it for cool for summer. I'm sure you already know that even on an even slightly sunny day in the winter. the greenhouse can still be much warmer than outside given you have no windows or doors open.

I understand how wet and cloudy it can be a little further north, but we get quite a bit of cloud cover in the winter months here. we get storms and cloud cover that goes on for weeks sometimes during the rainy season. maybe giving the greenhouse a few hours a week in the sun at best. my friend who has two lives even higher up around 4000ft and is surrounded by tall pines.

not trying to convince you to make one or anything, just understand why and how it works. I'm going to be doing it and will keep updated on progress once I get the supplies.

[DoubleDogFarm]

not trying to convince you to make one or anything, just understand why and how it works. I'm going to be doing it and will keep updated on progress once I get the supplies.

I don't need convincing, I'm already there, I need data.

I'm not picturing the heat storage lasting into the Fall / winter. I see it running out rather quickly. We do have sun on occasion during the winter, but it also could be in the teens temperature.

Not sure how to calculate. Say you get your soil temperature up to 100 degrees 2 or 3ft down. I have read that a foot underground is not deep enough. Then you are pumping 70 degree at it in the early fall. How long does it take until the soil becomes 70 degrees? Does the stored heat reduction start out slow and progressively gets quicker?

Stored heat------Pumped heat

100f-- 100f = 100f
100f--80f = 90f?
90f--100f = 95f?
95f--70f = 82.5f
82.5f--70f = 76.25f

What are the fluctuations?

More reading on my part

Eric

[soil]

I'm not really a data person eric. I just mimic the results I witness.

there are other websites that also explain, you might just need to do some personal research for numbers.

[DoubleDogFarm]

OK, can do.

Tell me some of your plans.

Depth?
4" perforated pipe or something else?
Will the pipe be surrounded in crushed rock?
Heat collection at the ceiling. What material, size? painted?
Will you be using a barrel for transition?

Brain picking
Eric

[soil]

PostPosted: Fri Apr 15, 2011 5:03 am Post subject:
OK, can do.

Tell me some of your plans. - still gathering materials and planning as of now but here we go

Depth? - not sure yet
4" perforated pipe or something else?probably will go with 3 inch preforated pipe as its a small greenhouse
Will the pipe be surrounded in crushed rock?most likely some sort of sand/gravel
Heat collection at the ceiling. What material, size? painted?do you mean the roof material? right now its 6 mil clear plastic
Will you be using a barrel for transition?yes I'm pretty sure you need it to make the system work and to stay clean

did you read the link yet?

[fintuckyfarms]

I have not looked at the site yet, but I thought it worked on the premise that the ground temp is an even 50ish degrees. In the summer you push the hot air thru and it cools it to the 50ish degrees and in winter, you push the cold air thru and it heats it to the 50ish degrees. Then you just have to heat/cool the difference from the 50ish to what you want. Wrong system?

[sierrareef]

No expert here, but I'm in the process of buying a geodesic greenhouse from Growing Spaces, and their website talks a little about the undersoil heating method they use - it sounds like it's what is discussed in this thread. You can find the brief explanation at the Growing Spaces website under the Benefits tab.