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Old 12-17-18, 09:10 AM   #1
DoctorDoctor
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Join Date: Sep 2011
Location: Colorado
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Default Combination vertical/horizontal geothermal

My idea is this: dig 10 to 20 ten foot wells and use, say 6 or 8 inch pvc pipes (available at the box stores). Put a plug at the bottom. have a reducing T-connector and a PVC plug in the top. Have a 2 inch pipe going through a hole drilled in the top plug that goes down 9 feet. Connect with 2 inch pvc: the effluent comes out of the T-connector and is connected to the center inner pipe of the next large vertical pipe.

Advantages over a large slinky trench system:

1) Pouiseille's Law!!! The slinky field is long and narrow. Resistance to flow is proportional to the length and inversely proportional to the fourth power of the diameter. Pushing water through the long irrigation tubing is no small matter. The higher pressure required can lead to leaks.
2) If you are using a 2 inch pipe in a 6 inch pipe, the cross sectional area of the down flow central pipe is pi (3.14) and the annulus is pi x ( 9 - 1 = 25. This means the upward flow velocity is about 8 times slower. This gives it plenty of time to exchange heat.
3) There are plenty of youtube videos on DIY digging shallow wells.

Many questions, though both technical and mundane. First and foremost, how many vertical wells would be needed? What are the ideal diameters for the inner and outer concentric pipes?

By using the vertical dimension, much less square footage of the property should be needed.

Mundane: The reducing T-connector is easy, but how about the plumbing of the inner pipe through the top plug?

I have a sketch of what I am talking about.

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