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This has been done before in NC, and is well documented. I wanted to try it, to see if it is worth doing in the Hoop Houses at New Garden Farm. So, I gathered our leftover PVC piping and designed a small system for heating and cooling my shop.
Earth Tubes are sometimes called a Climate Battery, but I don't like that name because it doesn't work the way in which that name evolved. All it is, is a heat exchanger for air, buried in the ground. I first saw it in the video describing a Kansas farmer growing citrus all year round, in a greenhouse heated by pipes buried 8' deep. You blow air down the pipe, and it comes up 50*F, or thereabouts, all year long. In the winter, it provides heated air. In the summer it provides cooled air.
Some folks make them using perforated flexible pipe. The idea is that any water that condenses will exit through the perforations. I chose to install pump outs instead.
The big question is, how deep must you dig to get a relatively constant temperature? I chose three feet. If this works, we will be able to use this system to heat and cool our Hoop Houses and our big Greenhouse, allowing us to grow year round. We just need to figure out how deep to dig, how much length of pipe is required, and what air flow works best.
Here is how it works. A squirrel cage fan blows air into a 6" flexible, single wall, non-perforated pipe that goes out of my shop and down to the underground heat exchanger. It first flows through an 8" PVC pipe 18' long to an 8" manifold. The manifold has three 4" pipes connected to it, each 20' long. The 4" pipes connect to another 8" manifold, to which is connected the 6" flex that goes back up into the shop.
Here is the Air Heat Exchanger where I assembled it.
We then laid it in the hole.
I connected a pump out pipe to each manifold using 3/4" pipe. The manifolds are slightly low on that end. I also hammered a 4" pipe into the ground, so I can monitor the ground temperature using a remote digital thermometer. Finally, I connected the flex pipe that will lead up into the shop.
Filled in all...
...and covered it with leaf mulch that's a few years old. The whole area is going to become a vegetable and flower garden.
Now I need to rake out the leaf mulch and mix it with the clay. I will run the flex into the shop. Where the flex is above ground, I will cover it and insulate it. In about a week, I will connect the fan and see what happens!
You can see the shadow of the solar panels that will power the squirrel cage fan. Once installed, this is free HVAC!
Earth Tubes are sometimes called a Climate Battery, but I don't like that name because it doesn't work the way in which that name evolved. All it is, is a heat exchanger for air, buried in the ground. I first saw it in the video describing a Kansas farmer growing citrus all year round, in a greenhouse heated by pipes buried 8' deep. You blow air down the pipe, and it comes up 50*F, or thereabouts, all year long. In the winter, it provides heated air. In the summer it provides cooled air.
Some folks make them using perforated flexible pipe. The idea is that any water that condenses will exit through the perforations. I chose to install pump outs instead.
The big question is, how deep must you dig to get a relatively constant temperature? I chose three feet. If this works, we will be able to use this system to heat and cool our Hoop Houses and our big Greenhouse, allowing us to grow year round. We just need to figure out how deep to dig, how much length of pipe is required, and what air flow works best.
Here is how it works. A squirrel cage fan blows air into a 6" flexible, single wall, non-perforated pipe that goes out of my shop and down to the underground heat exchanger. It first flows through an 8" PVC pipe 18' long to an 8" manifold. The manifold has three 4" pipes connected to it, each 20' long. The 4" pipes connect to another 8" manifold, to which is connected the 6" flex that goes back up into the shop.
Here is the Air Heat Exchanger where I assembled it.
We then laid it in the hole.
I connected a pump out pipe to each manifold using 3/4" pipe. The manifolds are slightly low on that end. I also hammered a 4" pipe into the ground, so I can monitor the ground temperature using a remote digital thermometer. Finally, I connected the flex pipe that will lead up into the shop.
Filled in all...
...and covered it with leaf mulch that's a few years old. The whole area is going to become a vegetable and flower garden.
Now I need to rake out the leaf mulch and mix it with the clay. I will run the flex into the shop. Where the flex is above ground, I will cover it and insulate it. In about a week, I will connect the fan and see what happens!
You can see the shadow of the solar panels that will power the squirrel cage fan. Once installed, this is free HVAC!
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