DIY Geothermal Greenhouse Part 7: Earth Battery MISTAKE!

DIY Geothermal Greenhouse Part 7: Earth Battery MISTAKE!

#116 After starting to build our DIY EMT electrical metal conduit (1.25″) greenhouse two years ago, we are finally back to completing this project.

We readily admit we are not experts at this (we are not engineers, greenhouse experts, or thermodynamic scientists), but a family doing our best to do it all ourselves and install based on all that we have read or watched on YouTube (don’t believe everything you see on the internet) to date and in line with our limited budget. Based on comments on videos, we already know some things should be done differently. Hopefully, it still works well enough, even if not optimally. We plan to share the results regardless.

In this video we must admit a mistake and correct it. The supply, return, and manifold originally installed were too small. So we’re fixing that and trying to do a better job of explaining the whole system.

Background on the project: Our farm homestead came with metal pipes in the ground from a former 16′ x 50′ hoop house. It also had water lines run from the farm well (which also needed to be restored) and a 60 amp electric service. In the first video we installed the 1.25″ EMT conduit that serves as the frame. In future videos we’ll frame the end walls, run electric, and get the plastic cover on in time for winter.

Each rib or section of the greenhouse consists of three 10′ pipes, no cutting. They are joined by stock EMT connectors. The two outer angles are 117.3. The ridge angle is 125.4. Sides are 6′ tall. Just over 10′ to the ridge. 16′ wide.

Ultimately, this will be a double wall plastic film greenhouse.



Jason Shaw: “Landra’s Dream”



St. Isidore’s Farm


What do you think?


Written by Aleksandar

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  1. The 6 inch vs 4 inch is probably a little worse than 2.25 difference. (6/4 = 1.5, and the area is proportional to the square. 1.5 squared is 2.25) With fluid dynamics, and similarly with air flow, there is friction/drag in the air flow near the walls of the pipe. Thus, the effective diameter is a little smaller. Example: a 4 inch pipe has the same cross sectional area as 16 one inch pipes, but will let far more air through quicker/less pressure.

    Nice videos.

  2. Question…
    For heating purposes, wouldn't it be better to pull air from the floor and push it out a higher vent pointing down?
    And vice versa for cooling..

  3. So for 6144 cubic feet of air your greenhouse is what size? Also I heard you must have commercial dehumidifier during the summer? I am located in New Jersey

  4. Who convinced you that air is a adequate heat transfer media? They lied! Use a truck radiator connected to a water pipe that you lay in a s shape in the dirt, a regular fan to move the heat from the air to the radiator and a circulation pump for the water loop and you have a system that will work both for moving heat from the air and returning it when the air cools. what you get is a thermal load that will slow both heating and cooling of your green house. Good luck. Ps. the more water you have in the system the more energy can be stored.

  5. That is not an earth battery son. An earth battery is two plates of dis-similar metals (copper and zinc for instance) burried about 12 feet apart making an earth battery cell. Lots of amperage but low voltage (about 1.5 volts per cell). But 8 of them strung in secession will give you 12 volts forever, day and night, with no generator!!! They ran the telegraphs with earth batteries for decades in the 1800s. But you made a mess here 🙂 Looks like your wiring a floor or ceiling for "ceiling heat". Now a 12 inch corrogated drive way tile burried cornor to cornor 5 feet deep, with a 4 or 6 inch input and output would slow the volumn in that pipe enough to convert the air to 57 degrees (which is all your gonna get anyway). A heat strip in the output pipe would only have to raise 57 degree air by 13 degrees to achieve 70 degree air!!!!! A thermostat and zitty-boom-bop 😉 It ain't rocket science 🙂 Did you check to see what the numbers would be if you used the 4 inch you had and boosted the output to 70 degrees instead of 57? Now that wouldn't run much except in extreme weather, because the thermostat wouldn't come on till the air dropped to 50 or you would be blowing air hotter than 57 into the pipe!! Good luck youngin' 😉

  6. Similar to the concept of using a series of 2 litre bottles to cool a room. Hot air in the open cut off bottom becomes compressed by the narrowing of the neck and final opening when forced through. That compression, cools the air. One of the reasons we purse our lips to blow across something we want cooled. Try it, there is a very significant temperature difference between air blown through pursed lips, and air blown through an open mouth at same velocity.

  7. You might want to turn the fan down anyway. You might as well give the air a chance to exchange some heat as it does it's lap underground. A short section of pipe can handle a high air speed just like a fuse can handle lots of current. If you turn your fan speed down you will save money, does it heat both ends from each roof top end or does all the hot air go to one end and then traverse the greenhouse floor? I saw someone complaining that they had got this wrong and had ended up with uneven soil temps.


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