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    Michael Ermann

    Vertical wells are best on a compact site.

    In summer, geothermal heat pumps couple the hot condenser with water that has been cooled by pumping it through the ground—creating a more efficient system than a normative air-cooled condenser. The compressor (pump) doesn’t have to work as hard because the hot side doesn’t have to cool itself in 100-deegree air. In the winter, the system is reversed and the cold side doesn’t have to heat itself in 0-degree air, and can instead access 50-degree water heated underground.

    Digging the earth for these loops of water are, from an architect or owner’s point of view, the dominant factor when considering the geothermal option. The pipes, which are actually more like continuous flexible tubing, can snake and loop through horizontal “trenches,” about three feet below the surface, or snake through vertical “wells,” that extend hundreds of feet downward. Both options prove expensive and disruptive to the land, especially if it’s difficult to get large equipment access to the site or if it’s been raining lately and the earth is soft.

    As you might imagine, horizontal trenches, which look like this and this are a better option if land is available to house them. Vertical wells are more expensive but the only option in, for instance, a tight urban infill site. They look like this and this (you can see why this is an expensive option).

    The systems I described above are “closed loop” systems where the same water (perhaps with a little anti-freeze mixed in) is recirculated between the indoor equipment and the ground in perpetuity. If there happens to be an underground aquifer or a pond on the site, an open-loop system may prove the best (least disruptive, and least expensive) option, whereby temperate water is drawn up through a pipe from the source, used to cool (or, in wintertime, heat) the refrigerant, and then returned to the body of water while new water is siphoned up to replace it. An open loop tied to an aquifer looks like this; an open loop tied to an on-site pond looks like this.--Michael Ermann, Amber Book creator.

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    Carie Penabad

    Dear Michael,


    Thank you so for your thorough explanation.  You have clarified this topic for me.  I have purchased your book and find it to be among the best resources out there.  

    Once again thank you for taking the time to carefully answer this question.




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    Joseph Petrarca

    I had a question in PPD that asked what the best geothermal was for a site that had rock fairly close to surface and had limited site area! There were four diagrams. In real life, of course, when Owner is presented with the contractors or cost estimator's numbers for the system, they will say.... "Whoa.... Forget it". I've seen it happen a number of times. That wasn't a choice in the exam! LOL.

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