DIY Geothermal Ground Loop

A geothermal ground loop is part of a heating and cooling system that uses the earth's constant temperature to heat or cool a building. These systems are very common in volcanic areas like Iceland, where the earth can be 80 to 90 degrees a few feet below the surface. In most other places, the ground loop can be coupled with a heat pump, to draw warmth from the 50-to-60-degree earth in the winter, and to deposit heat during the summer.

Shovel or backhoe
Tubing (1 to 3 inches in diameter)
Tubing joints (L's and T's)
Plumber's glue/solder and blowtorch

Instructions

- 1
  Dig a hole adjacent to the building approximately half of the footprint of the building. The hole needs to be 2 feet deeper than the frost line (for temperate climates) and 2 feet into the geothermal zone (for volcanic areas).
- 2
  Lay out the tubing along the bottom of the hole. The tubing should be run in either an 'S' shape for temperate climates or it can be run in parallel lines for volcanic areas. In either situation, parallel sections of tubing need to be 18 to 24 inches apart.
- 3
  Connect the parallel lengths of tubing together with the tubing joints. Use L joints to make an "S" shape or use T joints for parallel lines. Either setup needs to have an input point and an output point.
- 4
  Run tubing from the input and the output to the edge of the building. The tubing should be run at depth until it gets to the building, then run straight up to the entrance point on the building.
- 5
  Seal the tubing to each joint using plumber's glue for PVC tubing or solder and blowtorch for metal tubing. The joints need to be watertight.

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