Horizontal loops
These are often considered when adequate land surface is available. Pipes are placed in trenches that range in length from 100 to 400 feet.

Vertical loops
These are the ideal choice when available land surface is limited. Drilling equipment is used to bore small-diameter holes from 75 to 300 feet deep.

Pond (lake) loops
These are very economical to install when a body of water is available, because excavation costs are virtually eliminated. Coils of pipe are simply placed on the bottom of the pond or lake.

Open loops
These use groundwater as a direct energy source. In ideal conditions, an open-loop application can be the most economical type of geothermal system.