A horizontal ground loop is one of the most commonly installed ground loop types. It is achieved by burying thousands of feet of pipe in trenches or a pit-style excavation. The pipe is buried at a depth of 6-8 feet to provide adequate frost protection. A large amount of land is needed to run those trenches, but if that land is available, it can be an easy and economical way of building a ground loop.
The size of the loop and amount of trenching needed are dependent on things like your heating load need and soil type. The heating load will be the greatest factor in the sizing of the loop, and obviously the larger the house, the larger the heating load, the larger the ground loop needed to supply that heat.
Soil type is also a very important point to consider because some soils, like gravel and dry sand, don’t provide as good of a heat conductor as soils like wet dirt, clay, or static water.
Many times horizontal loops are installed as “Slinky Loops” because of the large amount of pipe and trenching required for a horizontal loop.