A vertical ground loop system may be installed in vertical boreholes 150- to 300-feet deep. Each hole contains two pipes with a U-bend at the bottom. After the pipe is inserted, the hole is backfilled and grouted. The number of loops required depends on ground conditions, air conditioning and heating loads, and the depth of each hole. This design is well suited for retrofit applications where landscaping is already complete.
A horizontal ground loop system is usually selected when adequate space is available and trenching can be easily accomplished. A series of pipes is laid out in trenches 4 to 6 feet below the ground surface, then backfilled. Often multiple pipes are used to maximize the heat transfer capacity of each trench. The amount of pipe and the size of the ground loop field are based on ground conditions, heating, and cooling requirements.