Ground source heat pumps: ground loop design

A crucial element of the design of any ground source heat pump system is the ground loop, which works to collect and disperse heat underground. Installation methods vary, and are chosen to fit the needs of the individual system. The ground loop design can vary based on excavation costs, terrain, climate, and the heating and cooling requirement of the structure. The most popular ground loop design configurations are the vertical and horizontal closed loop, and the pond loop, which are discussed below.

Horizontal closed loop

A horizontal closed loop absorbs the natural heat below ground for use inside the structure, and also deposits unneeded heat back into the earth. As the name implies, horizontal loops are installed horizontally across the available ground. A horizontal loop requires more ground space, as the piping is laid at a shallow depth rather than in deep wells- the trenches where the piping is installed are approximately 6 feet deep. Ground temperatures closer to the surface vary with the changing seasons.

Vertical closed loop

Instead of laying the piping in shallow trenches, a vertical closed loop is installed several hundred feet below ground in deep bore holes. By drilling deep holes, less surface area is needed for installation because of the consent temperature. The ground temperatures at 25 to 30 feet start to become constant. Ground source heat pump system applications which do not have significant ground space are ideal candidates for vertical closed loop design and installation.

Pond loops

Instead of utilizing underground temperatures for heat exchange, a pond loop utilizes a body of water. In this scenario, a lake or pond near the building is used for installation, and the ground loop placed below the surface. If there is not an existing body of water, one may be constructed specifically to meet the needs of a ground source heat pump system. Not all bodies of water are suitable for ground loop placement- the depth and size of the pond or lake must be able to withstand the heating and cooling load of the building.

When designing a ground source heat pump system, loop design is a crucial factor which can determine the success and efficiency of your system. The experts at Smith Sustainable Design will survey the available area and factor in the building’s heating and cooling need to determine which ground loop design is appropriate for each application.