GEOTHERMAL TYPES
Vertical Loop
Most commercial and institutional projects using geothermal heat pumps incorporate the use of a vertical closed loop. The advantage of a vertical loop system, which consists of pipe inserted into vertical bore holes, is less space required. Several factors are considered when designing the loop field including total heating and cooling requirements, the amount of space available, and drilling conditions. While each vertical loop field is somewhat unique, generally, one bore hole (one circuit) handles one ton (or more) of total heating and cooling capacity. Holes are generally spaced 15 feet apart to minimize the effects of neighboring loops. After drilling each hole, the pipe is inserted into the hole. These pipes are generally 3/4" to 1-1/4" in diameter. The hole is then filled from the bottom up, with a grout or other sealing material to provide good contact around the pipe and to ensure that surface water does not flow directly into an aquifer. After the holes are drilled, the pipe inserted, and the hole is grouted, the pipes from each bore hole are then connected together to the horizontal piping and header system. Generally, several headers will be used to connect the multiple bore holes.
Pond Loop
A large body of water such as a pond or lake can also be utilized to provide the heat source and heat sink for a geothermal application. With this application, coils of geothermal pipe are connected to a header system. Weights are attached to each coil to keep it positioned at the bottom of the body of water. Where an existing pond is used, the coils are floated into location and filled with fluid. As the coils are filled, they slowly sink to the bottom. Ponds and lakes are excellent applications for geothermal systems since water provides superb heat transfer to or from the pipe. In colder climates where ice forms on the surface, the temperature at the bottom of the pond remains relatively constant and unfrozen providing an abundant supply of geothermal heat. Pond/lake loops are generally less expensive to install than horizontal or vertical loops since excavating requirements are minimized.
Depending on the climate and operating temperatures of the loop during the heating season, anti-freeze may be added to the closed loop system to provide freeze protection. There are several types of anti-freeze solutions that are recommended for their heat transfer properties.
Horizontal Loops
Earth loops can also be installed horizontally in trenches. Tthe depth of the trenches will vary according to design and soil characteristics, but is generally 5' -8' deep. Horizontal loops require much more surface area than vertical loops, and are therefore used less frequently for large projects. However, it may be an effective option for smaller projects with plenty of available land space.
Most commercial and institutional projects using geothermal heat pumps incorporate the use of a vertical closed loop. The advantage of a vertical loop system, which consists of pipe inserted into vertical bore holes, is less space required. Several factors are considered when designing the loop field including total heating and cooling requirements, the amount of space available, and drilling conditions. While each vertical loop field is somewhat unique, generally, one bore hole (one circuit) handles one ton (or more) of total heating and cooling capacity. Holes are generally spaced 15 feet apart to minimize the effects of neighboring loops. After drilling each hole, the pipe is inserted into the hole. These pipes are generally 3/4" to 1-1/4" in diameter. The hole is then filled from the bottom up, with a grout or other sealing material to provide good contact around the pipe and to ensure that surface water does not flow directly into an aquifer. After the holes are drilled, the pipe inserted, and the hole is grouted, the pipes from each bore hole are then connected together to the horizontal piping and header system. Generally, several headers will be used to connect the multiple bore holes.
Pond Loop
A large body of water such as a pond or lake can also be utilized to provide the heat source and heat sink for a geothermal application. With this application, coils of geothermal pipe are connected to a header system. Weights are attached to each coil to keep it positioned at the bottom of the body of water. Where an existing pond is used, the coils are floated into location and filled with fluid. As the coils are filled, they slowly sink to the bottom. Ponds and lakes are excellent applications for geothermal systems since water provides superb heat transfer to or from the pipe. In colder climates where ice forms on the surface, the temperature at the bottom of the pond remains relatively constant and unfrozen providing an abundant supply of geothermal heat. Pond/lake loops are generally less expensive to install than horizontal or vertical loops since excavating requirements are minimized.
Depending on the climate and operating temperatures of the loop during the heating season, anti-freeze may be added to the closed loop system to provide freeze protection. There are several types of anti-freeze solutions that are recommended for their heat transfer properties.
Horizontal Loops
Earth loops can also be installed horizontally in trenches. Tthe depth of the trenches will vary according to design and soil characteristics, but is generally 5' -8' deep. Horizontal loops require much more surface area than vertical loops, and are therefore used less frequently for large projects. However, it may be an effective option for smaller projects with plenty of available land space.