All Heat Pumps

Because shallow ground temperatures are relatively constant
throughout the United States, geothermal heat pumps (GHPs) can be
effectively used almost anywhere. However, the specific geological,
hydrological, and spatial characteristics of your land will help your
local system supplier/installer determine the best type of ground loop
for your site:

Geology

Factors such as the composition and properties of your soil and rock
(which can affect heat transfer rates) require consideration when
designing a ground loop. For example, soil with good heat transfer
properties requires less piping to gather a certain amount of heat than
soil with poor heat transfer properties. The amount of soil available
contributes to system design as well — system suppliers in areas with
extensive hard rock or soil too shallow to trench may install vertical
ground loops instead of horizontal loops.

Hydrology

Ground or surface water availability also plays a part in deciding
what type of ground loop to use. Depending on factors such as depth,
volume, and water quality, bodies of surface water can be used as a
source of water for an open-loop system, or as a repository for coils
of piping in a closed-loop system. Ground water can also be used as a
source for open-loop systems, provided the water quality is suitable
and all ground water discharge regulations are met.

Before you purchase an open-loop system, you will want to be sure
your system supplier/installer has fully investigated your site’s
hydrology, so you can avoid potential problems such as aquifer
depletion and groundwater contamination. Antifreeze fluids circulated
through closed-loop systems generally pose little to no environmental
hazard.

Land Availability

The amount and layout of your land, your landscaping, and the
location of underground utilities or sprinkler systems also contribute
to your system design. Horizontal ground loops (generally the most
economical) are typically used for newly constructed buildings with
sufficient land. Vertical installations or more compact horizontal
“Slinky™” installations are often used for existing buildings because
they minimize the disturbance to the landscape.