these—horizontal, vertical, and pond/lake—are closed-loop systems. The
fourth type of system is the open-loop option. All of these approaches can be used for residential
and commercial building applications.
type of installation is generally most cost effective for residential
installations. This type of system uses a well or surface body water as
the heat exchange fluid that circulates directly through the geothermal
heat pump system. Once it has circulated through the system, the water
returns to the ground via a dry well or
surface discharge totally
unchanged. This option is obviously practical only where there
adequate supply of water.
trenches at least four feet deep.
most common layouts either use two pipes, one buried at six feet, and
the other at four feet, or two pipes placed side-by-side at five feet
in the ground in a two-foot wide trench.
supply line pipe is run underground from the building to the water and
coiled into circles at least eight feet under the surface to prevent
freezing. The coils should only be placed in a water source that meets
minimum volume, depth, and quality criteria.
commercial buildings and schools often use vertical systems because the
land area required for horizontal loops would be prohibitive. Vertical
loops are also used where the soil is too shallow for trenching, and
they minimize the disturbance to existing landscaping. For a vertical
system, holes (approximately four inches in diameter) are drilled about
20 feet apart and 100–400 feet deep. Into these holes go two pipes that
are connected at the bottom with a U-bend to form a loop. The vertical
loops are connected with horizontal pipe (i.e., manifold), placed in
trenches, and connected to the heat pump in the building. This type of
system will usually cost more due to the added price
of drilling each