Earth Coupled
Another term used to
describe homes and buildings using geothermal heat pumps is that they are
"Earth coupled" in that they are using the Earth as a heat source (in
winter) and a heat sink in the summer. The Earth coupled system uses a series
of pipes, commonly called a "loop" which is buried in the ground near
the building to be heated or cooled. The loop can be buried either vertically
or horizontally. It circulates a fluid (water, or a mixture of water and
antifreeze) that absorbs heat from, or gives heat to, the surrounding soil,
depending on whether the ambient air is colder or warmer than the soil.
Heat Pump
Subsystem
For heating, a
geothermal heat pump removes the heat from the fluid in the Earth connection,
concentrates it, and then transfers it to the building. For cooling, the
process is reversed.
Heat Distribution Subsystem
Conventional ductwork
is generally used to distribute heated or cooled air from the geothermal heat
pump throughout the building.
Residential Hot Water
In addition to space
conditioning, geothermal heat pumps can be used to provide domestic hot water
when the system is operating. Many residential systems are now equipped with
desuperheaters that transfer excess heat from the geothermal heat pump's
compressor to the house's hot water tank. A desuperheater provides no hot water
during the spring and fall when the geothermal heat pump system is not
operating; however, because the geothermal heat pump is so much more efficient
than other means of water heating, manufacturers are beginning to offer
"full demand" systems that use a separate heat exchanger to meet all
of a household's hot water needs. These units cost-effectively provide hot
water as quickly as any competing system.