How A Geothermal System Works
Geothermal heating and cooling
systems are also known as
geoexchange systems, ground
source heat pumps, or ground
coupled heat exchangers.
No matter what they are called,
all geothermal systems work
on the same principle of
extracting stored solar heat
from below ground for winter
heating or using the same
patch of ground as a heat sink
to deposit heat extracted from
the house during the warmer
summer months.
systems are also known as
geoexchange systems, ground
source heat pumps, or ground
coupled heat exchangers.
No matter what they are called,
all geothermal systems work
on the same principle of
extracting stored solar heat
from below ground for winter
heating or using the same
patch of ground as a heat sink
to deposit heat extracted from
the house during the warmer
summer months.
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Alternative-Heating-Info.com
A geothermal system is composed of three sub-systems which are described next.
1. Earth connection system (loops)
During the winter, heat is extracted from the ground by a water/antifreeze solution
circulating through polyethylene tubing 3/4 to 2 inches in diameter. During the summer the
process is reversed. Heat is extracted from the home and the circulating fluid deposits the
heat back into the ground.
The tubing is hundreds of feet long and each section of tubing connected to the heat pump
is called a loop.
The loops in a closed loop system are installed either horizontally in trenches or vertically in
bore holes. The length of the loops is determined by the heating and cooling load. A typical
horizontal loop will require 400-600 feet of tubing per ton of heating and cooling capacity.
Another requirement for horizontal loops is 1,500-3,000 square feet of land area for every
ton of capacity depending on soil properties and ground temperatures.
Where land is at a premium, or you don't want to disturb the landscaping, vertical loop
installations are used. A vertical loop system is installed by drilling bore holes between
200-300 feet deep and then placing the loop into the bore hole. Depending on the soil
conditions and the climate bore holes are placed between 15-20 feet apart.
One to two bore holes are needed for every one ton of system load. A vertical loop system
typically requires 150 to 300 square feet of land per ton of system load. To put this into
perspective, the average residential building has a system load of 3 tons.
Open loop systems, used in conjunction with well water, are also installed but aren't as
popular as closed loop systems since the well water used as the circulating fluid contains
contaminants likely to foul the heat pump.
2. Heat pump
The loops are connected to a corresponding supply or return manifold, which provides a
junction where the loops converge. From the manifold, the refrigerant/water is channeled
through return/supply lines and connected to the ground source heat pump.
The ground source heat pump is also known as a compressor, water furnace or heat pump
and works the same way as a refrigerator's compressor only it is reversible. The heat
pump pressurizes the fluid according to the need for heating or cooling, based on the
thermostat setting.
3. Distribution system
Heat energy released by the pressurized fluid may be channeled through a water to air
heat exchanger and air handler for distribution through the home's ductwork or channeled
through a water to water heat exchanger for distribution to radiant baseboards, in-floor
tubing, or radiators.
1. Earth connection system (loops)
During the winter, heat is extracted from the ground by a water/antifreeze solution
circulating through polyethylene tubing 3/4 to 2 inches in diameter. During the summer the
process is reversed. Heat is extracted from the home and the circulating fluid deposits the
heat back into the ground.
The tubing is hundreds of feet long and each section of tubing connected to the heat pump
is called a loop.
The loops in a closed loop system are installed either horizontally in trenches or vertically in
bore holes. The length of the loops is determined by the heating and cooling load. A typical
horizontal loop will require 400-600 feet of tubing per ton of heating and cooling capacity.
Another requirement for horizontal loops is 1,500-3,000 square feet of land area for every
ton of capacity depending on soil properties and ground temperatures.
Where land is at a premium, or you don't want to disturb the landscaping, vertical loop
installations are used. A vertical loop system is installed by drilling bore holes between
200-300 feet deep and then placing the loop into the bore hole. Depending on the soil
conditions and the climate bore holes are placed between 15-20 feet apart.
One to two bore holes are needed for every one ton of system load. A vertical loop system
typically requires 150 to 300 square feet of land per ton of system load. To put this into
perspective, the average residential building has a system load of 3 tons.
Open loop systems, used in conjunction with well water, are also installed but aren't as
popular as closed loop systems since the well water used as the circulating fluid contains
contaminants likely to foul the heat pump.
2. Heat pump
The loops are connected to a corresponding supply or return manifold, which provides a
junction where the loops converge. From the manifold, the refrigerant/water is channeled
through return/supply lines and connected to the ground source heat pump.
The ground source heat pump is also known as a compressor, water furnace or heat pump
and works the same way as a refrigerator's compressor only it is reversible. The heat
pump pressurizes the fluid according to the need for heating or cooling, based on the
thermostat setting.
3. Distribution system
Heat energy released by the pressurized fluid may be channeled through a water to air
heat exchanger and air handler for distribution through the home's ductwork or channeled
through a water to water heat exchanger for distribution to radiant baseboards, in-floor
tubing, or radiators.
