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GEOTHERMAL
HEATING
AND COOLING
SYSTEMS
HISTORY OF LOW GRADE GEOTHERMAL
HEAT PUMPS
Humankind didn’t always know that the earth stored
solar energy. Nor did we know that this stored solar
energy is in the form of heat (measured as
temperature) and that the stored solar energy
(temperature) remains very nearly constant for each
point on the earth.
That is to say, cold climate areas have less stored
solar heat so their below ground temperatures
remain constant, but at a lower reading
(temperature) than the below ground temperatures
of warmer climate areas of the earth. Although the
temperatures vary according to latitude, at six feet
underground, temperatures range from
approximately 45 degrees to 75 degrees Fahrenheit
in the United States.
Mean annual earth temperature observations at
individual stations, superimposed on well-water
temperature contours.
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