Name:   Summer Place - Subject:   Natural Gas Heating rather than Heat Pump Date:   7/13/2010 3:47:07 PM

WHY IS A GEOTHERMAL HEAT PUMP BETTER?
Water stores tremendous quantities of heat. In nature, few substances have a higher specific heat (one BTU per pound) than does water, making it an ideal heat storage medium for both natural and man-made phenomena.

Air, on the other hand has a very low specific heat (.018 BTU per cubic foot). There is 3472 times more heat stored in a cubic foot of water (62.5 BTU per degree F) as in a cubic foot of air . In other words it would be necessary to move 3472 cubic feet of air through a heat exchanger in an air-to-air heat pump in order to expose that heat exchanger to the same quantity of heat stored in a cubic foot of water (7 1/2 gallons) that is moved thru a geothermal heat pump.

Furthermore, Enviroteq geothermal heat pump units have such low resistance to water flow (pressure drop) that about two cubic feet per minute (15 gallons) is the average water flow through an Enviroteq geothermal heat pump utilizing only about 235 watts of energy compared to well over 1000 watts to move nearly 7000 cfm of air through the air-source heat pump.

While these differences are significant, there is more: the heat transfer characteristics of water make it superior to air. Conduction is more rapid, more complete, and more efficient a heat transfer phenomenon than convection. A ground-water heat pump extracting heat from water at freezing is approximately equal in performance to that of an air-source heat pump extracting heat from 60 degree air.