Ground Source Heat Pumps (GSHP) are a relatively new technology to most people. Exotic! And “exotic” means undependable ~ risky! Clearly, the GSHP industry needs to work harder on its public relations, much harder.
GSHPs have been around almost as long as air conditioning itself. Over two million GSHPs have been installed worldwide (mostly in the U.S., Indonesia, Mexico, Japan, and around the Mediterranean. Fifty thousand new GSHP systems are installed each year in the U.S. (versus 3 million air-source heat pumps).
You don’t need an underground hot spring or other extraordinary heat anomalies for GSHPs to work. They work perfectly well in any ground conditions. GSHPs are far more efficient in the winter than regular air-source heat pumps. They maintain a consistent Coefficient of Performance (COP) around 3.0 down to well below 0 F. Regular heat pumps have a COP of 3.0 at 60 F, steadily decreasing to 1.0 (equal to pure electric “strip” heat, extremely inefficient) at 0 F.
In other words, at 0 F, a GSHP is three times as efficient as an air-source system. So, if you live in a northern state with very long, cold winters (including Alaska), the added cost of a GSHP will be paid off in only a couple of years (the “payback” of choosing a GSHP over a conventional heat pump) ~ less if you’re looking at a high-efficiency, multi-stage HVAC system. After those 2-3 years, the much lower operating cost of the GSHP system means direct savings on your utility bills for the life of the system ~ 20 years and more!
GSHPs work at a lower operating temperature and pressure than regular heat pumps, making geothermal systems very dependable and long-lasting. Ground source systems cost more to install because of the ground-loop piping, but the long-term operating cost exceeds air-source heat pumps ~ especially since GSHPs last 20+ years, versus 8-10 years for the competition.
In the much longer term, the ground loop piping is typically GUARANTEED for 80-100 years (it can last 200 years and more). So when it comes time to replace the heat pump, the cost is half that of replacing an air-source system.
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Excerpted from Going Green, available as an eBook at this list of eBook retailers online.