| Abstract |
The first geothermal heat pump system in the United States was installed in the Commonwealth Building in downtown Portland, Oregon, in 1946. This extremely successful and highly publicized project led to the installation of numerous installations throughout the Northwest and eventually the entire United States. Now, after 50 plus years of operating experience, it is time to take a close look at how well these systems have performed, their operating and maintenance histories, cost competitive, and longterm customer satisfaction. Case histories of over 20 systems have been developed representing a range of system designs, end-use applications, and geographic areas. Despite some problems related almost exclusively to poor maintenance or, in some instances, to wells, an overwhelming majority of owners and operators are highly satisfied with their system, often citing cost savings and a lack of operation and maintenance problems as significant advantages over other systems. |