Renewable Energy Vermont has posted a really concise and helpful sheet on geothermal heating and cooling. Download it here. If you want to look through their website, which is also quite good, you’ll find compelling statements such as: “Because a properly designed and installed geothermal system can offer much better efficiencies than electric or gas heating systems, along with longevity, the technology has been recognized internationally and nationally as an intelligent alternative to heating with fossil fuels.” In addition, they also provide a link to all installers and certified geo techs in Vermont. It also has lots of Q&A for prospective geothermal installers (this would be you, the homeowner). It is a most helpful site.
For a national listing of installers, visit IGSHPA, whose tongue-twister acronym stands for the International Ground Source Heat Pump Association. It is aimed at industry professionals and lists lots of training sessions and workshops, but it also offers a list of members, so you can find one in your neighborhood.