For specifics on geothermal heat pump systems, including types, benefits and selection and installation, visit the U.S. Department of Energy website:
A good geothermal contractor should have a current C20 license for the mechanical system installation and the driller (if applicable) should have a C57 license for drilling the vertical ground heat exchanger. We recommend that the contractor installing the geothermal system be an IGSHPA Accredited Installer. Check the IGSHPA website to locate contractors that are currently accredited with this organization.
Many of the heat pump manufacturers have their own certifications for installation of their equipment. If you prefer a particular geothermal heat pump manufacturer, we suggest you contact their local distributor for references of dealers or installers of their products.