Selection of a contractor for a geothermal heat pump system is very important, particularly for ground-coupled systems. There are several places to look for information.
Local utilities often have promotional and/or certification programs for both ASHP and GHP contractors. The utility may maintain a list of approved contractors to which they can refer you.
Manufacturers (see list at FAQ 9) of heat pump equipment can direct you to a dealer/contractor in your area. The International Ground Source Heat Pump Association (IGSHPA) maintains a list of contractors on their web site on the internet (http://www.igshpa.okstate.edu). The list is organized by state.
The search for a groundwater system contractor is somewhat simpler. In this case, most general heating and air conditioning contractors can handle the installation without any special training. It is necessary for him to coordinate with the well pump contractor to assure that an adequately sized well pump and tank are installed.