Geothermal.contractors

Hefel Geothermal is a specialized ground-source geothermal contractor based in Hazel Green, Wisconsin, in the southwestern corner of the state near the Iowa and Illinois borders. Owner Terry Hefel has been installing heating and cooling systems since 1984 and is described as the first licensed geothermal contractor in the Tri-State Area covering Wisconsin, Iowa, and Illinois. The company installs ClimateMaster geothermal equipment ranging from standard forced-air systems to triple-function units for combined heating, cooling, and domestic hot water. With decades of hands-on experience and hundreds of installations, Hefel Geothermal provides direct owner engagement and personalized project consulting for residential clients throughout Grant County and neighboring regions. Verified active operator per hefel-geothermal.com (geothermal contractor since 1984, hundreds of installs) + Iowa & Wisconsin Heat Pump Association membership — WI bundle audit 2026-06-02