Terry Hefel started Hefel Geothermal in 1984.  He holds Heating Ventilation and Air Conditioning (HVAC) licenses in both Iowa and Wisconsin.  He is a member of both the Iowa and Wisconsin Heat Pump Associations and is an associate member of Dubuque Homebuilders and Associates.  He has installed several hundred systems, including the first horizontal slinky loop system in the Tri-State Area.