Cromwell, Minnesota, Is Going Geothermal! Willow River Geothermal has definitely had a hand in that! We're a heating and cooling contractor who’s specialty is installing and servicing geothermal systems right here in Cromwell, Minnesota. Area homeowners place their confidence in us for ... our experienced, highly educated staff our expert geothermal installation and service capabilities the planning assistance and advice we give - to help Cromwell customers get the most from their geothermal installations If you've been thinking of going geothermal, contact Willow River Geothermal today, Cromwell's top geothermal contractor. (For a quick overview of the kind savings your family could experience with a geothermal heating and cooling system, try our handy Geothermal Savings Calculator.)