Annandale, Minnesota, Geothermal Geothermal Concept is the best WaterFurnace geothermal contractor in Annandale, Minnesota. We'll help you understand all the benefits of geothermal heating and cooling. We’ll make sure your WaterFurnace system is correctly installed, too. And when it comes time for service? Nobody in Annandale does it better! Contact Geothermal Concept today. Like a little up-front look at the savings a WaterFurnace geothermal heating and cooling system can provide? Use our simple Geothermal Savings Calculator.