We're Lamoni's Primary Geothermal Contractor! Lamoni, Iowa, residents have all kinds of reasons for wanting a geothermal heating and cooling system: phenomenal comfort all year – no matter how crazy the seasonal variations stable operating performance energy performance (They’d be hard-pressed to find a more "green," more natural way to heat and cool their homes!) significant – often outstanding – savings on their energy bills noteworthy installation and maintenance from Sherman Co. LLC, Lamoni's geothermal experts. Learn more about what a geothermal heating and cooling system can do to increase your family's comfort. Look at our Geothermal Savings Calculator. Then contact Sherman Co. LLC. We sell, install, and maintain WaterFurnace geothermal systems, the finest in the industry today.