We're Jefferson County's Primary Geothermal Contractor! Jefferson County, Washington, homeowners have all sorts of reasons for desiring a geothermal heating and cooling system: exceptional year-round comfort – no matter how crazy the weather variations smooth operating performance energy efficiency (They’d be hard-pressed to find a more "green," more natural way to heat and cool their homes!) significant – sometimes outstanding – savings on their energy bills superior installation and maintenance from Thermal Systems, Jefferson County's geothermal professionals. Learn more about what a geothermal heating and cooling system can do to benefit your family's comfort. Look at our Geothermal Savings Calculator. Then contact Thermal Systems. We sell, install, and maintain WaterFurnace geothermal systems, the finest in the industry today.