The Reliable Renewable Geothermal gives you the freedom to focus on life WaterFurnace geothermal systems provide reliable operation 24 hours a day, 7 days a week, 365 days a year—rain or shine, day or night, windy or not. They use the stored solar energy in the ground to provide your family luxurious comfort and incredible savings. In fact, it’s the only HVAC system that’ll pay you back—and with the renewed 30% federal tax credit*, there’s never been a better time to switch to the Reliable Renewable. Want to know how much you can expect to save on your energy costs with a geothermal system in Charleston, Custom Climate Heating & Air? Find out with our geothermal savings calculator! * The 30% credit is available through the end of 2019, but it’s set to decrease each year through 2021. The credit amount drops to 26% in 2020 and down to 22% in 2021.