Is a Geothermal Air Filter Worth It? Homeowner Benefits, When to Replace, and More Geothermal heating and cooling systems are a smart and greener way to keep your living environment comfortable year-round. But to keep them running smoothly over time, you need to choose quality air filters for geothermal systems.... Is a Geothermal Air Filter Worth It? Homeowner Benefits, When to Replace, and More Geothermal heating and cooling systems are a smart and greener way to keep your living environment comfortable year-round. But to keep them running smoothly over time, you need to choose quality air filters for geothermal systems....