Our Freedom® Furnaces range in efficiency from 80 to more than 92 percent. Every member of the family is designed to provide maximum heat for minimum fuel usage. However, as you climb the ladder from single-stage to two-stage and Two-Stage/Variable speed (Comfort-R) ™ furnaces, you'll find an increasing number of benefits along the way. For example, two-stage heating makes a big difference when you need just a little heat, which is often in South Carolina. And our two stage/variable speed Comfort-R™ furnaces are perfect for circulating air throughout the house to keep the temperature even and the air filtered and clean.