Two-stage heating permits the furnace to heat at two levels of output: high for cold winter days and low for mild ones. Approximately 80 percent of the time, your home’s heating requirements can be met when the furnace is kept on the low setting, permitting your two-stage unit to run for longer periods of time. Two-stage units also provide more even heat distribution, fewer temperature swings, quiet operation, better air filtration, and energy efficiency.