These upflow/horizontal modulating burner furnaces come with a variable speed blower and operate at 97% AFUE. Meaning that 97 cents of every dollar of gas used goes into heating your home.
A modulating burner means your unit will operate at between 50% and 100% capacity, depending on how much is needed. This results in long cycles and very even heat throughout your home without spending more on your energy bill.
With a variable speed blower you can say goodbye to the "poof" and sudden rush of air when your furnace turns on. Instead you'll just notice a slow but steady increase in air flow as the unit adjusts to what your home needs.