AFUE (Annual Fuel Utilization Efficiency) is the standard measurement of efficiency for gas fired furnaces and boilers. Given in percentages, this number tells you how much of your fuel is used to heat your home and how much fuel is wasted. The higher the AFUE rating, the greater the efficiency.
Cost Savings: If you have an older furnace (with an AFUE of approximately 60%), you could save up to 40% on your heating bills by replacing it with a new high efficiency furnace! The cost to replace your old, inefficient furnace is paid back through lower utility bills.