If your thinking replacing your old furnace but wondering how much energy you will save or how much more efficient a new one would be think about the AFUE of the furnace. AFUE stands for Annual Fuel Utilization Efficiency. Or in other words if the AFUE is 80 that means that 80 percent of the fuel is used by the furnace and the other 20 percent escapes as exhaust with combustion gases. Most new furnaces are 95% efficient. So if your furnace was new in 1992 it’s probably 78% efficient or less. The average life span of a furnace is 25 years. Plus older furnaces use a pilot light rather than a more efficient two stage closed-combustion gas fired model. Call your Denver furnace repair experts today!