Upgrading to a condensing furnace puts you on the fast track to energy savings in the winter. Such a furnace has substantially better energy efficiency than a standard, noncondensing furnace or boiler. The term “condensing” refers to the last step in the heating cycle the furnace goes through.
If you're in the market for a new furnace, you definitely should be considering the superior energy efficiency and performance you'll get with a condensing furnace. The percentage of furnace fuel converted to heat is expressed as AFUE, or annual fuel utilization efficiency, and the condensing furnace delivers the highest AFUE ratings available today.