All of today’s modern Furnaces and Boilers efficiency is measured by annual fuel utilization efficiency (AFUE). To be more specific, AFUE is the ratio of annual heat output of the furnace or boiler compared to the total fossil fuel energy consumed by a furnace or boiler in a year.
For example, a furnace rated at 80 AFUE means for every dollar you spend to heat your home 80 cents is returned in heat and 20 cents is lost. The AFUE rating does not include how much heat energy is lost through the ductwork of the heating system. Leaking ducts or non-insulated ductwork running through a cold attic will increase how much is lost.
An 80 AFUE rated furnace compared to older furnaces which recover only 45-65 cents worth of heat, these 80 AFUE furnaces are affordable and good choices for your home. To get the maximum worth out of each dollar spent on gas, a 98% plus operating furnace is the best option available. Each dollar spent in turn brings over 98 cents back in heat to your home.