What is the typical AFUE rating for a conventional oil furnace with a cast-iron burner?

The typical Annual Fuel Utilization Efficiency (AFUE) rating for a conventional oil furnace with a cast-iron burner is approximately 60%. AFUE is a measure of a furnace's efficiency in converting fuel to heat over a typical year, expressed as a percentage.

For conventional oil furnaces, especially those using cast-iron burners, 60% AFUE is representative of older furnace designs that were prevalent before advancements in heating technology. These systems tend to lose significant heat through exhaust and other inefficiencies, resulting in a lower AFUE rating.

In comparison, higher AFUE ratings, such as those above 70% or 80%, are indicative of more modern, high-efficiency furnaces that incorporate advanced designs and materials to better retain heat and utilize fuel more effectively. Therefore, knowing that conventional oil furnaces with cast-iron burners typically achieve around 60% efficiency helps to set expectations when evaluating older heating systems in homes.