A furnace with an AFUE of 90% or higher has what feature?

A furnace with an Annual Fuel Utilization Efficiency (AFUE) of 90% or higher is designed to maximize heat extraction from the fuel it consumes. This high efficiency is typically achieved through the incorporation of both primary and secondary heat exchangers.

The primary heat exchanger captures heat from the combustion gases produced during fuel combustion. In a high-efficiency furnace, the secondary heat exchanger further allows for the extraction of additional heat from these gases, which would otherwise be vented out and wasted. This dual-exchanger system enhances the furnace's ability to transfer heat to the home's air while minimizing energy loss, leading to a higher AFUE rating.

High-efficiency furnaces are a key component in reducing overall energy consumption and improving indoor comfort. Therefore, the presence of both primary and secondary heat exchangers is a defining feature of furnaces with an AFUE of 90% or higher, solidifying their status as efficient units within the HVAC industry.