Gas Heat ESCO Practice Exam 2025 – Comprehensive All-in-One Guide for Exam Success!

The AFUE (Annual Fuel Utilization Efficiency) rating measures a furnace's efficiency in converting fuel to heat over the course of a year. Typical condensing furnaces are designed to exceed standard efficiency levels due to their advanced technology, which allows them to extract more heat from the fuel they consume.

Condensing furnaces generally have a minimum AFUE rating of around 90%. Many modern models surpass this threshold, achieving ratings of 95% or higher. The significance of this higher rating is that it reflects the furnace’s ability to recover and utilize heat that would otherwise be lost in the exhaust. This makes it a more economical choice for homeowners, as higher efficiency means lower fuel costs.

While 80% may represent the efficiency of older, less advanced furnace models, it does not meet the criterion for typical condensing furnaces, which excel in efficiency. Therefore, a strong understanding of what constitutes a condensing furnace is essential when determining their expected performance metrics.