What AFUE means
AFUE stands for Annual Fuel Utilization Efficiency. It is the percentage of the fuel a furnace burns that becomes usable heat in your home. An 80% AFUE furnace sends 20% of the fuel up the flue; a 96% furnace wastes only 4%.
| AFUE | Tier | Best for |
|---|---|---|
| 80% | Standard efficiency | Mild climates, shorter heating seasons, tight budgets |
| 90 to 95% | High efficiency | Cold climates wanting lower fuel bills |
| 96 to 98% | Top efficiency | Long, cold heating seasons; long-term owners |
How to choose
Heating season length
The longer and colder your winter, the faster a high-AFUE furnace pays back its higher cost through fuel savings. In a mild climate, an 80% furnace can be the better value.
Venting
High-efficiency (90%+) furnaces are condensing units that vent through PVC and produce condensate that needs a drain. An 80% furnace vents through a metal flue. Your existing venting can affect installation.
Comfort features
High-AFUE furnaces often pair with two-stage or variable-speed blowers, which improve comfort and quiet, separate from the efficiency number.
Shop gas furnaces by AFUE
Browse standard and high-efficiency furnaces.
Common AFUE questions
Is a 96% AFUE furnace worth it?
What is the minimum AFUE?
Do high-efficiency furnaces need special venting?
Does higher AFUE mean better comfort?
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