A furnace is a heating unit that works in conjunction with an air conditioner or heat pump in an HVAC system. Types of furnaces include gas furnaces, oil furnaces, and gas-electric packaged units. Which type of furnace you have will depend on where you live and the size of your home.
If you live in a warmer climate, you may not have a furnace at all, but you might have a heat pump system to take care of your heating and cooling needs.
In a central heating system, a furnace delivers heated air through your home’s ductwork. The furnace ignites the fuel (gas or oil) and the flames heat the heat exchanger. The heat exchanger warms the air flowing into the furnace, and the blower fan blows the warm air into the ductwork and out into your home.
AFUE stands for Annual Fuel Utilization Efficiency. It measures how efficiently a furnace converts gas to heat energy. The higher the AFUE rating, the more efficient the furnace is.
To explore further, an AFUE rating of 90 means that the furnace utilizes approximately 90% of the fuel to provide warmth to your home, while the remaining 10% escapes as exhaust. To qualify for ENERGY STAR® energy tax credits, furnaces must meet certain AFUE ratings, as shown in the table below.
| Equipment | Required AFUE Rating |
| Gas Furnaces Key Product Criteria | Rating of 90% AFUE or greater for U.S. South gas furnaces Rating of 95% AFUE or greater for U.S. North gas furnaces |
| Oil Furnaces Key Product Criteria | Rating of 85% AFUE or greater |
ENERGY STAR®-certified furnaces can be up to 15% more energy efficient than base models.
If your furnace isn’t heating your home, schedule repair services. If you’re tired of making repairs to an older unit every year, think about replacing the unit. Contact your local American Standard dealer to schedule a furnace installation quote.
Thinking about upgrading to a more efficient system? Browse our furnaces.
By Anne Fonda, Content Writer
Expert review by John Kim, Senior Product Manager, Furnaces
AFUE, or Annual Fuel Utilization Efficiency, measures how efficiently a gas furnace converts fuel to energy. The higher the AFUE, the more efficient the gas furnace.
FER, or Fan Energy Rating, is an energy efficiency standard of airflow for residential furnace fans and gas packaged units.
Split systems have units in two places, typically one inside and one outside the home.
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