The fuel efficiency of Bryant gas furnaces depends on the model, but some offer an annualized fuel utilization efficiency rating of over 98 percent, as of 2015. Several of the company's models also qualify for ENERGY STAR certification.
The AFUE is a percentage comparison of the heat the unit produces to the heat available in the fuel it consumes. The Federal Trade Commission requires all new furnaces to display their AFUE ratings. Using these ratings allows consumers to determine the best furnace for their needs. A 90 percent AFUE furnace often cost $1,000 more than one with an 80 percent rating, as of 2015.
Bryant's top model uses several features to achieve its higher rating. The unit's gas modulation regulates the amount of gas it burns when heating a room. On warmer days, it lowers the burner setting to conserve fuel, but when the weather is cold, the maximized setting warms the home quickly. The two-stage fan reduces the large dips in temperature that typically occur during the cycle of a forced-air furnace.
Other Bryant furnaces only meet the minimum AFUE requirement of the U.S. Department of Energy. As of 2015, the minimum AFUE for a non-weatherized furnace is 80 percent, the same as several of Bryant's lower-end furnaces. However, furnaces from the 1970s often operate at a 65 percent AFUE or lower.