As of February 2015, the most efficient Trane furnace models are the XC95m, XV95 and XL95. The XC95m boasts an annual efficiency rating up to 97.3 percent.
Trane's most efficient model, the XC95m, contains ComfortLink II technology that allows the furnace to continually calibrate itself and make any necessary adjustments to achieve optimal performance. With a variable-speed blower motor, this furnace is able to operate quietly and provide an even flow of warm air. For additional comfort, air purification is an option with this model. Select XC95m models are also Energy Star qualified.
Like the XC95m, the XV95 is also Energy Star qualified. Its annual efficiency rating is slightly lower at 97 percent. This furnace features two-stage heating, which prevents temperature swings, and offers improved dehumidification with Comfort-R technology. This model contains many of the same features as the XC95m, but it does not provide the constant calibration of the ComfortLink technology.
The XL95, unlike the other two models, is not Energy Star qualified, but it does offer a high annual efficiency rating of 96 percent. Instead of a variable speed motor, this furnace only has a four-speed one.
Trane furnaces come with lifetime limited warranties for the heat exchanger, and 10-year limited warranties for internal components. All products must be registered within 60 days on installation.