The Bradford White eF Series offers remarkable thermal efficiency ratings as high as 99.1%. A three-pass heat exchanger accounts for the incredible heat transfer. The eF Series also features outstanding installation flexibility. All models can be power-vented or power-direct-vented vertically or horizontally and are approved for unbalanced, direct-vent closed-combustion applications. Several models in the line are Energy Star-certified and all feature ultra-quiet operation. The eF Series also features the company’s exclusive ICON HD commercial control system.