- Exclusive SRT™ Scale Reduction Technology - Up to 0.95 Energy Factor - ENERGY STAR® qualified - Ultra low NOx vertical modulating burner design - Dual fan configuration - Dual heat exchanger - Built-In digital temperature control and diagnostics - Active bypass - superior temperature stability - Venting flexibility - Gas connection flexibility - Inlet water filter - full frontal access for easy maintenance - Space saving installation - Built-in freeze protection - Interior and exterior installation capability - Cascading kit (optional) - 12-year limited residential heat exchanger warranty - 5-year limited parts warranty