As of 2015, A.O. Smith manufactures over 30 different models of water heaters. These models are grouped into both commercial and residential lines. Within those broad categories are gas, solar, electric, hybrid and tankless water heaters.
A.O. Smith's popular commercial line includes the MasterFit, Cyclone and Conservationist gas models. The company's electric commercial models include Dura-Power, Gold Series DRE and DVE, and the Custom Xi DSE line. The A.O. Smith residential line includes the ProMax and Conservationist electric water heaters and the Effex line of gas models. Among the residential tankless models are the ATI 540H-N Condensing, the ATI 540H-P Condensing and the ATI-320H-N Condensing models.