A. O. Smith redesigned its ProMax Direct Vent Gas Water Heater to utilize improvements to the power vent line. Now outfitted with 2-in. foam insulation, the water heater improves its energy efficiency to an energy factor up to .60. Available in 40-, 50- and 75-gal. capacities, the water heater is offered in four models: indoor, GDV-40; indoor, GDV-50; indoor, GDVT-50; and indoor, GDV-75.