A. O. Smith offers a large selection of gas water heater models from innovative high efficiency designs to standard energy-efficient units for both natural gas and propane applications. The innovative streak that runs through all A. O. Smith products is also proudly on display in the commercial electric line. With features such as the intelligent control system (DVE & DSE models) and the now standard 24k gold elements (optional on DSE models), A.O. Smith water heaters can sustain that performance even in the harshest water conditions. A. O. Smith offers dual-fuel units (natural gas/oil or propane/oil) which are great for large commercial, industrial and institutional applications. They provide storage capacity up to 575 gallons and up to 2.5 million BTU/hr input. All models feature multiple anodic protection to guard against tank corrosion. The Energy Saver models meet all of today's governmental requirements for manufactured housing installation. The units are available in either standard vent or direct vent models, with your choice of natural gas or propane operation. Through an inspired blend of innovation, efficiency and years of industry expertise, A. O. Smith has created a state-of-the-art family of Vertex™ products that provide a long-lasting supply of hot water. They are easy to install, with dimensions and installation requirements comparable to standard power-vent and power direct-vent units.The ProMax® family of gas water heaters offers a wide range of water heating solutions. The high efficiency, side loop venting, Ultra-Low NOx and high recovery models are ideal for families with high demand for hot water. It's a simple fact: our Effex® product line is the most efficient and advanced line of conventional vent gas water heaters on the market. This makes it an ideal choice for the homeowner who wants to replace an older, inefficient water heater without the hassle.