Today’s homes demand more hot water than ever before, and the 94% efficient Nautilus™ power vent gas water heater offers unprecedented levels of performance to meet the need. The 50-gallon Nautilus™ delivers more hot water than a standard 75-gallon atmospheric gas water heater. In fact, the fully condensing Nautilus™ design is so advanced, it can deliver “continuous hot water for shower after shower” at a constant flow of over 3 gpm at a 40° rise. Yet Nautilus™ is easy to install, with height, diameter and installation requirements similar to standard power vent units. ENERGY STAR® qualified 6-year limited Tank warranty, 6-year parts warranty for Residential applications Helical Internal Heat Exchanger - Spiral heat exchanger keeps hot combustion gases in the tank longer lengthening the heat transfer cycle Power Vent design uses 2" or 3" Schedule 40 PVC pipe for intake and exhaust and can be vented vertically thru-the-roof or horizontally thru-the-wall Modular Blower - Equipped with 120 volt, 60 Hz electrical system (rating 5 amps or less), 6-foot cord with standard 3-prong connector, 2” PVC pipe, elbows and condensate drain supplied to connect heat exchanger outlet to blower Side-mounted hot and cold recirculating taps allows water heaters to be installed as part of combination space heating/water heating applications Intelli-Vent™ Gas Control - Equipped with nearly indestructible silicon nitride hot surface ignitor — no standing pilot, advanced electronics for more precise control of water temperature and easy-to-understand system diagnostics Two heavy-duty Anode Rods provide added protection against corrosion Commercial grade glass lining protects all interior tank surfaces including inside and outside of the helical heat exchanger Green Choice® gas burner has a patented 'Eco-Friendly' design that reduces NOx emissions of less than 10 ng/j Factory installed CSA Certified and ASME Rated Temperature & Pressure (T&P) relief valve