Direct Vent water heaters utilize a co-axial (pipe inside a pipe) vent pipe that takes air in from the outside (outer vent) and vents combustion gases directly back to the outside (outer vent). It is the perfect choice for situations with insufficient combustion air. No electricity required.
Bradford White® Defender Safety System® Gas Water Heater, 36000 Btu/hr Heating, Liquid Propane Fuel, 1/2 in Gas Connection, 40 gal Tank, Piezo Ignition, Direct Vent, 3 x 4 in Vent, 41 gph Recovery Rate, 0.6, 3/4 in NPT Water Connection, 150 psi Pressure, No Ultra Low NOx, 22 in Dia x 31 in D x 63-1/2 in H, Domestic