A maker of tankless gas water heaters has introduced a new high-efficiency water heater, the The Power Direct Vent (PDV) water heater, which brings condensing technology to residential tank design. It’s 80 percent energy efficient—the highest available for residential tank water heaters and at less than $20 a month operating costs, promises considerable utility savings. The main flue is capped at the top of the unit, forcing gasses down through a submerged heat exchanger that loops around the center flue. As a result, more heat is transferred to the water, and less emanates from the venting, which is done with PVC piping. The unit comes with a factory-installed exhaust riser that vents at the top of the unit, rather than via side riser. Available in 38- and 48- gallon capacities. Rheem. www.rheem.com