Navien NPE series condensing tankless water heaters are the industry’s proven favorites for high-efficiency, endless hot water, the company states. With cascade capability up to 16 units and common vent capability up to eight units, NPE is the clear choice for any size system, Navien notes. Commercial NPE condensing tankless water heater systems provide the highest efficiency of any tankless water heater system with up to 0.97 UEF. The system features built-in ComfortFlow technology that includes an internal recirculation pump and buffer tank (NPE-A models only) and system longevity from dual stainless steel heat exchangers with an 8-year commercial warranty, Navien points out. Navien | www.navieninc.com