Navien’s NPE-A series condensing tankless water heaters feature an internal circulator and buffer tank. It features: 1/2” gas pipe capability, 2” PVC venting, dual stainless steel heat exchangers, ComfortFlow recirculation including pump and buffer tank, field gas convertibility and an elegant compact design. Up to 16 units can be cascaded together without an external control and are ideal for commercial and residential applications. Highly efficient at 0.97EF or 0.96 UEF: NPE-180A, NPE-210A, NPE-240A. The max input for each is 150,000 Btu, 180,000 Btu and 199,900 Btu respectively. They are also available with on-demand activation and NaviLink Wi-Fi control.