Navien’s NPE-S Series of tankless water heaters is identical to the NPE-A Series, but excludes the internal buffer tank and recirculation pump. The series offers three models: the NPE 180S, 210S and 240S. Maximum heat capacity input for each model is 150,000 Btu/hr., 180,000 Btu/hr. and 199,900 Btu/hr., respectively. Flow rates for each model are 8.4 gpm, 10.1 gpm and 11.1 gpm, respectively. Highlights include an energy factor of 0.98, the ability to use 1/2” gas pipe up to 24’ and 2” PVC venting up to 60’.