Navien’s NPE-S series condensing tankless water heaters feature an efficiency of 0.99EF. The models supply maximum inputs from 150,000 to 199,900 Btu/hr., and efficient outputs from 148,500 to 197,900 Btu/hr. Maximum flow rates are from 8.4 gpm to 11.1 gpm. Other features include: 1/2” gas pipe capability up to 24’, 2” PVC venting up to 60’, dual stainless-steel heat exchangers, field gas convertibility and cascade capability up to 16 units without an external control box.