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 Btuh and efficient outputs from 148,500 to 197,900 Btuh. Maximum flow rates are from 8.4 gal. per min. to 11.1 gpm. Other features include: ½” gas pipe capability up to 24’, 2” PVC venting up to 60’, dual stainless-steel heat exchangers, field gas convertibility and cascade up to 16 units without an external control box.