Navien has begun distribution of the new NFB series high-efficiency condensing fire tube boilers. The NFB series is now available in two models, NFB-175 (175,000 BTU/H) and NFB-200 (199,900 BTU/H), each featuring a new, patented fire tube heat exchanger.

The in-house designed and manufactured patented heat exchanger takes fire tube technology to a completely new level.

The heat exchanger is form-pressed and robotic laser welded to minimize the number of weak points that could be prone to thermal stress and corrosion. Oval shaped tubes within the heat exchanger contain internal turbulators designed to improve both the heat transfer rate and the structural integrity of the assembly.

A specific water flow is generated by baffles inside the heat exchanger to extract the maximum amount of heat from flue gasses while the non-metallic base provides additional protection against corrosion caused by acidic condensate.

Additional features of the Energy Star Most Efficient 95 percent AFUE NFB series include advanced user interface controls, built-in zone controllers, 10:1 turndown ratio from a sophisticated gas flow control system, easy field gas convertibility, extremely low NOx levels, cascade capability up to 16 units, common venting capability up to 8 units and remote accessibility when installed with NaviLink Wi-Fi control system.