Navien has introduced its new NFB series high-efficiency condensing fire tube boilers. They are available in two models (NFB-175 and NFB-200). The heat exchanger is form-pressed and robotic laser welded to minimize the number of wear points. 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. Additional features include, built-in zone controllers, 10 to one turndown ratio, extremely low NOx levels, and remote accessibility when installed with the company’s NaviLink Wi-Fi control system.