Fire tube boilers

Navien introduces its upgraded NFB-H high-output condensing fire tube boilers in two sizes: NFB-175H and NFB200H. Both models include Navien’s patented stainless steel fire tube heat exchanger with a non-metallic condensate drain pan, and form-pressed combustion chamber to resist corrosion. New high-efficiency features include turndown ratios up to 15:1, powered connections for three zone pumps or
three zone valves, two-in. venting up to 65 ft. and 3-in. venting up to 150 ft.