U.S. Boiler’s Burnham K2 condensing boiler features a combination of high efficiency, performance and high value. At up to 94% AFUE, this Energy Star-rated boiler uses a proven stainless-steel heat exchanger and Sage 2.1 control system with factory presets. Touchscreen diagnostic display and free five-year parts and limited labor warranty offer additional benefits. It is available in five sizes ranging from 80 to 180 MBH, and features: a 5:1 turndown; a cold burner door that’s safe to touch even while firing; a hinged inner door that isolates electronics and controls; a pre-installed high-capacity boiler loop circulator; and a split-voltage junction box.