U.S. Boiler’s new Firetube condensing gas boiler joins the K2 high-efficiency series. The 95% AFUE K2 Firetube features a stainless-steel vertical fire-tube heat exchanger and is available in six sizes from 85 mbh to 270 mbh. A combi version is also available (155 mbh). All models can be wall-hung. Features include 5:1 modulation; an ergonomically angled touch-screen display; 3-in-1 vent connection; top or bottom supply/return/gas connections; a split voltage junction box with fused connection boards; and a full-height side access panel.