The MagnaTherm FT condensing boiler is available in 1,000, 1,500, 2,000 and 3,000 MBH sizes with up to 20:1 turndown. Each unit is equipped with a robust, stainless steel fire tube condensing heat exchanger and the latest in real-time O2 trim compensation. Ideal combustion air-to-fuel ratios are maintained, producing optimal performance with 95% thermal efficiency. The boiler includes the Laars Linc intuitive control system with color touchscreen, which features an easy-to-navigate, icon-driven interface that displays key performance measures, a quick start option, USB input for easy parameter upload and can cascade up to eight units. Laars Heating Systems.