ThermaForce combi boilers are packed with efficiency-improving features in addition to a super high-efficiency condensing heat exchanger. Built-in high-efficiency variable speed boiler pump uses less electricity than a standard pump. Outdoor reset technology adjusts the boiler supply temperature automatically based on outdoor temperature fluctuations. ENERGY STAR certified with up to 96% AFUE and ASME-rated (excludes 160K combi model).