Raypak’s XPakFT has a stainless-steel, fire-tube heat exchanger design which allows for a broader range of flow rates, requiring reduced pump energy for maximum operating efficiencies. The heat exchanger is ASME-certified and National Board-registered. For commercial and residential applications, this boiler meets or exceeds Energy Star requirements because of its 95% AFUE rating, modulating condensing design with up to 10:1 turndown and low NOx emissions.