The upgraded EZ Series of Residential Condensing Tankless Water Heaters from Noritz America has an improved Uniform Energy Factor of 0.96 while maintaining a 25-year warranty on its redesigned, dual stainless-steel heat exchangers. The higher UEF should deliver substantial energy savings and lower monthly fuel bills to the home or business owner over the extended life of the water heaters. The key to the warranty and efficiency gain is the blending of two types of high-grade stainless steel in the heat exchangers. The primary heat exchanger is made of a higher- tensile-strength stainless material to resist heat shock and cracking under the high temperatures it routinely handles. The secondary exchanger extracts latent heat from the combustion process, producing an acidic condensate. As a result, it features a stainless material that is especially adept at resisting corrosion and scale buildup, even after years of demanding usage.