Crown manufactures 16 boiler models that have received ENERGY STAR certification as energy efficient, with models receiving annual fuel utilization efficiency ratings ranging between 87 and 95 percent. Crown also makes boiler models that are not ENERGY STAR certified. Certification requires a AFUE rating of at least 85 percent.
To receive ENERGY STAR certification, boilers must meet stringent standards set by the U.S. Environmental Protection Agency. The EPA and the U.S. Department of Energy developed the ENERGY STAR program in 1992, and boilers have qualified for certification since 1996.
Higher efficiency rates in boilers have been achieved through the use of electronic ignition, new combustion technologies and sealed combustion chambers to reduce drafts.