Most homes in the US are heated by central furnaces or boilers. Boilers provide steam or hot water for heating. Boilers send steam through pipes to steam radiators or send hot water to baseboard radiators or radiant floor heating. Steam boilers are inherently less efficient, but efficient versions of boilers are available.
The efficiency rating for a boiler is measured by annual fuel utilization efficiency or AFUE, which is the ratio of heat produced for the home to use compared to the total energy consumed by the boiler. For example, a boiler with a 90% AFUE rating means that 90% of the total energy consumed can be used by the home for heating and 10% is lost to the atmosphere. Replacing an existing 60% AFUE boiler with a 90% AFUE boiler can save you 33% on your heating costs! See the Energy Savers for more detailed information.
Estimate your potential to save energy and money by installing this product, please see the U.S. Department of Energy's Home Energy Saver calculator.