ANSI/ASHRAE 103-2007
Supersedes Standard 103-1993This standard is an industry standard specifying the method of testing for determining the Annual Fuel Utilization Efficiency (AFUE) of residential and light commercial furnaces and boilers. This standard includes a test method for cyclic and part-load performance, methods for interpolating and extrapolating test data, and calculation procedures for establishing seasonal performance. This standard applies to central furnaces with inputs less than 225,000 Btu/h and boilers with inputs less than 300,000 Btu/h, having gas, oil, or electric input, intended for use in residential applications. This standard also applies to furnaces contained within the same cabinet with central air conditioners that have rated cooling capacities of 65,000 Btu/h or less.This revision and update of the standard reflects improvements and changes in equipment design that were not adequately covered by the previous version of the standard. In particular, attention was given to the modern classes of two-stage and modulating equipment that have come out on the market, and equipment whose performance is affected by post purge of the combustion chamber. Also, greater understanding and clarity regarding losses from equipment were incorporated into the standard. Finally, changes in nomenclature and definitions were included to clarify meaning within the standard as reflected by questions and issues handled by the committee members over the past 10 years. Also, editorially, the errata from the previous version were incorporated into this version.Keywords: AFUE, residential furnace, residential boiler