Heating

Furnaces

The efficiency of new furnaces is measured by the annual fuel utilization efficiency (AFUE), a measure of seasonal performance. Furnaces today are between 78% AFUE and 96% AFUE. Traditional “power combustion” furnaces are 80-82% AFUE. Above 90% AFUE, a furnace is “condensing,” which means it recaptures some of the heat wasted in traditional systems by condensing escaping water vapor. Consider the following when selecting a new furnace:

Condensing Models
ACEEE strongly recommends a condensing furnace (AFUE 90% or higher), unless you live in a warm climate (in this case, you may want to consider retrofitting your system with a heat pump instead)

High Electrical Efficiency
A furnace can use a significant amount of electricity, mostly to power the fan motor. Variable speed fan motors are generally more efficient than standard (“PSC”) motors and may save you hundreds of dollars per year. Electrically efficient furnaces can be found on the Gas Appliance Manufacturers Association’s website (www.gamanet.org).

Proper Sizing
Make sure the heating capacity of the furnace is not too high for your home. Most furnaces are substantially oversized. Insist that your contractor do an “ACCA Manual J” (www.acca.org) or better heat loss analysis.