To buy a top-rated furnace, determine what type of furnace you need and compare reviews of those furnaces. Contact local heating contractors for estimates, which may include installation. Most manufacturers only sell furnaces through contractors and dealers, not through retail stores.
Furnaces are fueled by oil or gas and have an Annual Fuel Utilization Efficiency rating of 80 percent or better. Furnaces with a lower AFUE may be cheaper but don't convert fuel to heat as well. In colder climates, a furnace with a higher AFUE may have a higher price but may lower overall heating bills. Some gas furnaces have additional features to increase efficiency, such as a two-stage valve, an electronic spark ignition and a second heat exchanger.