If you live in an area that has high heat bills and want to really save
then a condensing furnace is the way to go. You pretty much add 10 - 15%
efficiency over non condensing. Non condensing are around 80-83% and
condensing easily up to 94.5% on several makes. Vents can be run a
specified distance to help in location of vent-exhaust. Everything has
its drawbacks.