#4 - How old is your furnace?
Take a quick look at your furnace. If it was manufactured before 1992, replacing it with a new higher-efficiency furnace most likely would save you money. Furnaces with a large vent to allow fresh air for combustion air and a metal chimney for exhaust gases are called draft inverter furnaces and generally are, at best, 60 percent efficient.
So, 40 percent of your heat bill is simply wasted to the outdoors. Newer furnaces are up to 96 percent efficient, meaning only 4 percent of the heat is lost through the exhaust. Most heaters will have a yellow ENERGY GUIDE label that will provide information on the energy use.