For those bashing propane as being expensive, I somewhat disagree. Yes, more expensive than natural gas but should not be compared with oil or electricity.
Here is my experience. Over the last month, our average temp has been 9 degrees and I used about 140 gallons of propane. I prepaid my propane this summer at around $1.70 a gallon (give or take 10 cents). So my monthly heating cost for an insanely cold Maine winter was about $240.
I have a new home, about 2200 square feet two story, modern boiler, own my propane tank, tankless hotwater, baseboard heat on two floors, insulated basement, R30 walls, R60 in the attic.
Last year I seriously considered a heat pump or a pellet stove, however when I did the math of what my current propane consumption is weighed against $3,000-$5,000 to add a heating pump or a pellet stove, I decided just to stick with propane for now.