Amazing what a few hours tightening up the house will do. Last year we bought a small (1100 square foot) house and decided to buy a 10-CPM to heat it with. It did a good job heating last winter but the house was wicked drafty so over the summer I insulated all the external wall outlets, removed an A/C that had been cut into the wall and replaced it with a window, insulated the attic hatch, tweaked the exterior doors so they shut better, and built some interior storm windows using 4mil super clear vinyl and stained 1x2's for frames. What a difference -- these past couple of nights here in Maine we had lows in the low 20's and I had the stove loaded with decent pellets and running on the lowest setting and I had to get up during the night and shut it off -- had the house at 78..too hot to sleep.