I purchased a Kozy King 400-09 furnace from Obadiahs Woodstoves for my 3 story log home. I probably could have gotten a smaller one but I wanted to be able to cut my firewood at 24 inches and still have room in the firebox.At -3 degrees it can run you out if you fill it.It holds fire for 8 to 12 hours depending on how cold it is outside and how much wood you put in it.I am amazed at how much wood you can get in it. It can get to -30 degrees here so I'll se how it does then but I have no doubt it will work fine and use less wood and keep us warmer than our old furnace. It was a great purchase. Obadiahs were great to work with also as it arrived with damage which they took care of.