I currently have an old wood furnace (1970's - 1980's vintage I'm guessing) in the basement which was in the house when I purchased it. It has worked ok for me for the last 4 yrs, although I'm looking to upgrade and after lots of reading on this site (thanks to all), I'm going with one of the PSG products. My house is 1600 sg ft today, although a few years down the road I will be adding on so I will have around 2500 sq ft to heat, although I have new windows and added insulation (house is pretty energy efficient). I know this isn't the best way (heat load calculation!), but it gives some background. I have been talking with PSG and they recommend the Caddy for 1600 - 1800 sq ft, therefore they suggest the Max Caddy if I'm going to add on down the road. To quote the manufacturer "it is far easier to reduce heat output from a unit than increase it". My concern with the Max Caddy, is possibly always operating the unit on the lower side in terms of burn rate, therefore creating creosote. I get a significant amount of creosote from my current furnace when I operate on the low slow burn, but I'm also assuming the new technology in these will help with that. Some of you folks with PSG Caddy's, what size house are you heating with no problems. I'm in the Western NY area (Buffalo) which should help give you a sense of what my winters are like!