I have a Daka 521 and am on my 4th year of use(age of home too). I have it piped to my furnace plenum with two 8" ducts and have the plenum dampered. I also have 2 8" ducts ran to the cold air return. I have the barometric regulator installed in the flue and the furnace uses the automatic spring and chain type for air intake. My flue is about 30' long from basement through attic. My problem is the massive amount of wood this thing eats without a ton of heat. It does heat the house but I only get 2-3hrs max burn times. I usually load it up full 3-4 times in 30-40 degree outside temps. I generally burn elm and cherry as this is all that is available to me for free. I hear everone else talking about 2 loadings a day and their house is 75 degrees with the furnace dialed back.. I have to load mine 3 times a night to get to 68 degrees. I have played with the automatic damper and barometric damper with no success. Does anyone have any suggestions on what else i can try to get more heat with less wood out of this thing? My next step is to get a stack thermometer to make sure I'm getting the right temps. On the new dakas I noticed they had a spinner on the door. I thought that was a great idea to add secondary air to make the fire hotter. From what i read on hear, secondary air is the way to go while cutting down the primary from the automatic damper. When I called Daka they said that spinner was for burning coal. I think I still want to buy that door to see if helps. What are your thoughts? Any suggestions would be appreciated.