I was forced to buy a cord of unseasoned wood ($150 a cord). I called everyone who has wood and no one had seasoned firewood at this time of year. I am almost out and not ready to stop burning. So...despite what I know about burning, I am burning unseasoned Oak. The stove is running like a top with tremendous heat out put and no problems keeping a fire. I am having secondary combustion and little smoke output. Yea yea, I know I will have to sweep far more frequently, but I am shocked, this wood has been down for less than a month and the Jotul F400 is kicking A.