So, people here are always talking about dry wood, and how you're not getting your full potential from wood that's less than optimally seasoned. It's been stated more than once here that, "this is because you're spending a lot of your BTU's on boiling water," but that math does not support that statement. Instead, I suspect the majority of the impact has to do with your secondary burn system not firing off (whether it be catalytic or non-catalytic), due to the low temperature steam coming off of the too-wet wood rapidly drying in your stove. First, consider a 2 cu.ft. load of oak at 20% MC, with density of roughly 3350 lb./cord, or 26 lb./cu.ft. as typically stacked cordwood. So, there's a roughly 52 lb. load of wood in your stove at 20% moisture content, meaning 43 lb. of wood plus 9 lb. of water. It takes roughly 1000 BTU/lb. of water to get from room temperature to steam, so you're spending roughly 9000 BTU's on converting water in the wood to steam. Take the same load green, at 35% moisture content, and now you have 58 lb. for the same 2 cu.ft. load. You're now spending 15,000 BTU boiling off water. At 26,000,000 BTU/cord, one oft-quoted value for oak, you have roughly 203,000 BTU/cu.ft. So, for 20% MC, you're spending 2% of your available BTU's on boiling water. For 35% MC, you're still spending less than 4% of your available BTU's on boiling water. Not much difference. Sitting here tonight, struggling with a less than optimally seasoned load myself, I think the primary troubles with wet wood are the difficulty in lighting, and the trouble it causes for our secondary burn systems, by lowering firebox temperatures so much during the first half hour or more of the burn cycle. After all, I suspect almost all of the 9000 or 15,000 BTU's quoted above are taken in the first 30 minutes of the burn cycle.