First of all, I have a full liner (uninsulated) to the top, sealed & insulated at the top. Now let analyze for a second. No block off plate, allows heat to escape up the flue surrounding my 6" SS liner, annd slowly deminshing as it reaches and stops at the top of my 22 foot chimney. Should this "wasted heat", not at least warm my 6" SS liner and aid in draft? Or is the masonary above the old damper, some kind of "devil's Triangle, super effecient, heat sink" that absorbs heat without a trace? ie: warmed hearth, chimney in garage warmed up. The only way 2 + 2 = 4, in this case would be, that the insert is so "border line", that the heat is so evenly absorbed, you can't even feel where it evaporated to! Kind of reminds me of going to the Dodge Dakota site, and all the "band-aid ways" of trying to make a 3.9 V6 perform and get the MPG of the 4.7 V8. Kind of sucks, as I have about 6-7 bush cords of wood for burning, but at this point, I might as well just "bend over" for the gas company, stop raising my blood pressure, and quit trying to stoke the almighty 5000 btu insert. Sorry for the crappy attitude, but if I could have my warpped Emira 1600 sucking up my wood, house at 78 degrees F, giving additional heat to my garage, I'd be happy. I dread to think, how weak the jotul 450 must be when it is installed flush with the surround! Maybe as a freestanding stove, it would impress? It'll make a nice orniment in the living room fire place. A little big for a boat anchor! Cheers, Mike