The chimney is around 20 feet. I’m not sure if it’s insulated it’s the one the company installed that goes with the unit I believe. I purchased an air circulation fan and it have angled up towards the ceiling on an angle so it will blow the heat through the rafters. If I turn it off it does show at least 10 degrees hotter up there. I know the wood said under 16% moisture when split but maybe it’s still a little to wet. If I use those enviro blocks in the fireplace it burns the coals up more but still not fully. I get around 1 1/2 hours to 2 of burning them the rest of the time it’s just fighting the coals to break down so I can add more wood. I also was thinking maybe it’s just to large of an area and will never warm it up past 60’s.It seems odd that you can’t get higher temperatures with a full box of dry wood. What is your chimney setup? Do you have an insulated liner from stove to cap? How tall is the chimney?
Even without the stove getting to six hundred degrees, I’m surprised that there isn’t heat peaking at your ceiling. It sounds like there is decent insulation, but it does make me wonder about air infiltration. Something just doesn’t seem right, but, of course, you don’t need me to tell you that. It’s why you’re here asking questions.