ok so from burning the exact same stove with the exact same coal with the exact same chimney height....
theres mucho heat available.... id be willin to bet lots of your heat is going up the pipe and more of it is being sucked down and into the floor, then the rest into the blocks...
also the first year i put a box fan behind it on low to "wash off" the heat toward the living space ...worked ok
the factory twin squirrel cage set up with the factory speed control is by far the way to go for heat extraction
i can suggest you lift and slip a 3x5 sheet or two of heat stop board (ie dura-rock, hardie, ect) under it to slow the heat drop to the floor. then hilti or tapcon or nail some furring strips to your block and tack or glue on some pink tounge and grove 1" styrafoam insulation on the walls..
best place for thermometer is on top right area of stove. 3" from top load door's back right corner toward back right corner of stove...thats the hottest place. then a few inches out of the outlet on the pipe. see the difference between the two
. big question??? how do you have the inside rear hanging steel baffle ? hanging straight down? or angled sloping back so as the bottom of the plate hits the stove back?
so right now i have 450 top 100 pipe draft is .06 heat is ...LOTS