I had all but forgotten about this thread as with many I have started only reminded of it just today by someone thanking me for a post in it.
Let me make an update while the heat reclaiming chamber I made functioned admirably the first winter I used it I later removed it for reasons of difficulty in cleaning of the many passage ways. the cleaning plate I had in it really needed some modifications but as the unit was welded up solid the only way to do this would have been to cut it open make the mods then weld it back up.
However with a hot enough fire the soot would not form on the surfaces and previously deposited soot would eventually be expelled this was hardly possible to do in my house as even on the days that winter that dropped into the single digits due to the amount of reclaimed useable heat available we never were able to build a large extremely hot fire for long enough periods of time or often enough to maintain a decent enough draw velocity which would pull the flames fare enough into the chamber to help with the cleaning. Smaller fires were more than sufeincent to heat nearly the entire 1850 sq ft of the house while not making the living room so unbearably hot. on one day where the temps did not rise above the mid teens we actually had many of the windows and the kitchen door open for a good part of the day because the heater had brought the living room temp to over 100°f and the kitchen to 90°f. For that reason and reasons that it wasn't very aesthetically pleasing
The following winter after removing the chamber I placed about 300 lbs. of ceramic tiles on the top of the stove to serve as thermal mass I still have to watch how large of a fire I build in the thing and not even think about building a fire in the mornings if the outside temps are going to rise into the 50s or better the thermal mass will still radiate enough heat to last until the outside warms up.
I saved the chamber to eventually install in my more than 6000 sq ft work shop but the heater I plan to construct to go under it may possibly be a tri fuel IE wood, oil, or propane