mm wrote:


But my question is, If the firebox IS ok, how is it possible that
there are streaks/areas of soot on the wall at the outlets for the
heated air?


Any smokers or candle burning in the apartment? Both will leave the type
of soot deposits you describe.





How does the soot from the firebox get to the household air on the
other side of the firewall?


See above, the crap is in the household air.