had this boiler to look at yesterday. took over two hrs to get the soot vacuumed out. top passagesways were 2"+ deep in soot, and the side passages were 80%ish plugged. customer said black smoke would come out chimney.
if anyone knows what the combustion chamber in this is supposed to look like, would like to know. had a box that had collapsed, but did not see the dish target wall most of these have.