I’ve never had a coal furnace, but my ex’s grandparents did and he tells a funny story about it…
grandpa wanted to clean out the coal furnace ducts/tubing/pipes (dint know the right term)
anyway, he went down into the cellar and detached a section of pipe to empty it but the pipe buckled and dumped coal dust all over the cellar floor
so he goes upstairs and gets Grandma’s *new* Electrolux vacuum cleaner (I can hear the groans now), and proceeds to vacuum up the dust
said dust clogs up the holes in the vacuum bag and *BANG* Now there is coal dust everywhere
not to be outdone, grandpa meticulously sweeps up all the dust into a bushel basket, comes up from the cellar and goes out the back door to empty the basket.
Corner of concrete step gives way as he steps on it, basket flips upside down as he sits precipitously and dumps coal dust all over him
the end