Like most boys of that era, one of my important chores was removing clinkers from the furnace with a long rod-like implement that had metal claws to grab them. I'd deposit them in a fireproof bucket and haul them to the alley when they cooled off for the garbage truck -- they were heavy!
Every night after school I had to check the coal hopper and fill it with coal slack from the coal room next to the furnace. The hopper had an electric worm gear that fed coal to the furnace at a steady rate -- most of the time. But occasional belches of nasty-smelling black sulferous smoke pouring through the heat registers are a vivid memory too. People today would be aghast at the smoke pollution. We often had foggy overcast and with everyone heating with high-sulfer coal the poisonous black smoke was heavy. We didn't notice -- warmth was a lot more important than pollution during those frigid Idaho winters.
My dad often said that we didn't appreciate how clean the air was (in the 60's) from when he grew up. Indianapolis mostly heated with coal until oil-burners (and later gas and electric furnaces) came on the market. He said some days you could hardly see downtown, the coal smoke was so thick.