When I was a kid growing up in the early 60’s our house was still heated by coal. There was a little door like the one in the picture (see quoted url). I don’t recall how often the truck came to fill it up but I remember it being a “big event” to a 2-3 yo kid. The truck came, backed-up along the side of the house and they opened the coal door and sorta half-ramped and half-shoveled the coal into the coal chute. A similar thing happend at my babysitter’s house. They had coal there too. It was still pretty common in the town I grew up in.