“I miss radiators. I grew up in an apartment where the whole complex was heated with coal through hot water radiators.”
Sounds like you grew up with a hot water heater. I wasn’t as lucky, had a gas heater and a gas water heater.
I just remember that there were two (three?) big boiler rooms on the property, and trucks would bring loads of coal to them now and then; and the hot water ran through pipes to each apartment.
We never lacked or ran out of hot water.