[Benanov]

Radiators were originally designed to heat more than needed, so you could open the windows.

In New York, at least - the standards were never changed to accomodate for closed windows in 1920. Snopes has a rundown. https://www.snopes.com/fact-check/apartment-radiator-pandemi...

[organsnyder]

My house (built in 1916) was insanely over-provisioned. When we upgraded to a modulating-condensing boiler, we halved the BTUs and are still able to easily keep the house heated to any desired temperature even on the coldest winter days.