Does anyone have any experience with seeing those large wall vent fans in non-industrial buildings?
I remember that small school I went to from grades 4-5 which was originally built in the 1940s and had no central AC until 2005, on the stairwells on both sides of the building (from the hallway) way above the exit doors there were these large 40-inches or something wall building fan that I was quite terrified of. During the winter season when it had to be insulated cardboard or some kind of material covered up the fan’s exterior vent. It was especially scary when the fans were turned on during warm days and they were quite loud. Those fans would also do a loud “bang” noise when it was first started up.