Wall vent fans in buildings

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.

Not sure I know what you’re talking about. Do you have a picture?

To me the only thing that comes to mind although it’s probably not it, are pressurization and depressurization fans used in large schools. YouTube user Nic’s Systems and Electric did a video on them. I believe they can be manually started.

my school has those located in the lunch room

I’m guessing you’re talking about one of these? (random pic pulled from Google)


As far as I can recall these could be fitted with a set of metal slats that would be pushed by the air flowing through the fan as it ran… And when those opened it could make a fair bit of noise.

I’ve seen only one of these once in my life in a underground parking where one of these was installed to pull air from inside (edit) in the event of a fire.

If it pulled air from outside it would supply the fire with air, intern causing the fire to spread faster and turn into a inferno within minutes

Not exactly. There are fans that pull the air out that just came in. They’re used to clear smoke and pull ot more air than can be put in. It will spread just a tad bit faster than usual none the less but it won’t get out of control quickly. Also only certain detectors activate them.

Corrected, thanks… I got my wires crossed :rofl:

The fans probably exhausted to the outside of the building, here is a wikipedia article explaining the method used. With the advent of modern air conditioning these have thankfully gone out of favor, a lot of houses in the south from the 40s-70s have these in the ceiling, most are disabled when I come across them.

The bang is typical for those big motors, they were never meant to be luxurious, just had to provide enough airflow.

Similar to this one but don’t remember the exact model and don’t think it had the grille on it.