Steam Radiator Ambience — I went to military school in South Carolina in the 90s, it was a bit like Harry Potter sans magic and the Forbidden Forest. We did have impossibly large roaches that appeared in our dorms and they would have befriended Hagrid.
Like Hogwarts, our school dorms were ancient, built before world wars. No air conditioning, and steam Radiators in every room. The radiators would come to life in the middle of the night hissing their parseltongues. And I got used to it.