Actually, lets look at the stuff. In Vault 3 you're supposed to look for a reverse pulse cleaner. Where is it? In the maintenance wing. Makes sense, doesn't it? In Vault 22 you're supposed to look for HEPA cartridge filters, which are on 2nd Level - Oxygen Recycling, again, makes sense. In Vault 11 you look for a differential pressure controller, but this time it's more tricky, as it's in a flooded section of the vault in the lower level. The fact that it's a pressure controller kinda, sorta, in a way could make you think of deep underwater, but only a genius or a very creative person would figure it out I'm afraid. So it's not quite that random, it has some logic to it, though the last one could be hidden in a better place.