In the basement of my apartment block we have several little storage rooms (~65 sq ft), one for each tenant. Inside of mine the humidity gets a little high to my liking because although it has 2 holes in the wall with gratings that communicate with the rest of the basement, the air doesn't really move and becomes stagnant, which I think makes the humidity rise. The humidity outside that room in the same basement is OK, since it has good ventilation.
The 2 gratings are in the same wall, one at the floor level and the other at ceiling level. So I thought that in order to circulate some air and potentially reduce the humidity, I should install a fan in (at least) one of the two grates.
My question is: what grate would be the best choice for this purpose? The top or the bottom? And what direction should the air flow? Would I benefit from putting two fans, one in each grate?
My understanding using (possibly flawed) logic would be to use the top one and blow the air to the outside of the room, because the humid air would accumulate near the ceiling and this way it would be ejected out.
Best Answer
Dry air is more dense than humid air, so your thinking about humid air accumulating near the ceiling makes sense. Because it's a basement, however, I'm going to assume humidity is coming through the floor or walls. Tackling the source of the humidity by letting drier air circulate along the floor and walls will probably be most effective at drying the space.
Your best bet may be to mount the fan as an intake on the bottom grate, so less humid air blows onto the floor and quickly disperses rising moisture. It would also help to open up some air space along the floor. You could achieve this by storing your items on a raised shelf or pallet. Providing this extra space for air circulation might even be enough to keep your storage room sufficiently dry without forced ventilation.