I have a few buddies with them. One places his in front of the small door, pulls air from outside, then keeps the big door open about a foot. Lik Vince says, they work good in low humidity. Higher humidity, freeze some water in cardboard milk cartons, drop one or 2 in the bottom, it helps. Start running it in the morning when it's cool and that will help. They will contribute to rust factors, moist air across bare steel. Cheap to run tho, I'd do it.
"When I was younger, I could remember anything, whether it had happened or not." - Mark Twain