Nitro...actually I dislike swamp coolers...it makes everything rust. In our previous shop, if you cut a piece of metal, it was rusty in a day or two from the swamp cooler's affect on the humidity. Now, we are 100% air conditioned and have had bare bodies (cars, not women) in our shop for 3 years with zero rust. Of course, the down side to a/c is the electric bill.

mike in tucson