Like CycloneBax, I put one in a few years ago. It cost $70-$80 from Sears, but I think they stopped selling them. Had to use tin snips to put a hole in the main inlet duct, and a hole in the main outlet duct near the A/C coil. It had a shutoff plate for the summer. It had a rotary foam wheel that turned as it soaked in water. The tough part was cleaning the foam wheel, removing the scale and lime, as its efficiency would decrease over time. It was easier to buy an new foam element every year. Depending on where you put the outlet, it can it cause your coil or other parts to corrode sooner than necessary? I don't know, but that is my concern. It did work great, but had manual adjustment, that you did have to lower, as the temp dropped outside, to prevent excess condensation.