Drill through what? The freezer lid or the corian? For my two tap keezer tower, I ditched the original freezer lid and built a new lid, insulated it & added weatherstripping, and tiled the top. I have a computer fan in there, but for only moving air in the keezer itself -- I don't have it aimed up the tower. FWIW, I've never had an issue with foaming on the first pour and there is probably only an ounce or so of beer in the lines in the tower.