Frank, a closet is real nice if you have the space, but I think you may be able to do without it. I have had to rebuild my Oneida once (defective impeller) and if it was in that small of a closet, my neighbors would have learned some "new" words. The internal filter would be a real bear in that small space too. The external filter could be outside of the closet but that defeats some of the sound abatement. If I were you I would install it without the closet, use it for awhile, and if the noise is a problem, then build it around it. I have mine outside of my shop with the external filter on the inside of my shop.