Above information is good advice. Only thing I could add is stay away from direct drive units. Get a belt driven two stage compressor that tells you what CFM it makes, and gives you an honest HP rating. I saw a CH compressor in Sundays paper in a Lowes ad. It said it was 7HP and 115 volts, what a crock. You cannot run an honest 7hp motor on a standard residential 115 volt citcuit.