How common is it to see what I would consider a rooftop unit (gas pac) used on a residential application. Sit unit on the ground & duct run from side of unit, (not bottom) into a crawl space, or up the side of the house into the attic. In my area you see this all the time. Its been a while since I've done residential, but I have always wondered if systems were set up like this in other parts of the country. Oh, by the way I'm from KY.