I recently saw the finished installation of a 4 ton Unico system in an old house. I think the installer said he had to use 6 outlets per ton, so there was over 20 holes throughout the house. YUK!! the poor house was swiss cheesed!! Kinda like huge termites ate holes everywhere. Then, there was one mammoth return upstairs and one downstairs, the return grills were bigger than my Weber gas grill that I'm able to cook 16 burgers on!! I guess the HO will know where all the kids toys will end up, hopefully stopped by the air cleaner!!