Abstract: The air handling apparatus provides a separate heating mixing air deck and a separate cooling mixing air deck each with their own return air and outdoor air supplies to maximize indoor air directed to the heating deck and monitor the cooling deck to utilize either return or outside air for greatest efficiency in the cooling deck. Near the rooms serviced by the system the air from the respective heating and cooling decks is mixed and directed through a control plate which can accommodate various filters including a germicide type. The control plate also has a bypass door allowing the filter to be bypassed if desired.