Wall curb for air treatment system

An air treatment unit with an integrated sound reducing plenum, comprising:

• a unit housing including opposed front and back panels, spaced apart longitudinal side panels and opposed bottom and top panels;
• a unit supply opening formed in said back panel;
• a unit return opening formed in said back panel and spaced from said unit supply opening a first distance;
• a curb frame including a curb back panel, spaced apart longitudinal curb side panels and opposed curb bottom and curb top panels defining an interior chamber;
• a partition extending between said longitudinal curb side panels and defining with said curb frame a supply plenum in an upper portion of said interior chamber in communication with said unit supply opening and a return plenum in a lower portion of said interior chamber in communication with said unit return opening;
• a curb supply opening formed through said curb back panel in communication with said supply plenum;
• and
• a curb return opening formed through said curb back panel in communication with said return plenum, wherein said curb return opening is positioned so as to define a non-linear air flow path through said return plenum with said unit return opening so as to reduce the level of noise transmitted therethrough, and further including a sound absorbing material positioned on at least some inside surfaces of said return plenum, and further including a dehumidification mechanism disposed within said return plenum.