Abstract: An air flow producer of non-rectangular shape is adapted for installation in a rectangular opening of a drop ceiling. In preferred form, the producer has a circular housing with an open bottom covered with a grill. A fan with a rotary blade assembly is mounted in the housing to produce a downward air flow, and a circular metal band surrounding the rotary blade assembly defines an air discharge zone centered in the grill and an annular air intake zone surrounding the discharge zone. Flow rates are optimized by positioning the band close to the grill. The grill is preferably integrally molded with a rectangular flange that seats in the drop ceiling opening. The flange supports the housing from the framework and closes the opening to prevent the producer from drawing air from the plenum above the drop ceiling.

Abstract: An air flow producer mounted at the ceiling of a room generates an air flow toward the floor, reducing temperature gradients and improving heating and cooling efficiency. A housing defines a circular cylindrical, vertical flow passage that receives the air flow. A discharge chamber discharges the air flow through a grill toward the floor. The discharge chamber has a cross-section that expands progressively from the outlet of the flow passage to the outlet of the discharge chamber. The air flow through the housing is produced by a fan with a rotary blade assembly, and the blade assembly extends partially into the discharge chamber. The position of the blade assembly and the expanding cross-section of the discharge chamber cooperate to increase air flows through the housing. Optionally, an air intake chamber of generally inverted frustoconical shape may be mounted at the upper inlet end of the cylindrical flow passage to smooth flows further.