- from the low horizontal to displacement (DISPLACEMENT)
Air return at the top (roof), flow down the front, low speed
- from the low horizontal (CONVENTIONAL)
High air return (at the roof), front delivery
- towards the low vertical (UNDERFLOOR)
High air return (at the roof), delivery low underfloor
- underfloor upwards (HIGH-FRONT)
Air return from low front, delivery upwards (roof)