Along the line of what I was going to say. If you have the right terminal, with the right throw, the right induction, and all that, than the ceiling is not necessarily a bad place for it. Also, the supply registers have the most affect on comfort, given that they have the most influence on air movement. Therefore, return location generally isn't that critical. Even though it's moving air, the velocities are very low except for right at the grille.Originally posted by atphvac
Since first reading this thread I did some more research. Typical supply duct velocity at the register is 300 to 600 feet per minute. We design systems with ceiling heat registers for about 600 fpm (we use zoning systems for basements which increase velocity)and the register we typically use is a 10"x6" Hart and Cooley 831 which at that face velocity has a throw of 14 feet. Even when the face velocity drops to 400 fpm the throw is still 9 feet. I think simple design and register selection is why some guys think it works better in the ceiling while some feel it is better close to the floor. My register in the ceiling works better for us simply because of the design and register selection. With low supply air velocity you are probably making the right choice by going low with the duct.