I am just starting on my basement and have questions on installing HVAC return lines for my theater. My room has two existing 6" round furnace feeds that are at opposite ends of the room. There isn't a return line in room. I plan on adding one, and want to know the best method. The room has three exterior walls and one interior wall. The interior wall is the closest to the return trunk. The interior and exterior walls are constructed of 2x4's spaced 16" o.c. The existing furnace feeds are placed on the ceiling, but could easily be moved.

Is it best to place the return on the floor? Should I run ducting inside the wall or just use the cavity as the return?

After doing some more research, I am considering just exchanging the air in my theater with the adjacent basement room that does have return lines already fed into it (similar to the dead vent principle http://www.soundproofingcompany.com/index.php?/library/articles/the_dead_vent).

My question is does this type of setup require an fan? Also if you do use a fan how is it controlled? Do you leave it on all of the time or is it on a thermostat?

Hi Green,

You'll need a fan or two. Depending on volume. I have two, one for supply, one for return. Dead Vent on each.

The fans are on variable speed controllers used for ceiling fans. I keep them on 24/7 and there is never a hint of the fact that you are in a basement.