Being in Houston, and with the theater on the 2nd floor, A/C was definitely a concern. When the house was built, the upstairs A/C unit was sized to accommodate the additional room. But that doesn't mean it would cool a closed room loaded with wall-to-wall people. I had planned on zoning the 2nd floor during construction, but after discussing the costs involved, I decided to delay that until the theater would actually be built. The
cost to zone the system later wouldn't be much different that it would during home construction, so it was a good candidate to defer.
But now, 18 months later, very obvious that the zoning would be needed. We divided the 2nd floor into three zones: game room area, the theater, and the 2 bedrooms on the other side of the house. Each zone is controlled with an electric damper and it's own thermostat.
The theater itself gets 4 vents in the ceiling, spaced away from the seating, a return, all connected using flexible ductwork (which is standard construction practice in Houston, anyway). The return for the zone is in the ceiling of the entry hallway. I was concerned as they planned to "sister" the return to the game room return nearby - thinking this was too close and would allow sound to easily transmit in or out of the theater.
The HVAC guys wanted it that way explaining it would work better, as opposed to running a separate return line back to the unit in the attic. After discussion, and assurances that it wouldn't ruin all the sound isolation (and a willingness to change it if it did), we went ahead with that plan. After construction was complete, I'd find that the HVAC guys were correct, as I don't hear sound enter or exit the room via those returns.
MISTAKE: I probably should have looked into different grills for the theater - as the 'normal' grills do produce some air noise when the system is running. But honestly, it's not objectionable, and is mostly audible in the back row. And in Houston, no one is going to complain about the A/C being on...
The other HVAC issue to contend with is cooling the rack. There's not a huge amount of equipment in my rack, but I certainly didn't want to dump *more* heat into the room, and certainly wanted future capacity in case I went amp crazy in the future. I installed a Cool Components Ceiling Vent System in my A/V closet, which uses the HVAC return to vent the space.
As that works well, I decided to do the same thing above the rack, again
using the HVAC return for exhaust:
Cool Components has since released a (replacement?) product which uses an in-line blower instead of the fan array in the grill. If I was doing this today, I'd use that model certainly for the A/V closet, as it runs 24/7. The rack fan power is switched on with the rest of the equipment.
MISTAKE: The ceiling of rack niche is just above the top of the rack. Luckily I realized in time that as the rack has a mostly solid top, I needed to raise the vent grill several inches to allow airflow. I should have just had the rack ceiling framed at room-ceiling height behind the wall.
The most important step of any build at this point is to document everything behind the walls and ceiling just prior to insulation and drywall. This is true for theater and home construction. I took ~500 pictures of the house in this condition, and still have a few areas that I didn't get enough images for 100% coverage. I was focusing on the wiring and missed some of the framing details in areas where there is no ductwork or wiring.
In hindsight, I didn't need to focus on the wiring - I knew where every wire was - it was the plumbing, framing, HVAC - stuff that I didn't know intimately - that I should have focused on.
Next up, insulation and drywall (finally!)...
Edited by jautor - 6/6/12 at 5:30pm