Alright. Thanks for diving in; let's see where this takes us. Here are some images for reference. First, a partial photo of the model information on the side of the unit; notice the model number.
At amana-hac.com we find product information for this series of air handler. (link to pdf
) from which we take a few images. First, the way to decode the model number:
(notice the model number indicates 3-speed fan)
And next, the specs - particularly the cooling and airflow ratings, highlighted for my unit, in red:
It looks like my air handler is rated for 2 1/2 ton capacity. (30,000/12,000=2.5). It should deliver between 1000 and 1300 CFM depending on the "external static pressure." You can see the nominal rating of 1240 at high fan in that chart, but notice the asterisk. A chart a couple pages later gives the range (more or less). This is pretty well in line with your rule of thumb (400cfm/ton).
So far so good...
I haven't gone outside to inspect the compressor and fan, but I think they should be complementary: the HVAC guys came out before we closed on the house and had a good look at the whole system - I'm pretty sure they would have said something if it was out of line, but I'll go do some more research there anyway.
I'm similarly going to stipulate the the whole system will cool the basement. The previous owners made a fair number of upgrades to the house, and they all seem to have been pretty well engineered. Add that to the common experience that HVAC designers tend to overestimate the required tonnage, and I feel pretty comfortable, even with the extra heat load of the theater. Previously, there were three windows (two large southern openings, and one small northern), and I've eliminated one of the large southern windows. Also, the only heaters inside my finished theater will be people and projector - no amps or players (well, maybe sub amps).
And we come to my concern: the 6" duct. Wasn't this the exact problem that BIG and Morph1c just finished dealing with in the Black Cat Theater? The 6" duct, that should be good for "most home theaters" meant the inline fan was required to get enough air exchanges, and as a result the air velocity resulted in significant vent noise.
Actually, Morph1c's theater is not much different from mine in size (his is about 10-15% wider, but 10% shorter and not quite as tall - very similar volume). So, I guess that tells me that the flow without inline fans will be lacking. He's ended up with larger ducts and large registers and boots, which was a problem for him because he had already finished drywall, but that's not my scenario. I wonder if his solution is the best solution. Maybe I need to PM him for input...
You're suggesting dead vents, which I assume would need inline fans. Do you think that's a better solution than dampers or just using fans in the normal lines?