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# The Once and Future Theater - Page 5

I'm not sure that a booster fan in your HVAC lines will get you the flow you are looking for. I.e. adding a 300 cfm fan in your 6" HVAC line will probably not give 300 cfm total flow, and if I had to guess it would cause problems with cooling in other parts of the basement.

If it were my theater, I would supplement the HVAC line with another supply and return that pull from and exhaust to another part of the basement (i.e. dead vents), each with an inline fan. It's probably overkill, but if you are planning sound isolation, that room is going to be sealed up and you won't have any other air exchange. This does two things, it will supplement your cooling from the AC by pulling cool air from other rooms and exhausting hot air, and it will also keep fresh air moving in.

The issue that Big and Morph1c had is a result of high air velocity. As an example, if you use a 6" flex line connected to a 300 cfm fan then the air in that line is moving at

Cross section area (A) = pi*(r)^2 = pi*(0.25')^2 = 0.196 s.f.
Flow velocity = cfm/A = 300/0.196 = 1,530 fpm

That's way too fast and will be very noisy. If that 6" line connected to your HVAC is only moving 75 cfm, then the velocity drops to

Flow Velocity = 75/.196 = 382 fpm

Still too fast, but then again you can usually hear the air coming out of the registers in your house, so it's a reasonable number I think. Also, if you look at this post, someone actually measured the flow coming from their 5" supply, and it roughly agrees with the numbers we're playing with, and the chart with regard to flow.

So, the solution to all that is to slow down the air before it gets to and/or enters your theater. For the HVAC supply, you're probably OK with a large register as this will allow the air to slow down. For the dead vents, since they will probably be moving more air, you can do what Big and Morph1c did by either adding a few feet of 8" just before your register, or if you have the room, just run a larger duct for the entire length. You can combine this with a lot of area that those ducts have to transition from the duct to the room to help things as well. The higher the cfm, the more cross sectional area is needed. A box is not ideal because turbulent air is noisy, too, but if it's big enough you shouldn't have a problem. Ideally, you would have a smooth transition from your duct to your register (like the shroud on a ducted fan).

Whew! I think I'm getting a repetitive stress injury from all this typing Of course, all this advice is worth exactly what you've paid for it, so I'd seek a second opinion if you can! My line of work has a lot more to do with electrons than this mechanical stuff

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J_P_A, thanks for taking the time. You're solution seems thoroughly considered, and may be what I do, ultimately.

My initial gut reaction was, "Why don't I replace the distribution box on top of the air handler with something that includes dampers, so I can just close off the rest of the basement when I use the theater?"

There must be some good reason people don't do this. Too much space required for the dampers? The pressure doesn't allow the flow you want anyway? The rest of the basement suffers too much? There is no such combination of dampers?
You should be able to do that as well. You're talking about a zoned system, and considering that you have a variable speed AHU, it's probably capable of being zoned. Assuming assuming that's the case, and assuming that it's not already, to make it automated you will probably need a new controller (to operate the dampers) as well as at least one new thermostat for the theater zone and possibly two depending on what you already have. I agree with RT that zoning a basement would probably be best left to the pro's, and in this case you would be able to tell them that you need cooling for X number of people, and you need a minimum of 6 air exchanges per hour, with a maximum velocity of 250 fpm. I would ask to see the manual J as well, and double check to make sure they are not just telling you they've met all those requirements.

The cost of adding a zone to an already zoned system is minimal, I think it was around \$600 for me. However, once I reached the limit on the number of zones for my controller, it was more like \$1,000 - \$1,500 to upgrade controllers and add the zone. I'm sure costs will vary from area to area, but that gives you an idea.
Quote:
Originally Posted by J_P_A

The cost of adding a zone to an already zoned system is minimal, I think it was around \$600 for me. However, once I reached the limit on the number of zones for my controller, it was more like \$1,000 - \$1,500 to upgrade controllers and add the zone. I'm sure costs will vary from area to area, but that gives you an idea.

It's not zoned at this point, and it doesn't have a thermostat either. So on the one hand, I know I'm going to have to buy some hardware, but on the other hand that sounds like a lot... my cheapskate button just got pushed. I'll need to price it out and see.

two thermostats, one controller, two dampers, some wiring... sounds like \$4-500 if I shop around. Still need a couple fans - but I shouldn't weigh that against the dead vents, because I'll need them for that anyway... plus I save the space of building the vents...
http://www.retrozone.com/Catalog/control_panels.htm
pressure relief damper??? oh man. more reading and learning.
Are the centrifugal fans that much nicer than the axial fans?

I've just bench-spent my budget for a Grafik Eye... there's a thought.

Alright. If that is comprehensible and anyone has a response, stream-of-consciousness or otherwise, I'd be happy for it.
Hmmmmm..... Well, there is another option.

First, you say you don't have an existing thermostat, but what controls the unit now ?

Assuming there is a thermostat for the basement, you could run two 7" or 8" lines from your HVAC to your theater. This would give you the necessary cfm (again, assuming all of my previous posts are even close to correct). You can then move your existing thermostat into the theater, and set it to run the blower whenever you are in there. Then you'll get your air exchanges and the AC will kick on whenever the temp gets too high. You can also get thermostats with a remote (handheld) thermostat that you can take from room to room, but that again requires you to buy another thermostat.

The downside is you'll be cooling the entire basement when the theater calls for AC. Although, I don't suppose that's much different than your current setup. This will be mitigated somewhat by running the blower continuously while you're in the theater.
Right now the unit never gets turned on. Somehow in the process of the previous owners moving out - and abandoning their mortgage, getting foreclosed upon - the thermostat got exchanged for a unit that doesn't work with heat pumps. It blew a fuse before I even saw the house, and we haven't swapped it over yet, since all this was going to get changed around and we aren't using the basement for anything at all right now.

I was thinking about this some last night after I went to bed (not sleeping): if I go with basically the idea you (J_P_A) suggested with 2 dead vents - which I initially felt weird about, but have since come to see how I can logistically make work and understand the advantages of - how would I control the fans? Can they be set to come on with the regular blower? Can a Grafik Eye control them?

Is there a way to use two thermostats without having a zone controller?
I don't know specific answers to your questions, but I think you should be able to either wire the fans to be triggered by your equipment (some amps/AVRs/etc have 12 V triggers I believe) or to turn on with the HVAC blower. It may require an intermediate relay, but I can't imagine it would be too complicated.

The next part of that question is something I asked my HVAC contractor a hundred different ways, but he was pretty adamant that you can't have two thermostats controlling one unit/zone. I wanted a thermostat in my theater and a thermostat in my game room that would both control the basement zone where one could be set to override the other. He said it didn't' work that way. He did, however, recommend a thermostat with a remote control. That way I could either take the remote into the theater or into the game room with me. The remote has a temp sensor, so it tries to keep the temp adjusted for whatever room it's in. I haven't decided which route I'm going to go yet.
Quote:
Originally Posted by J_P_A

The next part of that question is something I asked my HVAC contractor a hundred different ways, but he was pretty adamant that you can't have two thermostats controlling one unit/zone. I wanted a thermostat in my theater and a thermostat in my game room that would both control the basement zone where one could be set to override the other. He said it didn't' work that way...

This seems like it could work if it had a computer interface. It is not something I would be able to do, but maybe a Control4 or HTPC system would be able to make this work.
That's what I figured - so the thermostat goes in the theater, and either that's the extent of your temp control, or you run a zoned system with controller and multiple thermostats.

I was wishy-washy on the grafik eye idea, but if it will control inline fans as well as lights, I may spring for it. I'll go see what I can figure out. I'd be happy enough with the inline fans coming on with the blower and just setting the fan to on (not auto) when I'm watching movies, but it's be nice to leave the thermostat alone and allow the light controller to kick the fan on. If it cam down to using a wall switch, then oh well, that's just what I'd have to do.
I just thought I'd jump back in here to say that I've been busy... ...thinking... and planning.

I got around to some more complete and careful plans. They're not entirely complete yet, but they've gotten me this far:

From this vantage you can see the new riser/stair landing, and the weird way I've been thinking about dealing with the window and stair situation.

As you may recall (probably not - I'll recap), originally in order to avoid two doors and a walkway through the theater, I moved the entrance to the rear and planned to close the whole side wall. The new rear entrance and 20+ feet length required a new pathway into the "lobby" area. I opened the wall at the foot of the stairs (documented earlier) in order to have a new doorway. To have the entrance to the theater at riser height, I had to find a way to get the outside floor up to the same height, which was the same as the second step up the stairs... so the large riser is born...

From there, the simple choice is to have a straight rear wall, from the edge of the window straight across to the foot of the stairs. This wastes a little floor space and puts the rear wall only about 2.5 or 3 feet from the back of the second row. So by pushing back the center section of wall, I get a couple extra feet in the middle of the room and a convenient "nook" to build an equipment rack. I've drawn it here with access from the foot of the stairs and a small closet door to access the back of the components. I hope to install grafik eye components in there as well as routing exhaust air through there to both move "dead vent" air out of the theater as well as provide airflow across the components.

I'd love to hear thoughts about this compromise. Also, what can I do with the awkward space by the window? The corner is only about 3.5 feet from the window, so it's not big enough for a table, which was my original hope. Maybe a built in cabinet? not sure if it's worth trying to get plumbing for a wet bar there. Also, the window is pretty low there - less than three feet from the new floor, I think. I could drop the riser off into the corner if I needed the height, but it's still a small space...

For anyone interested, I've uploaded the sketchup file to sendspace.
http://www.sendspace.com/file/xub4wv
Could you put a built in bench there? Maybe something with cabinets or drawers under it? I think the standard chair height is around 16", so that window doesn't need to be too high above the floor for a bench to fit under it if it needs to.
Quote:
Originally Posted by HopefulFred

Also, what can I do with the awkward space by the window? The corner is only about 3.5 feet from the window, so it's not big enough for a table, which was my original hope. Maybe a built in cabinet? not sure if it's worth trying to get plumbing for a wet bar there. Also, the window is pretty low there - less than three feet from the new floor, I think. I could drop the riser off into the corner if I needed the height, but it's still a small space...

Maybe media storage? You could make it look like a library nook with floor-to-ceiling shelves for the media and a window seat under the window. You could store blankets and pillows under the window seat.

I like the big riser extension outside the theater entrance. That big platform setting a couple of steps up from the main floor could help create a pretty dramatic theater entrance.
Quote:
Originally Posted by J_P_A

Could you put a built in bench there? Maybe something with cabinets or drawers under it? I think the standard chair height is around 16", so that window doesn't need to be too high above the floor for a bench to fit under it if it needs to.

Indeed, a bench was my first thought. In fact, the pipe dream was/is that I would build a sealed cabinet/box there to be a seat and position it to run along the wall below the window. The idea was/is that, sealed properly, I could connect it to the theater space through the wall. The PVC tube that connects the two spaces would be cut to length to tune the box as a Helmholtz resonator. Being in the rear corner of the theater it wold be ideally placed in a region of high pressure to absorb for one of several modes, depending on tuning. I would just need to build a decorative cover (or broadband bass trap) to cover the other side.

The issue is the width of the space. It's fine for a bench. What would I do with a bench? If it's not useful for storage, it needs a table, right? The table
would block off access from the right (the sitter's left) meaning that you would have to walk/scoot around the window side to exit around a table. Can you see it differently?

A cabinet may be a more attractive alternative, but it would require I give up the idea of tuning a resonator in that space. I'm not sure I'm ready to give up on that dream yet.
Quote:
Originally Posted by HopefulFred

It's fine for a bench. What would I do with a bench? If it's not useful for storage, it needs a table, right?

You could use the space for a dead vent system pulling cool air into the theater. The hot air exit would need to go higher up on the wall inside the theater.
Dead vents are part of that plan as well. I haven't worked out the details exactly, but I think "cold" air will come in near there - hot out through the A/V cabinet (right rear of theater).

The issue is the space in front of the window, and to the left of that wall. (I don't mean to suggest that you didn't understand that, just reiterating) I want to keep the window, but still want the extra two or three feet for the entrance.

I'll try to mock up some ideas with cabinets or tables later this weekend. Not tonight - I'll be busy. In the mean time, other creative ideas are appreciated!
Quote:
Originally Posted by HopefulFred

Is there a way to use two thermostats without having a zone controller?

That's what my HVAC guys recommended. Either tstat can call for air, and the other "side" just gets heated or cooled more than necessary. At the time I thought it was nice they were trying to save me money. In retrospect, I think they may have just wanted to keep things simple (due to lack of competency).

If you used a dead vent to exchange air between the two "sides" it help mix the air, but I'm still not convinced dead vents are a good thing. I could see it as a passive air return, or possibly with a remote mounted blower, but the idea of putting an inline fan in the wall of the theater seems counter productive.
Quote:
Originally Posted by rabident

That's what my HVAC guys recommended. Either tstat can call for air, and the other "side" just gets heated or cooled more than necessary. At the time I thought it was nice they were trying to save me money. In retrospect, I think they may have just wanted to keep things simple (due to lack of competency).

If you used a dead vent to exchange air between the two "sides" it help mix the air, but I'm still not convinced dead vents are a good thing. I could see it as a passive air return, or possibly with a remote mounted blower, but the idea of putting an inline fan in the wall of the theater seems counter productive.

Dead vents will help with pressure differentials, but not temperature. And unless "powered" via a connected forced air duct line (either return or supply), the amount of flow felt between the spaces will only be the pressure differential between the two zones and will have negligible pressure impact on temperature.

Most of the talk with dead vents here on this forum is meant to eliminate the direct path of the air (and sound in both directions from leaving the room. I have never personally seen one used for anything other than sound dampening or pressure balancing.
The only method of air exchange that I have in my room are two dead vents to exchange air with the rest of the basement. I did not run any supplies or returns from the house's main HVAC sysyem.

The one drawing air out in the back of the room is powered with an inline fan and the one in the front is unpowered. Since the room is sealed up so tight from the soundproofing, the decrease in pressure from the return causes close to the same amount of airflow through the supply.

Since the room isn't finished yet, I haven't had a chance to actually sit through a two hour movie and test how comfortable it is, but so far with me working in there I haven't had a problem. I've seen dead vents used successfully quite a few times. Ted White's home theater stands out as one I can remember. He did the same thing as me and has had it running successfully for over 10 years.

The other nice thing about having dead vents is that it effectively seperates the theater from the rest of the house. For those periods in the spring and fall when heating or cooling aren't necessary and the windows are left open in the rest of the house, you don't have to turn on the home's HVAC just to make the theater comfortable.

I'm not saying that running actual HVAC supplies and returns to the theater is a bad thing; it's certainly a very good thing to do. But dead vents can be successful if employed correctly as well.
I haven't settled on any of my HVAC plans, and none of them has been presented to a professional for validation. That said, my current working plan is to use to one forced air supply ad one direct proper return, as well as two dead vents which will exchange air with adjacent, but not soundproofed, areas. each will have a small inline fan that is mounted in the non-soundproofed area. The dead supply will draw from near the floor outside, and the dead return (from the theater back into the rest of the basement) will exhaust through the equipment rack - hopefully killing two birds with one stone.

I felt like (a hunch) that the HVAC unit has adequate capacity to keep the room cool, as long as I can turn over the air often enough. The dead vents are there to make up volume as well as to keep vent air speeds down, so they aren't noisy. I figure that it will all get turned on when we are in the theater. I'll probably just set the main blower to "on" (not auto) before I head in, and then I'll kick the inline fans on separately. Assuming I have enough air moving in and out, I should do pretty well at keeping the temperature inside the theater the same as outside the theater, but I haven't thought about it enough to be confident - thus the interest in two thermostats controlling the same unit.

I wasn't able to come up with any time to puzzle out the weird window space in any detail, but I am working on an idea my wife has for a bar near there. The window and "nook" would end up behind the bar. Any ideas appreciated.
Well, I've almost made progress!

This is all pressure treated. Mostly 2x4 (a few destined for another project) - some 2x6.

You'll notice if you look very closely at my sketchup model that the rear wall is built on 2x6 to accommodate staggered studs. My sister's truck has only a normal 6' bed, so I didn't want to try to buy enough lumber to actually build the walls, but I have tentatively scheduled a delivery for next Wednesday. That will give me this weekend to confirm my layout on the ground and then set the base plates. I've borrowed my brother-in-laws "powder actuated tool" and I got some nails and charges for it today at the construction supply store. Hopefully the yellow charges are sufficient. We'll see...
Totally unacceptable.
Ummmmm............Time for plan B maybe? Not enough power Scotty! I need more power!

Regards,

RTROSE
Hopefully the loaner of the better version comes through in the next day or two, so I don't have to buy one or resort to a hammer drill and anchors. I'll still need to buy more nails and charges.

I was giving it all she's got...
Shameless Bump: I just won an eBay auction for a Grafik Eye, so I feel good about that. Paid more than I really wanted to, but it was the model I was dreaming for...

Still waiting for free tools.
Guess what today is!

Edited by HopefulFred - 6/27/12 at 3:29pm
Haircut and a Shave?
Time for some Captain Morgan??
Quote:
Originally Posted by HopefulFred

Shameless Bump: I just won an eBay auction for a Grafik Eye, so I feel good about that. Paid more than I really wanted to, but it was the model I was dreaming for...
Still waiting for free tools.

Hi Fred, I am mostly a lurker here but reading this reminded me of when I won my Grafik Eye off of Ebay. I totally know how you feel, you will love it, what model did you get? I was lucky enough to find a great deal on Ebay for the RS232 control module so now I can even control each of the individual zones intensities not just scenes its awesome! Good luck on your drywall stack!

-Brent
Quote:
Originally Posted by vanice

Time for some Captain Morgan??

+1 to that!! I was going to say that before I even saw your post. I guess great minds think alike....
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