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Discussion Starter #21
My first theater was about 1200 cubic feet and not sound proofed at all, and even with the equipment in another room, just two people and one projector made it REALLY uncomfortable after a couple hours. I installed an exhaust fan that pulled around 170 cfm out of the room opposite the door, and since the room was not sealed, relied on the gap at the bottom of the door for cooler air to come in from the hallway. It helped, but really without the A/C running it still wasn't enough.

At 2400 cu ft, if it is just you and the Mrs., circulation with the rest of the house alone will probably be fine. But when you add more people, you are going to feel the heat in the room, especially with the shorter ceiling height. Personally, I prefer to plan for the worst case scenario. I may only need to run both my circulation and my mini-split in that rare case when I invite people over for a movie, but if I don't have it, it will get stuffy in there when I need it most.


Honestly, if you are tight on time and don't feel you can DIY something yourself, then I would recommend hiring help from one of the designers that lurk around here for a detailed plan that you can give to a carpenter to build for you. I almost went that route myself and every day I wish I just had detailed plans to build from, but I am a glutton for punishment and choose to spend a ton of time researching, learning, designing, and building everything myself. Nothing wrong with skipping those steps and paying someone to do it for you, but it won't be cheap. Then again, getting it wrong and wasting all the effort to soundproof the room would be a pretty expensive mistake.

Muffling the sound is relatively easy, you can even buy duct mufflers that are prebuilt. Keeping the soundproof shell without opening your room up to flanking is the real trick. All the designs linked in this thread will accomplish that. I have seen at least 10 different designs just reading build threads, and each one is pretty specific to the situation but really they all do the same thing.


I can appreciate your desire to find the simplest and least complicated way to get this done, but frankly the ERV is not the solution for you IF you are not planning to pull in outside air with it. To reiterate, there are three major issues with using it to circulate air with the rest of the house:
  1. It is very low volume, designed to bring in a little fresh air to mix with the rest of the house, not exchange 2400 cubic feet of air a couple times an hour.
  2. The intake and exhaust are right next to each other, which is fine if you are piping one into the return and one into the main trunk of your HVAC, not so great if you are trying to circulate air in one room.
  3. The ERV's main purpose is to exchange the energy while exchanging the air, so it won't get rid of the heat in the room, it will be pumping it back in as well.
One more note: A regular HVAC guy will probably not have any experience with a room like this. They are used to dealing with air quality issues and know how to circulate air in a regular house, but this is a sealed room with special considerations for sound proofing, and most of what they would do in a regular house will not work well here. Be careful when talking with them. What is acceptable for a room with a 40db noise floor will not be acceptable in a soundproofed room with a 20db noise floor.
Thanks dkersten. I’ve decided to not use the ERV route and look at dead vents and mini split. @BigMoutinDC in dkersten’s post he mentions hiring someone to come up with a plan for me. Would you be interested in this? PM me if so.

I do appreciate all the help guys, thanks.
 

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Discussion Starter #22
Okay so after much more reading maybe I had this staring me in the face all along. As you can see in the attached pics I have my existing HVAC duct work right outside the double wall of where the theater room will be. Will I be able to use a dead vent like dkersten built (pic attached) and tie it into the existing hvac unit? Would a fan be needed for this? Could I then just build a second dead vent for the return just moving the air into the adjacent room?
 

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maybe, you need a push/pull system for the room. Supply and return.
The capacity of the unit needs to be sufficient to handle the additional area
when you tie in you need to do it such that you aren't diverting too much of the supply that is being distributed to the rest of the house,
You need to be happy with whatever is going on in the rest of the house, If it is winter and the house wants heat that is what the theater will get.
You can set your fan to run continuously mixing the air in the theater with the rest of the house. Let the theater heat the house.
Consider adding dampers in the duct lines so you can fiddle with the right balance depending on season. Like shutting off the heat in the winter.
 

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I second what Big said about the home HVAC. It will function like any other room in the house and unless you zone the system and make the theater an independent zone, you will have no way to call for AC when the room heats up. And if the rest of the house calls for heat and you are already hot, you will be wanting to close the vents, which can add noise and will stop all circulation, so it is less than ideal. If you are in a warmer climate, it may work just fine for you.

If it is just you or just you and one other, you will probably never notice it getting too stuffy, but the moment you put a few extra people in there, you will find the regular HVAC to be insufficient. That's the decision you need to make.

And yes, if you are going to tie in your HVAC, use some kind of sound proofing technique like the one I posted or the ones Big posted.
 

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Discussion Starter #25
Okay I have an HVAC guy coming out Saturday to take a look. I do have two separate hvac systems and the section of the basement that will become the theater had two supplies in the duct I want to tie into in the picture that I’m closing off. Not sure if that will make any difference. We shall see.
 

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Discussion Starter #27
I'm going to build two dead vents this weekend for air circulation in the room. One for the supply and one for return. The supply dead vent I'm going to use an inline fan, and I don't plan on using one for the return dead vent.

Was looking for some thoughts on design. In the soundproofing PDF they use 2x4's insulation and then just Double drywall with green glue and 6" PVC entrance to the room. Will this be sufficient or should I build something more along the lines of Dkerstens that is MDF (I think) with what I assume is drywall and GG as a second layer inside and more like a box overall then the soundproofing company design in the PDF?

Is the 6" PVC entering the room large enough to not cause concern for noise?

Also I plan on purchasing some of the Novaflex Fibraflex acoustic duct BIG linked above. I found a website selling it when I first looked and now can't find any for sale for the life of me. Anyone have a link on where I can purchase this? I'll keep searching as well.
 

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Discussion Starter #29
Thanks BIG!
 

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Discussion Starter #30
If you go with a mini split and the dead vent is more about fresh air than cooling the volume requirement is greatly diminished. You could probably use a Panasonic whisper quiet bathroom fan to push/pull air out of your theater. Those are really quiet.
sorry to keep bugging you with this BIG but I had missed this part you posted about possibly using a Panasonic Whisper quiet bathroom fan. Would this be just installed in the ceiling or wall with a backer box or in some type of dead vent?
 

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