AVS Forum banner

1 - 20 of 80 Posts

·
Registered
Joined
·
112 Posts
Discussion Starter #1
Looking for some help with my HVAC design…I just finished framing my basement, which includes a dedicated theater. Existing house HVAC unit is sized so it is sufficient to take care of both the middle floor and a finished basement. This week, I have several HVAC companies coming to give me an estimate, so I’m looking for some advice to finalize my approach to basement and theater HVAC systems.
Theater Construction: EG designed. 22’ x 16’x 8’6”. DD + GG. Equipment will be outside theater in external rack. Projector will be in a hush box. Seats for 7 people. Located in DC area.
Planned HVAC: One 7” flex duct supply + one 7” return that will both dump into area of the future soffits. Once the shell is constructed, I’ll extend the lines, build the plenums and install 2 supplies (up high) at the front of the theater + 2 returns in the rear (up high). In addition, one small return (3”?) to go into the projector hush box.
Originally, I thought about dead vents and a ducted mini-split. However, after much thought and deliberation, I’m leaning towards one of the following options:
Option 1: Install a separate 4 ton unit for just the theater with its own thermostat. Heat from the rack mixes with rest of basement, which is on the same unit as the middle floor.
Option 2: Take existing middle floor HVAC unit and add electronic dampers so that it can control 3 zones separately: middle floor, basement, theater. I guess the limitation would be if there were ever a time when the theater is calling for a/c, but another zone is asking for heat. Being in MD, we’re not as cold as the norther states, so maybe this won’t be a real issue.
Any thoughts on which way to go? Just let the price decide? Are there any other recommendations for what else I should be asking for from the HVAC installers?
Thanks for the help!:)
 

·
RETIRED theater builder
Joined
·
33,849 Posts
Just a knee jerk reaction, a 4 ton unit for just the theater and equipment sounds really excessive. Not sure why you ruled out the mini-split. You may want to connect with LovingDVD here on the forum as he just finished his theater (in MD) and he used a ducted mini.

Locally (NoVA) there is a guy not often on the forum with an EG designed theater and he used the zone system, your option two. here is his thread: http://www.avsforum.com/forum/19-dedicated-theater-design-construction/767522-36-month-ht-construction-first-timer-done.html
I see that he hasn't posted in a couple of years but he still lives in the area and I can give you his linkedin info if you want to make contact.
 

·
Registered
Joined
·
112 Posts
Discussion Starter #3
Just a knee jerk reaction, a 4 ton unit for just the theater and equipment sounds really excessive. Not sure why you ruled out the mini-split. You may want to connect with LovingDVD here on the forum as he just finished his theater (in MD) and he used a ducted mini.

Locally (NoVA) there is a guy not often on the forum with an EG designed theater and he used the zone system, your option two. here is his thread: http://www.avsforum.com/forum/19-dedicated-theater-design-construction/767522-36-month-ht-construction-first-timer-done.html
I see that he hasn't posted in a couple of years but he still lives in the area and I can give you his linkedin info if you want to make contact.
Thank you so much Big! That gives me a lot to think about. Let me PM you.
 

·
Registered
Joined
·
1,230 Posts
...Originally, I thought about dead vents and a ducted mini-split...

Any particular reason you ruled out a mini-split?

I installed one for my HT and it has been 100% perfect for the 3years we have used it. It's not a ducted unit, but from a performance/noise sound point it provides similar results.


HERE is where I detail where and how I installed my mini-split, and HERE is where I detail my fresh air system.


.
 

·
Registered
Joined
·
112 Posts
Discussion Starter #5
Any particular reason you ruled out a mini-split?

I installed one for my HT and it has been 100% perfect for the 3years we have used it. It's not a ducted unit, but from a performance/noise sound point it provides similar results.


HERE is where I detail where and how I installed my mini-split, and HERE is where I detail my fresh air system.


.
Wow! I love the unique look of your theater and have read a lot of your posts on various topics. I really appreciate the suggestions and like your mini-split/dead vent setup. I originally ruled out the mini-split on the advice of the guy would designed the theater. I can see that maybe I misunderstood something and I need to do more research....


So does a mini-split need to be centered high on the back wall to work best? (It would have to be under my projector hush box, which is also under some existing 10"x 20" ducting that I can't move and am building the rear soffit around) Or do you think it would be OK if it were placed in the rear, but along the side wall?


Thanks. :)
 

·
Registered
Joined
·
1,230 Posts
Wow! I love the unique look of your theater and have read a lot of your posts on various topics. I really appreciate the suggestions and like your mini-split/dead vent setup. I originally ruled out the mini-split on the advice of the guy would designed the theater. I can see that maybe I misunderstood something and I need to do more research....


So does a mini-split need to be centered high on the back wall to work best? (It would have to be under my projector hush box, which is also under some existing 10"x 20" ducting that I can't move and am building the rear soffit around) Or do you think it would be OK if it were placed in the rear, but along the side wall?


Thanks. :)


You can literally place the air handler anywhere you want. Cold air is heavy and falls, so you would want to mount it high. The vanes on mine have an oscillating feature (as do most...i think) so it moves the air around nicely.

THX for the props :D


.
 

·
Registered
Joined
·
112 Posts
Discussion Starter #7
Thanks. I'll see what I can come up with for a good place to put it in the back of the theater. I've got two rear speakers that are only about 4'-5' apart and centered on the rear wall below the projector hush box. Between them is an acoustic treatment in the middle of the rear pilaster. The bottom 18" is to be covered in wainscoting. However, placing it that low would not leave any space under it to let the cold air drop.


Seems like the only place I would really have is on a side wall near the rear, but that would make for kind of weird airflow, maybe diagonal across the theater.


The good news is that I have an AVS legend coming over on Saturday to look over the situation and give me some expert guidance...For once, it pays to live in the DC area!:cool:
 

·
Premium Member
Joined
·
449 Posts
+1 on the mini split. Nice and quite and super efficient. Get a model that has a heat pump for heat also for a little extra $.
 

·
Registered
Joined
·
1,430 Posts
+1 for the minisplit. You can also get the inside unit as a ceiling cassette if you want it closer to the center of the room. I like the Mitsubishi units and you can get an adapter for them that allows you to use any third party thermostat.
 
  • Like
Reactions: Modicen

·
Registered
Joined
·
112 Posts
Discussion Starter #10
Thanks guys. I'm starting to see the mini-split as a good option, especially with the heat pump. I now see the ceiling cassettes and that gives me some better options. I could either place it in the center of the ceiling tray (and work a star ceiling around it) if I could get it up between my 16" OC floor joists. However, the Mitsubishi website shows the units are roughly 22.5" square.


Otherwise, there is another spot in the front of the soffit that is just in front screen. If I put dead vent returns at the rear of the room, it would pull that air backwards.


Thanks.
 

·
Registered
Joined
·
673 Posts
You can't pull air out of a room without providing a supply of replacement air.
Right. An in-room mini split just cools and recirculates the air already in the room, it does not provide fresh air from some other source. The air in the theater will get stale even if it is cooled by the mini split. If you do a ductless mini split, you will need two dead vents, one supply and one exhaust. If you do a ducted mini split, you can avoid the need for a separate supply (depending on how you set up the ductwork).
 

·
Registered
Joined
·
112 Posts
Discussion Starter #14
Right. An in-room mini split just cools and recirculates the air already in the room, it does not provide fresh air from some other source. The air in the theater will get stale even if it is cooled by the mini split. If you do a ductless mini split, you will need two dead vents, one supply and one exhaust. If you do a ducted mini split, you can avoid the need for a separate supply (depending on how you set up the ductwork).
Big came over last weekend and we came up with a plan. Run a ducted mini-split from an adjacent big storage room (that also contains my equipment rack) with one big supply trunk going to the front of the theater and then branching off into two supply plenums in the soffit above the stage. Since the storage room is directly behind the rear theater wall, the returns just go back through the rear wall and penetrate the soundproof shell via backer boxes/plenums.


Could you please explain a little more about not needing a dead-vent supply with a ducted mini-split? How would I connect that up?


Also, I'm wondering what size unit is appropriate for a 21'x16'x9' room. 12,0000 BTU? 15,000BTU? 18,000 BTU?


Thank you so much.
 

·
Registered
Joined
·
112 Posts
Discussion Starter #15
You can literally place the air handler anywhere you want. Cold air is heavy and falls, so you would want to mount it high. The vanes on mine have an oscillating feature (as do most...i think) so it moves the air around nicely.

THX for the props :D


.
I'm trying to figure out what size unit is appropriate for a 21'x16'x9' room. 12,0000 BTU? 15,000BTU? 18,000 BTU? What size is your unit?
Thanks :)
 

·
Registered
Joined
·
1,230 Posts
I'm trying to figure out what size unit is appropriate for a 21'x16'x9' room. 12,0000 BTU? 15,000BTU? 18,000 BTU? What size is your unit?
Thanks :)
I'm using THIS model rated for 12,000BTU. My room ~ 21'W x 27'L x 10'H. It cools the room fine and heats it up in about 10 minutes during the winter.


.
 

·
Registered
Joined
·
673 Posts
Big came over last weekend and we came up with a plan. Run a ducted mini-split from an adjacent big storage room (that also contains my equipment rack) with one big supply trunk going to the front of the theater and then branching off into two supply plenums in the soffit above the stage. Since the storage room is directly behind the rear theater wall, the returns just go back through the rear wall and penetrate the soundproof shell via backer boxes/plenums.


Could you please explain a little more about not needing a dead-vent supply with a ducted mini-split? How would I connect that up?


Also, I'm wondering what size unit is appropriate for a 21'x16'x9' room. 12,0000 BTU? 15,000BTU? 18,000 BTU?


Thank you so much.


I think 12000 BTU should be ok for your space, but I am not a HVAC guy (I am using a 12,000 BTU unit and my space is 14.5X21X8.5, but it hasn't been turned on yet)


If you are pulling from a different room and returning to that room, and that room is large and/or open to a larger space, you will have the effect of air exchanges with that larger volume of air so that it does not get stale. I believe with your current proposed setup, you will not need any additional dead vents for air exchanges.
 

·
Registered
Joined
·
112 Posts
Discussion Starter #19
I think 12000 BTU should be ok for your space, but I am not a HVAC guy (I am using a 12,000 BTU unit and my space is 14.5X21X8.5, but it hasn't been turned on yet)


If you are pulling from a different room and returning to that room, and that room is large and/or open to a larger space, you will have the effect of air exchanges with that larger volume of air so that it does not get stale. I believe with your current proposed setup, you will not need any additional dead vents for air exchanges.
I see (said the blind man). The air goes into the room from the ducted mini and is drawn out of the theater by the fan in dead vent and sent to the large common area room. Then you set up a return from the opposite side of that large room (or on the other side of the basement) that feeds air back into the mini split to go around the cycle again.:cool:


Would you wire up the dead vent fan on some type of relay so that it goes on whenever the mini-split fan is on? Or just leave it on some type of timer?


I sure appreciate the help.
 

·
Registered
Joined
·
20 Posts
Keep us updated on the mini split. I am thinking I will have to do something similar in my theater build. I don't have an easy way to pull ducting from the original layout as my theater will be in our garage.

Sent from my SAMSUNG-SM-G920A using Tapatalk
 
1 - 20 of 80 Posts
Top