Where should I position my vents? - AVS Forum
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post #1 of 16 Old 07-25-2014, 12:29 PM - Thread Starter
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Where should I position my vents?

Sorry for the basic questions.
Please see room schematic below:
Intake - I can place a vent taking air in from the outside (rest of basement) into the HT - on the screen side of the room,
does it need to be in the middle or can I put it next to the door?
Should it be high or low?
Do I put the dead vent on the inside or outside of the room?
Venting Out- I can put this in the opposite wall (behind the couch). It would vent into the equip room (see schematic) - Is that OK?
Is it a problem that the equip room is adjacent to the boiler room?
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post #2 of 16 Old 07-26-2014, 07:52 AM
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Normally you would want to introduce cool air near the screen end at the ceiling - what I would normally call supply. The cool air will mix if blown it at adequate velocity (so position left to right is of little significance), and then settle toward the ground, forcing warm air up and to the rear. So you position the return vent high and in the rear to collect this warmer moister air.

Since (if I read correctly) you're supplying air from another conditioned space instead of directly from the ducts, I would think it would be best to collect that air near the floor in the room it comes from. Any fans in this sort of scenario are quietest when placed at the end away from the theater, and I would think all of the ducting would be best outside any soundproofed area.

I don't see any problem with the way the equipment and boiler rooms fit together, but the equipment room probably needs exhaust.
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post #3 of 16 Old 07-28-2014, 11:41 AM - Thread Starter
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Quote:
Originally Posted by HopefulFred View Post
Normally you would want to introduce cool air near the screen end at the ceiling - what I would normally call supply. The cool air will mix if blown it at adequate velocity (so position left to right is of little significance), and then settle toward the ground, forcing warm air up and to the rear. So you position the return vent high and in the rear to collect this warmer moister air.

Since (if I read correctly) you're supplying air from another conditioned space instead of directly from the ducts, I would think it would be best to collect that air near the floor in the room it comes from. Any fans in this sort of scenario are quietest when placed at the end away from the theater, and I would think all of the ducting would be best outside any soundproofed area.

I don't see any problem with the way the equipment and boiler rooms fit together, but the equipment room probably needs exhaust.
Thanks - since you don't go into the equip room (very rarely) - why would it need exhaust?
I was thinking of opening a hole in the wall between the HT (back) and equip. room and putting a fan in the equip room to draw the old air out of the HT into the equip room.
I'd put another fan and duct work behind the front wall (near the door) to draw "good" air from a duct on the floor (as you suggested) in the main playroom to go into a vent near the ceiling of the HT - Is this correct?
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post #4 of 16 Old 07-28-2014, 04:44 PM
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The supply scheme looks good, though it probably won't produce and ideal amount of airflow - it's the best option short of actual HVAC duct from the air handler. The return, or warm air exhaust into the equipment room is okay, but poses a problem if the equipment room is sealed in any way. The air pressure in that room will build up and you won't get enough flow, most likely. The other concern is that the equipment itself will not get enough cooling - that will depend on how much equipment in what size space, and with what airflow.

Basically, I'm concerned that you're under-doing it. More flow is better for all considerations.
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post #5 of 16 Old 07-28-2014, 05:34 PM - Thread Starter
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Quote:
Originally Posted by HopefulFred View Post
The supply scheme looks good, though it probably won't produce and ideal amount of airflow - it's the best option short of actual HVAC duct from the air handler. The return, or warm air exhaust into the equipment room is okay, but poses a problem if the equipment room is sealed in any way. The air pressure in that room will build up and you won't get enough flow, most likely. The other concern is that the equipment itself will not get enough cooling - that will depend on how much equipment in what size space, and with what airflow.

Basically, I'm concerned that you're under-doing it. More flow is better for all considerations.
I leave the equip room door open, but thanks for the info in case I change that.
How would you suggest that I get more air flow?
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post #6 of 16 Old 07-28-2014, 06:15 PM
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More ducts - and/or larger ducts.

The ideal goal is to exchange the air 6 times per hour. That's a lot of air. I'll be luck to get four exchanges through my room every hour, with 2x 6" flex duct supplies and 1 8" flex duct return. (2300 cuft)
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post #7 of 16 Old 07-29-2014, 06:44 AM - Thread Starter
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Quote:
Originally Posted by HopefulFred View Post
More ducts - and/or larger ducts.

The ideal goal is to exchange the air 6 times per hour. That's a lot of air. I'll be luck to get four exchanges through my room every hour, with 2x 6" flex duct supplies and 1 8" flex duct return. (2300 cuft)
Gotcha - I'm gonna start with 2 vents both 8" and each with its own fan. What are your opinions on the following options regarding placement?(especially options 4 ,5)
Option 1
- (1) 8" supply on the front wall and (1) 8" return on the rear wall. Being that I'm planning/hoping for just these 2 - should they be at opposite corners of the room? i.e. see revised diagram below (red "x" = location of vents - pretty much the only spots that I have access to). One is in the front - right corner, the other about 3' from the right wall (total room width about 12') - will that also circulate the air near the right wall of the room?

Option2
OR since I'm going to put a fan in each vent - can I put both supply and return vents side by side on the same wall (as less work and can put both ducts in the same dead vent)?
Option 3
OR Can should I put the return vent below the projector(see 2nd diagram)
Option 4 (makes most sense to me)
OR What if I put the return vent facing the projector - in this way I can close off the projector soffit when watching a movie (noise is distracting somewhat), and if I close the bottom of the soffit with something slideable - I an keep it open the rest of the time, to allow the air from the room to flow in see 3rd pic below for actual photo (actually come to think of it, how do people make a hush box, and let air in?

OR Option 5 - put the return vent next to projector (as in option 4) and supply vent in front wall corner (as in option 1). Or will the 8" fan be wayyy too strong for the projector
thx



Option 3 (and 4)





Actual pic of back wall/projector
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post #8 of 16 Old 07-29-2014, 04:16 PM
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Sorry if I missed it in this thread somewhere, but where are you getting the air from to supply the room? Are you doing this for ventilation of the room or to cool the equipment?

If you're doing this for cooling of the room; In general, you want to place your air supply grills in the corners furthest from the door, and place the return/exhaust grill near the door. This provides even coverage and draws the air towards the return grill near the door. You don't want to place supply grills near the door because the second the door opens, you lose all your cooling.

In your case, I'd recommend one grill in each corner on each side of the screen, and the return grill by the door. If you want to only install one supply grill, I suggest putting it near the corner furthest from the door. Having the Equipment rack near near the return/exhaust grill in your case works out even better to draw the heat away from the equipment. If it was me, I'd also add a small supply air grill in the equipment closet.
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post #9 of 16 Old 07-29-2014, 04:28 PM - Thread Starter
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Quote:
Originally Posted by thucker View Post
Sorry if I missed it in this thread somewhere, but where are you getting the air from to supply the room? Are you doing this for ventilation of the room or to cool the equipment?

If you're doing this for cooling of the room; In general, you want to place your air supply grills in the corners furthest from the door, and place the return/exhaust grill near the door. This provides even coverage and draws the air towards the return grill near the door. You don't want to place supply grills near the door because the second the door opens, you lose all your cooling.

In your case, I'd recommend one grill in each corner on each side of the screen, and the return grill by the door. If you want to only install one supply grill, I suggest putting it near the corner furthest from the door. Having the Equipment rack near near the return/exhaust grill in your case works out even better to draw the heat away from the equipment. If it was me, I'd also add a small supply air grill in the equipment closet.
being that the room is surrounded on 3 sides by the concrete foundation (and walls are already up) - I only have access to install a vent in the area behind the front screen wall door and in the area adjacent to the equip room. Also note (I didn't explain this before) - the door by the front screen wall - is an emergency exit only door (i.e. I hope to never have to open it) - it leads to a stuffy closet. Also the equip room is adjacent to the boiler. That being that case, I figured that I didn't want either of those areas to supply the air as it would be "bad" air from the boiler room or from that stuffy closet - so my thought was to run ducts to supply air from the main basement (either running the ducts through that closet opening to the main basement or through the equiproom and boiler room to the main basement (going via the closet is MUCH easier)
Let me know what you think
thx
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post #10 of 16 Old 07-29-2014, 05:01 PM
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I'm not sure what you're saying about putting the duct by the projector, but it's important that the two ducts not be near one another. They will short-circuit and not mix air throughout the room.
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post #11 of 16 Old 07-30-2014, 09:44 PM - Thread Starter
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Quote:
Originally Posted by thucker View Post
Sorry if I missed it in this thread somewhere, but where are you getting the air from to supply the room? Are you doing this for ventilation of the room or to cool the equipment?

If you're doing this for cooling of the room; In general, you want to place your air supply grills in the corners furthest from the door, and place the return/exhaust grill near the door. This provides even coverage and draws the air towards the return grill near the door. You don't want to place supply grills near the door because the second the door opens, you lose all your cooling.

In your case, I'd recommend one grill in each corner on each side of the screen, and the return grill by the door. If you want to only install one supply grill, I suggest putting it near the corner furthest from the door. Having the Equipment rack near near the return/exhaust grill in your case works out even better to draw the heat away from the equipment. If it was me, I'd also add a small supply air grill in the equipment closet.
Here's the pic of front and back of room - with spots where I'm thinking of putting the grills. Note - door by screen is for emergency only and kept closed. I would like some cooling, but it's not the main desire. The spot where I have the grill on the screen wall, is as far as I have access to get behind the wall.
In the back (with desk, proj, etc) - I'm guessing that I'll have to add a soffit below the existing shelf where the proj. currently rests. I'm not crazy about adding that for aesthetic reasons, but I'm guessing that I need it in order to have the vents on opposite corners of the room (Front-right / Back-left).
The other option would be to put the exhaust grill along the wall to the right, or perhaps in the middle - is it a big difference from having in the back-corner (making it worth adding the soffit)?







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post #12 of 16 Old 07-31-2014, 12:13 PM - Thread Starter
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After further thought - this diagram below most clearly shows my Q and what would be the best place to put the grills as far as aesthetics and practical considerations are concerned. (room size approx. 12x22x6.5 feet high).
Is this OK - or are there major problems with this setup?
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post #13 of 16 Old 07-31-2014, 08:44 PM
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I think this is fine. I don't see any reason to go to further lengths to locate the return anywhere else (and in fact if it can effectively take heat from the projector - all the better). I'm still not sure about the volume of air you can move, but the limits are the limits.
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post #14 of 16 Old 08-01-2014, 12:17 AM
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Quote:
Originally Posted by cgott42 View Post
After further thought - this diagram below most clearly shows my Q and what would be the best place to put the grills as far as aesthetics and practical considerations are concerned. (room size approx. 12x22x6.5 feet high).
Is this OK - or are there major problems with this setup?
This will work, if you can't get another grill on the other side of the front wall. Just keep the door closed when you are using the room, otherwise you will not get proper air circulation in the room.

What are you using to get the air in and out? We can help you size the grill and duct accordingly.
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post #15 of 16 Old 08-05-2014, 09:28 PM - Thread Starter
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Quote:
Originally Posted by thucker View Post
This will work, if you can't get another grill on the other side of the front wall. Just keep the door closed when you are using the room, otherwise you will not get proper air circulation in the room.

What are you using to get the air in and out? We can help you size the grill and duct accordingly.
thanks, I definitely appreciate the help.
I am using 2 of these 8" fans (1 for supply, the other for exhaust)
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post #16 of 16 Old 08-07-2014, 11:12 AM - Thread Starter
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Quote:
Originally Posted by thucker View Post
This will work, if you can't get another grill on the other side of the front wall. Just keep the door closed when you are using the room, otherwise you will not get proper air circulation in the room.

What are you using to get the air in and out? We can help you size the grill and duct accordingly.
Yep - I will keep my door closed to help the circulation.
re: positioning of the grills:
  1. Assuming that the supply grill is near the ceiling, should I put the return near the floor (see pic below as the desk might block the air flow (there's about 12" gap between the desk and where the grill would be)
  2. Can I reverse things and put the supply grill near the floor, and the return near the ceiling?
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