I instructed my builder not to put a AC return in the HT room(24x17.5) for fear of compromising sound proofing. He told me thats fine however, for proper heating/cooling I'll need to leave the door open. In a way this does make sense to me(air pressure, et all). I just want to make sure that this was the right decision before its too late.

Does the room border the furnace room? That is only reason I could see why you wouldn't want a return grille.

You NEED a return grille. It is quite ironic to not put a return grille in for sound reasons but then leave your door open! ;)

You can put a booted return if you have space behind the wall to your furnace room and line it with duct liner that should kill the majority of the sound.

Or you could install a dedicated split system for the room that is not run off the central heating and cooling system. Be careful though as these can be quite noisy too.

It is quite ironic to not put a return grille in for sound reasons but then leave your door open!
+1, although “ironic” isn’t the word I would have used!

Your AC guy is right – if you have an airtight room (as a soundproofed room should be), your AC isn’t going to work without a return. Don’t know what he has planned for it, but a return grill ducted into the attic back to the air handler won’t compromise soundproofing anymore than the incoming-air vent would.

Regards,
Wayne

Yeah I could see that working if the return was in the ceiling, I don't think they can/want to do that. He didn't say I couldn't shut the door of course, just that I should leave it open when possible. But he wanted to put the return in the wall, i.e. through all of the DD+GG I'm putting in and it would be in one of the living space adjacent walls.

You must have at least one air return in your room.
Sounds like you're going full-on with DD & GG.
Trust me on this, your room will be stifling if you don't.
Without anything to equalize the pressure, you won't get any circulation.
You will forever regret not having one.
Do you have any columns? Is there a way to run the return inside a column?

Opening a door is going to compromise your sound containment FAR more than a cold air return duct and it will likely f*ck up your acoustics as well.
Have your HVAC guy put a couple of 90 degree bends in the ductwork and use insulated ducting.

:confused:Maybe it's just me, but I think leaving the door open "will compromise sound proofing".

I'm convinced. I'm thinking of either the ceiling or in one of the exterior walls in the rear of the room. Is any one location better then the other?

I'm convinced. I'm thinking of either the ceiling or in one of the exterior walls in the rear of the room. Is any one location better then the other?

The supply should be up front and a return at the rear. This way your air will push and have a circular "wash" effect.

+1, although “ironic” isn’t the word I would have used!

Your AC guy is right – if you have an airtight room (as a soundproofed room should be), your AC isn’t going to work without a return. Don’t know what he has planned for it, but a return grill ducted into the attic back to the air handler won’t compromise soundproofing anymore than the incoming-air vent would.

Regards,
Wayne


I actually had "stupid" but I went back to soften the blow...:D

If its in the ceiling there will be a chase in the wall, then crawlspace. Or I can put it in the exterior wall and the chase would go just in the crawlspace.

To not compromise all the money you spent on sound proofing, the return needs to be constructed as a soundproofed duct not a open grill to an adjoining room or joist cavity. Also the duct needs to be constructed in such a manner that sound can't carry down the length of the duct into the HVAC system servicing the rest of the house.

Using acoustic duct liner with a couple of bends is one such method.

You MUST have a return, the sound problems are fairly easily addressed if you do it now. Leaving the door open totally BLOWS your sound treatment.
This would be a huge mistake.

One other thing you might want to consider is placing the return(s) in fairly close proximity to your pj so that the hot air vented from the pj will be pulled into the return faster and hopefully keep the pj a little cooler.

To not compromise all the money you spent on sound proofing, the return needs to be constructed as a soundproofed duct not a open grill to an adjoining room or joist cavity. Also the duct needs to be constructed in such a manner that sound can't carry down the length of the duct into the HVAC system servicing the rest of the house.

Using acoustic duct liner with a couple of bends is one such method.

If you need to build it into a wall or joist cavity, you can also use the same design principles as a car muffler using blocking. Below is a crude side view of what I'm talking about. You're basically forcing the sound waves to go around the blocking, which will cancel out the vast majority of them. It does cut down on airflow a bit obviously, but you can size the duct to compensate for that. I did that for one of my returns and it worked great. For my other return I used the method BIG mentioned, which also worked. There is zero sound transmission through the HVAC system.

|__ |
| __|
|__ |
| __|
|__ |
| __|