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R/E/P => R/E/P Archives => Acoustics in Motion => Topic started by: bblackwood on June 26, 2009, 07:46:34 pm

Title: Low resistance fabrics for air returns?
Post by: bblackwood on June 26, 2009, 07:46:34 pm
Hello all, I figure this fine forum would be the perfect place to ask this - now that my room acoustics are in order and the room is trimmed out, my AC return vent is bugging me as it doesn't match the room aesthetically. This afternoon I spent a couple of hours making one out of left over trim wood and matching Guilford fabric (FR 702/2100) and was disappointed to find that fabric has enough resistance to add a slight 'shhh' sound to the room when the AC is running (the AC is virtually silent with the vent removed). I'm hoping there is a fabric (or an idea you may have) that will allow me to  'hide' this return vent (which is approximately 10" tall by 32" wide) but not obstruct the air flow.

All ideas welcome, and thanks in advance!
Title: Re: Low resistance fabrics for air returns?
Post by: jimmyjazz on June 27, 2009, 01:06:25 am
Got any photos?  What would an appropriate aesthetic be?

It seems to me that, if you're having problems with audible noise through what is purported to be a "transparent" fabric, you're going to have to knock the air velocity down, or build something that has even less resistance but looks acceptable.  Towards the latter, I'm thinking of something either like a perforated grill or perhaps a "plenum" of sorts that redirects the vent down (or up) but which has the same aesthetic as the wall.  Tough call without photos.
Title: Re: Low resistance fabrics for air returns?
Post by: bblackwood on June 27, 2009, 09:48:14 am
Good call, here's what I'm working with (sorry, haven't tied the cables there yet):

http://euphonicmasters.com/misc/vent_1.JPG
http://euphonicmasters.com/misc/vent_2.JPG
http://euphonicmasters.com/misc/vent_3.JPG

The more I think about it the more I think I need to have the HVAC guys add a secondary return to the room. If I can avoid that it would be great (hate drywall dust), but we'll do what we have to if we can't come up with any ideas here...
Title: Re: Low resistance fabrics for air returns?
Post by: jimmyjazz on June 27, 2009, 11:14:20 am
Thanks for the photos, Brad.  That helps, and it's definitely not what I expected to see!  I like your idea of a second return -- that will proportionally decrease the air velocity and should help knock wind noise down several dB.
Title: Re: Low resistance fabrics for air returns?
Post by: tom eaton on June 27, 2009, 12:48:22 pm
bblackwood wrote on Sat, 27 June 2009 09:48

If I can avoid that it would be great (hate drywall dust)...


You might want to vacuum out your return then... cause you're clogging your hvac filters with it!

Personally, I'd paint the inside of the opening black and then put a grille made out of (blask mesh) porch screen over the hole.  If no direct light hits the thing it'll just disappear.


t
Title: Re: Low resistance fabrics for air returns?
Post by: bblackwood on June 27, 2009, 01:30:38 pm
tom eaton wrote on Sat, 27 June 2009 11:48

Personally, I'd paint the inside of the opening black and then put a grille made out of (blask mesh) porch screen over the hole.  If no direct light hits the thing it'll just disappear.

Hrmm, I think a trip to Lowes may be in order to see how that works. Of course, if it's not back to practically silent I'm just going to add the second return - I really spent a ton on getting this AC quiet!

Thanks for the idea, Tom.
Title: Re: Low resistance fabrics for air returns?
Post by: franman on June 28, 2009, 09:51:08 am
Brad,

You could use a speaker grill cloth style fabric, but unless it's black or close to it, it's just gonna get jammed up with dust and look dirty within weeks... I suggest the black out treatment and just leaving it open in some way that looks clean. We do a lot of return air "Slots" in ceilings, with no grills.. just openings in the stretched fabric that lead up to oversized plenums and then to return air ducts. I like the look (sometimes) of no grills.. If they are strategically placed they can also conceal track lighting to highlight things in the room... good luck

FM
Title: Re: Low resistance fabrics for air returns?
Post by: Thomas Jouanjean on June 28, 2009, 05:03:56 pm
bblackwood wrote on Sat, 27 June 2009 12:30

tom eaton wrote on Sat, 27 June 2009 11:48

Personally, I'd paint the inside of the opening black and then put a grille made out of (blask mesh) porch screen over the hole.  If no direct light hits the thing it'll just disappear.

Hrmm, I think a trip to Lowes may be in order to see how that works. Of course, if it's not back to practically silent I'm just going to add the second return - I really spent a ton on getting this AC quiet!

Thanks for the idea, Tom.


Brad, I have a system that may work for you. Gimme 24 hours, I'll post this idea in CAD. Should look good and make the returns almost invisible and quiet.
Title: Re: Low resistance fabrics for air returns?
Post by: bblackwood on June 28, 2009, 08:00:52 pm
Thomas Jouanjean wrote on Sun, 28 June 2009 16:03

Brad, I have a system that may work for you. Gimme 24 hours, I'll post this idea in CAD. Should look good and make the returns almost invisible and quiet.

Oooooh, very nice!

*rubs hands together with glee*

I'm certain Thomas' answer will look better and perform equally well (if not better), but today I threw this together as a test - works perfectly:

http://euphonicmasters.com/misc/vent_4.JPG
http://euphonicmasters.com/misc/vent_5.JPG
Title: Re: Low resistance fabrics for air returns?
Post by: tom eaton on June 28, 2009, 08:37:50 pm
Looks great to me, Brad.  Nice work!

t
Title: Re: Low resistance fabrics for air returns?
Post by: Thomas Jouanjean on June 30, 2009, 03:11:50 am
This should work - sorry the plans are basic. But they show what they need to show.

There should be no noise whatsoever, and air moves without extra resistance through.

There is an opening in the "added" box, the fabric covered fiberglass panel is a few centimeters inside the box. Visually you will see the box + fabric and nothing else. The cables can also run in the new box and will be hidden.
Title: Re: Low resistance fabrics for air returns?
Post by: bblackwood on June 30, 2009, 08:16:18 am
And of course the idea is fantastic - thank you, Tom!

Will try to get this built sometime this week and will report back...
Title: Re: Low resistance fabrics for air returns?
Post by: bblackwood on July 22, 2009, 02:54:32 pm
Finally got this built - and it works GREAT!

Thanks, Tom. Your genius never ceases to amaze me.

I think it looks better (final trim isn't done around the vent) and it's SILENT!

http://www.euphonicmasters.com/misc/vent_6.JPG

http://www.euphonicmasters.com/misc/vent_7.JPG
Title: Re: Low resistance fabrics for air returns?
Post by: Thomas Jouanjean on July 22, 2009, 05:08:43 pm
Excellent! It was well built too!  Smile
Title: Re: Low resistance fabrics for air returns?
Post by: bblackwood on July 29, 2009, 04:54:24 pm
Installed the final trim this afternoon, hope to get the photographer out soon!

Thanks again for all your help, guys (especially Tom) - it looks great and is dead quiet!

http://euphonicmasters.com/misc/vent_8.JPG