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  1. #1
    Join Date
    Mar 2006
    Posts
    254

    Fairly whooshy vent return problem

    I just had a Carrier 2 ton AC and Performance 80 installed in a 887 sq ft. condo.
    The return grill is in my hallway closet. 26"x16". With the AC going, it's
    noiser than I would like. I have a pic for some suggestions to baffle or
    reduce the sound. It almost seems that cavity is huge and could well
    do with some noise reduction remedy. It's like a mini hurricane in there.
    What I mean by that is that there's actually downward flow too and some
    of the light insulation debris can be seen moving around by the turbulence.
    It that normal? The duct work is pretty good sized round.
    The vents on the walls are fine, sound wise.

    Anyways, some ppl are limited to their return vent area to mess with.
    I'm sure not. That white texture overspray is where air enters in.
    I'd appreciate some baffle suggestions. What's better than carpet to lay on the floor in there?




  2. #2
    Join Date
    Apr 2007
    Posts
    623
    By choking it down, most likely you are going to increase or at best just change the noise. You may see if you can have the installers, insulate this area, that will reduce the noise, but have them do it, because we are not talking about regular household insulation here. Unfortunately it will only get so good, do to it being almost directly at the blower. But it can be improved.

  3. #3
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Quieturn vanes ,will do the best jo,IMO.


    Go to www.durodyne.com

    then Glassline Catolog,look for Quieturn Vanes.

    The space can be lined with ductboard,which wiil hold the vanes in place,
    .

    Chances are you'll need to show the vanes to your Pro,as s/he may not be familar with them.

  4. #4
    Join Date
    Jun 2008
    Posts
    20
    Interesting. Where would you position the vanes in his installation?

  5. #5
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Quote Originally Posted by Weaselboy View Post
    Interesting. Where would you position the vanes in his installation?
    Hard to describe.A box the size of the equipment inlet,down to the floor, would be built to hold the vanes.Vanes would be installed at the needed angle,not 45 degrees in this case.

    Then a transition from the inlet to the box,flaring out going to the return grille size.

    Ductboard is ideal as all this can be cut and fitted in place at the jobsite.Mastic on the inside seams is ideal to hold it all in place.

  6. #6
    Join Date
    Apr 2003
    Location
    Levittown, PA
    Posts
    818
    Is that Air Cleaner new? Looks like it, i don't see a transition on it and I wonder what the static is across that. Have the installers check the T.E.S.P of the system. The whooshing sound and turbulence could be from the flanges on that cleaner.
    Last edited by sparks; 07-13-2008 at 01:51 PM. Reason: spelling
    Sometimes when I consider what tremendous consequences come from little things, I am tempted to think there are no little things!

  7. #7
    Join Date
    Sep 2002
    Posts
    13,551

    Sound travels in straight lines - air turbulence creates noise

    So you want to avoid a straight path for the air to follow and you want the flow-path to be very smooth.

    First: did they do a heat load calculation to determine that you actually need 2 tons of cooling and the aproximately 800 cubic feet of air flow for it?

    Next: did they test to prove that you are getting the correct airflow? Or did they just set the blower for "the highest speed for cooling" and run out the door with the check? <g>

    After the above two questions are answered correctly, and if you can tolerate the loss of space, a blank, well overlapping 'baffle plate' can be spaced out from the wall to cover the return opening.

    Or two sets of 45 degree vanes could be installed internally in the air return path.
    PHM
    --------
    The conventional view serves to protect us from the painful job of thinking.

  8. #8
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    Quote Originally Posted by sparks View Post
    Is that Air Cleaner new? Looks like it, i don't see a transition on it and I wonder what the static is across that. Have the installers check the T.E.S.P of the system. The whoshing sound and turbulence could be from the flanges on that cleaner.
    Good point,also wonder if the platform is cutout the full size of the air cleaner,if not more restriction and noise.

  9. #9
    Join Date
    Apr 2003
    Location
    Levittown, PA
    Posts
    818
    Quote Originally Posted by dash View Post
    Good point,also wonder if the platform is cutout the full size of the air cleaner,if not more restriction and noise.
    Yeah, you can't really tell from the pict's but it looks smaller than the inlet.

    Hey caslon can you post a few more pictures it may help us help you. Supply transition, where the furnace connects to the duct work and one from the return to the bottom of the air cleaner.

    I don't know how much we can help with just pictures but maybe we can give you a few more ideas to approach the installers with.
    Sometimes when I consider what tremendous consequences come from little things, I am tempted to think there are no little things!

  10. #10
    Join Date
    Mar 2006
    Posts
    254
    First of all, thanks for the replies. I believe the whooshing noise CAN be lessened...somehow.

    I noted to the installer before he left that the whooshing sound seemed excessive. He said it was the blower motor sound being in such close
    proximity to the return cavity. He didn't seem to want to do much about
    it, seeing as how the system was working pretty well.

    They offer 100 &#37; satisfaction guaranteed, but if they aren't talented enough to
    deal with it...what good is that?

    I will DEFINATELY explain to them that I am getting so much draw that I can
    actually feel backpressure air coming out thru the return grate. To me that is
    just wrong. That is priority # 1....don't you guys agree?

    Can the blower motor speed actually be tweaked? I thought you didn't want to do that.
    Also, the cutout IS the full size of the filter, btw.

    If my return cavity space was farther away, I probably would not have this problem. The sound isn't maddening (but excessive), and that backflow of air coming out the return grate COULD/SHOULD/CAN be corrected IMO.


  11. #11
    Join Date
    Mar 2006
    Posts
    254
    Quote Originally Posted by dash View Post
    Hard to describe.A box the size of the equipment inlet,down to the floor, would be built to hold the vanes.Vanes would be installed at the needed angle,not 45 degrees in this case.

    Then a transition from the inlet to the box,flaring out going to the return grille size.

    Ductboard is ideal as all this can be cut and fitted in place at the jobsite.Mastic on the inside seams is ideal to hold it all in place.
    I understand for the most part, but that flaring out to something the full size of my intake opening seems a bit much for to want to have fabricated.

    How about this: Run the box down to an insulated floor like you said, then
    with the 6" clearance on each side, run out 4" sideways on each side with somewhat smaller
    ducts (big, but not 24" big). Remember, rectangle filter opening is 24"x12".
    That would give 2" clearence on 2 sides for the air to get in and
    take 2 right turns upwards. I could even sound insulate the inside of
    the sheet metal. Ample flow of air would still get to the filter and there
    would be not one, but 2 right turn ducts at the bottom. I may not even
    have to use those vains (or could).

    With how oblong a retangle it is now, that rectangle gets up to the front in a hurry. Too much so for your design.

  12. #12
    Join Date
    Aug 2002
    Location
    Office and warehouse in both Crystal River & New Port Richey ,FL
    Posts
    18,836
    With ductboard you just cut and fit on the job,very esay for them.The other reson to use the vanes is to have the airflow evenly,as directed by the vanes,thru the filter.3 to 4 feet of stright would do the same,but not possible.



    If you follow your plan,ductboard is easier then metal to fab.

  13. #13
    Join Date
    Jul 2008
    Location
    Vancouver Canada
    Posts
    9
    This may have been over looked, but a very simple solution to your problem is to buy a grill with larger louvers on it. Get one with more space in between them, this will if nothing at all lessen the noise.
    I did a few jobs where the unit was right ontop or directly beside the r/a and insulation helped but the grill let the air flow through easier and reduced the noise by over 50&#37;. If you have to you can get a custom grill made up with 1/2" x 1/2" square. Egg crate is what we call it here.
    Last edited by TrueAirBC; 07-13-2008 at 09:49 PM.

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