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  1. #1
    Join Date
    Mar 2006
    Posts
    254

    Duct muffler, anyone had one installed?

    Anyone pros ever installed one, yet alone heard of them? I'd settle for a 5db reduction. Without going into details, everything else has been tried.

    # Duct Diameter: 8"
    # Unit Weight: 7.75 Lbs.
    # Does not restrict airflow through duct
    # Easy to install
    # Maintenence free
    # Housing Length: 24"
    # Building Code Compliant, Meets NFPA Standards 90A and 90B
    # UL Listed, Class I Air Duct
    # Noise Reduction: 9.4@250Hz, 17.1@500Hz, 21.5@1000Hz

    FAQ's

    Why do I need a DuctMuffler?

    The DuctMuffler will reduce sound traveling through the ducts of a forced air system, i.e. loud music from adjacent rooms, snoring, speech and noise generated by the furnace blower.

    How do I install a DuctMuffler?

    Simply remove a section of air duct from the offending duct run and insert a DuctMuffler. The DuctMuffler is a heavy product and must be properly supported using duct support brackets available at your favorite Home Center.

    How effective is a DuctMuffler?

    The DuctMuffler will attenuate noise levels by almost 10 dBA. Please note that every 3 dBA in noise level reduction cuts your perception of noise by half.

    Does the DuctMuffler affect airflow through my ducts?

    No. The open bore of the muffler is the same as the duct in which it is installed. There are no baffles or barriers.

  2. #2
    Join Date
    Feb 2008
    Location
    Dallas & Longview, TX
    Posts
    629
    What noise are you trying to eliminate? The velocity of the air though the diffuser won't be effected by the DuctMuffler I suspect. Only noises behind the duct.

  3. #3
    Join Date
    Aug 2003
    Location
    Fort Worth, TX
    Posts
    11,315
    Your problem remains as poor duct design and installation.

    Your solution remains the same...good duct design and installation. A "duct muffler" might help, might not. Properly sized and installed ductwork WILL help...a lot. You'll get a comfort performance boost to boot, and possibly energy savings. Duct muffler can't deliver that promise, just reduce noise...maybe.

    In the commercial sector we call "duct mufflers" sound attenuation. Would be worth pinging the OEM of this device for any stated pressure drop, even if their sales hype says to the contrary. Sound attenuating duct is essentially perforated sheetmetal backed by insulation. May or may not create notable pressure drop.

    For a residence, I wouldn't opt for this product.

  4. #4
    Join Date
    Mar 2006
    Posts
    254
    It just seems as if the company I hired (and about 3 others estimators) just
    don't really care about a 887 sq. ft condo with a hall furnace closet in your lap and a nice large return directly under the closet. I'm still trying to sound insulate that cavity under the closet (its as friggen large as the small closet).

    The blower motor is well powerfull, almost too much, and I'm against turning down the speed. Bigger duct work is probably my only option (8" now at BR and VERY short run to LR, 3- 6" off 8" trunk that goes to my back bedroom).
    I'd settle for improving the sound at my Living Room vent, thus the muffler idea. I'm exploring running a longer line to it.

    I've probably wasted enough bandwidth here and your guys time, but I kinda am a bit dissapointed with the noise It's a dissapointment I may have to just live with. It's not terrible, but a challenge that I wish someone in my area would/is able to address. There's no NIC contractors here.

    Please tolerate my being obsessed (not overly I hope) with just trying to quiet down this cool new AC/furnace (a bit more) that I had installed 2 weeks or so ago.

    P.S. The duct noise is very tolerable at my back Bedroom and even the other registers.
    It's the noise coming from the closet (which I am working on) and that one loud register
    at living room that is so close to the plenum. That's where I spend all my comfort time.

  5. #5
    Join Date
    Feb 2008
    Location
    Dallas & Longview, TX
    Posts
    629
    Ask about a quality diffuser that may be less noisy. If the plenum has a damper it could be closed a bit to decrease the velocity through the one vent. If the static is to high, maybe a larger duct and diffuser or split into 2 would work. The muffler will only have a possible effect on the actual blower motor sound traveling through the duct.

  6. #6
    Join Date
    Mar 2006
    Posts
    254
    A diffuser would look un-esthetic. Right now there's both air noise and
    blower noise coming outta the short run from plenum LR 12 X 6 vent box.

    If I go with bigger duct work (which might be ok), then I might have to reconsider doing the rest (for balance).

    I kinda hate to go with larger then my fairly slimline 12 x 6 duct box above my couch at ceiling. One alternative might to put 2 of them side by side?

    It might look less ugly than a big honking bigger vent register on my fairly neat modern condo. It still might look a little wierd tho, lol. Paint them wall color.

    If I go bigger vents all around, I'd change every one. What do you guys suggest? Replace the 12x6 8" duct box with 10" duct flex? Man..that means a bigger more noticble register there. Might not look too awfull big if painted.
    Any bigger than that and that's getting butt ugly big.

    Would an appreciable difference in blower rush noise be had with going from? 8" to 10"? 12" duct to a huge LR register would be (my god) BIG!

    I bet if I could beam a few of you over here...you'd all confer for 10 minutes and give me an answer my installer company isn't willing to risk.

  7. #7
    Join Date
    Jan 2001
    Location
    Pamnyra VA.
    Posts
    710
    is the return grill noisy? or is it the supply side? if it is the return side,try removing the return grill and seeing whats inside the space. you may be able to use sheets of armaflex with adhesive spray.if it's on the supply side ,change all runs to flex and leave a little extra turns in the flex if you can.

  8. #8
    Join Date
    Mar 2006
    Posts
    254
    Anyone else pondering the limitations of a small condo with a furnace closet in my lap need merely to click on my nick and look back at all my pics, etc.

    BTW, I've ordered some more sound proofing materials. Damn this gets expensive. Worth it to me tho.

    I don't wan't to restrict the airflow with any kind of dampner. Forget that.
    Bigger ductwork? Maybe. That entails bigger uglier register, especially at LR. Maybe.

    A longer run from that short run from plenum to my LR register? Could drop db by 3.
    Adding in a muffler? Possibly. Tune out the noise? That too. I hate that part, lol.

  9. #9
    Join Date
    Apr 2010
    Location
    NC Sandhills
    Posts
    404
    As far as the return/closet noise, is the return box insulated? if not, adding foam or insulation to inside may help unless it is undersized which by your description I doubt. What size return grill/s and size unit? The actual return grille may be to small. On supply side 8" duct moves alot of air for an average residential room. Flex or metal? But a living room area usually needs more than one supply register. If you have one 8" supply going into the living room maybe "Y" it to 2 - 6" or 8" runs to the supply registers.
    8"x8"x8or6" wye
    _____ 8"_____to existing register__[]
    ----existing 8"-----<
    _____ 6" or 8" to added registger_________________[]

  10. #10
    Join Date
    Jan 2001
    Location
    Pamnyra VA.
    Posts
    710
    Never have I installed a duct muffler in my 20 plus years of doing this type of work.Any contractor that suggests such an item isn't very professional.Blower speed set too high,wrong registers,wrong duct size,restricted blower wheel,...Pics would help

  11. #11
    Join Date
    Jan 2009
    Location
    Keokuk, IA
    Posts
    5,520
    THis is a small condo. It probably doesn't need more tha nthe smallest furnace and AC unit available in any climate. These small condos are oftne best served with hydronic air handlers with combi boilers, then jsut a small 1.5 ton AC, which only needs 600CFM. A 45k BTU single stage furnace only needs just a little more that that.

    Rather than soundproofing, I'd be saving up for new, properly sized equipment or a different system altogether. I know a 2 ton 2 stage 2 ton AC only needs 500 CFM on 1st stage and a 2 stage 45k BTU furnace needs about 400 CFM in low stage. An equipment upgrade might be best combiend with finding a way to increase the lenght of hte return duct, line bot hthe supply and return plenum ot absorb sound, and make sure the systme is st-up correctly.


    A lot of noise issues start with oversized equipment. I don't know if that's the case here. That was the case in my house.

  12. #12
    Join Date
    Jan 2008
    Location
    Texas
    Posts
    1,734
    Like you suggested add aditional supply, and if the noise at return decreases when grill is off then you can open the louvers up some which will help alot.

  13. #13
    Join Date
    Jun 2001
    Location
    Moore, Oklahoma, United States
    Posts
    4,177
    Quote Originally Posted by motoguy128 View Post
    THis is a small condo. It probably doesn't need more tha nthe smallest furnace and AC unit available in any climate. These small condos are oftne best served with hydronic air handlers with combi boilers, then jsut a small 1.5 ton AC, which only needs 600CFM. A 45k BTU single stage furnace only needs just a little more that that.

    Rather than soundproofing, I'd be saving up for new, properly sized equipment or a different system altogether. I know a 2 ton 2 stage 2 ton AC only needs 500 CFM on 1st stage and a 2 stage 45k BTU furnace needs about 400 CFM in low stage. An equipment upgrade might be best combiend with finding a way to increase the lenght of hte return duct, line bot hthe supply and return plenum ot absorb sound, and make sure the systme is st-up correctly.


    A lot of noise issues start with oversized equipment. I don't know if that's the case here. That was the case in my house.
    +1. Sometimes an ordinary water heater is all thats needed for a heat source for the hydronic air handler instead of a boiler.

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