clinresga

vent hoods and noise: the real scoop on vah!

clinresga
12 years ago

OK: I've been following with great interest keitel's post on VAH hoods and noise. I'm in his camp: our VAH is noisy as all get-out. Others including shannonplus2, juliet3, and john.com have disagreed, arguing that their VAH's are "almost unoticeable on low" to quote john.

So, I figured, time to get some objectivity into this discussion (excuse my ego, but I started a new post cuz I think this is of general interest and worried it would get lost in a VAH post).

I pulled out my trusty Radio Shack SPL meter, normally used to calibrate the home theater, and took some readings (measuring from ear level when standing at usual cooking distance from range):

Our Vent a Hood 42'' 600 cfm hood liner at the lake:

65 decibels at low

67 decibels at high

Our Modern-Aire 64'' (1200 cfm) hood liner with remote inline Fantech FKD 10XL blower and LD10 silencer at the main house:

60 decibels at high

What does that mean? Well remember decibels are a measure of sound energy on a log scale. Thus, a three decibel increase represents a 10-fold increase in sound energy. Thus, 67 db represents about a 100-fold higher sound energy level versus 60 db.

A more useful way of comparing these noise levels would be to reference them to everyday sounds. Here are some examples:

60 db: "normal conversation"

[Ref: http://www.howstuffworks.com/question124.htm]

60 db: "conversation in quiet living room"

[Ref http://www.epd.gov.hk/epd/noise_education/web/ENG_EPD_HTML/m1/intro_5.html]

In contrast:

65 db: "average road traffic at 25 meters from busy primary distribution road"

see www.epd.gov above

67 db: level of noise that Caltrans feels justifies construction of a soundwall by an existing freeway

Ref: http://www.dot.ca.gov/dist07/resources/soundwalls/samples/synopsis.htm

69 db: the sound of loud snoring

70 db: vacuum cleaner at 10 feet

Ref: http://trace.wisc.edu/docs/2004-About-dB/

That's a fancy way of saying that the VAH is way noisy, and the MA/remote blower is very quiet.

Could it be our ducting making our VAH noisy? Doubt it, since as I posted before it's a straight shot up from the hood directly into the attic (it's a one story house) and out the roof through 10'' ductwork. Could we have an unbalanced blower? I guess, though both of the two 300 cfm blowers in the VAh are equally noisy and I'd be surprised if they were both defective.

Bottom line: this is an apples and oranges comparison. There is no way that it's fair to compare our inexpensive VAH to the very high end Modern-Aire liner/Fantech blower and silencer combo, and I'm not disparaging the VAH hoods, which obviously many folks have had a good experience with.

I do think though that this reinforces my belief that if:

1) you want high cfm ventilation

2) noise is a major concern

3) cost is not a primary issue

then remote blowers, preferably with silencer, are clearly superior.

Just my obsessive 2 cents worth :-)

Comments (61)

  • john_com
    12 years ago

    You could rent one from a store that does concert or band rentals. Maybe a home theater place could help you.

  • clinresga
    Original Author
    12 years ago

    cinamom: thanks for giving useful explanations of the whole decibel/perceived loudness issue. I love hearing from folks who actually know what they are talking about.

    lascatx and john: FWIW, they're actually pretty cheap. Radio Shack sells the newer digital model (not as well loved by the AV community as the analog version but not bad) at $49.99.

    Actually, if you have a home theater, it's a great investment anyway, as it's the only way to get anywhere close to correct calibration for parameters like speaker balance and subwoofer level setting. Plus, you can obsessively use it to annoy folks on GW :-)

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  • eseibert
    12 years ago

    Thank you for posting all this fabulous information.

    I have a question regarding the external fan option - I live in a very tight urban environment - if we vent externally then the fan will be about 10 feet above the ground, about 10 feet away from our neighbour's house - we can't get a finite answer on how loud it will be for our neighbours - some say "like an air conditioner". If that's the case that's OK, especially considering it will rarely be used late at night.....can anyone comment on that aspect?

    Until I read this post and the I hate my VAH post - we were considering a 42 " VAH for installation over a Capital 36' grill unit.... (actually the latest was 48" to get 1200 CFM which we requested - the 42 is rated at 900 I think plus plus the Magic Lung effect which is hard to quantify). Going to look into these other options as the VAH is already pricey ($3400 CDN)

    Thanks

  • clinresga
    Original Author
    12 years ago

    I'd agree, it's not annoyingly loud outside. It's above my bedroom in the attic and it's not really noticeable unless you listen hard for it when it's running. Plus it's "white noise" which in an urban environment should attract no attention. And, selfishly, I'd rather have that noise heading outside than two feet from my ears.

    I really don't think I could recommend a VAH if there were other options, and that's from a VAH owner. I am just so blown away (sorry :-) at how much better our Modern Aire hood with inline blower is, both from the sound standpoint (at low to medium speed, quieter than our Miele dishwashers, which is pretty quiet!--and at high, way less annoying than the VAH at low). And, I definitely don't see evidence of the "Magic Lung 300 cfm = conventional 600 cfm" equation. Our 1200 cfm MA absolutely runs rings around our 600 cfm VAH ventilation-wise.

    If you can swing it, cost and space wise, and if noise and ventilation performance are an issue for you, then I'd look into hood liners from dedicated hood companies like MA (also Prestige, Independent, Metallo Arts, etc) with a remote blower, and Fantech leads that pack in my mind (many if not all of the inline blowers I've seen or heard discussed are merely relabelled Fantechs).

  • parrym
    12 years ago

    I measured my OTR micro hood this weekend before I took it out. I have a Radio Shack digital SPL meter. Holding at year level (I'm 5'9") in the normal cooking position, set for C-weighting.... 71 dB on high, 70 dB on low.... All for a measly 300cfm that covers the rear burners only.... No wonder I never turn it on.

    I'll remeasure and post results when I put the new Kobe in.

  • eseibert
    12 years ago

    Thank you again - yes noise is really important to us. I'm going to investigate Modern Aire - found the Canadian distributor. Quick question - what is a liner?

    Also - can you give me an idea on the cost - as mentioned the 48" VAH island model was quoted at about $3500 (not installed) - are we in the same ballpark with the MA? Space isn't a problem - it's one 90 and then a 7 foot run and we can accommodate a 10" pipe.

  • clinresga
    Original Author
    12 years ago

    eseibert: a liner is a plain metal hood designed to sit inside a custom hood surround. Surrounds are commonplace -- see any kitchen magazine -- they can be constructed of wood, stone, stucco, metal, etc. In our case, we have our range in a true alcove, so it's surrounded by walls on either side, and there is a hood liner hidden inside the alcove.

    $3500 seems ridiculously high for the VAH, esp given the exchange rate currently. I just checked my original quote, and my Modern Aire custom hood liner, 64'' wide, with 10'' ductwork, damper, remote switches, a Fantech FKD 10XL 1200 cfm inline blower, an LD10 Fantech silencer all together came in at less than that!!! That's NUTS!

  • clinresga
    Original Author
    12 years ago

    I just did note that your quote was for an island hood, a more complex install than my simple liner, so the price may not be quite as outrageous as I initially thought. Still, check with MA -- if they are close to competitive it's a no brainer IMHO.

  • eseibert
    12 years ago

    Also that quote was for the 48" if that makes a difference - we're just looking for a stainless hood - not something that fits into cabinetry, etc - does that change matters? Anyway - I'll contact MA on that - so glad I found this posting!

  • clinresga
    Original Author
    12 years ago

    parrym: wow, that's a loud hood. Love that you used the SPL meter too. We can start a whole new trend in objective kitchen appliance evaluations.

  • eseibert
    12 years ago

    clinresga - I just had a long conversation with the Modern Aire distributor in Canada - he was terrific.

    We're going to his showroom on Tuesday - where I think we can hear an external motor.............thanks again for your postings.

  • lambic
    12 years ago

    Clinresga:
    Superb post. Thanks for the info- there's nothing like actual data to clarify previously subjective comments.

    As for the $CDN exchange rate, there have been minor price drops on some items with the rise in the Canadian dollar versus the US, but nothing close to the actual exchange. For the most part, we are seeing proof of prices being downward inflexible. I suspect the distributors are simply enjoying the adding profit.

    Eseibert:
    Where are you in Canada? I'm interested in the BlueStar hood, which I'm 99% sure is the Prestige hood, because I have a local BlueStar dealer. I've been quoted $2100 for the hood (w/o blower). On the strength of clinresga's and another's posts, I'm looking at a remote blower plus the fantech silencer.

  • clinresga
    Original Author
    12 years ago

    eseibert: good luck! Glad the MA guy in Canada was good. One advantage I had was actually that MA does not have a distributor in Georgia and thus I was able to deal directly with the factory, which was a great experience. Sounds like you may have similar luck up north. Hope you get to hear one: for me it is truly night and day, but I can imagine that for some the difference might not matter as much.

    lambic: While I can't speak to longevity (our fantech kitchen fan is new, and our bathroom fan is less than two years ago) the performance of both has been stellar. I hope they meet my high expectations over time.

    I do think the silencer is worth the effort/price, if you have the space (it's huge!). Previous posts here on external blowers indicated a significant number of people could still hear motor noise from their remote blowers through the ductwork. I can't hear any motor sound, just airflow, with the silencer in place.

  • lambic
    12 years ago

    clinresga:

    Do you know what the installed length of the LD10 Silencer ended up being? With a roof-mounted blower with built-in damper, I have 38" on the low side (angled roof) directly up through the attic, give or take an inch or two. Can I squeeze the LD10 in that space?

  • clinresga
    Original Author
    12 years ago

    Fantech website lists dimensions as
    LD 10 10'' duct 14'' diam 35 1/2'' length

    I think that it should fit, as it joins directly on either end to ductwork, with no need for any type of spacer or connector that might consume more room. BUT...I'd give them a call for sure and not just trust me! I've called them and they are very friendly and responsive.

    Here is a link that might be useful: fantech website

  • parrym
    12 years ago

    Ok, so I put in the Kobe range hood (CH2230SQ) this weekend and it is much, much better than the OTH Microhood. (no surprise). The best part is I did not have to modify any cabinets to put it in. This is a great unit for a modest remodel.

    There are 4 speeds ranging from 300CFM to 800CFM. Here's how the noise level came out. Again, all measurements are at ear level (~ 5'7") standing in cooking position in front of the stove.

    QuietMode - 380cfm, 1.0 sones, 51dB
    Low Speed - 560 cfm, 3.0 sones, 66 dB
    Medium Speed - 720 cfm, 4.5 sones, 74dB
    High Speed - 800 cfm, 4.8 sones, 75 dB.

    The lowest mode is almost unnoticeable if there is any ambient noise (radio, talking) and does a good job of whisking away light steam, etc.

    The Low speed is quite acceptable to have running while cooking and can pull enough air for most of my needs so far.

    The two higher speeds are noticeably louder and I would only use them for brief periods of high smoke & steam.

    The hood does not have much capture area (22in deep and flush on the bottom surface) so it is not ideal for grilling/stir frying, but will be great for me.

    Hope this helps add some data/perspective for people out there.

    Here is a link that might be useful: Kobe Hood

  • clinresga
    Original Author
    12 years ago

    parrym: I love that you took the time to measure SPL levels. I actually think that over time if others will do the same we'll begin to build a real world database of measured sound levels for various hoods. Between you and me, we already have levels for VAH, a remote inline Fantech with silencer, and your Kobe. Anyone else with a Radio Shack meter?

    Sounds like the Kobe worked out great for you: going from 70 db at low for your OTR MW to an incredibly quiet 51 db is a huge improvement. Even 66 db should be a noticeable improvement versus the70 db.

    Keep up the good work!

  • parrym
    12 years ago

    clinresga - I like your idea. It would be great to have a real world database of hood noise in helping people sort through their choices. All too often manufacturer data is a theoretical or best case number that doesn't turn out to be as good in a real world setting. Of course, everyones set up is different and can lead to much worse results, but with a large enough sample size, this can be averaged out.

    The Kobe has worked out great, though I suppose any hood would have been better than the OTH micro. In addition to the difference in SPL, the sound quality is much more pleasant with the hood, even at the highest levels.

    Now, if only the BS range was ready.....

  • clinresga
    Original Author
    12 years ago

    Total ego, but I'm bumping this cuz I am constantly referring back to it.

  • rnest44
    12 years ago

    Thanks for bumping. My GC/Kd has been talking about Fantech so I went to the website; didn't find it too helpful. This discussion was easier to follow and my GC is a techie so we'll go that direction. I need to make a final selection on my range before he can choose a system and price it. I'm out of my comfort zone here.
    Great thread!

  • chipshot
    12 years ago

    While numbers would be helpful, I would like to be able to hear how different hoods and installations sound. I know maintaining recording consistency would be a challenge, but the benefits would make it worthwhile.

  • paddy_99
    12 years ago

    You can not go wrong with the Fantech 10XL and matching silencer. Mine on high is quieter than any of the about 20 Vent a Hood, Broan,Monogram or Kitchen Aid hoods that I have seen.

  • lululemon
    12 years ago

    I came across this thread while reading about rangehoods and it brought up a few questions for me.

    1) My hood will vent directly outside as the cooktop is on an outside wall. Does this make a silencer more or less necessary?

    2) DH really likes the look of the slideout hoods but they are only rated at 350CFM. Am I right this will not be enough for a 36" gas cooktop? Can I improve it by installing an external blower or is the capacity a maximum no matter what?

    3) Where does the silencer get installed if I need one?

    I want to have some answers before I go to the store so I don't end up with whatever the salesman has to sell.

    Thanks

  • drtom77
    12 years ago

    lulu- What do you mean by a slideout hood?

  • salmon_slayer
    12 years ago

    lulu, i'm pretty sure you will not be happy with the slide out hoods and 350 cfm. The ones I am familiar with have no capture area. A silencer can be used depending on how you route the exhaust once you go through the wall. If you go up to the roof, you may be able to put one in. If the vent is diectly on the outside wall and your range is on the same wall, you will not have room.

    Be careful selecting a hood that vents directly through the wall. Pay attention to how high you are going to mount the hood, the dimensions of the hood, and where the house framing is. It can make a big difference in what you select.

  • fandlil
    12 years ago

    I think the slide out models are weak in exhaust capacity. You want a hood with a basin at least 3-6 inches deep so it captures the grease/smoke from the cooking. The hood should also extend out so that it "covers" the front burners. Most hoods extend just half way over the front burners. You also need to make sure the distance between the burners and the hood are as recommended by the hood manufacturer.

    If you want to minimize noise, you will need to install the blower someplace other than inside the hood, for example, if your house is one story, run the duct up into the attic and put the blower in the attic just adjacent to the opening to the outside where the exhaust is blown to the outside. That way you do not hear the motor. You hear just the rushing of air. This can be minimized if you select a hood that has a large capture area, one where the whole underside of the hood (not just a couple of small openings) draw into the exhaust. Then you also need to make sure that the size of your duct matches the capacity of the blower. Lots to think about.

    Do a search on the KITCHEN forum for more info.

  • lululemon
    12 years ago

    Dr Tom - the slide out hood is available from Kitchenaid and I think Miele. It is about 2 inches thick and sits driectly under the cabinets above the range. To turn it on you pull the front out. Try the KA website if you are interested.

    salmon slayer and haus proud - the vent I currently have goes directly outside near the ceiling of the first floor(not through the roof). It vents between my house and my neighbors. Neither of us has any windows in this area as the space is only about 6 feet wide. I will have to make a new hole since the cooktop will be moving about 3 feet to the left of it's current location. The Fantech 10XL mentioned in the thread looks good from what I can see on the website but I am worried about noise. If I understand it correctly the blower is actually mounted outside the house.

    We haven't really made a decision about the hood itself. I have been bowled over by how expensive a good hood/blower is. I am already having to rework the budget (I had only allowed about $400). I am going to have DH open up the supposedly empty in that area soffit and he can check the framing position at that time. Thanks for the heads up - I had not thought at all about where the vent hose would go and if there would be room for it.

    BTW I did do a search in the kitchen forum but this thread was the most informative I found in terms of noise - the primary reason I never use the hood I have (builders special POS)

  • clinresga
    Original Author
    12 years ago

    A silencer (at least, the Fantech LD10, which is the only one I'm aware of) is huge. It's a cylinder about 3.5 feet long and about 18'' in diameter. Not something that could be hidden inside a wall. It pretty much demands an installation in an attic, so it would not be an option if you duct straight out the wall. It's a nice thing to have, but the vast majority of folks don't use one. Still, I love it as I can run our blower (the 10XL) full blast and hear essentially no motor noise at all.

  • kaseki
    12 years ago

    clinresga:

    I have an LD10 ready to go in series with a Wolf (Broan most likely) 1500 cfm rated external blower, but that part of the project is still some time off.

    My question is: Given your suppressed blower noise, how loud do you find the hood baffle noise to be when your fan is on full power?

    Thanks

    kas

  • clinresga
    Original Author
    12 years ago

    kas--Extremely quiet. At high, it's a quiet background whooshing sound. To me, it's in the ilk of, say, a running stream behind the house--pleasant white noise. That is a dramatic difference versus our VAH, which I find actively annoying even on lower settings.

    I think it helps that the airflow is distributed across the full width of our rather large hood liner--it's 64'' wide, and the baffles extend to within about 6'' of each end, so about 56'' of actual baffle width. 10'' duct likely also helps. Still I am delighted with the outcome for whatever reasons.

  • sbedelman
    12 years ago

    It doesn't surprise me the the VAH is loud as it is the nature of the beast. They have to maintain a fairly high speed unlike other blowers because of the way they handle grease. While running only one smaller fan at a time is going to be quieter than two, its still going to be a lot noisier than running a single larger bladed fan at a low rpm. So I guess it all depends which is more important to you noise or dealing with filters.

    Likewise I don't think there is a question that a remote blower, whether inline or roof/wall mounted is going to be quieter than one with the blower right in the hood. Add a silencer to that remote blower and that is probably about as good as it gets.

    Unfortunately not everyone has room for an external blower so the question becomes how much difference is there between the various manufacturers for the same design, i.e. with an in hood blower? Except for VAH I'd venture not a lot. There is only so much you can do with good fan blade design although I guess perhaps its possible to muck it up if your fan is wrong (a problem for a long time with Sub-Zero fridges btw).

    Measuring anything in different environments let alone with different equipment lacking a standardized methodology (like where in the hood you measure) could swamp any meaningful differences, but it would be nice to try. If anyone has numbers on Broan, Best/Wolf, Kobe or any other wall mounts it would be great if you would post them.

    I'd also like to know if anyone has experience with the Kobe CH100 series? They make a big deal of their low noise and while it doesn't look like anything much fancier than a very low speed perhaps the fact that they're pushing how quiet the unit is means they made have paid closer attention to this than other vendors including getting the fan blade geometry right.

    The problem is they have practically no distribution. The closest dealer to Portland Oregon is Seattle and he doesn't even stock them let alone have one hooked up for demo.

    Anybody bought one? How do you like it?

    Likewise if anyone has any feedback on the Wolf/Best or Broan that would be wonderful.

    Thanks.

  • clinresga
    Original Author
    12 years ago

    sbedelman: nice, insightful comments. Agree the VAH design requires high fan rpm to "sling" grease into the trap. Problem in my mind is that even with the "filterless" design, you're still stuck with periodically cleaning out the fan housing, which is a huge PITA versus throwing my baffles into the dishwasher.

    There is a debate as to whether the VAH fan housing can be put into the DW. I believe the official position is that they can, but there have been posts here from VAH owners who found that the paint peeled off after that. So I've laboriously hand washed the VAH fan housing, which I hate. So, in my mind, it's loud AND a pain to clean. Give me my baffles and remote blower any day.

    I wish that others would post measurements of other hoods and blowers. I agree totally that my methodology is totally non-scientific, but I still think it's useful as a way to at least grossly compare different setups.

  • sbedelman
    11 years ago

    Anybody out there have a Kobe? I would love to know what your experience has been.

    Thanks

  • parrym
    11 years ago

    sbedelman,

    See my posting earlier this thread (Oct 8/08). I have a Kobe 2230 hood and am quite fond of it.

  • sbedelman
    11 years ago

    parrym,

    Am I right the the Kobe like the VAH in that it uses impellers and throws the grease into collection containers rather than filters?

    If so what confuses me is that some models like the CH-100 series seem to have both filters and collection. Hmmm.

  • parrym
    11 years ago

    The smaller Kobe hoods, like mine, use impellers with collection containers. The larger ones, like the CH-100 have baffle filters.

  • sbedelman
    11 years ago

    parrym,

    Thanks for the followup. I finally reached someone about the same time you were posting and they confirmed this. It seems kind of strange that they go with different methods depending on the model. I asked why but didn't get a clear answer. My best guess is that they use whatever motors are available to them and the impellers are generally smaller cfm. So for the small hoods they use those since they can get enough flow with two.

    With the larger hoods they go with larger fans and filter again keeping the motor count to two. VAH wedded as they are to impellers, needs to use 4 or even 5 motors in their large hoods so it would appear that this is either the only alternative if you want to avoid filters or larger impellers aren't readily available or cost effective (although I think they might be used in large commercial hoods).

    I don't have anything against multiple impellers except

    1) I think they might tend to be more noisy than an equivalent hood (meaning both have the motors in the hood, not remote) with a smaller number of larger bladed fans (but I'm not sure)

    2) that VAH can't seem to design an easy to use interface. Rather than a speed control that sequences each motor on and from low to high) so it looks like a single blower they make you throw all those switches. Well maybe 20 years ago when microprocessors where costly this made some sense, but not now. Clearly they don't give a darn about a good user interface, or may their customers don't, but it strikes me as absurd.

    The Kobe seems to have fixed this (at least on some models), for which reason alone I applaud them. On the other hand it might have issues of it's own.

    Time will tell.

  • dp215
    11 years ago

    Thanks so much for all this info. I am having real problems picking a range hood - am buying a bluestar with real firepower (more for the gas convection stove than the 22,000 btu burner) and don't know how many cfm's I need - 700 or 1200?? I don't stirfry or grill on the top, on the other hand, I do like to cook. Also, I guess I need something deep. I liked Kobe but am not sure they are powerful enough. Don't want to spend $2000 on one (bluestar's price!)

  • kaseki
    11 years ago

    In order for the baffles to work in larger hoods, the total flow rate has to be higher, or put another way, the flow across each square foot (meter, ell, whatever) of baffle has to be high enough for the baffle to perform the "slinging" function its way. Larger fans and motors are more cost compatible with the more expensive larger hoods that mount baffles.

    Hoods and fans sold at various price points will use technologies appropriate to those price points. Also, in some cases a technology is adopted to be distinctive in advertising. Hence certain "magic" products.

    VAH can get adequate flow as well as grease collection with small motors using their slinging scheme. I think more noise is inevitable with their choice of design. Low cost, low noise, high flow: You can only have two out of three at best.

    kas

  • kaseki
    11 years ago

    I was finally able to perform a sound measurement on my hood and attached system. The hood is a Wolf 66-inch Pro Island hood, and uses a Wolf (Broan) 1500 cfm (at zero static pressure) exhaust blower on the roof. In the ducting path is a Fantech "silencer."

    The predominant noise is a rumble that may be due to the roof construction. When it is cooler both outside and in the attic I intend to try to minimize that. There is also some baffle hiss.

    I have wrapped leaded plastic automotive floor dampener to a section of ducting below the blower. This is intended to damp any rattle induced in the ducting. I think it is quieter with it, as observed in the attic, but I didn't notice a reduction in the kitchen. I'm unsure that there would be a measurable reduction because rattle frequencies would be expected to be suppressed in the silencer.

    The measuring device is a "Realistic" analog sound pressure level meter. For you young-uns, Realistic is a trade name used by Radio Shack when it was young (barely out of the shack). This meter has no weighting modes. "A" weighting would be desirable for comparing annoyance noise.

    Having bought it at a surplus equipment sale, I do not have a manual that might specify bandwidth. Its calibration is also unknown, and may have been modified by its previous owners. Hence, while useful for comparative measurements involving only itself, comparison with measurements such as described in the messages above is extremely risky.

    The lowest meter scale setting is marked 70 dB; the analog meter can read to -10 dB relative to the setting. The lack of any meter reading when the hood system is off, even though there was a fair amount of ambient noise in the area, supports my guess that the meter calibration is not consistent with clinresga's ambient noise description in the first post.

    I obtained the following readings as a function of the continuous fan speed control position. Meter microphone was 6-inches below the hood edge aimed horizontally toward the hood center. This would be my approximate ear position when cooking.

    off -- below the lowest meter reading of 60 dB
    100% - 75 dB
    75% -- 74 dB
    50% -- 68 dB
    min -- 60 dB - barely audible over the ambient

    From clinresga's first post, one would believe that at 100% power (75 dB) it would be very difficult to converse at normal levels near my hood, but that is not the case. Normal conversation is possible and demonstrated. Helping here is that the rumble is fairly low in frequency. Between calibration and possible weighting differences, attempting to compare my measurements to clinresga's may be unrealistic (sorry). In any case, my intent is to get rid of the rumble, either by structural changes, or by fan balancing.

    kas

  • guadalupe
    11 years ago

    all hoods make noise the loud ones are usually the ones that are improperly installed. The interest in noise levels has gone over the top, noise is a sign of life, silence is a sign of no life.

  • kaseki
    11 years ago

    Signs of life
    Reach into the kitchen
    Without noise

    kas

  • dave_jacobson
    10 years ago

    I just called Independent and got their noise ratings:

    Independent 600 CFM: 54db-75db
    Independent 1200 CFM: 55db-77db

  • hilltop1155
    9 years ago

    A question about silencers: My brother-in-law was told by his rep that he shouldn't install one because it would collect grease in the duct. You obviously wouldn't want to have to take it apart and clean it. Does a silencer collect more grease than the rest of the duct?

    In addition to the grease problem it seems like the grease buildup would affect the ultimate performance of the silencer if that were correct. I'm in the process of selecting a system right now and would like to know what to expect. Thanks for your advice.

  • kaseki
    9 years ago

    Grease collection will be a function of the temperature of the silencer and the velocity of the effluent. This is why one wants to be in the 1500 to 2000 fpm range of flow velocity if the silencer is in a cold attic. The simple answer is some grease particles will condense. Whether this is a significant amount over the lifetime of the user is unclear to me.

    Cleaning a silencer would be a project for sure. Beyond disconnecting it from the ducting and getting it out of the attic, it isn't designed to come apart. Degreasers would have to be applied at one end and the interior washed out. Maybe the solution would be to use a car wash wand with auto soap injection.

    kas

  • clinresga
    Original Author
    9 years ago

    kas: Just pulled up some of these old posts and realized I never properly credited you with the only ventilation haiku I've ever heard. Nice work.

  • Derek87
    9 years ago

    weird to add to this old thread, but i wanted to add som other data...

    @clinresga: i wish i had read your post when i was trying to sort this all out last year...but fortunately, i think i ended up in the right place.

    i'll be upfront before providing more info: i am happy with my Ventahood. if i had the option of a remote blower, there is no question, i would have considered it, but in replacing an under the cabinet, microwave combo unit, the Ventahood one because of it's quietness at realistic speeds.

    anyway, i wanted to add the numbers i had recorded from a previous email to a friend last year when i ran into the imfamous "sticking flap" problem. (i'd be happy to elaborate on that if people want to know more about it)

    what i found (when the flap problem was corrected), using my Radio Shack meter at cooking location in front of the hood:

    Fan1 low: 57db (150 cfm)
    Fan1 high: 65 db (300 cfm)
    Fan2 high: 64 db (300 cfm)
    Fan 1 and Fan 2 on high: 67 db (600 cfm)

    as you can see, my numbers aren't too far off what was previously reported except for the lowest fan speed which is much quieter.

    nevertheless, i have to say that i often run Fan2 not only because of it's slightly lower volume objectively, but my subjective preference for the "whiter noise" nature of that blower. in fact, without the sound level meter, i had first thought oddly that a full 600cfm on was quieter than the fan1 on full speed on its own.

    i looked into a few other units including a Kobe, a Broan, and a couple other powerful "chinese hoods" that was crazy quiet at low speeds, but much louder to my ears (in the showroom) than the Ventahood.

    in short, i think some of the disagreement in VAH comes down to:

    - subjectiveness
    - stuck flaps
    - inproper ducting. (ie, installing it on a 6" or smaller duct)

    btw, i don't buy the whole Magic Lung giving me 900 effective cfm necessarily, but this is true from experience: the 300 cfm (one fan on full) pulls out much odor than our supposed turboboosted microwave hood did at its 420 cfm rating...i would guess the Ventahood at 150cfm still bests it!

    not all cfm are created equal when specified by the manufacturer :)

  • attofarad
    8 years ago

    I will chime in here with a bit of measured data on the Fantech LD10 duct silencer. I will be installing one, with a Broan 331H 600CFM roof mounted blower, and a Broan E60E35SS (36") hood, with 10" duct all the way.

    I set up the following experiment:

    First, the LD10 , which is 3 feet long. My wife held her hairdryer at one end of the duct, facing out. i.e., pulling air from the duct. I measured the noise level, A-weighted and C-weighted, at the other end.

    I repeated the test for a section of regular 10" duct, 5 feet long.

    Results, dBA / dBC :

    Fantech LD10.......73 / 76
    Regular 10 inch.....94 / 96

    Attenuation results are pretty much in keeping with the specs on the Fantech site.

    Subjectively, much less noisy with the LD10. The resulting noise was more like a hiss, which tells me that the lower frequencies were more attenuated than the higher ones.

    Here is a link that might be useful: Silencer specifications

  • attofarad
    8 years ago

    I'm bumping this since,for some reason, it didn't show up on the most recent threads as having been appended.

  • barjohng
    8 years ago

    This has been an interesting thread. I am in the process of trying to select a 30" hood to put over a Bluestar 30" range. I can't change the cabinet configuration but it is on an outside wall so the ducting only needs to run about 12" including the turn to the outside wall. I listened to the Ventahood in the showroom and I didn't find the sound level objectionable. Ventahood claims 6.5 Sones for the 600 CFM and 5.4 Sones for 300 CFM. On the newer models the grease catching tray slides out easily for cleaning. For the 600 CFM model they claim an effective 900 CFM rating when compared to traditional baffle units. I don't know where manufacturers take their readings or how they take their readings but I suspect they take them in a way that optimizes their numbers. I do know that baffles or screens will impede airflow so that fact that a particular fan can move 1000 CFM doesn't mean it actually will if it is partially blocked. If anyone knows how they take their measurements it would be great to post it. It would appear that their sound ratings are pretty honest which leads me to conclude that their other claims may be too.

    Interestingly, I have read in this thread complaints about the multiple switches and whether they had heard about microprocessor controls. Personally, that is a big plus to me that they don't use microprocessor controls. For the same reason I didn't want them on my range. First, they can fail and will fail far faster than a switch and be far more expensive to replace. Second, they rapidly become obsolete and the manufacturer can no longer buy the ones he used in your unit and must offer a newer design at some point that may not be compatible with your unit.

    A little disclosure, I work for the US Navy developing advanced measurement systems and one of the biggest problems we face is the rapid obsolescence of commercial off the shelf components and systems (COTS) to us. In the Mil-Spec days we could have a vendor guarantee us 20 years of parts availability today we are very lucky when we get 5. Something to consider.