As to the statement re: hood loudness: Would I agree that a single measure of an 8db difference would be "louder," from two different sound sources in two different kitchens? No. Wrong measure and flawed methodology. First, decibels don't measure loudness and second no conclusions could be drawn from a single person's report comparing the loudness of two different sound sources in two different settings. Perceived loudness is measured by multiple subjects under highly controlled conditions and is highly variable across individuals. Decibels are a physical measure of sound pressure; loudness is a psychological/perceptual measure of individual judgments. Decibels don't measure loudness for the same reason temperature doesn't measure warmth and weight doesn't measure heaviness. 85F in NOLA and 85F in Phoenix will not be perceived as equally warm because you already know that humidity, wind, clothing and your own individual body's response to these factors will vary. If we were to put a group of people in a controlled room and vary humidity, air circulation and type of clothing while varying temperature and ask them when they perceived a noticeable difference we would find that we would get the same report of perceived warmth at very different temperatures. In this case a decibel is a very similar measure to temperature and loudness is similar to perceived warmth. Depending on different sound pressures (decibels) your perception of loudness will vary significantly by the sound's frequency, if that frequency modulates, if the db level modulates, your proximity to the sound source, how reflective surfaces shape the sound, your individual hearing capability and sensitivities and (unfortunately) your age. If you look at a graph of where subjects perceive different sounds as pretty much equal in loudness while frequency and db levels are varied you'll find that sounds that at least half the group find equal in loudness can vary as much as 10 db or more. Human ears are very frequency sensitive. So, if a single observer's reported that 2 different sound sources were 8 db off in two different environments I don't see how any relative judgments could be made (and most kitchens with tile, polished wood surfaces, relative hard floors and glass windows can be expected to reflect sound in very different ways.) I won't speculate on all the methodological issues present to make a valid comparison of two different hoods' loudness levels in two different kitchens but a decibel meter would be largely irrelevant to the experimental design (you don't care about decibels, you care about perceived loudness). And to add insult to injury, you might well find out that even when you hit the standard that over half of the subjects agreed on the loudness findings you would still find other judges insisting some hoods were louder than others. That's pretty much how perceptual judgments tend to go. . .

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 :)

opaone opined. I think there is a fairly direct relationship between the baffle area, CFM's and noise. More CFMs for a given set of baffles (and constant baffle area) will increase baffle turbulence noise. However, baffle noise (generally a hiss sound) is not dominant unless a silencer is used with a remote blower. Otherwise, blower blade turbulence noise can be expected to dominate at the flow rates needed when cooking with hot pans (grease or oil near the smoke point). The larger the baffles the less the noise for any given CFM. I assume though that likewise the larger the baffle/CFM the less grease is removed? Two things are happening here. First, if the flow velocity near the baffles is not high enough, rising effluent will reflect from baffle surfaces and potentially escape from the hood aperture. Second, if the velocity in the baffles is not high enough, grease particles from the larger end of the particle spectrum will not be collected as well as they should be, causing them to pass into the ducting where they may condense on the duct surfaces. @Kaseki, do you know if there are any guidelines for baffle design/size/CFM for proper residue removal? Certainly those in the business of designing hoods and baffles will have design rules they use. I haven't come across any specific baffle design guidelines, but hood guidelines for use of particular baffles exist for those sources that produce baffles for commercial uses. Below are links to two example baffle (systems) with their pressure characteristics. (Links may need to be copied and inserted into one's browser.) http://productadmin.componenthardware.com/pdfRepository/repositoryFiles/20120906_025437_type%20i_product%20info_11-2011.pdf http://productadmin.componenthardware.com/pdfRepository/repositoryFiles/20120906_025211_type%20ii_product%20info_11-2011.pdf Baffles are going to be relatively simple on residential baffle arrays, and may have been experimentally tested and revised before production to yield decent effectiveness at minimal production cost. Are there trade-offs to that 90 CFM per sq ft aperture? EG, what happens if it's only 75 CFM? My simplifications are intended to avoid the extreme complexity of a problem space that can best be analyzed by computational fluid dynamics (CFD). What we have is a plume extent that has a shape, and associated with that shape is a velocity profile. The velocity changes with height and angle. When this plume enters the flow field close to the baffles, a lot of possible flow effects can happen, depending on the plume momentum and baffle details. There are also the tapered sides of the hood to consider as well as flat surfaces around the baffles. Picking the worst case plume velocity (~1.2 m/s) and demanding it be met by the baffle air velocity at the baffle gaps, and treating the plume shape (relatively bi-variate Gaussian) as a 10-degree constant velocity expanding cone for capture analysis seem to be adequate assumptions to avoid having readers later whine that their hoods were inadequate. 90 ft/min averaged over the aperture is just one of those approximations where the reality is that cooler cooking will require less, hence induction will require less than gas cooking due to lack of entrained hot gas combustion products in the plume, and in some cases will require more, except that the hood typically extends beyond some parts of any given plume thereby aiding containment of some momentum-degraded sideways drifting effluent near the baffles. Further, the overall air flow has some small capture influence beyond the edges of the hood entrance aperture, particularly for the lower velocity portions of the higher angle plume portions, and the overall flow over the cooking surface tends to move air toward the hood which also has some influence farther down for low velocity effluent. So, for many cases 75 CFM/sq.ft. may be adequate. Below is a copy of a table providing recommended updraft velocities for different cooking devices taken from one of the most useful of on-line sources, the Greenheck guide available at: http://www.greenheck.com/media/pdf/otherinfo/KVSApplDesign_catalog.pdf Note that this is for a 4-ft x 9-ft commercial hood probably 7 ft above the floor. Also note that there are various factors involved in using these numbers that may be found in the accompanying text. And of particular interest to me is that "wok" is listed with the "extra-heavy" category. This is probably applicable to Asian restaurant wok burners providing 100k - 200k BTU/hr gas jets. For residential wok cooking, the plume effects from the burner will be much less, but the temperature at the wok surface may be similar -- meaning that some parts of the plume velocities may be similar. So where should a residential wok be located in the table? I have induction for both cooktop and wok hob, and roughly 90 CFM/sq. ft. maximum air flow rate into my Wolf Pro Island hood, mounted at 34-inches over a peninsula, and it does a pretty good capture and containment job. Wall mount instead of island mount, gentle cooking instead of grilling or wokking, induction instead of gas, and other factors such as no cross drafts or an oversized hood may allow lower specific flow rates to be adequate relative to the table or others' experiences. Further, the reality is that for the most affordable MUA schemes, the inherent pressure loss will degrade the hood flow rate beyond that due to just duct and baffle pressure losses. So the renovator's task when contemplating 90 CFM/sq.ft. is to divine the degree to which my conservatism is overkill in the context of the entire ventilation system, kitchen layout, and cooking style, and design accordingly. kas

Tyler, so how is it going with the cooktop/hood? We are planning a remodel and considering a similar situation. We are in Florida, so I’d like to avoid MUA if possible as it is painfully humid and hot AF here 360 days of the year and one of my main goals of this remodel is to keep the hot air out. We have an older 1959 home, 94” ceilings. Our kitchen designer wants to put a 36” wolf gas range-style cooktop in front of a 104” window with a 6” backsplash/ledge using a wolf or zephyr 48” ceiling mounted hood at 600 or 700 CFM. So if the cooktop lands at 36”, that puts the vent 4’8”away from the countertop on the ceiling. I’m looking for functionality of suckage (sorry, I never made it past geometry into trig, so “suckage” is as good as it gets for me—lol) and if I have to use a different island hood that hangs 36” above the cooktop, so be it. I’m curious how it’s going for you, especially cleaning the window after cooking. Is it a daily chore or weekly? (I don’t see the window as a cleaning issue, when I cook, most of the splatter winds up on me or flies sideways, but rarely backward—but I’ve been wrong before, and I’ll be wrong again). I just don’t want to make the hood mistake. Any and all input is appreciated ;)