You called?

We have a lot of "discussions" here that touch on noise, and I will provide a list of references on ventilation hereinafter. In summary, the requirement for good containment of what is captured by your hood more or less overlapping cooking plumes (don't forget potential drafts deviating the plumes) is, for residential hood configurations and in my opinion, 90 ft/min air flow rate at full blower power. This requires 90 CFM per square foot of hood entry aperture, and depending on pressure losses (baffles and MUA usually dominate), this will mean choosing a blower with a rated flow rate equivalent to 1.5 x 90 or 135 ft/min. As an example, for a 2 ft x 4 ft hood, the entry aperture is 8 square feet for a required flow rate of 720 CFM and rated flow rate of 1100 CFM.

Now to noise. While the VaH doesn't have baffles that will generate hiss at the required flow rate, it does put the squirrel cage blowers right above the cook, so the blower noise is "in your face" so to speak. A blower behind the baffles is barely less buffered, but the blower design is not limited to that which efficiently achieves a fire stop and grease extractor. So it could be quieter, although I don't have experience with an internal blower in my Wolf hood.

With a short duct, there is no room for a silencer. This leaves only two practical approaches for quieting: use an oversized external blower and only operate it at the lower flow rate needed for plume containment, or put in an external chase that provides room for a silencer as you duct upward. Potentially, a chase without a silencer but using some larger sized axial blower could be used, but that would require some guessing about what noise might result. (Wolf/Broan/NuTone roof/wall blowers are centrifugal; some Fantech blowers are axial. I vaguely recall @opaone is using an in-line axial blower.)

References follow in my next post.

References:

@clinresga on VaH

• https://www.houzz.com/discussions/2324336/vent-hoods-and-noise-the-real-scoop-on-vah
• https://www.houzz.com/discussions/6417748/hood-depth-question#n=10

@opaone ventilation information:

• https://bamasotan.us/range-exhaust-hood-faq/
• https://www.houzz.com/discussions/5745986/commercial-range-hood-install#n=129

Greenheck guide:

• https://www.tagengineering.ca/wp-content/uploads/2015/02/KVSApplDesign_catalog.pdf

Various FAQs

• https://www.houzz.com/discussions/2328297/range-hood-faq-personal-notes-updated-10-31-2007#n=20
• https://www.houzz.com/discussions/5161173/hood-faq#n=101
• https://www.houzz.com/discussions/6099827/exhaust-hood-faq-ii#n=113
• https://www.houzz.com/discussions/6040827/range-hood-noise-project

I don’t think noise matters much if it’s only when you’re high heat wok cooking, since that only lasts 5-10 minutes. The rests of the time, the fan can run on low and be quiet.

You can also choose a hood with a large capture volume. For short bursts of effluent like when wok cooking, capture volume can partly substitute for cfm.

I use a commercial hood with a lot of capture volume and overhang so it needs only 1,000 cfm and I could use a smaller and cheaper 120v blower rather than running a 240v circuit.

Nothing escapes the hood, whether wok cooking or coffee roasting - the latter is a stern test if roasting over-dark and inadvertently burning beans!

The blower is on the outside of the house, which helps a little with the noise. There is no silencer.

wow thank you all for these quick responses!

@kaseki - I've come across many of these posts but there always seem to be more so thank you for that! Good to see others are working through mounting their exhausts right behind their hoods. I don't think the HOA will be happy to have an external chaise on the exterior wall facing the street so I think I'm stuck with mounting the blower right outside the hood or having an internal hood. I think I'll just deal with the fact that there will be a lot of noise no matter what at high CFM, so I may just go with the 1200 CFM internal to simplify maintenance and such (with both the internal and external blowers being centrifugal, I guess it doesn't matter). Do you think the outdoor hood with 33" is overkill?

@Patricia Colwell Consulting - I agree, I don't think anyone needs a 48" range in the house, but with the 36" wolf wok rangetop, there are only 3 burners with the wok burner taking the right 2/3rds of the top. I wanted the 48" so that when I'm entertaining and having cooking parties, we can have 3 cooking "lanes" that aren't bumping into each other (2 stacked burners to the left, 1 wok burner in the middle, 2 stacked burners to the right). No matter what we are going to have noise so I'm coming to terms with that. Re: the VAH, glad to see you are enjoying it! I guess there is just a large vocal minority when it comes to people online that seems to voice negative opinions. Have you have experience with other classic baffle hoods and still highly prefer the VAH even with the difference in cleaning/maintenance? How often do you have to pull down the components and clean them as compared to a traditional hood? I'm speculating every 2 weeks vs every month or so.

@John Liu - Which commercial hood did you get? The only company that got back to me was Hoodmart and the baffles are 20"x20" which would need me to remove the center rack in the dishwasher if I wanted to wash them like that. Also, do you know what the 3" air gap is for ni the back and if thse is good or bad for a residential application? And did you mount your hood on an exterior wall like what I have to do?

Given a wall mounted hood and central wok burner, I would think the 27-inch hood would provide adequate capture. Ensure that the wok edge to hood edge angle from vertical is at least 10 degrees.

CaptiveAire 48” low clearance hood. “Low clearance” means the front edge is shorter than the rear, for headroom in kitchens with ceilings lower than a typical commercial kitchen (read: most houses). I set the hood for 6’1” clearance at the front edge, so I can freely walk and stand inside the hood.

It overhangs the front of the range by a few inches and the sides by 6”. The hood body stands off the wall (fire reasons? not sure) but the hood sides go all the way to the wall so there is no visible gap.

You can see what I mean by capture volume.

Here it is during the current kitchen reno. Ignore the plywood sinks, I made them from scrap and epoxy lined them, installed and used them for s couple months, gradually cutting them shorter until I found a height I liked, then had custom sinks made.

I took off the side panels as they aren’t necessary with 36” range under a 48” hood. If I ever move in a larger range, the panels might be handy. I have yet to have panels made to enclose the space above the hood, mostly because I can’t decide what I want (wood? stainless? copper? with speaker grilles or not?).

These hoods (and most commercial hoods AFAIK) are hung from the ceiling, not from the wall. Multiple big lag bolts into joists have worked fine for me. A single bolt has a pullout force exceeding 500 lb IIRC.

The duct is at the top of the hood, though it might be possible to order a hood with a rear duct. It is round, 12” diameter maybe? can’t recall. I had a plenum built by a local sheet metal shop to adapt 12” round to 10” square, and they made the ducting too. The range wall is the wall to my stairwell down to the basement and side door. The duct makes a 90 deg bend and runs 6’ to the exterior wall. It is in the ceiling, since the stairs to second floor are right above there is a convenient void there.

I guess I could have used an inline fan but CaptiveAire doesn’t have them so I used their upblast blower, model DU50 or something like that, mounted as sideblast. It is their largest fan that runs on 120v which mattered because at the time I was limited on panel space. Today I’d use a 240v fan. Here are my son and I installing the thing. With an HOA, I’m sure you will use an inline or inhood fan.

The baffles fit in my dishwasher. You don’t need to wash them often, as we’re not restaurants and are generating a miniscule fraction of the grease they do. I wash mine every few months and they are not particularly dirty. A hose sprayer, some Simple Green in a spray bottle, and some thirsty grass would work fine.

CaptiveAir now make a so-called ”residential” model with inhood fan. It is meant for schools and other settings with space constraints. I don’t know about the noise but I bet they have decibel ratings if you call.

@John Liu thanks for sharing those reno photos, that really puts into perspective how industrial and official these commercial hoods look like without shrouds! I found the WRH residential hood you mentioned, this is an interesting option. I am very interested in a large capture volume after all of the posts from kaseki and opaone. It looks like the WRH hood is back mounted instead of ceiling. Also good to hear about the baffles fitting in the dishwasher, the hoodmart baffles being 20"x20" wouldn't fit though I guess I could just wipe them down like you said.

Are you located in the east coast and can share the a rep you worked with? I haven't been able to get in contact with the captive aire group in Bethesda, MD.

I’m in the Pacific Northwest and used the CaptiveAire office in Vancouver WA.

Commercial equipment mfgrs can be bad about responding to individuals. Try contacting them through main office, or through a restaurant supply store.

Let us know what you learn about the CaptiveAire WRH, please.

I think it is an interesting option - most of the function of a pukka commercial hood, in a residential friendly, or at least not residential unfriendly, package. If it had been available when I did my hood, I would probably have gone for it.

I did my hood in the early part of Covid, when we didn’t want tradespeople or anyone in the house, so it was entirely DIY and OMG it took work. Those 48” commercial hoods are heavy as hell, two people can just carry it, how does a DIY’er lift it to the ceiling? I ended up cutting open the ceiling and bolting a chain hoist to the joists. The blower had to be carried up a ladder on my back while my son stabilized it with a rope from above. Then fishing electrical and the duct. If there’d been the option of simply hanging a WRH from a cleat on the wall . . .

I'll be sure to report back if I get a response from CaptiveAire soon. Otherwise I'll just go with the Wolf 27" Pro wall hood with an internal 1200 CFM blower and call it a day.

Hi John: Not quite DIY, but when doing my kitchen reno ca. 2010, I and my contractor installed my "66-inch" Wolf Pro island hood using his hydraulic lift normally intended for ceiling sheet rock (gypsum board) installation. Even if one had two people who could handle the weight for several minutes, another would be needed to align bolt holes and populate them.

I should have rented such a lift. But had no way to transport it.

You know what. I should get a pickup truck. Not a giant machoman 4x4 truck that costs the median family income. A $2,000 beater. Just to carry stuff.

Hey hood geeks - I was tossing some cold water in a pan of hot oil . . . what, you don’t do this? It is a useful trick for releasing stuck-on proteins like, say, ”pot stickers” . . . and naturally it results in a big roiling column of oily steam.

I sipped my coffee and mused, not for the first time, how nice it is to not mind at all, because you have a Good Hood.

Vent this, stylish slimline fashion hood! Weep, downdraft pretender!

Illustration of capture volume.

Too bad I'm only allowed one like.

Notice something else that was first tested and reported by the California Air Resources Board: a shelf under a commercial hood does not materially disrupt plume capture and containment. This was a surprise to CARB, as I recall.

My greatest regret is that ceiling height and hood dimensions conspired to deny my Salamander Dreams. So I have Consolation Shelf.

"I have a1200CFM hood that does a great job of capture and yes it is noisy and no matter on the outside wall or inside they are noisy."

Only if bad choices are made. Designed properly they can be very quiet.

At 500 actual CFM (equivalent to about an 1100 CFM U.S. consumer hood*) our hood is completely silent. We increased the low setting to 600 CFM so that it CAN be heard a little bit just so that we know it's on - it can be heard when cooking but still cannot be heard standing 3' away from the range.

At full (1400 actual CFM) it is still quieter than most (or any?) U.S. consumer hoods on low.

@John Liu, have you done any noise measurements on yours? I'd guess it is fairly quiet as well.

* U.S. consumer range hood CFM ratings are at 0" static pressure. In average residential homes they produce an actual CFM of about 1/3 to 1/2 the rated CFM, so a hood advertised as 1200 CFM will actually do only about 400-600 CFM. Even with good MUA I don't think I've ever seen one produce better than about 70% of rated.

Commercial hood systems use stronger blowers (shallower fan curve) that produce the rated CFM at higher static pressure. So a 1400 CFM system produces 1400 CFM.

More important though... consumer hoods lack sufficient containment volume. Which is actually worth more than CFM's. But CFM's are easier to mislead U.S. consumers. :-)

More on hood noise here: https://bamasotan.us/range-exhaust-hood-faq/

And yes, commercial hoods can be aesthetically pleasing. Our Accurex:

Quiet boils down to use of a long enough duct to allow insertion of a silencer (muffler), or use of a larger, slower blade tip blower, or both. The commercial hood approach of using a large reservoir volume before the baffles allows cooking plume averaging across the baffles, so except in cases where all burners are raging, lower flow rates (CFM) can be used with attendant lower noise levels. @opaone makes use of all of these techniques, as I recall.

"using a large reservoir volume before the baffles allows cooking plume averaging across the baffles, so except in cases where all burners are raging, lower flow rates (CFM) can be used with attendant lower noise levels."

Excellent point that I don't think I'd thought of.

A 1200 CFM Vent-a-Hood range hood with the "Magic Lung" blower system effectively moves 1800 CFM of air due to its unique filterless ventilation design, according to AJ Madison and Vent-A-Hood. This system uses multi-blower technology to achieve this higher airflow, while maintaining a relatively low sound level, specifically 6.6 sones at high speed.
This is my hood and belive me when it is in use it sucks up all the steam I make. BTW I have worked in maybe a dozen commercial kitchens none of them had stuff on a shelf behing a grill since that would not pass health inspection to start.

@opaone, my hood is quiet. The blower is audible. It is a upblast fan mounted as sideblast to the side of the house. It is very much audible when outside on that side of the house. Inside the kitchen, I know its on, but that’s helpful as I then remember to turn it off.

No Patricia. The VaH moves 1200 CFM as a blower-hood combination hanging in free air, whereas a baffle type hood using a blower rated 1800 CFM in free air would also move (nominally) 1200 CFM as a combination. Neither will move 1200 CFM when duct and particularly MUA pressure losses are present, and the effect of these pressure losses is worse for the VaH squirrel-cage blower than typical centrifugal blowers used on roofs, or for axial blowers that might be used in-line.

Nor is the Magic Lung filterless in the sense that it applies to the high flow rate region of use. It uses centrifugal extraction at the blower blades instead of at the baffles to remove grease and moisture from the larger end of the particle spectrum. (The smaller particles are hoped to be driven into the atmosphere and not onto the duct surface.) Only low flow OTR microwave ovens and tiny hoods can use actual filters, e.g., mesh screens, for grease.

Ironically, it was Magic Lung propaganda that motivated me to research kitchen ventilation back in 2007 because engineering doesn't generally make use of magic. (Sorry, J.K.)

"A 1200 CFM Vent-a-Hood range hood with the "Magic Lung" blower system effectively moves 1800 CFM of air due to its unique filterless ventilation design"

Nope. You are believing marketing propaganda. It's 1200 CFM and that only at 0" static pressure (free air flow). The CFM rate falls very quickly as static pressure (ducts, house) increases. I believe the highest I've ever measured one on high is around 550 CFM with most being well below that.

On top of that, CFM rate falls even faster as the blades build up with gunk. If they are not cleaned frequently, weekly/monthly, they can get down to around 50 CFM quickly. This is why commercial hoods and better consumer hoods all have baffles prior to the blowers - baffles result in less, like near zero, degredation as gunk builds up and are easier to clean.

They say that it's the 'equivalent of 1800' because of using a centrifugal separator but that's pure propaganda. The one thing I will give them is that they have better containment volume than most U.S. consumer hoods so actual produced CFM for actual produced CFM will perform better.

As to noise. Here are the results of actual measurements taken on installed units by people on this forum. More in https://bamasotan.us/range-exhaust-hood-faq/

FWIW, I've owned two homes with VAH. Both were inferior in both extraction and noise compared to other hoods and massively less effective and much louder compared to our current Accurex.

@John Liu, it'd be interesting to add your system to this chart: https://www.houzz.com/discussions/6040827/range-hood-noise-project

"because engineering doesn't generally make use of magic. "

Well said!

Now, lets talk about my world - quantum entanglement. :-)

My wok burner is used often to boil water quickly but it is in the front left of my 6 burners so not really in the way when cooking without it in use . I find usually when doing a dinner with a wok the other burners do not come into play much

"Now, lets talk about my world - quantum entanglement. :-)" Spooky action at a distance, but not magic -- Einstein wanted to say.

:-)

Oops, I meant to post below on the other thread. Will do that now.

My hood.

Amb 54.5

Low 57.2

Med 57.5

High 59.5

Amb 54.4

All are 15s avg (estimated by me) and it looked like peak was up to 0.7 dB higher. Not sure what kind of dB, whatever the Decibel X app defaults to when started.

Sorry, I have never used the app before. I can take some remedial training and try again.

Phone 15, held per instructions.

CaptiveAire 48” low-clearance hood, 10” square duct about 10’ to CaptiveAire upblast fan on side of house.

At low and med, most of the sound is humming from the speed controller. I didn’t know enough to get a fan that had VSC, instead I just have a potentiometer type control. I usually run the fan on high anyway since that’s the first position after the dial clicks ”on”.