I wouldn't go with "unbounded cost" but as the hood is the only appliance that is definitely being purchased (it's the main reason for the re-do), and I know what a bad hood results in, I have no intention of cheaping out. So as I mentioned, 42" wide, probably in what my husband calls a "lampshade shape".

There are no issues regarding homeowner associations or anything like that. Central hall colonial, well separated from neighbors who might otherwise get annoyed.

And it does need to be "quite powerful" but I'm not sure I understand the definition of "powerful" with respect to hoods just yet. I don't know what the cost universe looks like, but I'm assuming low-ish 4 digits. Again, it's the hood that is triggering the need to do the project. From what I've seen of photos, we are looking for something that's pretty standard - there are no known issues that would cause us to need a completely custom built hood. This is a working kitchen - while we obviously want something that looks good, this needs to be something that is going to be used, probably heavily, on a daily basis. Bonus points for really nice aesthetics, but the kitchen is there to be used, not simply sighed over. Visually, there is actually a very well populated ceiling-mounted potrack that will obstruct direct views of the hood.

Here's another question: where should the MUA be positioned in relation to the hood?

When you say vented outside, do you mean right behind the hood? Or up through the attic or whatever? How about noise concerns for yourself?

Your last question can bring up a lot of opinions.

The vent is essentially directly behind the hood - not up through an attic. If the hood is excessively noisy such that I can't have normal conversations with other people as I cook, then it will be a problem. If it is a "normal" noise level, then I really don't care. When we are not in the kitchen, we are generally far enough away that "ordinary noise" won't bother us. I don't expect an exhaust fan to be silent.

Under most circumstances, the quietest configuration uses a duct long enough to insert a silencer between the hood and blower. If the duct is not that long, then one has to live with the blade turbulence noise dominating the baffle turbulence noise. One can generally talk across the baffle noise (hiss), but blower noise close to the cook can be stronger.

So, let us look at the high end, say Wolf. The Wolf design guide, downloadable from their web site, presents a variety of hoods and compatible blowers. This document may be used to provide some insight into hood configurations and sizes, even if some other hood is eventually chosen. Costs may be determined by contacting a Wolf dealer.

For scoping out the universe of hoods, a good start may be perusing AJ Madison's web site.

To scale the blower, assume a 42 by 27 inch hood aperture. (Hoods are usually sized by external dimensions, so this is generous.) This area is 7.88 square feet. For reasons I won't address here, but have in numerous other threads, an air velocity of 90 ft/min should be sufficient to contain (move past the baffles without reflection) captured (caught by the hood aperture) cooking plumes from the hottest surfaces expected in residential cooking. 90 ft/min is equivalent to 90 CFM/sq. ft., leading to a requirement for an actual flow rate of about 700 CFM. (Scale down to fit the actual aperture when a particular hood is selected.)

In any case, the blower has to be sized larger than this value because it will only flow air at its nominal flow rate when hanging by itself in air, not when pulling air through some MUA path, past the baffles, and through the duct. Lacking any other information, adjust upward by 1.5X to be sure. This gets the blower rating to around 1000 CFM. A 1200 CFM blower could also be used and run at less than full power for potential noise reduction. Besides Wolf (which uses Broan blowers, last I knew), there is Broan/Best/NuTone and Abbaka as candidate exterior wall blower sources.

kas

I have Best by Broan with an external fan and the baffles (not the mesh). I usually run it at the lowest speed and it is barely heard -- really only noticed if you are standing right under it. I would look at them rather than paying more for a Wolf version - and mine sits over a Wolf rangetop.

Thank you. Very useful information.

we have a prestige pro-line 36" bull nose SS hood with baffles and a 1200 CFM blower over a 36" wolf all gas 6 burner range. the duct goes straight up to the roof and it is a short run because the kitchen is on the top floor. i put it on "full blast" and it sucks up everything but it is LOUD. our house never has any food smells though. i haven't tried running it lower because i am psycho about food smells- our old co-op had a microwave vent over the stove which is useless and i used to loathe the house smelling like whatever i just cooked for days. they do have a remote blower option and i would have loved to do that but we chose the vent/blower combo after we ran the electric and the electrician was unhelpful as i was trying to figure out between him and prestige what had to be done to wire for the external blower so i left it alone. the baffles clean beautifully in the dishwasher but i find them a little annoying to remove. i would definitely look at prestige:prestige

Windcrest hood (made in CA.) 1200 cfm 10" ducting, three settings low-med-hi 450cfm-900cfm-1200cfm with easy to clean baffles, hi-lo halogen light settings. 30"w x 27"d x 18"h. Does a great job over my Bluestar RNB range....highly recommend. http://www.windcrestcnp.com/

I had a Broan with my bluestar that vented out. Not overly noisy but powerful. Very happy with it.

I can barely hear the Vent-a-Hood I recently installed.

Vent-a-hood is by far the best. A little pricier but well worth it. Most effective and the quietest that I have experienced.

I was looking at VAH too when making my purchase, and was leaning that way until I saw the parts that had to be removed for a thorough cleaning. It was then that I checked off VAH from my list. I cook way too much and create a lot of grease. I did not want something with that many parts to remove and clean on a regular basis. My baffles come off I degrease and clean in the sink and replace, done. I don't doubt VAH is a good unit but in my case I have a stove that is heavily used and I need a hood that is easy to maintain....IMHO

Bear in mind that nine times out of ten you're only going to remove the bottom tray to clean. The other parts are more of an annual cleaning.

Wouldn't that time frame (annual) be dependent on the amount of cooking (grease and effluents) being created by the user on a daily basis? Here's a video of a VAH... is this accurate to your experience? Baffles are used for commercial ventilation systems for a good reason, easy maintenance and efficiency .....

Link>>>>https://www.youtube.com/watch?v=KgW5OkqnQXg

Of course, but the way the impellers work, the frequency you clean them is low compared to just cleaning the bottom tray. It also would depend upon how restrictive your vents are. I'd rather have the oil and such inside the impeller cabinet, where it's possible to clean them, rather than in the ductwork. I'd suggest that commercial kitchens have different standards than residential kitchens, so they're not really comparable.

kfunky_gw wrote: "Baffles are used for commercial ventilation systems for a good reason, easy maintenance and efficiency ....."

Another reason is pressure loss. While one might not think of a VaH blower as having pressure loss (after all, it is providing pressure gain), the squirrel cage blower is more susceptible to flow reduction from pressure losses in the overall ventilation path (including the MUA path) than the axial and centrifugal fans used in commercial (and other residential) systems.

Commercial hoods are large, usually, and the blower flow rates are well above the 1500 CFM limit of residential blower sizes. Large blowers are going to be designed for absolute best efficiency (CFM/watt at the existing pressure loss).

A third reason is that steep baffles are required in commercial systems to collect grease and reduce fire hazard. The VaH system is not conducive to draining away grease to a collection system, as far as I understand it.

A fourth reason is that the NFPA may not consider the VaH system, both operating and off, as good a fire-stop as conventional baffles are.

Commercial systems are required to inspect and clean their duct work once a year. On the other hand, given decent baffles or mesh filters, residential ducting may not collect significant grease over periods of decades.

The VaH constrains the residential cook to having the blower noise close to his ears. Where duct lengths and house configurations allow, blowers can be moved away and silencers added to the ducts for lower noise. In commercial settings, the blowers are on the roof and the cook can communicate with his staff even without silencers.

kas

Thanks for the more in depth explanation Kas....

OMG, this is so amusing...

Back in 2008 we were planning a major kitchen renovation and I lived on (then) the GardenWeb Appliance Forum. Fast forward, we are now renovating the lake house and I've started checking back on (now) Houzz to get an update. So I am totally struck by how the conversations are identical to those back in 2008! And so are some of the participants (Hi kas, I remember you well!).

So...on the issue of hood noise, and in particular of the miracle of Vent a Hood squirrel cage blowers. Jerry J and philbekins...I would get your hearing tested :-)

Our VAH at the lake is a 747 compared to the Modern Aire hood with remotely installed Fantech blower with silencer back home. And, many years ago, I not only claimed that, but tried to prove that I was right. So, from 2008:

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 :-)

Hi clinresga, have you decided to indulge in another reno for the fun of it?

While I'm saying "hi" I should assert a minor correction that addresses the following portion only:

"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."

Actually, in acoustics a bel (named after Alexander G.) is the log base 10 of the sound pressure level, and a decibel (dB) is one-tenth of that. Thus, one bel or 10 decibels is a factor of 10 in sound pressure level. Similarly, 3 dB is a factor of 2 change in sound pressure level, 6 dB is a factor of 4, 7 dB a factor of 5, and 9 dB is a factor of 8 (roughly). Twenty dB is a factor of 100.

All of your other comments are valid.

A measurement of more recent VaH products would be desirable because they may have made changes since your unit was fabricated. Even if they have become quieter over the years, VaH blowers have some fan curve limitations that make their flow rates more sensitive to restricted ducts or restricted MUA paths than many conventional hood blower designs. Cleaning inconvenience vs. baffles has been reported but I have no direct experience dealing with that aspect.

kas

Thanks--if you dig up the original (long) thread, you'll see that I was corrected by several folks who understand acoustic physics way better than I. Including you. So the correction in this new thread is much appreciated.

It would be fun to measure a newer VAH unit, but since one of my first priorities in redoing the kitchen will be to replace the existing VAH with a hood with external blower and silencer, I won't have one on hand to test personally. Maybe someone else can.

And yes, as they say, like pregnancy, pain fades in memory so that we can continue to do renovations (or have babies).

Better gravid than grave.