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Need Hood Advice for Range With Grill

Posted by madmadscientist (My Page) on
Sun, Apr 15, 12 at 17:22

Hello All,
New member here coming over from a couple of tradesmen message boards where they said that this was THE place to get this kind of info.

I have a Wolf R364C Range. Thats the 4 burners with the grill in the middle 36" wide.

At a previous house we had this stove with a 24" deep VAH and it could not keep up when we grilled marinated veggies, which we do often in the winter. It also was REALLY loud I thought, motor + air noise.

I've done some research and here is what I think would be the best setup for our situation.

36" wide by 27" deep hood with a 900cfm max airflow placed at no more than the max 36" above the stove. I know it would be better to go wider on the hood but we just can't because of space limitations.
With a remote mounted fan unit mounted to an exterior wall and an infinetely adjustable fan speed. I will use 10" venting that will go up from the hood approx 6' have one elbow then shoot over 20' to the exterior wall.

My research has led me to believe that this is the most quietest with the required cfm answer? How does that strike everyone?

I know that this is not going to be a cheap thing to do and I am fine with that reality....mostly.
Right now I have one quote for a Wolf setup.
Hood PW362718 $2039
Motor (1200CFM) 801642 $789

What other manf should I be looking at?

I don't know who makes quality stuff and who makes junk....I've looked online a bit but I'm just overwhelmed at the choices.

With the required spec's above can anyone offer other alternatives?

I'd especially like to know where I can find the sone ratings for these hoods? I spoke with Wolf's 'ventilation tech expert' who claimed that they didn't know what the sone readings where for their hoods??? That just blew me away.....$3k for a vent setup and they can't tell you how loud its going to be....

Any help would be greatly appreciated.
thanks,
Mads


Follow-Up Postings:

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RE: Need Hood Advice for Range With Grill

With 26' of duct run its going to be really quite as in ....REALLY QUITE.... so no need to know of worry about the sones. Sones are only of any interest when you are dealing with internal blowers, even then a lot of the noise can come from the install.

I would suggest keeping the hood lower than 36" maybe between 32" - 34"


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RE: Need Hood Advice for Range With Grill

Well geez, what I've been told up to now is that even with the motor that far away the sound of the air rushing through the hood would still be really, really loud?
Arrrgh....

Do you have any suggestions as to make/models I should be looking at other than the Wolf?
Thanks for the reply,
Mads


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RE: Need Hood Advicy for Range With Grill

When i say really quite what i mean by that is really quite compared to having an internal blower, i have yet to ever here of anyone who felt a remote blower over 15' was even close to noisy.

The fast majority of noise comes from 3 areas

1) The fan itself
2) Disturb area around the fan
3) Air moving through the baffles

Air moving though the baffles makes dramatically less noise than the first two.


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RE: Need Hood Advice for Range With Grill

Okay great so my research didn't lead me astray.
I believe that with the setup I'm looking at your 1&2 will be as minimized as possible.

So onto 3...
What I'm hoping to learn from the collected knowledge here is which hoods are better or worse for this setup.

Are there hoods that look good but perform horribly?
Is there a brand that I should be looking at over the Wolf?

Thanks,
Mads


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RE: Need Hood Advice for Range With Grill

OK, I"ll ramble on a bit on these topics.

I have a Wolf Pro Island hood (60-some inches wide, made by Independent) and a Wolf 1500 cfm nominal roof fan (actually made by Broan), with a Fantech silencer in between. The hiss through the baffles at maximum speed is modest, and certainly not inhibiting to conversation (unless one is whispering sweet nothings across the cooktop). The crackle and hiss of Wok cooking is louder.

The silencer (really a muffler) is the only addition you could make to reduce fan noise further.

To extend Trevor's remarks, the fan blades are not perfectly aerodynamic, and shed turbulence that causes noise. Also, there will be turbulence in the ducts that produces noise. There could also be motor rumble.

Few manufacturers provide the essential facts about their hoods, viz., noise versus flow rate, and pressure drop versus flow rate. Occasionally, one may run across a commercial hood with a pressure drop spec., but commercial kitchens are so noisy that baffle noise is the least of anyone's problems.

I'm not sure of Independent's status at present, but ModernAire is a potential hood source, as well as Abbaka and even local sheet metal fabricators providing hoods for commercial application. (You probably won't want one that meets the commercial requirements, but derivative designs might be suitable.) Broan is another candidate source.

The main goal is capture and containment, and this requires a cavity for collection and a flow rate sufficient to remove the effluent before it "reflects" back out of the hood. There are other sources of hoods, but some tend to emphasize aesthetics over function, so if function is more important, evaluate them from the point of view of capture and containment.

Unfortunately, the best we can do usually is guess at the fluid dynamics taking place in a candidate hood; the truth requires careful measurement, usually with Schlieren photography to see what is happening to the effluent as a function of cfm.

kas


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RE: Need Hood Advice for Range With Grill

Hi Kas,
Your 60" hood will be significantly quieter than my 36" at the same CFM sooo...

I looked into the custom hood option a bit and it looked significantly more expensive.

Another issue seems to be the required 27" depth...not every manufacturer makes one. I looked and I don't think Broan does? VAH doesn't......

Guess I'm beating a dead horse now.....
1. I think its almost criminal that high end hoods that can cost as much as a good used car don't have sone readings...
2. I'm still hoping that the collective wisdom here can at least point to which manf hoods are higher quality and which to avoid.


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RE: Need Hood Advice for Range With Grill

Will you have cabinets flanking both sides of the hood? If not, then I would upsize to 42" in order to have some overlap at the sides.


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RE: Need Hood Advice for Range With Grill

Yes I will have cabinets flanking both sides of the hood.


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RE: Need Hood Advice for Range With Grill

The hood size requirements result from the fact that the rising effluent expands as it rises. (Think 45-degree cone as an approximation.) So if you put your pans on the stove (in your minds eye) and grow cones from them upwards. The tip of the cone is below the cooking surface. The hood needs to overlap those cones.

The airflow, though, has to be enough to keep the air velocity high enough at the baffles to pull in the effluent and not let it reflect back downward (fluid dynamics wise, it will appear to curl downward). This flow is determined by the hood aperture, the effluent velocity (about 3 ft/s), and some fractional factor that accounts for how the hood is internally configured. (I would guess that for trapezoidal shaped hoods with sloped baffles, the factor might be around a half.)

Cabinets and back wall keep the cones on those sides constrained to stay under the hood, so the front to back depth is mainly set by where the pans are, how big they can be, and how high the hood is from the cooktop.

kas


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RE: Need Hood Advice for Range With Grill

Trevor @ Eurostoves has a video of a smoke-bomb placed in a WOK to demonstrate the capture of effluent into a Modern-Air hood ... impressive!!
Am instrested myself, don't know price yet.


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RE: Need Hood Advice for Range With Grill

Independent went out of business but was acquired. Call modernaire and get them to work out a quote. The powdered metal finishes are much cheaper than fancy copper, bronze etc.. I paired it with an external Abbaka blower and silencer. Making the hood bigger than the cooktop was the best GW advice ever.


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RE: Need Hood Advice for Range With Grill

BTW: two 45* turns is better than one 90* elbow.


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