600cfm or more. Not less.

Before you decide on your max CFMs, consult your local building codes regarding make up air (MUA) requirements. Folks here on GW thought I was crazy for bringing up this subject when I renovated 4+ years ago and discovered that the heated MUA I needed to feed a 600 CFM vent cost more than my range and fridge combined!!! Since then more and more jurisdictions are insisting on providing idiot-proof (opening a window doesn't cut it) MUA systems to ensure that oversized vents don't cause other combustion appliances/fireplaces to backdraft, possibly filling your home with toxic gases.

I echo cooknsews. The Berta 30" only puts out 36,000 BTUs, so if you are in a strict locality you may get by with less (say 350 to 400 cfms) as long as your duct run is short, the duct large, and the capture area at 24".

Did you have a budget in mind? Is it wall mount or island mount? Is there cabinetry nearby? Did you get the all-stainless or a color?

The air flow rate (cfm) required is not a function of the BTU rating (unless it is too low to cook anything). It is a function of the need to contain the uprising effluent. The rough requirement for CFM is 60 s/min times the product of the effluent velocity (~ 3 ft/s), the aperture area collecting the effluent (sq. ft), and some efficiency factor accounting for aerodynamic effects at the baffles (maybe 0.5). (Note that for flush mesh filters the area is the size of the mesh times the effective clear area ratio, something not so easy to account for, particularly for complex mesh structures.)

Further, the CFM calculated above should be the actual CFM achieved. Hood and duct transitions, baffle friction, duct friction, house negative pressure due to imperfect MUA will cause the hood blower to move less air than it is rated for. People who have lived with recirculating hoods, or OTR microwave oven ventilation, or the poser kitchens widely published in the media that have no ventilation, will be able to get away with less flow and still be ahead of where they were.

The aperture has to be large enough to capture the expanding uprising effluent. Expansion half angle varies around 22.5 degrees from every point on the pan surface hot enough to cook and generate water and grease vapor. The hood aperture should overhang the locus of these projected points at the planned height of the hood.

kas

This is not my engineering field, but effluent velocity itself has to be a function of the energy output of the source (along with other factors).

But really, the OP asked a question about recommended products in a certain style.

For more on the variations of effluent characteristics such as velocity as a function of cooking type, see the thermal plume references at "my clippings," second listed post.

In my view, this subject is already complicated enough without me caveating each approximation with its scope of validity.

You are correct, gooster, my comment doesn't answer the style question; I leave style to others, and don't recommend hoods that I haven't used.

My comment was directed at your comment on stove BTUs lest someone mis-associate hood requirements with BTUs. There are rules of thumb that are BTU-based, but these are in my view not very relevant. They derive from commercial cooking surfaces that are fully utilized.

It is true that higher BTUs are correlated with more combustion effluent, but it is the grease and steam effluent capture and containment that is of greater concern to most. A properly tuned gas cooktop will not need much air removal to meet respiration safely requirements for combustion products, but pour those BTUs into searing steaks and you will find that a lot more air flow is required to keep the grease off of the walls.

kas

I like my Kobe hood. It's quiet, has baffles, easy to clean, can accommodate various sizes of ductwork. I got it from Ventingdirect.com because there are no Kobe dealers anywhere near here. Mine is 720 CFM, but I have to believe they make lower CFM models. I just looked at pictures online until I found one I liked. Mine has curved corners so no one will gouge his forehead.

Bertazzoni makes hoods, too, don't they?

Thank you for all the great info!

Well, I wanted something that is deep at least 24'' so it covers the range. I will have cabinets from both sides of the hood and I need a stainless one.

Bertazzoni has hoods but I am a little skeptical as far as quality and they are not very cheap.

My budget is $600-1000.

I am looking at Vent-a-hood and maybe Zephyr and Kobe.

Ginny20: which model is your Kobe? My friend was telling me that they are pretty good. Thank you!

Mine is CH9136SQB. The 36 is the size, so CH91 is the model group. It was a little over $900 in 2011 from ventingdirect.com. Although it's rated at 720, I have a lot of ducting with a few turns, so the effective maximum CFM is definitely lower, and I rarely run it on high anyway. The link below is what it looks like. It can be under a cab or wall mounted with a cover over the duct like a chimney.

Kobe customer service was great when I took it apart too far to clean it and couldn't figure out how to reassemble it. Very responsive and helpful. I bought Kobe sight unseen because of recommendations on GW, and I've been very happy with it.

Here is a link that might be useful: Kobe CH91 series

I have the same one as ginny20 but in 30 inch wide sitting in my living room waiting for install next month. Quiet for the CFM it has, baffles, LED lights, round corners, relatively small profile, and 22 inches deep. Everything I was hoping for! (Ok, i did want back venting instead of up, but guess you cant have everything) Looking forward to having a real vent hood!

Got it with a 10% off coupon at Christmas :-)

Thank you both! I would need it to be wall mounted as a chimney ( no top cabinets for me ) - I hope I can find a pic on the web with the duct cover look as a chimney style. Just cannot picture it yet.

I found it

http://www.koberangehoods.com/product/CH-191.html