there are some real experts out here on this topic that I hope weigh in for you (and me since I am looking at the exact range top :-) )

I think that range top has 5 15K btu burners and a 9.2K btu - for a total output of just over 84,000 btu - a think the rule of thumb I have heard is divide that by 100 to get to hood cfm - or in this case 900 cfm - and taking into account what type of cooking you do - lots of high heat wok cooking for instance may justify going up a bit - and if you have a range top with a grill certainly step up some - but in this case without the infrared grill I am thinking something between 900 - 1200 would suffice.

I have also heard some thoughts about going bigger and then not having to run the hood full blast to meet your needs and maybe that helps keep the noise level down a bit.

Hoping some with much more insights than I have weigh in

If you can swing it 42" wide. Will you need a MAU, or make up air unit? It depends on where you live. You need 900 cfm if you use a system with baffles or screens. 600 cfm if you use Vent-A-Hood. You also need to decide if you want an internal or external blower. Last, how will it vent and how many bends in the vent. Lot's of good brands out there.

kaseki always provides good information. I suspect in his other life he may be an engineer.

You can make this process as complicated as you want. From a practical standpoint, very few of us will work our range tops at the maximum amount of capability. We just don't run all of the burners simultaneously at full flame. Even in a restaurant setting, each burner is at a different level and some are cycling on and off during periods of peak demand. To buy the maximum amount of capability may prove to be an unnecessary luxury.

Try to get as big an capture area as is practical in your application. In my case, I have two cooks in the kitchen, one short, one tall. We have to compromise to make it work. I use a 24" deep hood, not 27". It works for us.

I have personal experience with Best by Broan, Zephyr and Vent-A-Hood. They are all good units from reputable companies. I have had both internal and external blowers. They all make noise.

If one of the options you consider is a little less than the maximum necessary and you really like it, don't stress over it. I'm not being cheap, just interjecting a little bit of compromise. Read the threads on ventilation prior to going to the appliance store. You will be better educated and prepared to make a smart purchase.

I see a lot of suggestions to look into 27" deep hoods, but not sure who makes them at that dimension - would be looking at either a 36 or 42 wide - when I search (and maybe it is user error) on sites like AJMadison it seems like just about everything is listed as 24" deep. Who makes a broad line of 27" deep units to research?

Thanks for the insights -

Ventahood is your best option. They do offer pretty much all of their pro style hoods in a 27" deep configuration (NPH becomes NPXH if my memory is any good). You can use their 600CFM because its filterless and more efficient than most. If you have to in the 42" you can upgrade to their 900CFM for a little extra pull.

The important part of this is how you use the range. If you plan on using 5-6 burners, searing multiple items or making any high heat, high grease items (Wok cooking) then go with as much as you can manage. If you are like the other 95% of us and will be using 1-2 burners daily and on holidays MIGHT get to 3 or 4...600 CFM will do fine.

thank you everyone. Before I made this post, appliance salesman recommended this hood to go along with the 36" 6-Burner Wolf rangetop (I'm doing a custom cabinet).

http://www.ajmadison.com/cgi-bin/ajmadison/PK2239.html

Now that I look at its specs, it's 36.5" wide and only 15.5" deep. Does this mean that I was recommended an insufficient one though it is 1100CFM? Should I try to find something that is more deep since most of you said I need 24 or 27" deep? Thanks so much!!!

Chances are you were recommended the one that generated the best commission. 24" deep is counter top deep. Everyone needs either 24" or 27". I have a Vent-A-Hood. I like it and can recommend it.

I have a 36" BS with a 36" x 24" 600 cfm Vent-A-Hood. It's fine. I didn't buy it, it came with the house.

There may be law and regulation, perhaps in your local gas code. Follow it as it is there for a reason. Your installer may be liable if the installer knowingly installs the wrong sized extractor fan. In Toronto, Ontario - and it may be Canadian gas code, you need a minimum of 550 CFM for a gas cooktop, and then, as stated before, "a think the rule of thumb I have heard is divide that by 100 to get to hood cfm" dfb_jlw - So, total up your total full-on BTUs, then 100 CFM per 10,000 BTU but never less than 550 CFM and you will be fine (Subject to your own local gas code- your appliance retailer is happy to talk about this and to convince you of the need for more CFM's!) . Obviously you need at least a 36" hood . Tons of options for you at all segments of the market.

Are you doing an insert? The PK2239 isn't a bad hood. but its relatively shallow. If you are doing a liner, do a fitted unit. Something like a INPL3622SS from Faber or a BH234PSLDSS. Those are 22 1/2" deep and will offer very good performance.