Since your hood will be an island hood, and so there won't be surrounding cabinets to contain the smoke/grease from cooking, you need to have the hood be 6" wider than your cooktop (i.e. 3" wider on each side). Furthermore, the rule of thumb is 10CFM per 1000BTU of burner capacity. So, add up the btu's of all the burners on your cooktop. If e.g. the btu's add up to 90K, you should have a 900cfm hood. While you won't always be using all your burners, it's good to have the cfm's when you need them. Furthermore, it will be quieter to run a higher-cfm hood on its lower setting, than to have to run a lower-cfm hood on its highest setting all the time.

A lot of people opt for a glass canopy for an island hood so as not to block sightlines. The downside of a glass canopy is that it will show spots and splatter, and need frequent cleaning, so that is a personal decision whether that would bother you or not. I also prefer baffle filters over mesh, cause mesh filters get clogged quickly with grease and need to be cleaned more often or they won't work. Glass canopies though typically come with mesh filters not baffle filters. If you opt for stainless steel instead, a stainless steel hood can be dramatic and add "wow factor" in your kitchen.

Since you are installing ductwork, make sure the duct diameter is 8" or 10", not smaller. Most hoods require an 8" diameter duct or larger. If you go smaller than that, you will have increased noise and decreased efficiency of your hood.

The Make-up Air issue depends on how many cfms your hood has, how tight or drafty your house is, your climate, and local Building Codes. There are several threads on this forum about Makeup Air, so you can do a search in the search box to pull up threads about it.

As to brands, there are so many, and at many different price points. You should try to establish a budget for your hood which will help narrow down the choices. Read threads on this forum about the various brands to help you decide.

In my opinion, a kitchen renovation, whether modest or extravagant, is a big deal -- a bigger deal for large scope projects, and a lesser big deal for facelifts. Big deals require big planning, planning requires research, and research requires commitment of time. Either you have to perform the research, or you have to pay someone else to do it, and accept the result as perhaps not optimal.

So, I suggest spending a few months snacking on the posts in this and the kitchen forum, following up leads at manufacturer's web sites, and asking questions here that you don't find answered. These may be questions that you wouldn't have thought of without the research. We have here a vast cornucopia of information in the current posts and in the searchable past posts. (Searching is easier using Google than this site's search engine; just plug in the web address on the advanced page to tailor the search to here.) For example, searching on hood, vent, blower, duct, etc. will bring up many ventilation posts.

Once the pieces are sufficiently defined, the whole can be evaluated and tweaked to make everything fit, achieve one's aesthetic ends, and promote efficient operation in the kitchen.

I started my research here in August 2007, and now I'm about 95% done (maybe 99% excluding the make-up air system). In my case, the project extended to basement, attic, LR, and hall, so it was a bigger big deal for me. I believe my result would be significantly inferior if I hadn't used this site as a place from which to begin and continue research. (Formal thank yous will be provided with photos in the fullness of time.)

kas

Thank you so much to both of you. akchicago-That was EXACTLY what I needed...now I feel like I have the basics so I can really research this!

akchicago - one question about the width of the hood being an additional 6" more than the width of the range. You mentioned that because this was an island hood it should be wider but what about if the range was located along a wall. Should you still be getting something 6" wider?

Some people recommend 3" extra on both sides of a hood even with a wall hood. However, many people have the hood the same size as the range particularly if you have cabinets on both sides.

Kmg67 - For an island hood, with no cabinets to contain the smoke/grease, the 6" extra width is a must. For a wall hood, it's not a must, but if you want the ideal set-up, then a wall hood would also be 6" wider than the cooktop. However, we all make compromises in our kitchens--who can achieve the ideal, right? If you don't have the space on your wall, then a wall hood the same size as your cooktop against the wall is absolutely fine. In that case, it is important that your hood have enough depth to capture the smoke/grease; you should look for a wall hood with 24" depth (many are 22" deep which is not enough).

Another thing to avoid is a flat hood. While many love the design aesthetic of a flat hood, it is not good for capturing smoke/grease. You want a hood that is curved/umbrella-like for good capture. I mentioned glass island hoods in my post above; typically they are flat, or with a very slight curvature, which is another reason why I don't like glass hoods, though understandably people want glass hoods for the sightline issue I mentioned above.

How do you calculate the CFMs for an induction cooktop, which isn't measured in BTUs?

Enmnm - I don't know how you'd calculate specifically for induction like you can for gas btu's. I would ballpark it according to how wide your induction cooktop is, and what you like to cook. On one end of the scale would be a vegetarian family with little grease or smoke from cooking; on the other end would be a cook who likes to stir fry/wok meats, fry hamburgers, fish, and the like. I think 600 cfm's is a good bet for the average kitchen, but if you are doing a lot of frying, and/or high-heat cooking, then 900cfms or more. Keeping in mind the makeup air issue too.

Maybe I need to rethink this a bit. I was leaning towards something like the 30" Broan - http://www.broan.com/display/router.asp?ProductID=100619. It is only 22" deep though. I'm not sure I know what you mean by umbrella shape. Can you send me a link as an example of what you are talking about?

Sorry, I think my use of "umbrella" was poorly worded. What I meant was just to contrast flat hoods, i.e., when you look up into the hood, there are sides to it, a curvature that will capture smoke/grease. You can see this at any appliance store selling hoods. Conversely, a flat hood will not enable that capture, as there are no curved sides to contain the smoke/grease.

Regarding the Broan hood you linked, it is not the flat style I was counseling against. However, the 22" depth means it will not capture very well the smoke/grease from the front burners. Also, that Broan hood is 10" tall. If you must have that 10" height to fit your kitchen cabinetry, then it will be hard to find a 24" depth. Usually the 24" depth undercabinet wall hoods are also 18" tall. Furthermore, an 18" tall, 24" deep hood will be at a higher price point, which you may not want to spend. If the Broan hood fits your budget, then go for it. As I said above, you can't always have the ideal set-up, and only you can decide where you want to compromise.

I have also been window shopping for range hoods and have a question. I have been looking at under cabinet Kobe models, and prefer one that is only 22" deep. Is it possible to gain depth by bumping out the hood two or three inches from the wall, putting a filler strip in the back? The top of the hood wouldn't sit flush with the cabinet, but that doesn't bother me.
--AlienAcres