Ours is 600CFM, and seems adequate. I personally don't think the published CFM's are all that accurate, or directly comparable, but it's just a hunch.

You don't have to get a 42" hood, but it will work much better than a smaller one. I wouldn't go smaller.

The hoods I looked at all seemed to recommend 26-32" inch height above cooktop. Ours is at 32", and I don't think it would be very effect if it were higher. At that height it doesn't block sight lines very much, especially for my 5' 6" wife.

I took a look at the Spagna Vetro for reasonable price, but we went with a Monogram to qualify for a package discount. I've read some people say they're happy with the Spagna.

BTW- Ours is 36" hood on 30" cooktop.

Here is a link that might be useful: Spagna Vetro

As height above the surface increases, a hood's aperture needs to get larger so it can capture all of the expanding rising effluent. And as the hood aperture area increases, so should the flow rate (cfm) for most designs to ensure successful containment.

Use of islands and peninsulas for cooking imposes greater visual and performance costs than wall cooking.

kas

thanks to both of you. kas-I know it's a terrible place to have it, but I'm stuck with it b/c we're only doing a cosmetic update of our kitchen, no new cabinets, no layout change, etc. I really don't want a hood hanging down in the middle of my kitchen and I've never had one so I'm used to it, but everyone here has convinced me how important ventilation is. I'm so tempted to not do it b/c of looks, but I know that's just dumb.

Get the hood. We have (I think) a 42" above our 36" gas range and it is truly wonderful. I also use heat-generating appliances on the countertop next to the range so that the hood will suck up some of the heat - pannini press, rice cooker, slow cooker, toaster, etc. If we've been using the pizza oven (double convection oven opposite range), the hood still helps the heat circulate out of the kitchen.

When you walk into the house, you can't really smell what's cooking for dinner until you walk right into the kitchen close to the range. It's when you're coming up the driveway that our house smells really good. (The outside vent is on the front side of the roof and the prevailing sea breeze helps)

We set ours at the height for my husband, so he can see under it into the lanai and backyard - 33" above the top of the range. I'm shorter, so no problem. I think it was in a Broan catalog that showed the height/size/cfm relationship. Higher means bigger, of course, but it's worth it if you are tall.

It's a solid Wolf hood, so it's a heavy presence in the kitchen, but since we cook, it's welcome.