Realistically speaking...IMHO, I think the answer depends on what type of cooking you do, as well as, aesthetically, what look do you like?

In my former home, I had a Thermador cooktop and downdraft in an island. I don't think I ran the downdraft more than a few times. I didn't do a lot of frying, greasy, or smokey cooking then. I had a very open floor plan and lots of windows. It just didn't seem to be a problem not running it.

In this house, I have a range and hood on a wall. I didn't care for the look of a hood over an island, so I went with a wall placement. Plus, my cooking style has changed as my children have gotten older and I do a lot more high heat, greasy, smokey, etc, type cooking...so I have my blower on all the time. Being a hood, being on a wall, turning it on before I cook, I think it's pretty doggone effective.

I think my current cooking habits might not be well-served with a downdraft. I don't know...maybe a good 14" one would really perform good enough. I just don't know from experience.

If I knew my cooking habits didn't involve greasy, high heat (like a wok), smokey events...I wouldn't hesitate, in an island situation, to get a downdraft only because that's my personal preference as far as looks are concerned! Oh, and get a remote blower!!

I didn't directly answer your question, but I hope I gave you some things to think about! :)

I also don't really have an answer to your question. But I did have a downdraft and like you found that it was basically useless. When I redid my kitchen, downdraft was not an option. In my case I reconfigured my kitchen. But if I had to keep the same location, I no doubt would have gone with a hood. I highly doubt that the hood configuration you described would perform the same as a downdraft. I think that even at 42" above the range, the hood would perform much better than the downdraft. Can you go to 1200 CFM or even 900 CFM?

We are planning on a 36" cooktop with a Dacor Renaissance Epicure ERV3615 downdraft that is 15" tall, with an external blower having 1000 CFM. Cost is $ 2348.00.

What size is your existing ductwork? That will determine how many cfm you can force through it. It should have been designed for your existing ventilation which would make it inadequate for the much larger airflow of a newer/better downdraft.

Potential lost capture from putting a hood higher than the usual recommendation of 30 inches so one can work under it can be compensated by using a large enough hood. Imagine expanding cones of effluent rising upward. Assume a total cone angle of 45 degrees and the tip of the cone somewhere in the base cabinet such that the cone diameter equals the pan diameter at each pan location. Then the preferred hood size is that which overlaps these cones at the intended height of the hood.

Keep in mind that bending over to look into pots will tend to reduce one's height under the hood.

I doubt that any adequately-powered, reasonably-sized overhead hood will have the capture and containment limitations of typical downdraft hoods, even in conditions of cross drafts.

kas

Thaks All for the feedback.

Still my preferance would be to have a hood but I am leaning towards the Thermador downdraft with 600cfm blower. The kitchen is a decent size and in the past we have cooked some pretty gnalry meals and really have not any big of problems, the house is 20 years old and no yellow stains on the ceiling. Most of my cooking is pretty standard and i will sear a steak from time to time and cook with a wok a couple times a month and when im frying something its probably on one burner so i am not prodcing a bunch of smoke, steam, etc and in the summer we love to BBQ outside. So when I factor in the cost and more imporatntly the aestetics of looking the hood (which I personally dont really mind) in a kitchen that is more transitional/contemporay. If we were to do a total remodal I would for sure relocate the cooking surface to a wall.

@aliceinwonderland, I think the existing ductowrk is 6 inch flex tubing......I hope it goes to regular square ductwork. What is the minimum requirements for 600 cfm?

Lastly I am thinking of going to the Bluestar cooktop vs the Wolf. I really like the open burner look and the additional power. Would this be a bad decision on my part when used with the Thermador downdraft?

Thanks again!

Minimum requirements are dependent upon the length of your duct, number of elbows and type of ducting, and the amount of noise you can live with. Flex tube is evil - you have to use a larger size to run the same airflow, and it is noisy.

6" duct is the absolute minimum for a 600 cfm vent. However, if you have more than one elbow or your duct is over 25' long, 6" will be excessively noisy and/or you won't actually get 600 cfm. The flex duct is also a problem - I would replace that portion of the duct.

If those 20 year old appliances are in 20 year old cabinets, it's a false economy to simply try to replace your appliances for a kitchen redo. You should bite the bullet and reconfigure the space so that it functions better before dropping that much money into bad technology. You can spend less on appliances if you get that cooktop off of it's island. Put the money you save into a better layout and cabinets to last you the next 20 years.