Q & A on Downdraft Ventilation

Q.
Hi Peggy,

I stumbled on your blogs this evening. Great reading!

I'm actually in the process of moving out of San Francisco next week as I'm building a house in Maui.

So, I've got a very nice large kitchen planned with a 4' by 12' island in the center that will contain a prep sink and a 36" electric induction cooktop (maybe GE, as that's a reasonably priced one). To keep the open feeling of the kitchen with the ocean views at the windows, I'd like to use a downdraft venting system, such as the Thermador one, with a remote inline blower which will go under the patio next to the kitchen.

Any thoughts about these downdraft vents? Is it worth the money for the Thermador (almost $2000) since it seems a bit more efficient with the taller riser? Is 600 CFM and a 6" duct enough? Any reason to use 7" ducting and reduce down to 6" at the inline fan? My total vent run is about 35', and there will be 2 elbows. Any objections to an inline fan for a downdraft vent? (I saw your reasoning against these being fires for regular vents).

Yes, I know downdrafts don't work nearly as well, but my reasons are:
1. I really don't want to use an island hood
2. Seems fun to be able to cook facing your guests
3. With the big windows, not a ton of wall space, unless I got rid of the desk at the end.
4. I get a nice work triangle of the prep sink, refrigerator, and cooktop.
5. For grilling meat or anything that would be really stinky or smoky, I could use the patio BBQ which vents to the sky

Also, I found your advice for avoiding microwave fans interesting. My builder thinks they are great and that most places he's fixed up in San Francisco use the recirculation option.

Thanks in advance for any advice.

Aloha,

Justin

A.
A fellow blogger recently posted on this issue.

You should read Susan Serra's post before you decide.

I agree.
Downdrafts just don't work.

In fact, if I were you and there weren't any local codes to prevent it, I would just forget ventilation entirely rather than spend $2000 on a system that won't work.

Do you have attic space above the kitchen?
If so a ceiling hood might be a better approach.

Otherwise go for a polished metal hood like the Abbaka.



























They are pricey but they practically disappear in a room.

I also agree that an island is often the best place to put a cooktop to create a functional work triangle.

You could consider putting your sink and dishwasher on the island and the cooktop/hood and prep sink in front of non-operable windows.
Such a look can be quite smashing.

Without more information I am at a loss to go further.
You need a designer to help you work these issues out.

Peggy