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Ductwork for Bosch downdraft - island ventilation

7 years ago
last modified: 7 years ago

We'll be installing a 30" Bosch induction cooktop along with 30" DD vent (internal blower) in our island. Our current island (24" - pictured) isn't deep/wide enough to accommodate the DD, so we'll be expanding ~ 10-12" to the right (plenty of room on that side). To the left is the kitchen sink and DW. We currently have a fixed 6" duct venting to the outside (under foundation), so that can't be moved. However, it does rise 4" above the interior cabinet base, so it can be shaved to decrease its height.

I've mocked up the DD and blower unit (green - sorry for lo res). If I don't alter the relative location of cooktop+DD unit setup, the bottom of the blower vent opening would be 1" to the right of and 8" above the existing exit duct opening. What 6" flexible metal duct I've seen may not (?) be flexible enough to make that turn (from opening to opening)...or is it?


1. Scoot the cooktop/DD left (~ 7") in order to center vent openings atop each other: I can't enlarge the island to the left, thereby drastically reducing my work/prep zone aisle.

2. Scoot the cooktop/DD to the right slightly if that greater distance allows the flex duct to make the S turn. I know sometimes even an inch (or less) can make the difference. However, this would mean shifting the front edge of the cooktop further back, which isn't ergonomically the best for cooking. As you can see, the current cooktop is already set back 3-1/2" from the front counter edge. I found this pic on the internet -- does a space this wide (from cooktop to front edge) really work?!:

...but I digress.

To continue with #2 above: one thought is to shift the entire footprint of the island to the right a few inches (so I can maintain -- or decrease -- the current 3-1/2 edge), but the tile beneath is cut right up to the island's edge. I'd rather not contemplate busting up 20" (new) porcelain tile to make this work.

I guess the bottom line question is, given my pic above: what are the minimum distances (height and width) I'd need between the two vent openings to make this work? My appliance installer informed he's laid up for a couple of weeks, and I'm meeting w/ my KD tomorrow to go over specs. I really need to know where I'm going with the island.

Top view of my kitchen (I forgot to incorporate the counter overhang):

Thanks to the abundantly generous GWers for any advice!

Edited to add: moving the cooktop off the island is not an option for us.

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