Well THANK you Weissman, Breezy and Madeline for your strength on this! I'm recharged to have it done properly, according to Code. DH is on board with this too. We do not have a GC so will have to take the stand ourselves. Madeline, I was unaware of Coburn's. The closest one is in Athens TX, about 1.5 hours away, but I'm going to call them tomorrow. Thanks so much for sharing that. At least mine does not go up into the attic -- it is all self-contained in the hood itself, and goes straight out the wall behind the hood. But your point is well-taken -- one squish or kink in the flexduct and that can ruin the whole reason for having it. One more question for you: I see his problem. There is no access panel, so how is he supposed to get his hands up there to connect the unit to the rigid duct after he has pushed it up into the wood hood? Thus he's saying he needs the flexduct to dangle down... BUT, don't you think that with precise measurements and good care, he could arrange and position the rigid pipe so that it mates up perfectly with the unit when he pushes it up there?? Or should the cabinetmaker have made some kind of access panel on the front of the hood? I see a lot of pics of hoods that definitely don't look like they have access panels. I've just spoken to our plumber about this, who's coming tomorrow to hook up the sink etc., and he thinks the above is do-able (mate the two pipes as the unit is being pushed up and positioned.) What's your experience on this? Thank you again, I'm so glad I asked.

Maybe I should have opened up the email first. Check this out! My client asked me for a top designer and I told her to call Corey. I have know him for a long time and he is as anal about design as me. The big difference between us is that he is both a certified designer and NKBA design teacher/speaker - and I am not. I have opinions but am better building than designing I think - especially when it comes to Kitchens. This is going to be a Kick Ass project. Glad I have a small part in it. I love designers who can do these 3D drawings! Thanks Corey! http://www.houzz.com/pro/coreyklassen/corey-klassen-interior-design

While this question might be best aimed at Fantech, who will likely answer their 'phone, here are a few thoughts: The range hood for a 48-inch range should have at least 8 square feet of entrance aperture, with more being better, depending on the physical situation. At 8 square feet, the volumetric flow rate at full power should be 720 CFM. A blower that can yield this at the pressure losses of a proper duct with a proper make-up air (MUA) system supporting it would likely need to be rated at a bit over 1000 CFM (zero static pressure value). 720 CFM actual through an 8-inch duct yields a velocity of 2063 ft/s. This is at the high end of of the recommended duct velocity range of 1000 to 2000 ft/s. It will have a significant pressure loss if the duct length is longish, as the description implies. It seems likely, when accounting for baffle pressure loss and potential imperfect MUA, that the zero static pressure rating of the blower may need to be higher than 1000 CFM to actually achieve 720 CFM. To get to the actual question, when a blower is slightly gagged in its flow rate, it moves less air (see the Fantech fan curves -- I think they are in tabular form -- for flow vs. pressure loss). When it moves less air, it does less work, so harm is unlikely. In the limit, where the pressure loss gets to 2 inches or whatever for the particular blower, the blower moves very little air. (If there were no air movement, there would be no pressure loss.) Note that the zero flow rate pressure loss value is a tiny fraction of the actual air pressure, so blower over-speeding seems unlikely, but this is a question better asked of Fantech. tl;dr: The concept should work, probably better than an 8-inch FKD, but it will work marginally, at best, because the hood size demands a higher flow than one may get, depending on the hood. Use of a blower with a better flow rate at higher static pressures may be a better choice. Fantech may have options. Expect more noise. Use a Fantech silencer if it can be installed between hood and blower. Consider reconsidering your "not an option." Also, consider reconsidering the size of the range you want to use in an architecture that is not consistent with its needs. Last, marginal ventilation is better than no ventilation, so I don't want to discourage trying for the best that fits.

Love your cabinets! There are two types of units: recirculating (mentioned above) which runs the air through a filter. They don't work very well. All exhaust hoods are vented. They have to be. They run the air through a filter, through a duct (or directly through the wall) and outside. That is why you can smell coffee and fried chicken when you walk past a restaurant! The duct can run up through the ceiling or out the back. There are also (less efficient) downdraft models which run out through the floor or wall (down below). Some older homes vented into the attic, but that is generally no longer allowed (imagine your attic full of years of grease). The capacity of the hood is measured in CFM (cubic feet/minute). The more powerful ones also require makeup air - air coming in to replace the air being sucked out. It's not cheap because it needs to be heated/cooled. Some units can be converted from recirculating to exhaust. Where is your kitchen designer? All this should have been dealt with long ago - before the wall was closed in.