A real hood, mounted under-cabinet, will surely be better than an OTR microwave oven attempting to perform kitchen ventilation. A real hood rated at 400 CFM, and not too restricted by the house's ability to provide MUA, given short duct to outside without too many bends, might flow 250 - 300 CFM. I am confidant that any microwave oven claimed to be 400 CFM is actually just a 400 CFM in open air fan buried in the MW's tortuous duct path. I'd be surprised if it could flow even 200 CFM net. Note that the 400 CFM MUA rule is for hoods ducted outside; if a filtered (surely) recirculating hood were used, there is no MUA issue. VaH make an expensive but reportedly adequate for real cooking ARS recirculating hood. It might not fit your circumstances. ralph_zone8_ncwrote: "I agree the microvisor is just an eyebrow but wouldn't it block the air from going up to the ceiling and surrounding cabinets and if I turn the vent of the microwave to pull air, wouldnt it be able to capture some of the air?" With respect to eyebrow capture, it will (temporarily*) capture any part of the cooking plumes that strike it. However, they will reflect out again into the room if the blower flow rate is not high enough. Flow rate needed to assure successful capture and containment depends on the temperature of the grease being vaporized and the area over which the grease plume is being generated and whether combustion products are entrained. I recommend for most a value of 90 ft/min under the entire hood aperture when cooking with gas. This corresponds to 90 CFM per square foot of aperture. The value 60 may suffice if an induction cooktop is being used. But please note from the Figure 4 table on page 9 of Greenheck's guide -- your needed (or at least recommended) flow rate (CFM) may vary. http://www.greenheck.com/media/pdf/otherinfo/KVSApplDesign_catalog.pdf ----- *Because this eyebrow has minimal depth, the blower flow rate in its vicinity will be less than the average over the capture area. Reflection, at least of hot grease vapor may be insurmountable with a microwave oven fan system. Water vapor might be adequately dealt with if it makes it that high.

I'm excited by this, too! I love the placement of my microwave above the stove and was feeling sad that my eventual kitchen facelift might eliminate it. Like Sherriode I have exterior wall placement so I'll add ductwork to the project and hopefully keep steam away from my upper cabinet doors. I see lots of pasta and lobster in my future!

There is a lot of flow out of the outdoor exhaust vent. Where does the indoor air flow come from that comes out the front grill? Is it from the exhaust hood sucking from the range top, or somewhere else? I get flow out the grill whether the microwave it on or not, and at least when I tested it this airflow turned on and off with the range vent fan. The microwave was not running.

Wow, I'm very grateful to all of you who took the time to reply! Great to see your pictures, too. Some responses (if you're interested), now that I've finally been able to go through: Sammy and The Kitchen Place are correct that we could put it in the upper above the dishwasher — that's the only upper that is the right size that wouldn't block other cabinets. (Thanks for the pictures, The Kitchen Place!) I was intrigued by nidnay's idea of bumping into the bedroom closet, but that closet is filled with custom cabinetry so it would be a huge project to put the microwave there.If Icould put a Miele microwave (/speed oven) in an upper cabinet, I'd try for that, but of course our uppers are only 13" deep and the Miele opens down, so not workable. My better half is against mounting a "normal" microwave in an upper cabinet (he thinks in that case we might as well go OTR, and that it will pull away from the pretty stove/hood that's the whole reason for this conundrum). (ci_lantro questions the whole premise of opening the kitchen. Others in our building have done it and it makes a significant difference in the feeling of the whole unit—we're confident it's the right move, long term.) Helen, HU-41121833, Buehl, Interior Concept, RTHawk and others: Thanks for saying good things about the Sharp microwave drawer. nidnay, thanks for your criticisms of it, too! The slimline microwaves are attractive too! Unfortunately induction sounds great, but not in the cards for us. I do believe everybody who says we need something more powerful than a microwave fan — the Vent-A-Hood system does look quite good. kaseki, thanks for your hood comments. pittsburrito, I hear what you're saying about external ventilation. There is a small vent in the kitchen and windows in the living room, so we try to be careful. Thank you all! Still not sure what we'll do, but I'm grateful for all the advice on the Houzz forums.