I just bought an outside vent microwave about 6 months ago and no sales person ever asked about vent location so either I was really lucky they matched exactly or the location is standard. you could look at the online manuals for several models and compare the specs also or go to an appliance storemand inquire

They're installing a 22" OTR micro under the 24" wall cabinet, which presumably sits over their smaller 24" range. Personally I can't imagine an issue with using wood fillers. They'll be up at the level of the microwave, and I presume you have wood cabinets on either side of your 24" range dropping to 18-19" off the counter surface. What kind of range is it? There should be specs detailing the required space above the range before any combustible materials are allowed. Given these trim pieces would only encroach over the range area by 1" on either side, I wouldn't worry about it - unless you go crazy with greasy flambe cooking on your 24" cooker ;) Otherwise some simple metal trim painted white to match the micro would be relatively easy to make up using aluminum readily available at Home Depot or something - they should sell 1" x 1" aluminum stock (L shaped or full box) that you can cut easily with a hacksaw, sand the edges smooth and hit with some white Tremclad. Would cost you $10-$20 all in.

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.

That’s not venting. That’s placing the yuck somewhere else in inside the envelope. And it’s not allowed. If you’re going to vent, it must exit the building. Straight up, through the roof, is always choice #1. If not actually venting, no need for ductwork.