Thanks, gigelus. That was my biggest concern (the OTR MW not covering the front burners). We usually leave the kitchen window open which is less than 6 feet from the stove. I don't know what a MUA system is, but would this serve as a quasi-MUA?

There is always make-up air (MUA), else the house would implode. However, the MUA from house leakage is modest, and as a result the hood blower sees a pressure drop across itself, which causes less air to be moved. In the end, there is a balance between the leakage at a given differential pressure and the air moved by the blower up the ducting at that differential pressure. This is why once an actual flow rate is determined to be desirable/necessary (depending on one's view of odor and grease), the blower has to be sized for the pressure losses in the loop from cooking zone to outside, back to inside.

MUA systems operate to provide an air replacement path that doesn't require open windows. They can be passive and simple, or active and complex, depending on need.

kas

... but, if you open the kitchen window *every* time you turn on the hood, you'll be fine (and maybe annoyed after a while).

Yes, the kitchen window open can also amuse the neighbors... I understand the need for MUA, but I am not sure where to buy a MUA system. Any recommended ones? Thanks!

I looked up the specs on the microhood I linked before and it is 18.5" deep. Measuring from the back of my slide-in range installed flush with the exterior wall, 18.5" covers 3/4ths of the front burner. The whole cooking surface from the back wall to the front of the surface grates is 23". What is the correct depth of a vent hood for this?

For MUA, I recommend you start with reviewing all the threads on this forum that have "MUA" somewhere in their content. This effort will gradually clarify the issues and complexities of make-up air delivery. Unfortunately, this review requires significant time.

Also, solve the hood problem (select hood and blower), let us know what the flow rate is supposed to be, what other exhaust fans may be operating in the house, whether there are any combustion appliances in use not isolated from the kitchen (air wise), and any intention to use a fireplace while running the hood. From this base we can potentially advise on the sort of MUA system that is appropriate.

kas

While the expansion angle of rising cooking plumes varies somewhat with type and temperature of the cooking surface, it may be sufficient to assume a ten-degree expansion half angle originating at every point that is hot. The areas of hot points are usually the surfaces of whatever pans might be used on the burners, except that a grill will be the entire surface. The boundary of these conical plumes -- taken together at the height of the hood -- should be overlapped by the hood aperture (the opening where air can be captured).

kas