If you like reading, you have come to the right place, because we have a large number of hood related threads that can be read for as much theory and practice as you can stand.

There are at least two suppliers of recirculating hoods with sufficient filtering that they might quality as at least marginally effective (from my purist point of view). One is Vent-a-Hood and the other is (as I recall) Best by Broan. There may be others and I hope those here who have or know of them will pipe up. Searching the manufacturers' web sites should provide specific information. Good quality recirculating hoods will have a succession of filters to remove grease and odor.

CFM can be determined from the hood aperture area, and we don't yet know what size hood you may choose from among the limited number of recirculating hoods. For example, for a 2-ft front-to-back by 3-ft side-to-side aperture (6 sq. ft.) to achieve a goal of 90 ft/min across the hood aperture would require 540 CFM. Actual blower rating has to be higher due to pressure drops, but these may be accounted for in how a given recirculating hood is specified, so the usual factor of 1.5X that I suggest to make up for this may not be needed. Also, recirculating provides its own make-up air, so that factor is not applicable.

I'm assuming that there is a good reason for not attempting to duct the cooking effluent outside. Duct installation may range from easy to extremely difficult, and without knowing more I won't attempt to provide encouragement for adopting the superior approach of external exhaust.

kas

Thanks! The reason for not doing outside ducting at this time is I'm in a townhouse, the range is on a shared wall, and the outside is brick (and governed by an HOA). Which I think means any new ducting is going to be pretty extensive. I expect to redo the entire kitchen in 10 years or so and will probably pursue it then.

For now, I'm OK with the drawbacks involved with a recirculating hood.

Also, for all I know there may be a vent behind the microwave. The previous owners have proven to not be very proficient at any kind of home repair/maintenance/upgrades. I'm currently assuming there isn't because the microwave isn't hooked up to it. (I will check before buying a hood though).

Also, for all I know there may be a vent behind the microwave.

Yes, check this. I was looking townhouses in a particular community for a long time. Although they had been built with external venting (very unusual around here for condos/townhouses), most redos had opted to move the range from its original position and about 80% of those folks just did a recirc microhood rather than bother to do what was necessary to hook up to the existing duct.