Product review (3 stars): Do NOT use Allure hoods ductless
I bought this model because of its reputed quality; it's supposed to be quieter than most, with a powerful blower...  It costs enough!  I can't vent it to the outside of the house.  It comes configured to return the filtered air back into the room through TINY holes on the top.  Why so tiny???  Beats me, but the result is that even with the "performance ring" which must be installed on the squirrel cage which halves its performance, it sucks more air into the box than it can exhaust through the TINY holes.  The result: smoky, unfiltered air comes pouring out the holes for the lightbulbs. I called "support" at Broan/NuTone and was told that this is an excellent hood, and it was working as designed.  Holy mockery of a sham, Batman!  I ended up connecting a 24" long duct to the rear, removed the "performance" ring, and it works fine.