The first time we used our fan (cooking a ton of bacon in the oven) it recycled the air back into the kitchen.
When we told our contractor about it, he said it was because it was a cheap fan and they did that.
My fantastic magical husband fixed it.
And I'm making the smokiest (and best) roasted whole chicken right now and you wouldn't even know it.
NOT ONE SMOKE ALARM WENT OFF!
Remodel: totally worth it.