Boil some water and watch where the steam goes. Because it's pulling air from around the pot along with it, including the hot waste gasses that heated the pot in the first place.

Even on the highest settings, I've never seen one that even makes a dent, or moves the column at all. They're snake oil and fashion, nothing more. And that's before talking about the ones that don't have any ductwork, and just blow it back out into the room.

Commercial-grade ones that move ridiculous quantities of air definitely work, and a tiny tiny handful of people have these in their homes. The rest have essentially nothing.

Hm, that's not my experience: I used all three options (no hood [student dorm], circulation hood [currently in our house], outside duct hood [parents; last flat]). There is a huge difference between each. Having no hood is obviously not nice, since water vapor and fat end up everywhere. The circulation hood at least reduces the amount of fat. Not sure if by 20 or 80%, but there is a significant difference between turning it on or not. Especially the amount of fatty haze when making hamburgers is reduced a lot. Now for water vapor it does not help so well. It's okay for one pot of water (boiled eggs or pasta with pesto), but when doing some heavy cooking still a lot of water ends up condensing on the windows. With an outside duct (about 2m of duct work) water vapor becomes a non-issue and the amount of fat haze is reduced much better than with the circulation unit.

Also this isn't biased by "I don't cook". Quite the contrary :)

I've heard the grease thing quite a few times, especially with hamburgers, but... tbh it hasn't ever happened to me. And my past two apartments haven't had a range hood at all (just a microwave with a fan we never use).

Is it saturated fats or something? Burgers are definitely a rarity for me, but I cook plenty. It's just generally lean meat and veg/oil/etc.

Regardless of where the steam goes -- if the hood is not vented, it'll just spill the air back out in to the kitchen. The cabinets above our non-vented kitchen hood are always covered in grease from the cooking. I doubt a simple filter will make that air much healthier to breathe in.

If you put a paper towel right under the fan you’ll see the paper towel get sucked into the fan.

Right under the fan. Yes, they are useless.

interesting... i wonder if it's because of the height constrained by aesthetic inputs.. i'm pretty sure if you stuck the vent like 50cm above the stove it surely can be a bit more than useless...

I think it's really just because there are no objective and enforced standards for it. I used to have a kitchen with a pretty high ceiling and a fume extractor mounted way up high, so high it was controlled by an IR remote, and it worked great while making little sound. Currently I have one of those integrated with a microwave oven that makes a lot of noise, blocks my view of half the range, and doesn't work at all. Plus even if it did work, it would vent right into my eyes, not to the outdoors.

My vent is about 5 feet above the stove. We had to build a little soffit to get it just within code regulations. It has a huge blower that is located in a small attic space about 20 feet away. 100% recommend! You can’t hear it at all and you can watch all the vapor and smoke from the stove waft right up and away into the unit.

The remote eats a pair of CR2450 cells every three months, so that could have been done better.

Which model vent is it?

That sounds like horrible usability; it's going to be in the way all the time, especially if you're a tad tall. I bet that's the far more important reason than aesthetics. I already don't like the regular ones because I need to be careful not to bump my head in to it.