Do Kitchen Exhaust Fans Really Work?

Factual Questions
1

I have one of those built-in kitchen ventilation fans on the wall above the electric range. I don’t know if it’s the original-- the house was built in the early Fifties-- but it’s in working order and seems powerful enough.

It has one of those weird metallic-mesh filters behind the cover grill; again, I don’t know if it’s original, but it isn’t clogged-- one can see daylight through it if the fan is used in the daytime.

But when I turn it on, it’s impossible to tell visually if it’s really doing anything. I don’t exactly expect a cartoon-like vortex to magically suck out all the cooking smoke and fumes, but it doesn’t look as if it’s drawing smoke or steam to itself.

Unlike “hooded” ventilators, there doesn’t seem to be any aerodynamic engineering involved. Does it matter if the adjacent back door is open or closed when the fan is in use? In short, if these things really do work, is there anything one can do to make them maximally effective besides flipping the switch to “on”?

Or am I just overthinking the whole deal, and are these largely ornamental items-- another example of rip-off, fake technological innovation like public restroom hot-air hand dryers?

2

If your house is hermetically sealed, turning on the fan will only reduce the air pressure inside the house, so something has to be open (or leaky) somewhere for air to flow. That’s the reason for the cold air return in a forced-air heating system.

But are you asking if the fan is actually moving air? Why not try using a smoke generator like a cigarette, or a tiny piece of tissue to see if it is?

3

Some of these things blow the smoke back out the front, at you. I think they are largely ornamental, but they seem pretty common - maybe even the norm.

I think a good smoke generator is a match, if you let the head burn and then blow it out. You get a few seconds of a tidy little smoke stream and it doesn’t smell too bad.

4

My exhaust fan is ducted thru the wall, and I’m sure it works. I periodically put the metal filter/grille in the dishwasher or it gets all gummy.

5

They work great. You may need to crack a window if the house is well sealed so the air can come in to replace the expelled air. You get even better air circulation if the metal grease filter is not on the unit.

6

Installing a ventilor hood is harder than it looks. Therefore it is almost always done incorrectly-it seems like it is a always an afterthought.

Not only does one have to have a fan that draws air correctly, but the exhaust piping has to be properly sized and installed.

If you wish to troubleshoot the system, start from the outside and trace the exhaust pipe back to the kitchen. Bends are bad. Small tubes are bad.

Good luck.

7

If it vents to outside the house, then it is (potentially*) worthwhile. If it merely vents to elsewhere in the kitchen, or Og forbid into the ceiling space, it’s a waste of electricity to run it - indeed potentially dangerous.

  • assuming it’s placed so as to be able to draw in a significant amount of cooking smoke and fumes.
8

vent type benefit depends on climate.

in a heating environment the outside vents loose heat even when not in use.

circulating vents might work OK with good clean filters to trap odors.

in a cooling environment the outside vents might eject unwanted cooking heat.