A box fan works in a pinch, but it’s not a real vent.

A box fan can temporarily push steam and smells out of a bathroom or kitchen, but it won’t do the job a proper exhaust fan does. It’s a crutch, not a solution.

If you set it in an open window blowing outward, it’ll pull air out of the room — good for clearing cooking smoke or shower fog. But it won’t handle moisture the same way. A bathroom fan is designed to move humid air through a duct to the outside and keep up with condensation. A box fan just pushes air around, and if you don’t have a window for it to vent through, you’re mostly just stirring the air.

Also, box fans aren’t built for high humidity or grease. You’ll probably ruin it if you use it in a steamy bathroom for long. And in a kitchen, grease will gum up the blades fast.

Use it for a week while you install the real thing. Don’t call it a permanent fix.