system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: why can't dehumidifiers and humidifiers be the same machine that you can just switch directions?
gpt
Adding humidity is easy, just toss water into the air with a fan.

Removing humidity is much more complicated and requires a device similar to an air conditioner to cool the air until water condenses out.

Your home air conditioner is also technically a dehumidifier, and will have a drain somewhere to dump the water that it’s condensing.