I recently discovered how powerful humidifiers can be in terms of generating cold.

What happens if you run a humidifier in a small room that has an air conditioner?

The dehumidifier can produce air up to 12 degrees cooler than the ambient temperature. The air conditioner can take away the swampy humidity.

However, taking away the swampy humidity shouldn't take away the cold the humidifier had produced. Unless the reverse happens when the humidity condenses into water?

Anyway I presented this idea to my dad and he said that removing the excess humidity with the air conditioner would make the whole thing useless as the air conditioner would expand more power to get rid of humidity. What do you guys think?

  • The a/c and the humidifier would work against each other, and waste power. Commented Sep 1, 2017 at 10:28

2 Answers 2


Potentially, but not in the way you suggest. Evaporative coolers (aka swamp coolers) are an efficient way of cooling by adding moisture to the air. If the relative humidity is already high, then the additional moisture will need to be removed, with either an AC system or a dehumidifier, and any benefit will be lost and you will be worse off. If the relative humidity is low, then the additional moisture of the evaporative cooler is not an issue, and might even be desirable. In this case, there would be no need for an AC system or a dehumidifier.

If the relative humidity is moderate, you may be able to use both an evaporative cooler and an AC system. When the relative humidity is slightly low and the temperature is high, turn on the cooler. When the humidity is high and the temperature is high, turn on the AC system. Finding the perfect balance between temperature, humidity, and efficiency is going to be very hard.


I assume, in your post, you meant to say 'humidifier'.

You have a great idea there, but not without a couple small glitches. First, a standard HVAC system does not actually remove humidity. The perceived dehumidifying is simply the return air duct sucking the humidity from the air, but the humidity rests on the interior walls of your ducting. As you can probably imagine, that can cause issues - rust, calcium buildup, possibly mold, etc, etc The option to have a dehumidifier installed in the ductwork is a common option in HVAC systems, but in that case, your dad would be right - you're running a humidifier up top, and a dehumidifier underneath. The costs kinda offset.

Old guys are typically always right, especially dads. ;)

  • 1
    Hey. I have window units and no central ac. And ac units have cold parts on them which such the humidity out of the air. Some of the acs in our house are making gallons of water a day, with no humidifiers.
    – Web Master
    Commented Sep 1, 2017 at 10:07
  • 3
    correction "NPM" ---A/c units do remove humidity and the humidity does not rest on the interior walls of the ducts and I have never seen a dehumidifier installed in a residential A/C system, just in heavy commercial systems such as schools , hospitals and special applications.
    – d.george
    Commented Sep 1, 2017 at 11:33
  • It's noeant to run as a dehumidifier for excessive humidity. You're going to freeze up.
    – NPM
    Commented Sep 1, 2017 at 12:59
  • NPM, please explain your last comment (there was a typo)
    – d.george
    Commented Sep 1, 2017 at 13:57
  • The evaporator coils are not meant to be run as a dehumidifier for excessive moisture. You're going to freeze up the coils.
    – NPM
    Commented Sep 1, 2017 at 14:10

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