Do you ever feel warm or muggy, even if the air conditioner is on? It’s probably due to humidity, or the amount of moisture in the air. Most traditional air conditioners, especially window units and portables, don't do a great job removing humidity, so you could have a cool house and still be sweating.
The solution? Mini split air conditioners will keep you cool and dry in the summer thanks to a setting called “dry mode,” sometimes called air conditioner dehumidifier mode. Pressing it will turn on your air conditioner’s “dehumidifier” function (it’s not actually a dehumidifier), which will remove excess humidity from the air and improve your comfort.
Let’s look at how the dry setting on your AC works and why it’s used.
High humidity can make it more difficult to breathe, harder for your body to cool itself, and can encourage the growth of allergens, bacteria, and mold. In a less humid environment, you will feel more comfortable even if the air is warmer.
When you turn on your mini split, or any air conditioner, it automatically removes some humidity from the air. While in cooling mode, warm indoor air is drawn over a coil that's filled with cold refrigerant. The refrigerant absorbs the heat from the indoor air, dramatically reducing its temperature.
As its temperature decreases, the air becomes less capable of holding moisture. The water in the air condenses into a liquid, like the moisture on the outside of a cold glass of iced tea on a humid day and separates from the air moving across the coil.
The moisture that's removed is referred to as condensate and needs to be drained to a suitable location, sometimes with the aid of a condensate pump.
Although mini splits always remove at least some humidity, it’s not their focus. That’s where dry mode comes into play.
The dry setting on your mini split is specifically designed to remove humidity. Dry mode lowers the mini split’s fan speed so that the humid air moves more slowly over the cooling coil and loses more moisture than it otherwise would. With less moisture in the air, you’ll automatically feel cooler and more comfortable.
Many brands, such as Mitsubishi and LG, call dry mode dehumidification mode, but it's the same thing. Besides improving comfort, dry mode reduces the chance of mold growth and other property damage in the conditioned space.
The economics of dry mode depend on where you live. In moderate climates where the actual temperature isn’t very high and most of the heat you feel is coming from excess humidity, using dry mode can potentially save energy because the unit will work less hard to make you feel comfortable.
If, however, the weather is very hot and humid, merely removing the humidity won’t be enough to make you feel comfortable. Plus, due to heavy humidity, the unit would be working very hard to keep it down.
While a dehumidifier is specifically designed to remove all moisture from a space, the main job of a mini split air conditioner is to cool. Dry mode is an extra benefit but will only bring humidity down about 30%. If you have chronic humidity problems where you live, you should invest in a dehumidifier.
In areas with only light humidity, you probably don’t need a separate dehumidifier. This is where your mini split’s dry mode can be a great way to add comfort and maybe save some energy. At the end of the day, though, dry mode does not replace a dehumidifier if your main goal is to significantly lower humidity.
In summary, dry mode lowers the fan speed to remove humidity instead. In moderate climates with low humidity, it can be an effective alternative to cooling mode. However, it’s not a replacement for a dehumidifier and is not effective in very hot, muggy climates.
Used in the right circumstances, the dry setting on a Mini Split AC unit can be a great supplement to your comfort. To learn more, feel free to contact our mini split experts.