A homeowner on her living room couch points to a ductless Mini-split heat pump on the wall above the couch

Ductless mini-splits are popular because they don’t require much remodeling. However, their rapid temperature fluctuations and adjustments make many people wonder if they can affect the moisture content. After all, humidity reacts differently with varying temperatures.

Throughout this article, you’ll discover how a ductless mini-split system affects the humidity, whether or not you can use the appliance in place of a dehumidifier, and why it’s creating moisture.

Do Ductless Mini-Splits Dehumidify Effectively?

Ductless mini-splits are effective at dehumidifying because they adjust the temperature to create condensation. Moisture is removed from the condensation through the ductless mini-split system, lowering the room’s humidity. However, they’re not the best at dehumidifying in frigid climates.

How Much Does a Mini-Split Dehumidify?

A ductless mini-split can dehumidify by up to 30% compared to traditional air conditioners. However, you can invest in a mini-split system with a dehumidifying mode.

Side view of a mini-split's compressor unit next to a central AC outside a home

Check the label to know exactly how much you can lower the room’s ambient humidity. Remember, keeping the temperature comfortable will make the humidity less unbearable.

According to eComfort, you should get a dehumidifier instead of a mini-split if you live in a highly humid environment. 

Mini-split heat pumps can manage normal humidity levels, but they won’t get rid of enough moisture if your furniture is always drenched. So instead, increase the unit’s size and get one with a drying mode if you’re determined to use a mini-split system.

These ductless units are pretty powerful as dehumidifiers. They remove condensation and moisture from the air rather effectively. Nevertheless, you might be unable to use them as dehumidifiers if you have the wrong size, location, or ambient humidity.

Read on to learn more about whether or not your mini-split system will work in place of a dehumidifier.

Can a Mini-Split System Act as a Dehumidifier?

A ductless mini-split can act as a dehumidifier because it naturally removes moisture from the air. This process forces water outside through a drain pipe. The excess condensation can puddle under the pipe, so don’t forget to slope the area or remove the water to prevent mold and mildew. Use a hygrometer to check how much the humidity has dropped.

A ductless mini-split condensate drain at the bottom of line near the compressor
Courtesy of Quality Heating

Here’s what you should know when using a mini-split system to dehumidify a room:

  • Lowering the temperature will quickly reduce the ambient humidity – colder climates almost always have less moisture in the air. This process is why most people have dry skin or redness during the winter. When you reduce the temperature, your mini-split will prevent excess humidity in your home.
  • Some ductless systems have drying modes – John Cipollone explains you can choose a mini-split unit with a dry setting that acts as a dehumidifier. Using this mode will quickly reduce the humidity by 20% or more if you live in a humid climate. Remember, most homes should have a humidity level between 35-45%.
  • The ductless mini-split’s size affects how well it removes moisture from the air – if you have a massive unit, it might change the temperature too fast. In this case, you won’t be able to get rid of enough humidity to notice a difference. So instead, try to work in small increments to ensure the mini-split can dry the ambient moisture.
The head unit of a mini-split near the ceiling in a common areas of a home above two doors
  • Most mini-split heat pumps won’t lower the humidity to uncomfortably dry levels because they only take a portion of moisture from the air. This characteristic is crucial to your home because if the humidity gets too low in a room or an entire household, it can cause unwanted skin dryness, eye irritation, throat discomfort, and more. It can also damage the building’s structural integrity.
  • Ductless systems typically only reduce the humidity in a specific room – it’s important to remember that you can use a mini-split system instead of a whole-house dehumidifier. The heat pump only affects the room (and maybe a neighboring room, depending on the unit’s square footage capabilities).

If you want to use a ductless mini-split as a dehumidifier, it’s essential to remember that this method works best in moderate to warm climates. Most ductless heat pumps can’t remove too much moisture from the air when they’re freezing.

Therefore, check the manufacturer’s operation recommendations to know how well yours dehumidifies at any given temperature.

Why Is My Mini-Split Not Dehumidifying?

Your mini-split isn’t dehumidifying because there’s not enough moisture in the air, the dehumidifier is turned off, or there’s not enough airflow through the system. Additional causes include excess humidity outside of the house or not having the proper coil size for the heat pump system.

Let’s analyze each of these common causes.

  • A lack of moisture in the air – if there’s not a lot of humidity in the air, your mini-split heat pump likely won’t affect the moisture content too much. Most ductless systems won’t reduce the relative humidity below optimal ranges (35-45%, as mentioned above). However, they can still adjust the temperature.
  • Deactivated dehumidifier – if your mini-split unit has a drying mode, make sure it’s turned on. You won’t notice nearly as much humidity reduction when this mode is deactivated. That said, many ductless heat pump systems still slightly lower the moisture content, even if they have a deactivated drying mode.
  • Not enough airflow in the unit – there are plenty of reasons your ductless heat pump might not have enough airflow. These issues include clogged drain pipes, dirty coils, obstacles too close to the inlet or outlet, and faulty parts. In addition, if the system overheats, it won’t be able to produce enough power to promote optimal airflow.
A homeowner using a power washer to clean a mini-split condenser unit
  • Too much outside humidity – if it’s too humid outside, you might not be able to lower the moisture quickly enough. This issue occurs because the mini-split pulls moist air into the house. So while it goes through the coils to remove the interior humidity, the exterior dampness comes into the building, preventing it from lowering.
  • Oversized coils or mini-split systemsAir Cond Lounge claims that if your ductless heat pump is too big for the room, it’ll adjust the temperature before it removes any condensation from it. Thus, your room will feel humid, but the temperature will quickly move to the desired setting.

The good news is that most excessive humidity issues can be solved by cleaning the drain pipe and ramping up the ductless mini split. You can improve the airflow by removing excess debris and ensuring nothing’s too close to the indoor or outdoor units. Ensure your system is the right size for the room, too.

Do Mini-Splits Create Humidity?

Mini-split heat pumps don’t create humidity, but they can fail to dehumidify if they’re too big or too small for the space. 

For example, when the temperature adjusts too quickly, the coils don’t have enough time to remove enough moisture from the air. On the other hand, when the temperature changes too slowly, there’s not enough power to lower the humidity.

So, why is your mini-split increasing the humidity? Some explanations for this include:

  • The drain pipe is clogged, which builds up a lot of moisture in the air – when the water backs up through the drain pipe, it can evaporate. The indoor evaporation causes the room to feel humid. Fortunately, all you have to do is clear the clog in the drain pipe. Use a vacuum hose or a pressure hose to remove the debris.
  • If the cooling coils are dirty or broken, they won’t lower the humidity – ductless mini-split systems absorb condensation over the coils. If they aren’t working correctly, the absorption is eliminated. You might also notice that the appliance is overheating or can’t adjust the temperature.
  • Increasing the temperature will let more moisture bind to the air. Humidity is much more noticeable when it’s warm – this characteristic is because the water droplets hover at higher temperatures and dry out when it’s cold. The room will feel slightly more humid if you increase the temperature with your heat pump system.
  • Some mini-splits cause condensation on nearby windows before removing it from the air – give the unit a couple of hours before assuming it’s causing humidity. A properly functioning ductless heat pump won’t increase the humidity at all. Actually, these units are known for passively doing the opposite.

While it might seem like your heat pump system is increasing the ambient humidity, it’s almost impossible for this to happen. In most cases, it’s more likely that the system is malfunctioning and can’t remove moisture. You’ll notice the condensation because the temperature changes, but the appliance won’t get rid of the water as it should.

Final Thoughts

Ductless mini-splits and dehumidifying work hand-in-hand. While you might not be able to replace your dehumidifier completely, you can certainly remove quite a bit of water from the air. If you don’t live in a year-round humid climate, a mini-split heat pump might be all you need to control the ambient humidity.


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