The condesner unit of a ductless mini-split next to an air conditioner outside a home

Ductless mini-split heat pumps can maintain your home’s temperature comfortably throughout the year. They provide heating and cooling, making them an excellent investment for anyone living in an area with hot summers and cold winters, like many parts of the US.

Many people wonder, though, whether a mini-split can dehumidify their home and heat and cool it. Surely that’s too much to ask from one piece of technology.

Or is it?

This article will look at what a mini-split does and how that compares to a dehumidifier.

By the time you’ve finished reading, you’ll have a good idea of the differences between a mini-split heat pump and a dehumidifier and the results you should get from each.

Do Ductless Mini-Splits Dehumidify as Well as Cool?

Cool air holds less moisture than warm air, meaning that a mini-split heat pump will dehumidify the air somewhat as it cools your home. Dehumidifiers are better at removing moisture, but some mini-splits have a “dry mode,” providing similar dehumidification performance.

That’s great, but how do you know whether to invest in a specific dehumidification unit or leave it to a mini-split system?

First, let’s consider why you would want to dehumidify your home.

Is It Good to Dehumidify a Room?

According to the United States Environmental Protection Agency, humidity inside your home should be kept under 60%, with the recommended range between 30-50%.

Doing this will help avoid problems stemming from excessive moisture buildup in the home, such as mold and condensation.

Condensation can be a serious problem sometimes. We’ve already written a separate article to help you identify whether condensation in your home is a problem or not and what to do about it if it is.

Water pooling up at the interior base of window with condensation formed on it

Mold releases spores into the air, which can cause allergic responses in some people. Common problems include sneezing, runny nose, and watery eyes, but mold spores can cause difficulty breathing and tiredness with prolonged exposure.

As well as encouraging the growth of mold, high humidity can bring in unwanted pests such as silverfish, dust mites, and cockroaches.

Dust mites are a common cause of allergies around the home, but they hate cool, dry air. Dehumidifying your living space can help to get rid of these unwanted guests.

According to a paper published on the National Library of Medicine website, dust mites are composed of 75% water by weight and need a relative humidity of 65% to maintain their water balance.

Below 50% humidity, they cannot survive or reproduce as easily, which will help to control their numbers or eliminate them.

Does Every Home Need a Dehumidifier?

You can take steps to reduce humidity in your house that don’t involve a dehumidifier, such as ensuring appliances that generate a lot of moisture are vented to the outside, e.g., tumble dryers.

Opening windows and doors and taking cooler showers can also help to reduce humidity, but sometimes these passive measures are not enough.

A homeowner opens a set of exterior-leading plastic windows

If you live in a naturally humid area, you might benefit from running air conditioning or a dehumidifier to keep humidity within the recommended range. This is true, particularly if you suffer from asthma or allergies made worse by high humidity levels.

To learn more about reducing humidity in your home, read our article covering ways to remove humidity without buying a dehumidifier.

How Does a Mini-Split Work?

In cooling mode, a ductless mini-split moves heat from inside your home to outside, and in heating mode, it does the opposite.

It does this using the refrigeration cycle principles, pumping refrigerant via a compressor into a condenser, which removes heat from the refrigerant as it condenses to form a saturated liquid.

The refrigerant then passes across an expansion valve and on to the evaporator, where it flows through the evaporator coil.

Warm air from the room is blown across the evaporator by a fan in the air handler, causing it to be cooled. Water vapor in the air condenses onto the evaporator’s outside before being carried away by the condensate line.

The two parts of a mini-split are an outdoor heat pump, where the compressor is housed, and an internal air handler unit commonly mounted on an internal wall.

The two units are connected by refrigerant lines that allow the refrigerant to pass between them to cool or heat the building.

An illustrated diagram of how a ductless mini-split system functions

Mini-split heat pumps can keep your home cool during summer and heat it during winter, which is an advantage over standard air conditioning (assuming you need both, of course).

However, not everyone knows that mini-splits can also dehumidify your home if needed.

Many mini-split heat pumps have a “dry mode,” which reduces the speed of the fan in the air handler so that more moisture is removed from the air as it passes over the evaporator coil without cooling the room too much.

How Does a Dehumidifier Work?

Dehumidifiers work in a very similar way to mini-splits, except instead of cooling the air and then blowing it straight out into the room to keep the living area cool, dehumidifiers have a final stage where the air is warmed before it leaves the unit.

So, dehumidifiers don’t cool the air. They only remove moisture from it, which means they can be especially effective during winter.

They have a compressor, which pumps refrigerant around the system and uses the refrigeration cycle to cool the evaporator coils, across which warm, humid air is blown.

This process causes the water vapor in the air to condense on the evaporator coil because, as it cools, the air cannot hold as much moisture, so the vapor condenses onto the coil. You have probably seen a similar effect on the outside of a milk bottle taken out of the fridge on a warm, humid day.

The “sweat” that forms on the bottle is caused by the same condensation process employed in dehumidifiers.

Dehumidifiers collect the water that condenses and drain it into a reservoir that needs to be emptied periodically or use a drain that continuously takes the water away.

A homeowner opens the water collection chamber of a dehumidifier to empty it

The final step in a dehumidifier is to heat the cool air before it is blown back into the room. This feature is a key difference between a mini-split heat pump in dry mode, which slightly cools the room.

This step is vital to consider if you need dehumidification during the winter. In this case, a dehumidifier might be a better option because it blows out warm air, whereas a mini-split would cool the air slightly. 

Key Takeaways on Mini-Split Dehumidification

Ductless mini-split heat pumps and dehumidifiers both use the refrigeration cycle to do their job.

Cool air can hold less water vapor than warm air, so as well as controlling the temperature, a mini-split helps to dehumidify the air in your home when operating in cooling mode.

Some mini-split systems have a “dry mode,” which slows the fan down so that the air is blown across the evaporator coil in the air handler more slowly. This allows more moisture to be removed from the air while reducing the cooling effect.

Dehumidifiers do their job using the same refrigeration process as a mini-split heat pump, but they have a final stage where the air is heated before being blown back into the room.

Because dehumidifiers do not cool the air, they are recommended for dehumidifying your home during the winter.

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