Multiple mini-split condensers mounted on a red exterior wall

Ductless mini-splits are a heat pump system that provides heating and cooling for your home. They have become a popular alternative to central air systems.

They use the same technology as a traditional air conditioner but there are some differences. 

Mini splits do not require ductwork. This makes them great for homes with boiler heat and installations where adding to existing ductwork is difficult. 

They are typically used to provide climate control for small spaces, though they can be zoned for use throughout entire homes. Ductless air handlers are mounted to the wall where they provide both heating and cooling for the area.

But how exactly do these systems move enough air around your home?

What Is a Mini-Split Heat Pump?

Mini-splits are heat pumps. This means they can provide heating and cooling, but they do it via heat transfer. This is the same technology used in a traditional air conditioning system; the only difference is that heat pumps cand work in reverse.

Mini splits have two main components: the outdoor condenser and the indoor air handler(s).

The outdoor condenser is very similar to a central air conditioner, though it is a slightly different shape.

The indoor air handlers (also called “heads”) are connected to the outdoor condenser through the wall by copper lines. A mini split can have just one head or it can have several, depending on the needs of the home. 

To explain things a little further, heat pumps use a refrigerant that runs through their coils and lines that easily absorbs and transfers heat.

This refrigerant runs between the indoor air handler and the outdoor condenser and allows the system to move heat from one place to another.

On cooling mode, the system runs just like an AC. It takes heat from indoors and expels it at the outdoor condenser. 

On heating mode, it finds heat outside and moves it in. This may seem impossible, but there is heat to be found in outdoor air, even when temperatures drop below zero!

A ductless mini-split in the corner of a room below the ceiling

Do Ductless Mini-Splits Bring In Outside Air?

These systems circulate indoor air but they do not bring in outdoor air. It should be noted that central air conditioners do not do this either.

Indoor air is recirculated. If either of these systems brought in outside air, it would just be more warm air that the AC has to then cool.

While ventilation concerns are typically not an issue for residential homeowners, it may pose a problem for commercial building codes that have certain ventilation requirements.

In these situations, PTACs or PTHPs may be the better choice, even though their performance and efficiency is significantly lower than mini split units.

How Does a Mini-Split Recirculate Air?

We’ve already discussed how mini splits transfer heat. But how do they move that air around your home? 

Mini splits have a fan inside the indoor air handler. When the refrigerant moves through the coils in the unit, the fan blows over it and sends that air out into the room. 

For best performance, the unit heads should be placed high on the wall in a central location. This gives the fan the best reach and works with the naturally occurring convection current to move air throughout the space.

While these systems are efficient, they are not intended for heating and cooling large spaces. In a larger home, multiple heads will need to be installed.

Two mini-split compressor units outside a home in snowy conditions

How Can I Improve Airflow In My Home?

Opening windows and doors is one of the best ways to ventilate your home but that isn’t always possible, especially if you are running your heat or AC. 

Using ceiling fans is one of the best and cheapest ways to improve airflow in your home. This will help your mini split to move air around too!

If you are looking for more substantial options, you can install an extractor fan in your bathroom to remove the heat and humidity from hot showers. Similarly, an extractor fan in the kitchen will remove the heat from using the oven. 

During the summer months, the extractor fans will not only improve your home’s air quality, but they will make your AC’s job a little easier.

Helpful Tip: Remember to clean the air filters in your mini split every 4-6 weeks. They are located in the access compartment on the indoor head.

Simply rinse them off in the sink, allow them to dry and put them back in their places. Not only is this integral to your indoor air quality, but it is necessary for the longevity of your mini split.

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