Does Mini Split Circulate Air?

Mini split systems, also known as ductless air conditioning systems, do not directly bring fresh air into your home. Instead, they circulate heat energy to heat or cool your spaces by taking in the room’s heat energy, sending it through the refrigerants, and compressing it in the outdoor unit. They then return it through the refrigerants and decompress it into cool or hot air, depending on your needs.

How Mini Splits Circulate Air

  1. Heat Absorption: The indoor unit of a mini split system takes in the warm air from the room, absorbing the heat energy.

  2. Refrigerant Circulation: The absorbed heat energy is then transferred to the refrigerant, which circulates between the indoor and outdoor units.

  3. Compression and Condensation: In the outdoor unit, the refrigerant is compressed, causing the heat energy to be released. This heat is then dissipated into the outdoor air.

  4. Decompression and Heat Exchange: The now-cooled refrigerant is then decompressed, causing it to become cold. This cold refrigerant is then circulated back to the indoor unit, where it absorbs heat from the room, cooling the air.

  5. Air Circulation: The cooled air is then blown back into the room, circulating the air and providing cooling.

Improved Indoor Air Quality with Mini Splits

does mini split circulate airImage source: Flickr

While mini splits do not directly bring in fresh air, they do contribute to improved indoor air quality in the following ways:

  1. Filtration: Mini split systems contain air filters that trap impurities and contaminants as the air is circulated through the system.

  2. Humidity Control: Mini splits can help control indoor humidity levels, which can reduce the growth of mold, mildew, and other allergens.

  3. Air Purification: Some mini split models come equipped with additional air purification features, such as UV light disinfection or ionizers, further improving indoor air quality.

Ventilation Alternatives for Mini Splits

To bring in fresh outdoor air, you can consider the following ventilation alternatives:

  1. Exhaust-Only Ventilation: This system uses a fan to remove stale indoor air and draw in fresh outdoor air through cracks and openings in the building envelope.

  2. Suitable for homes with air tightness of 5 ACH/50 or higher.

  3. Helps prevent soil gas intrusion and depressurization of the home.

  4. Lunos Fans: These are small, energy-efficient, and quiet fans that can be installed in the walls or ceilings to provide balanced ventilation.

  5. Offer both supply and exhaust functions.

  6. Recover heat from the outgoing air to pre-heat the incoming fresh air.

  7. Heat Recovery Ventilators (HRVs): HRVs use a heat exchanger to transfer heat from the outgoing stale air to the incoming fresh air, improving energy efficiency.

  8. Provide balanced ventilation with both supply and exhaust functions.

  9. Suitable for colder climates where heat recovery is beneficial.

  10. Energy Recovery Ventilators (ERVs): ERVs work similarly to HRVs, but they also transfer moisture between the incoming and outgoing air streams, helping to maintain indoor humidity levels.

  11. Provide balanced ventilation with both supply and exhaust functions.

  12. Suitable for both hot and cold climates, where humidity control is important.

When choosing a ventilation alternative, it’s important to consider factors such as the climate, the airtightness of your home, and your specific indoor air quality needs.


While mini split systems do not directly bring in fresh air, they do contribute to improved indoor air quality by filtering impurities and can be combined with additional air purification features. To supplement the air circulation provided by mini splits, you can consider various ventilation alternatives, such as exhaust-only systems, Lunos fans, HRVs, or ERVs, depending on your home’s characteristics and air quality requirements.

Can Mini Split Systems Bring Fresh Air into Your Home?
Fresh Air for Minisplits
Do Ductless Mini Split Systems Improve Indoor Air Quality?