A mini-split is a heating and cooling system that has no ductwork. It uses an outdoor unit connected to one or more indoor units, so you can heat or cool specific rooms instead of the whole house at once.
Last reviewed: 09/2026
Sources checked: ENERGY STAR
Quick Answer
A mini-split (also called a ductless system) has two main parts: an outdoor compressor/condenser and an indoor air-handling unit. The two are connected by a small bundle of refrigerant lines, power and drain lines that passes through a small hole in the wall. Many models are heat pumps, meaning they can both cool and heat.
How a Mini-Split Is Built
- Outdoor unit: contains the compressor and condenser coil.
- Indoor unit(s): blow conditioned air into the room. Most are wall-mounted, but ceiling cassette and floor-mounted styles exist.
- Connection line set: carries refrigerant between indoor and outdoor units.
- Remote or app control: lets you set temperature, fan speed and mode.
Single-Zone vs Multi-Zone
A single-zone system connects one outdoor unit to one indoor unit. A multi-zone system connects one outdoor unit to several indoor units, each controlling its own room. [Link to: Single-Zone vs Multi-Zone Mini Split Systems]
Where Mini-Splits Make Sense
According to ENERGY STAR, ductless systems can be a good fit for homes without existing ductwork, additions, garages and spaces where installing ducts is difficult. [Verify wording and link to the source page.]
Advantages
- No ductwork required
- Room-by-room temperature control
- Heating and cooling in one system (heat pump models)
- Smaller installation opening than a ducted system
Limitations
- Upfront cost can be higher than a window unit
- Indoor units are visible on the wall or ceiling
- Sizing must match the space; a professional load calculation is recommended
When to Call a Professional
Mini-split installation involves refrigerant and electrical connections. Have a licensed HVAC contractor and, where required, a licensed electrician handle installation and confirm correct sizing.
Frequently Asked Questions
Do mini-splits need ductwork?
No. That is one of their main features. [Link to: Do Mini Splits Need Ductwork?]
Can a mini-split heat a house?
Heat pump models can provide heating as well as cooling. Performance depends on the model, climate and home. [Link to: Can a Mini Split Heat and Cool a House?]
Related Guides
- [How Does a Ductless Mini Split Work?]
- [Ductless Mini Split vs Central AC]
- [How Much Does a Mini Split Cost to Install in 2026?]