Can One Mini Split Cool Multiple Rooms?

Yes, you can cool multiple rooms with a single mini-split system. You’ll need a mini-split with multiple indoor air handlers, better known as a multi-zone mini-split.

Multi-zone mini slit systems comprise one outdoor compressor unit and two or more indoor air handlers. Since each air handler is controlled independently, you can install one in each room without compromising your convenience. It’s essentially like having a different air conditioner in each room.

How Multi-Zone Mini-Splits Work

Multi-zone mini-split systems work just like standard single-zone mini-split systems, except that they have two or more air handlers instead of one. Currently, mini-split systems can have up to eight air handlers.

The units are named as follows;

  • Two air handlers = two-zone or dual-zone mini split
  • Three air handlers = three-zone or tri-zone mini split
  • Four air handlers = four-zone or quad-zone mini split
  • Five air handlers = five-zone or Penta-zone mini split
  • Six air handlers = six-zone mini split
  • Seven air handlers = seven-zone mini split
  • Eight air handlers = eight-zone mini split

All the air handlers connect to the single compressor unit. However, each air handler has a different line set and electrical wiring. Each air handler also has an independent thermostat and remote control. This makes it possible to control each air handler independently of the other air conditions in the set.

When you switch on the mini-split, a control panel located in the compressor unit identifies and only processes requests from air handlers that are turned on.

For instance, you can have a 3-zone mini split air conditioner, with one air handler in the living room, the second in the bedroom, and the final one in the kitchen.

If you switch on the AC and only the air handler in the bedroom is ON, the other two units in the living room and kitchen will remain off even though all three connect to the same compressor unit.

The Working Mechanism

The working mechanism is straightforward. Upon switching on the air conditioner, each active air handler begins drawing air from the room with the help of a blowing system. It can be hot, stale air (in the summer) or cold, uncomfortably air (in winter).

Inside each indoor unit is an evaporator with coils. These coils carry refrigerant. In cooling mode, as the hot air passes over the extremely cold coils, the refrigerant absorbs most of the heat from the air, drastically lowering the temperature of the air.

The now-cool air is then passed to the supply side of the air handler and discharged into your home. The blower system helps “pump” the cool air into the room at pace and is also tasked with ensuring thorough and even cool air distribution throughout the room.

Meanwhile, the heat extracted is transported aboard the refrigerant via the line set to the compressor unit outside the house, where it’s dumped into the atmosphere. The refrigerant is then pressurized and sent back to the air handler to absorb even more heat.

The process is reversed during the cold months when the mini-split functions as a heat pump. The coolant material extracts heat from the air outside the house and dumps it inside the house, effectively raising temperatures inside the house.

Independent Controls

It’s a highly convenient setup where each air handler affords you independent control over the climate in the different rooms.

  • Independent Thermostats

Consumers are sometimes misled about thermostat sharing in multi-zone mini-split systems. In a multi-zone AC configuration, each air handler has a thermostat. Most manufacturers design their mini-splits such that the thermostats are embedded into the respective air handlers.

However, the package arrives with a separately installed wall thermostat for each air handler in a few cases. If this is the case, you’re required to match each air handler with its thermostat and ensure to install the thermostats in the right rooms.

The configuration makes it possible to control each air handler independently. For example, suppose you want to lower the temperature in the living area slightly. In that case, you can do so without affecting temperatures elsewhere, even though all the air handlers connect to the same outdoor compressor.

You can also change dehumidification, fan, timer, and mode settings in one room without affecting climate settings in the other rooms.

  • Independent Remote Control

Each air handler also arrives with an independent remote device. For example, a 5-zone multi-zone mini split will arrive with five remote devices, one each, for the five air handlers. A dual-zone unit will arrive with two remote devices.

This affords even greater control as you don’t have to move with remote devices from room to room. The risk of misplacing the remote devices also reduces. Better still, you can operate the remote device confidently, knowing that your actions won’t affect climate settings in the adjacent room.  

Independent remote control can prove especially vital when all rooms are actively in use. In a dual-zone system serving two bedrooms, everyone can lower/raise their air handler settings when they sleep without affecting those in the other bedroom.

Sizing and Zone Number Considerations

If you think that a multi-zone mini-split system would be best for your needs, you need to pay attention to two crucial factors – BTU size and the number of zones.

BTU Sizing

Multi-zone mini splits are typically bigger (in BTUs size) than single-zone models. However, this doesn’t mean that any multi-zone mini split would meet your needs. You must still find the right size in line with the size of the application.

Specifically, make sure to match each air handler to the cooling requirements of the allocated room. Forget about the outdoor condenser unit for a minute. Instead, focus on ensuring that the air handler can handle the cooling demands of the allocated room.

You need about 20 BTUs for every square foot. Therefore, you need a 10,000 BTU air handler for a 500 square-foot area. If you’re buying a multi-split system for three rooms in the house, each 500 square feet large, you’ll need a 3-zone mini-split with three air handlers, each rated 10,000 BTUs.

Remember that the exact BTU requirement may vary depending on other factors such as geographic location and home condition.

How Many Zones?

The zone number is a straightforward matter if you’re dealing with average-size rooms. Just count the number of rooms and find a mini-split system with as many air handlers. For example, if it’s five rooms, get a 5-zone mini-split system.

However, complications may arise in dealing with a large room or multi-purpose area. An excellent example is a living room that houses the dining area. These are essentially two rooms in one.

You can split the area into two zones so that you can switch the air conditioning on in the dining area only during meals and switch it off when you’re done. In this case, you need a two-zone mini-split.

We must also mention that since the biggest multi-zone mini-split systems only have up to eight air handlers, you may need two or more multi-zone systems for an extra-large home with nine or more rooms.

Key Takeaway

Yes, a single mini-split system can cool multiple rooms. Such systems are known as multi-zone mini splits and come with multiple, independently-controlled air handlers. They can be a convenient way to air-condition the entire house if the central AC is no longer helpful.