Determining how many mini-splits are required to efficiently heat and cool your space can be challenging. We highly recommend contacting a GREE certified HVAC contractor to help you determine the proper sizing for your mini-split system. In the meantime, we've prepared this guide to provide a starting point for your discussion, covering air handlers, room coverage, and more.

How Do Mini-Split Systems Work?

A mini-split system is a type of ductless heating and cooling system that provides targeted temperature control in individual rooms or spaces. It consists of two main components:

1. Indoor Air Handler Unit: The indoor unit is a compact air handler that is typically mounted on the wall or ceiling of the room it serves. It contains an evaporator coil, a blower fan, and an air filter. The indoor unit is responsible for distributing the conditioned air (heated or cooled) within the room or space.
2. Outdoor Condenser Unit: The outdoor unit is a condenser that houses the system's compressor, condenser coil, and a fan for heat exchange. It is responsible for releasing or absorbing heat, depending on whether the system is in cooling or heating mode. The outdoor unit is connected to the indoor unit(s) via electrical wiring and refrigerant lines.

These two components work together to provide efficient heating and cooling in individual rooms or spaces without the need for ductwork. This allows for greater energy efficiency, flexibility, and ease of installation compared to traditional ducted HVAC systems. There are a range of factors that impact what size mini-split system you need, but the most important ones are outlined below.

Factors Affecting the Number of Mini-Splits You Need

1. Square Footage: The total size of your space is the most critical factor in determining the size and power needed for your mini-split system. The larger the space, the larger the system you'll need for adequate coverage.
2. Number of Rooms: The number of rooms in your space will significantly impact the size of your mini-split system. Generally each room is serviced by its own indoor air-handler, and it's common for each room to have its own zone so that its climate can be controlled independently, but this can change depending on the size and layout of the home. Some GREE outdoor condenser units can connect to up to 5 indoor air-handlers and rooms, but beyond that you'll likely need an additional outdoor unit as well.
3. Insulation: Your space's insulation can play a role in the mini-split system you need. It doesn't necessarily dictate how many components you need, but a poorly insulated space may require a more powerful system to adequately control the temperature to compensate for heat loss.
4. Climate: Your region's climate can also influence the type of mini-split system you require. Colder climates may need more mini-split units for sufficient heating, while warmer climates may require more for adequate cooling. For instance, GREE's MULTI+ Ultra is designed with a 2-stage/3-cylinder variable speed compressor, and each outdoor coil has corrosion-resistant, acrylic resin coil coating, allowing it to maintain energy efficiency in the harshest climates. Additionally, while one indoor air-handler is typically significant for a room, climate can play a role in whether or not the room can adequately be covered by one indoor air handler or if more is required.
5. BTU's: To select the proper system and its components, your HVAC contractor will need to calculate to calculate the BTUs (British Thermal Units) required for heating and cooling. BTUs are a measure of the system's capacity to heat or cool a given area. A GREE certified installer can help you calculate the exact BTUs needed based on your space's size, insulation, and other factors.
6. Distance Between Air Handlers & Outdoor Units: Depending on the layout of your space, it can sometimes be more cost-effective, and be more efficient to have an outdoor unit on each side of your home, than to run the maximum number of air-handlers that one outdoor unit can handle. Multiple factors come into play here, including the length of piping that is needed to connect the farthest air-handler from the outdoor unit, and the cost of that installation. It is best to consult with a professional so that they can tell you what configuration is best based on the layout of your home, and where your indoor air-handlers will be located.

Common Mini-Split System Sizing Questions:

How Many Air Handlers Do I Need for My Mini-Split?

The number of air handlers needed for your mini-split depends on the number of zones you want to create. Multi-zone mini-split outdoor units can connect to multiple air handlers, allowing you to establish different zones in your space. Each air handler can be individually controlled, enabling temperature adjustments per your preferences. All of the factors outlined above impact how many air-handlers you'll need, but the most important factor is the number of rooms the system needs to service.

How Many Rooms Can a Single Mini-Split Cool or Heat?

A single mini-split air handler is generally sufficient for one room, depending on the layout of the space. Different mini-split outdoor unit models can service different numbers of zones, but GREE's MULTI+ ULTRA mini-split outdoor condenser unit can service up to 5 zones.

Do You Need a Mini-Split in Every Room?

A full mini-split system (IE, an outdoor condenser and indoor air-handler) isn't typically needed for every room, but an indoor air-handler likely is. You can use a single (multi-zone) mini-split system to create different zones in your space, but each zone will likely need its own air handler, especially if you want it to have independent temperature control.

How Many Square Feet Can a Mini-Split Cool?

A single mini-split system with one outdoor unit can typically cool or heat at least 300 square feet, and much more depending on the outdoor and indoor unit's capacity. However, factors like insulation, climate, and your space's layout can affect the actual square footage a mini-split can cool.

At GREE, we partner with certified HVAC specialists to make determining the optimal number of mini-splits for your space a breeze. By considering square footage, the number of rooms, insulation, and climate, your GREE certified installer will be able to work with you to build the perfect mini-split system for your space – Use our contractor locator tool to find a certified HVAC contractor in your area today! If you're an HVAC contractor working on sizing a system for your client, be sure to try GREE's new system builder tool to help you build the system with ease and efficiency!