One of the most popular types of air conditioners available today is the split system AC, also known as a split or mini split. While it serves the same purpose as a central AC system, a split air conditioner operates according to different and more efficient principles.
By understanding how a split AC system functions and how it differs from other solutions, you can appreciate why this type of air conditioner is an excellent choice for climate control in your home.
Basic Operation Principles
All air conditioners work under the same principle of removing warm air and releasing cool air to lower the indoor temperature. Heat pump systems invert this principle to increase the interior temperature.
Quality AC systems also reduce humidity levels by absorbing ambient moisture from indoor air. Additionally, their air filtration systems can remove dust, pollen, and other contaminants, thereby improving indoor air quality.
There are two main types of air conditioner configurations: packaged and split. Traditional air conditioners, which can also be called packaged, central, or all-in-one air conditioning, use a single outdoor unit containing heat exchangers, a compressor, a fan, and a blower. The outdoor unit blows hot or cool air through a system of ducts and vents into the various rooms in your home.
Split air conditioners, on the other hand, separate these elements into two different unit types: one outdoor unit and an indoor handler unit. Outdoor units contain a fan, a compressor, and an outdoor heat exchanger, while indoor units consist of a blower and an indoor heat exchanger.
Parts of a Split AC System
A typical split air conditioning system consists of multiple interconnected parts and elements that work together to control the temperature in your house. While some elements may vary slightly between models and manufacturers, all split AC systems feature an indoor unit, an outdoor unit, and connecting elements, each with its own set of parts. Split ACs also require a refrigerant to function properly, as it allows them to absorb hot air. The type of refrigerant you need will depend on the make and model of your system.
Outdoor unit
Although the outdoor unit of a split AC system is often referred to as the compressor, it actually contains several other components. These include a condenser, a cooling fan, and an expansion valve.
The condenser coils receive warm refrigerant from the indoor units, circulating it around the cooling fan, which pulls in cool exterior air to cool it down.
The compressor is the most critical element of the split AC outdoor unit. Its role is to compress incoming hot gas refrigerant, decreasing its temperature and increasing its pressure until it becomes a cool liquid again. The refrigerant then passes through an expansion valve, where it cools down further before being sent to the indoor units.
Indoor unit
A split system can have one or multiple indoor units, depending on the size of the area you need to heat or cool. Each indoor unit consists of evaporator coils, a blower, and air filters.
The evaporator coils inside the indoor unit receive cold refrigerant from the outdoor unit via the connecting line set. These coils circulate around a blower, pushing cold air into the room and absorbing warm air, thereby turning the refrigerant into a hot gas. The hot refrigerant then returns to the outdoor unit to complete the cycle.
Connecting elements
The elements that connect the indoor and outdoor units are the line set and the cable set.
The line set consists of two pipes: a refrigerant line and a water drain line. The refrigerant line circulates the refrigerant compound through the system, while the water drain line captures condensate generated in the indoor units and redirects it outside.
The cable set includes the electric line that powers the system and a few electronic control cables. These control cables allow the units to communicate with each other and with your devices, such as a remote control or smartphone.
One defining feature of a mini split AC system's connecting elements is the absence of traditional ducting used in central AC. Instead of a single unit distributing cool air through ducts, a split system delivers cool air directly at the indoor units.
Refrigerant compound
The refrigerant compound is the substance circulating through the refrigerant line of the AC system. It allows the system to distribute cool air inside and expel warm air outside. Currently, most AC systems on the market, such as LG split air conditioner systems, use a hydrofluorocarbon (HFC) refrigerant known as R-410A, also called Puron or Forane.
However, in September 2021, the Environmental Protection Agency (EPA) announced a plan to phase out R-410A and all other HFCs by 2023. Future split AC systems may utilize newer and more efficient refrigerants such as R-32 or R-454B.
Zones, Sizing, and Capacity
One of the key advantages of split air conditioning is the availability of zoning options. A split system can be either single-zone or multi-zone.
The number of zones in a multi-zone system refers to the maximum number of rooms that a single split AC system can simultaneously serve. Most multi-zone split systems can support between two and five zones.
In addition to the number of zones, each split system has a specific total capacity measured in British Thermal Units (BTUs). An air conditioner typically needs around 20 BTUs to effectively cool each square foot of living space. The higher the total BTU rating, the larger the area the unit can heat and cool.
Each indoor unit also has its own BTU capacity rating, expressed as a single number. This is crucial when determining which room the unit should serve. To obtain the BTU capacity, multiply this number by 1,000. For example, a unit with a rating of 9 means it is a 9,000 BTU unit.
Many multi-zone systems have indoor units with different individual capacities to control the climate in rooms of various sizes. For instance, a Mitsubishi mini split multi-zone system with a "9-12-18" rating indicates a tri-zone system. The indoor units have respective capacities of 9,000 BTU, 12,000 BTU, and 18,000 BTU.
How to Choose the Right Split AC System
To determine the zones and capacity of your split AC system, identify which rooms in your house require climate control and measure their sizes.
Common locations to consider include the main bedroom, guest or children's bedrooms, the living room, the kitchen, the basement, and the attic. Ensure that you select no more than four or five rooms to ensure a single AC system can support them all.
Measure the floor area of each zone you wish to cool. The minimum capacity of a single indoor unit is typically 6,000 BTU, which is sufficient for an area of 150-250 ft² (assuming a standard room height of 8 feet). Refer to the following chart to choose the appropriate capacity:
- 150-250 ft²: 6,000 BTU
- 250-300 ft²: 7,000 BTU
- 300-350 ft²: 8,000 BTU
- 350-400 ft²: 9,000 BTU
- 400-450 ft²: 10,000 BTU
- 450-550 ft²: 12,000 BTU
- 550-700 ft²: 14,000 BTU
- 700-1,000 ft²: 18,000 BTU
- 1,000-1,200 ft²: 21,000 BTU
- 1,200-1,400 ft²: 23,000 BTU
- 1,400-1,600 ft²: 24,000 BTU
For instance, the average living room area in the United States is about 340 ft², which requires a minimum of 8,000 BTU for efficient cooling.
After calculating the base BTU from the room's area, consider its specific characteristics and add any necessary adjustments:
- If the room is a kitchen, add 4,000 BTUs.
- If the ceiling height is higher than 8 feet, add 25% for every additional 2 feet of ceiling height.
- If the room is drafty or poorly insulated, such as a garage, add 20% to the original BTU calculation.
- If you live in an area with hot and humid summers regularly exceeding 90°F, add 30%.
Benefits and Advantages of Split Air Conditioners
Split AC systems offer numerous benefits over all-in-one packaged units. Here are the top six reasons you should consider a mini split for your home:
1. Complete climate control
While their primary function is to cool, most split air conditioner systems can also function as heat pumps. This allows you to use them throughout the colder months, offering year-round climate control.
Split AC systems are the perfect solution to maintain optimal temperatures in your home, regardless of the season or exterior conditions. Many split AC systems are programmable and compatible with mobile applications, enabling you to turn your home's AC on and off and even configure it remotely.
2. Low noise levels
The indoor units of a split AC system are designed to operate with minimal noise, making them suitable for use in any environment, from a busy kitchen to a quiet children's bedroom. According to data from IAC Acoustics, the average noise level of a typical centralized air conditioning unit is 60 dB (at 100 feet), which is about as loud as a television.
The noise levels produced by split AC units vary depending on their cooling capacity and whether the measurement is taken indoors or outdoors. The loudest parts of a split AC system are the outdoor fan and compressor.
However, independent testing has shown that even high-capacity split AC systems maintain noise levels between 37 and 45 dB inside the home, with outdoor units rarely exceeding 55 dB. These low noise levels make split AC systems the quietest way to cool your home, ideal for maintaining comfortable bedroom climates without disturbing sleep.
3. High efficiency
Most split AC systems are ductless, meaning they don't require ductwork to cool your home. The absence of ducts makes split AC systems highly energy-efficient because the cool air (or warm air in colder months) doesn't leak or dissipate in the ducts before reaching the room's interior.
Additionally, a split AC system doesn't have to run continuously, resulting in significant energy savings. A properly sized split AC system can set a specific temperature and only start cooling or heating when its sensors detect a significant difference between the target and current temperatures. If the target temperature has been reached, the only energy consumed is that required for the system's sensors and electronics.
4. Flexible zoning system
A split AC system operates according to a zoning system. After determining the number and size of zones that require climate control, your air conditioner can adapt to the needs of the areas you use most, minimizing waste.
In comparison, a traditional AC system can only be fully on or off, even in rooms that aren't being used. In contrast, a split AC system can independently detect if a specific zone requires cooling or heating. This flexibility allows it to work in the parts of your house that require it most and only turns on as necessary to control the climate.
5. Improved indoor air quality
Split AC systems do more than maintain a comfortable temperature in your home. The air filtration systems in each indoor unit are designed to capture various air pollutants and contaminants, such as dust, grime, or pollen. This ensures that indoor air quality remains high and healthy.
Additionally, split AC systems act as natural dehumidifiers. As indoor units cycle warm air out of the house, they also capture and separate condensate from the air.
6. Easy maintenance
Although a split AC system's functional elements and moving parts are separated between the indoor and outdoor units, maintenance is quick and easy.
Maintaining indoor units is simple; all you need to do is periodically remove and clean the air filters with water and mild detergent, at least once every three weeks. Cleaning the filters regularly is crucial to maintaining optimal cooling performance, air quality, and preventing the spread of bacteria in your home.
Outdoor units are also relatively easy to maintain. Keep them free of leaves, twigs, and other debris, ensuring that the outdoor fan isn't clogged. You can clean the exterior shell with a garden hose and cloth. Cleaning the interior of the outdoor unit is also straightforward; regularly check the fan, coils, and condensate pan, cleaning as necessary. Proper maintenance will help keep your AC system's efficiency at optimal levels.
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