The Components of a Mini Split AC System

Mini split systems consist of three groups: the outdoor unit, indoor unit(s), and the conduit that connects them both. These primary parts have several mini split components working together.

1. The Outdoor Compressor / Condenser Unit

The compressor or condenser unit is located outside the home. It looks like a rectangular box with a large fan. Its purpose is to release heat from the refrigerant:

• Compressor: The compressor is a device that pressurizes refrigerant gas, converting it from a hot gas into a liquid. It also pumps the liquid through refrigerant lines that run to every indoor unit in the home.
• Condenser coils: The condenser coils wind through several loops that give outside air time to absorb heat from the refrigerant. After exiting the condenser, the refrigerant will be a cool liquid.
• Outdoor fan: The fan blows air over the condenser coils, ensuring they cool down sufficiently.
• Expansion valve: This small valve allows the high-pressure liquid refrigerant to expand immediately before entering the evaporator unit. This cools it down even more.

Some homeowners choose mini split systems with heat pumps. A heat pump works essentially the same way as an air conditioner, except it has the ability to reverse the process in cold weather. This type of ductless system can absorb warmth from outside air and use it to heat rooms in winter.

2. The Indoor Evaporator Unit

Ductless A/C systems have one compressor outside that connects to at least one evaporator unit inside. Depending on the unit, the compressor can support up to eight evaporators in different rooms, essentially creating a network to cool the entire house. Here’s how:

• Evaporator coils: Cold refrigerant flows into the evaporator coils, absorbing heat automatically from the surrounding air. This causes the refrigerant to evaporate into a gas and carry room heat outside.
• Blower: The circular blower is responsible for drawing in warm air and blowing cool air back into the room. It’s very quiet compared to the fans of traditional air-conditioning units.
• Air filter: Cool air goes through the air filter before entering the room, capturing dirt particles, pet dander, mold spores, and other allergens. A great filter improves indoor air quality while keeping the home cool.

Evaporators are usually mounted on the wall, but you don’t have to choose that type of unit. There are floor-mounted evaporators, suspended ceiling units, concealed ceiling units, and even evaporators that work with partial ducts. Also, you can combine different styles for other rooms. This gives you the freedom to follow your design vision in any space.

3. Drain Lines, Refrigerant Tubing, and Electric Cables

There needs to be a way to transfer the hot gas from the inside to the outside compressor. That’s where the line set comes in. The line set specifically refers to the refrigerant tubing, but is often used to refer to the whole bundle which includes: 

• Refrigerant lines: This insulated copper tubing carries refrigerant through the system. The tubing size varies; refrigerant lines leaving the evaporator coil with hot gas are wider than the ones carrying cold refrigerant liquid.
• Drain lines: Any evaporator produces water from condensation during the cooling cycle. You don’t want any moisture leaking inside the home, so drain lines dispose of it outside.
• Electrical lines: Power cables from outside provide all the electricity indoor evaporator units require. That means there’s no need to rewire your home for mini splits to work correctly.
• Communication lines: Electronic control cables send signals between inside and outside parts, keeping everything working smoothly. The outdoor compressor only runs when it needs to, and at the right speed to keep the home at the temperature where you want.

How big does the conduit need to be for a mini split? Usually, 3” conduit works perfectly. HVAC contractors only need to make a 3-inch hole in the outside wall to run the necessary lines (which is completely sealed after).

How Do Mini Split Components Cool the Home?

Now that you’ve seen what mini split components do individually, how do they work together? The cooling process is easy to understand when you know how heat transfer works. In every system, heat always wants to move to cooler areas. This is a fundamental principle of thermodynamics.

The hot air in your home automatically moves towards cold refrigerant liquid in the evaporator, like the way your hands lose heat when you touch ice. Outside, the compressor uses the same principle by pressurizing warm refrigerant into a liquid that is hotter than the surrounding air, releasing heat and cooling the liquid.

This whole process is possible thanks to refrigerant, a special liquid with an extremely low boiling point. Even room temperature air of 60+ degrees is enough to change it from a cool liquid to a boiling gas.

Advantages of a Ductless Mini Split

Understanding how individual mini split components work can help you choose the right type of cooling for your home. Seeing how amazing mini split systems are compared to a central air conditioner may convince you to take your home into the 21st century!

• Energy efficiency: This type of system reigns supreme for energy efficiency. Compared to central air and older air conditioners, cooling costs can go down by as much as 30%. That saves you a lot of electricity and money.
• Zone cooling: Mini splits allow you to regulate the temperature in different rooms independently. This is known as zone cooling. Trust us when we say it’s the air-conditioning of the future. Why waste electricity cooling the kitchen if you’re not there?
• Smart thermostat options: Many mini splits have smart thermostat features that you can control from your smartphone or tablet. You don’t have to get up anymore to make rooms warmer or colder. The best part is you can personalize your settings for the bedroom for your sleeping preferences. Enjoy a great night’s sleep all night long, never feeling too cold or too hot.
• Simple installation: Because there are no complex ductwork systems to install, adding a mini split to your home is relative simple. Installation is faster and costs are lower because you only need that 3” hole for conduit.

Are you ready to choose a ductless A/C for your home? Visit our ductless mini split air-conditioners page to see all the options available for the cooling system of your dreams. Look at smart mini-splits for your home’s size, output needs and budget, including high-tech models from LG, GE, Panasonic and Friedrich. Find the parts, line sets and accessories you need for high-quality installation that lasts ages.

Do you still have questions? At Total Home Supply, we’re always happy to help! Don’t hesitate to email or give us a call at 1-877-847-0050 and speak to one of our qualified representatives today.

Learn more about Mini Splits

• What’s a Mini Split AC?
• Types of Mini Splits: Ceiling Cassettes, Wall Mounts, & More
• Mini Split System Cost: A Comprehensive Guide