Ultimate Guide: How Does A Ductless Mini Split Work?

Ultimate Guide: How Does A Ductless Mini Split Work?

Ultimate Guide: How Does A Ductless Mini Split Work?If you’ve been in the market for a new HVAC system or keep up with new technology in general, you’ve probably heard a lot about mini splits. And, if you’re not sure how they work, you’re in the right place. 

In this article, I’ll go through the basics of the mini split heating and cooling process and explain what each component does. You’ll also learn more about the benefits these systems offer and how they compare to more common HVAC systems.

All this information comes from my experience installing hundreds of HVAC systems in homes along the Philadelphia area’s Main Line section over the last decade. 

My family has operated Cipollone Heating and Cooling since the 1950s, and today we specialize in state-of-the-art, high-efficiency heating and cooling systems.

Based out of Havertown, I’m also very familiar with the types of homes in our area, from new construction to mid-century ranchers and Craftsman houses to estates a century old or older. 

If you’d like to learn more about these systems, get a copy of our free download below. Or, call us at (610) 446-7877 for a free consultation. 

How Mini Splits Work: Parts and The Heating/Cooling Process

How Ductless WorksA ductless mini split system uses a refrigeration cycle between indoor units and an outdoor compressor unit. 

You can configure this for single-zone or multi-zone heating and cooling: A single-zone system has one indoor unit to treat one room or “zone” in your home. A multi-zone setup has two or more indoor units to treat multiple zones or the entire house.

Each zone can have its own temperature settings, ensuring that frequently used rooms are comfortable while saving energy by not excessively heating or cooling unused areas.

To understand how this works, let’s start with the pieces involved:

Parts of a mini split

The mini split units are the heat pump, air handler, and lineset.

Heat Pump

The heat pump moves heat in or out of the house by moving refrigerant between the units. A fan draws air into or away from the unit, and a reverse valve changes the direction of the refrigerant flow depending on whether the system is in cooling or heating mode.

Air Handler

The air handler is the indoor unit of the mini split system, typically mounted on a wall or ceiling. It houses the evaporator cooling coils, fan, and indoor air blower. The air handler draws in air from the room, heats or cools it, and recirculates it. 


The lineset connects the indoor and outdoor units of the mini split system. It comprises power supplies, refrigeration lines, communication lines, and condensate drains:

The refrigeration lines carry the refrigerant between the indoor and outdoor units. When the refrigerant is very cold, it absorbs heat, or thermal energy, around it and evaporates into a gas. Then it travels from one unit to another, taking the heat with it. 

The comunication lines allow the air handlers and heat pumps to communicate how much refrigerant to circulate based on how much heating or cooling each room needs at the moment. 

The power lines run electricity to each unit.

The condensate line runs outside from the air handlers. It drains water from when the system dehumidifies warm air in the summer. 

How a mini split cools

A key component of ductless air conditioning is the evaporator in the indoor unit or air handler. As the refrigerant flows through the evaporator coils, it expands and absorbs heat from the indoor air, thus cooling it. 

The system also dehumidifies the air, which makes it feel cooler and helps provide a comfortable living environment. 

The refrigerant transfers thermal energy to the heat pump, which “dumps” that energy outside. Meanwhile, the indoor air blower pushes cool air back into the room. 

Do they have enough cooling power?

Ductless mini split systems can provide efficient cooling for virtually any size house or building. The heat pumps and air handlers come in various sizes and capacities to accommodate larger and smaller areas.  

How a mini split works for heat

A mini split works for heat by reversing the cooling process. Instead of extracting heat from the indoor air and transferring it outside, the heat pump absorbs heat from the outdoor air and moves it indoors.

Inside, the air handler draws in cold air from the room and passes it over the evaporator coil, which transfers the heat from the refrigerant to the air. The indoor unit then circulates the warm air. 

How do mini splits work in cold weather?

Modern mini split systems can operate efficiently in low outdoor temperatures, ensuring your home stays warm even during the coldest months. Even when it’s cold outside, there’s still some thermal energy in the air. 

The heat pump draws in that heat, which the refrigerant absorbs. Then, the unit uses a compressor to cram more refrigerant and, thus, more heat into the line. 

The compression ensures enough thermal energy travels to the air handlers to keep your home warm. 

The most robust heat pump can keep your home warm even in subzero temperatures. However, you may consider a backup heating source, as some models lose efficiency when the temp drops below zero. 

Your contractor can walk you through what to expect from various options. 

How Do Ducted Mini Splits Work?

A ducted mini split, or short-ducted run, connects small, usually flexible, ductwork from a single air handler to a few vents in multiple rooms. Like ductless air handlers, this indoor unit has a thermostat to regulate the temperature in its zone separately from units in other parts of the house.

While this versatile option is ideal for larger homes or houses with many small rooms, you’ll need a heat pump designed to accommodate ducted and ductless units. 

Benefits of a Ductless Mini Split System

Multi-Zone Heating and Cooling

Mitsubishi Electric How Ductless WorksOne of the main advantages of ductless mini split systems is their ability to provide multi-zone heating and cooling while letting you customize the temperature in each room individually. This feature conserves electricity and reduces your utility costs.

Quiet Operation

Ductless mini split systems are known for their quiet operation compared to traditional air conditioners and forced-air furnaces. In particular, the indoor units never get louder than leaves rustling outside. 

Easy Installation

With no ductwork required, you don’t need extensive construction or remodeling to install these HVAC units. The line sets only require small holes in the walls, which go behind the air handler where you can’t see them. 

A single-zone system takes less than a day to install. Even the most extensive multi-zone installations take five days or less. 

Energy Efficiency

Ductless mini split systems boast exceptional energy efficiency. You can compare their high SEER ratings (Seasonal Energy Efficiency Ratio) for cooling efficiency and high HSPF ratings (Heating Seasonal Performance Factor) for heating efficiency to industry standards. 

In particular, the heating process uses heat transfer instead of combustion. Running the refrigerant cycle requires fewer resources than burning fossil fuels from warmth. 

There’s also virtually no heat or cooling loss due to duct leakage, a common issue with ducted systems. 

Central HVAC vs. Zoned Heating and Cooling

Central HVAC systems can’t provide the same versatility and energy efficiency as comparable zoned heating and cooling solutions. Furnaces and central air rely on a single indoor unit and a network of ducts to distribute conditioned air throughout your home.

That results in less precise temperature control and potential energy loss through duct leakage.

On the other hand, zoned heating and cooling offers individualized temperature control in each room or area of your home. This setup not only improves comfort but also enhances energy efficiency. You avoid wasting energy on heating or cooling unused spaces. 

Ductless systems, in particular, eliminate energy loss found with duct systems. 

If you’d like to learn more about what it would take to install a mini split in your Wynnewood home or anywhere on the Main Line, call us at (610) 446-7877 or click below to set up a free consultation. 

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