A newer mini-split compressor outside the exterior of a home

When your air conditioner is loud or making strange noises, it is probably time to search for a replacement. A ductless mini-split should be a contender for a replacement HVAC system because of its compact design and flexible applications. 

A mini-split heat pump is ultra-efficient compared to traditional air conditioning equipment. If you are adding a room or another small area to your home or office, a ductless mini-split is ideal for cooling and heating this space.

However, many homeowners wonder if that improved efficiency contributes to less noise generation.

Please keep reading to learn how much noise mini-splits give off, how they function, the differences between conventional split air conditioning and mini-splits, and the many benefits of choosing this system.

Is a Ductless Mini-Split Heat Pump Loud or Quiet?

A mini-split heat pump is very quiet and efficient. Since there are no ducts, the system gives you one of the most silent cooling operations with a 30 SEER rating. They also typically have a low-noise mode that makes them almost undetectable.

For comparison, a wall unit air conditioner can emit almost seventy decibels, while a whole-home central air conditioner emits between fifty to seventy decibels. A mini-split emits around thirty-two decibels, comparable to someone whispering beside you. 

What Is a Ductless Mini-Split Heat Pump?

Mini-splits are a quiet HVAC system that requires no ductwork to heat or cool an existing room or series of spaces. The system has outdoor and indoor units for a complete comfort solution. 

This quiet setup is popular for several reasons, most notably due to the ability to customize the comfort level of any room in the house. For example, if you are a person who stays chilly, you can set your room temperature to a mild setting, while another person in the house who is hot can have the air conditioning blowing in their room.

How a Ductless Mini-Split Works

A mini-split heat pump can also be called a “zoned HVAC” system. It is perfect for adding a wing to your home where you don’t want to extend the ductwork.

Mini-splits are made up of the following components: 

The Evaporator

A mini-split air handler in the corner of a room just below the ceiling with a vent installed

The evaporator ( also know as the air handler or head unit) must remove moisture in the air to cool a room, which happens when humidity is drawn into the outside unit to pass over coiled tubing. 

Inside the copper tubing is refrigerant, which cools the air as it moves over the coils. The refrigerant is cold gas at this point. 

When the refrigerant releases the heat from the air, the air cools down. As the refrigerant moves back into the house to the indoor unit, it becomes liquid. 

The cold air over the refrigerant then blows back into the room. At the same time, more warm air pulls from the room and back to the evaporator to start the heat removal and cooling process again.  

The current refrigerant approved for use by the US federal government is R-410A. This refrigerant is called Freon or Puron, a safer coolant than those previously used. R-410A is safer for the environment and offers more efficiency for AC units. 

The Condenser 

A condenser works similarly to the evaporator. The condenser holds the refrigerant that absorbs heat from the indoor air—the refrigerant cycles through the condenser coils in the outdoor unit to release the heat outside.

The condenser unit of a mini-split next to a wall outside a home

The outdoor unit cools the condenser coils with a fan, and then the refrigerant in the coils returns to the indoor unit. 

The Compressor

The compressor of a mini-split is a key component. This unit increases the temperature and pressure of the refrigerant that has absorbed the heat from the air.

When the refrigerant reaches the outside unit, its temperature is higher than the air, allowing heat to dissipate into the air. Then, the refrigerant moves back to the indoor unit to absorb more heat to carry outside. 

The Expansion Valve

After the refrigerant leaves the compressor, it must cool off after being warm from the heat absorption on its way back to the evaporator. The expansion valve opens to expand the refrigerant, which reduces the temperature and pressure. 

The Ductless Mini-Split Heating Process 

Since you now know each mini-split component, here is the path this system follows to remove warm air from a room and replace it with cool air for optimal comfort:

  • First, the refrigerant moves into the system’s expansion valve
  • The expansion valve converts the refrigerant liquid to a gas, and also cools the refrigerant
  • The refrigerant next moves through coils in the evaporator
  • The evaporator fan blows the air
  • The system pulls warm air from the room, and the refrigerant heats up
  • As the refrigerant moves to the condenser, it pressurizes and compresses
  • The condenser removes the heat from the refrigerant and expels it into the outside air
  • The refrigerant flows back into the system’s expansion valve
  • Finally, the valve converts the refrigerant liquid to gas, and the process begins again

When cold weather arrives, a mini-split reverses the process by extracting heat from the outside air to bring it inside for a warm room. 

The Difference Between Mini-Splits and a Traditional Split System

A conventional HVAC system and a ductless mini-split differ in several significant ways. Each design offers benefits for your home, but one will be better than the other under specific circumstances.

The comparison below should help you understand the differences.

Traditional Split System Ductless Mini-Split Heat Pump
Cooling onlyHeats and cools 
Needs ductworkNo ductwork
Many energy-efficient modelsExceptionally efficient
Cooling for the whole houseCooling for one room or small area
Runs at a constant speedVariable refrigerant flow that uses temperature and pressure sensors to control the operation
No customizationCustomizable to each room
Audible noise from air moving through ducts in walls and ceilingsOne of the quietest cooling and heating systems on the market

Advantages of Ductless Mini-Splits

A ductless mini-split heat pump has several benefits for a room or small area. As a result, they are becoming increasingly popular, especially since you can control the temperature for personalized comfort in a room. 

Here are some of the primary advantages:

  • Mini-splits have no ductwork, making them easier to install. While extending your existing HVAC system would require adding ductwork to a home addition, mini-splits need only one hole drilled for the conduit. 
  • The outdoor and indoor units can be placed wherever is best for your home, offering complete flexibility to install them in an inconspicuous spot. For example, indoor units can be placed high on the wall, suspended from the ceiling, or closer to the floor.
A mini-split's ceiling-mounted air handler component
A ceiling cassette model of a mini-split’s evaporator unit
  • Most mini-splits have smart capability—you can control the system from your smartphone for maximum efficiency. 
  • Without ductwork, the system gives you more energy efficiency. Many conventional units lose warm and cool air through leaky ductwork. 
  • Better heating and cooling because each unit only serves one small area. This system lets each occupant decide the perfect temperature. 
  • They are easily installed in rooms of any size.
  • Some mini-splits can connect to more than one indoor unit. For example, you can choose a model that connects with one to four indoor units for efficient and customizable heating and cooling. 
  • They have an emergency cooling mode, ensuring your room will stay cool if the unit needs service. 

Factors That Affect a Ductless Mini-Split Heat Pump

Various factors will affect your choice in your search for a suitable model. When you consider outside variables that will influence performance, you will have a quiet, effective way to heat and cool a room.

Some considerations to help you make the best selection include:

  • The amount of sun exposure
  • The insulation level of the room
  • The level of humidity in the atmosphere
  • The height of the room

Conclusion 

A mini-split heat pump is not only quiet but delivers efficient cooling and heating to an individual room. Many people love the ability to adjust a room to their preferred comfort level without affecting others in the home. 

The compact design and flexibility of placement in a room are additional benefits that should persuade you to choose this type of unit for a home or office addition. 

Sources 

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