Ductless Mini Split Heat Pumps

How Do Ductless Heat Pumps Work?

So, how do ductless heat pumps work? A ductless heat pump works in much the same way standard split system, ducted heat pumps work. Both systems require an indoor unit and an outdoor unit. Both systems use a chemical compound called “refrigerant” that circulates between the indoor and outdoor units to help facilitate the heating and cooling process. And, both types of heat pumps can provide heat during the colder months as well as cooling during the hotter times of year.

As the name suggests, ductless mini split heat pumps provide comfort without using traditional ductwork. Its more targeted comfort because heated or cooled air blows directly out of the indoor fan coil unit into the living space. If comfort is needed in multiple rooms, an additional indoor unit will be needed for each area where heating and cooling is needed.

How Does a Mini Split Heat Pump Work? Components

Answering the question, “how does a mini split heat pump work?” requires taking a closer look at the components of the system. Mini split heat pump systems include an outdoor unit and an indoor unit. Mini split outdoor units house a compressor, condenser coil and expansion valve. Mini split indoor units include a blower fan and evaporator coil. The two units are connected with tubing that allows chemical refrigerant to circulate between the two units. Here’s a closer look at what each of these components do so that you have a better understand how heat pumps work to provide heating or cooling for your living space:

• Refrigerant: Refrigerant circulates in a closed loop through a ductless mini split system, passing through components in the indoor unit to the outdoor unit and back, usually through copper tubing. It is a chemical that can absorb heat in its liquid state and release heat in its gaseous state. The temperature and pressure of the refrigerant is controlled by the compressor and expansion valve to facilitate the heating or cooling process.
• Compressor: The compressor is housed in the system’s outdoor unit. It “compresses” the refrigerant to increase its pressure and temperature. The resulting rise in refrigerant temperature makes it easier for heat to be released (through the coil) outside the home during cooling, or inside the home during heating. Standard heat pump models often include a single-speed compressor, and higher efficiency heat pump models often include variable-speed compressors that can adjust as needed to best match heating and cooling needs.
• Evaporator Coil: The evaporator coil is located in the indoor unit of mini split heat pump system, also sometimes referred to as the air handler. Evaporator coils are often made of copper or aluminum tubing – metals that conduct heat efficiently and resist corrosion. To cool your home, refrigerant flowing through the evaporator coil absorbs heat and some humidity from indoor air. The resulting cooler air is circulated into the living space by the indoor unit’s fan. The refrigerant flows to the outdoor unit where heat is released outside via the system’s condenser coil. This process is reversed during heating. Heat absorbed from outdoor air is released by the indoor coil to provide comfort in your home.
• Condenser Coil: The condenser coil is located in the outdoor unit of your mini split heat pump system. Condenser coils are also typically made of copper or aluminum tubing. During cooling operation, liquid refrigerant flowing into the condenser coil releases heat collected from inside air and releases it outside. During heating, the process is reversed. Heat is absorbed from outdoor air (even in cooler temperatures!) and is released inside to provide heat in your living space.
• Expansion Valve: The expansion valve restricts refrigerant flowing into the evaporator coil, allowing the refrigerant to expand once it enters the coil. The expanding refrigerant causes a drop in pressure, and as a result the temperature drops as well to aid the cooling process.

Ductless vs Ducted Heat Pump

As previously described, ductless vs ducted heat pump operation is largely the same in terms of how they operate. To provide heat to your indoor spaces, both systems absorb heating energy from outside and transfer the heat to indoor air. During cooling operation, the process is reversed. Heat and humidity are absorbed from indoor air and that heat is released outside. The big difference comes with the delivery of heated or cooled air. With ducted HVAC systems, the type most commonly found in homes throughout the U.S., a central air handler unit called a fan coil circulates the conditioned air throughout the home. It uses a strong fan, usually called a blower, to push the air through ductwork that runs under floors, above ceilings or behind walls and out into your living areas. These types of systems are similar to central air conditioning and can heat or cool an entire house.

Because it is easier and more cost effective to install duct systems during a home’s initial construction, it would be very difficult and likely quite expensive to add a ducted heat pump or air conditioning system to an older home with no existing ductwork. Adding ducted heating and cooling to room additions and space conversions can also be challenging. These projects require connecting new duct runs to the existing network. The increased heating and cooling capacity need for the additional space may also require replacing the existing indoor and outdoor units with higher capacity models.

A ductless system is an excellent solution for adding comfort to older homes and room additions because they can provide comfort without requiring new duct runs. Ductless systems do require a direct connection between the indoor and outdoor units for both refrigerant tubing and electrical wiring. However, these connections are much less intrusive and less costly than installing new ductwork. And, for every additional room that needs heating or cooling, you will need a ductless indoor unit installed in that space.

Pros of Mini Split Heat Pumps

There are many advantages to using ductless mini split heat pumps when compared to their ducted counterparts.

• Energy efficiency: Ductless mini split systems provide exceptional energy efficiency, especially when compared to typical ducted systems. High efficiency ductless systems can provide up to 42 SEER cooling efficiency and up to 15 HSPF during heating. Many of these models meet the Department of Energy’s ENERGY STAR designation for high efficiency appliances.
• Savings on energy bills: When you combine the exceptional energy efficiency of a mini split heat pump with the savings from only using the system during times the space is being used, you might be surprised with the savings you can see on your energy bills.
• Improved air quality: Because ductless systems do not use ducts to distribute heated or cooled air, they can help minimize the spread of contaminated air from other areas of the home – such as smoke or odors from cooking or fireplaces. And, ductless systems are less likely to collect dust and other pollutants and recirculate them to other parts of the home.
• Installation versatility: Ductless outdoor units are often narrower than typical ducted outdoor units and can be placed in tighter outdoor spaces.
• Boost comfort: Ductless systems add comfort in rooms not attached to your home’s ducted system. They can also provide a comfort boost for rooms a ducted system is struggling to keep properly heated or cooled.

Cons of Mini Split Heat Pumps

We have certainly spent some time building up the advantages of ductless systems for heat pumps and air conditioners. Of course, there are a few disadvantages to consider when making your choice:

• Large up-front investment: According to Home Advisor, the average cost of a ductless mini split system can run between $1300 for a single unit to $13,000 for a five-zone system.¹ However, energy savings over time can help make the investment worth it, and if you are trying to add a ducted system where existing ductwork is not already in place, those costs can also add up quickly.
• Obtrusive indoor unit: Most mini-split indoor units for residential use are mounted on a wall in full view of the room. It’s a less elegant solution than a ducted system which delivers heated or cooled air through vents which are usually flush with the floor, ceiling or wall. The indoor unit for a ducted system is usually hidden in a basement or utility closet or placed out in the garage.
• Indoor unit in each zone or area: To provide comfort in multiple rooms, ductless systems will require an indoor unit for each room. This adds cost, but on the positive side, you can save on energy use by only heating or cooling the room you are using.
• Lower heating/cooling capacity: Ductless heat pumps are typically designed with lower heating or cooling capacities than ducted heat pumps in terms of Btu/h. However, both systems are “sized” by your HVAC contractor to match the needs of the space or home. As long as the ductless mini heat pump is properly sized for the area it is intended, it will provide ample comfort.

Why Choose a Carrier Mini Split Heat Pump?

When it comes to choosing a ductless mini split heat pump system for your home or room addition, Carrier is here to help. Carrier has been at the forefront of indoor comfort since Willis Carrier invented modern air conditioning in 1902. Since that time, we have continued to develop new technologies for improving comfort, system efficiency and long-term reliability. With Carrier, you not only get comfort and peace of mind, you get the value that comes with products that are designed to stand the test of time.

As you consider your options, be sure to read up on ductless systems, including how to install a mini split system and comparisons between a mini split vs central air. Understanding the similarities, differences and installation requirements can go a long way towards helping you decide which system works best for your particular needs.

To see if ductless mini split heat pump system is right for you, find a Carrier expert.

¹https://www.homeadvisor.com/cost/heating-and-cooling/ductless-heat-pump/