The Pros and Cons of Ductless Mini-Split Heat Pumps

Ductless mini-split heat pumps can provide both heating and cooling, giving you year-round comfort in your home.

These flexible, efficient units have become increasingly popular in recent years, with homeowners looking to take advantage of their ability to heat and cool different house zones to distinct temperatures.

The running costs are also appealing, coming in much lower than typical central air systems.

This article will go through the main pros and cons of mini-split heat pump systems in detail. But first a summation of the pros and cons of ductless mini-split systems in a single paragraph.

Do a Mini-Split Heat Pump’s Pros and Cons Outweigh a Cental AC System’s?

Ductless mini-split heat pumps are more efficient, have lower running costs, and offer greater flexibility than traditional air conditioning solutions. They are more expensive to install, but their lower running costs mean they work out to be cheaper in the long run.

We hope you’ll know whether a mini-split is for you by the time you’ve finished reading.

What Is a Ductless Mini-Split Heat Pump?

Before we cover the pros and cons of mini-split heat pumps in detail, let’s make sure you understand what they are so we avoid any confusion further down the line.

A ductless mini-split is permanently installed in your home and can provide heating and cooling—perfect if winter temperatures in your part of the country are on the chilly side.

Each installation comprises two pieces, an outdoor unit housing the compressor and an indoor unit, known as an air handler or head unit.

The outdoor unit does most of the heavy lifting and is responsible for pumping the refrigerant around the system.

The indoor unit is mounted in the room to be heated or cooled, typically high up on the wall, although several types afford flexibility in where they can be placed. In addition to wall-mounted units, it is possible to mount an inside head unit on the floor or the ceiling.

Refrigerant lines connect the two components, which pass through a two or three-inch hole in the wall. The hole also accommodates electrical cables that provide power and allow the units to communicate, and the condensate pipe that drains condensate from the head unit.

Pros of Mini-Split Heat Pumps

There are many reasons why a mini-split could be the best option for your home.

They have been popular in other parts of the world for many years, and now, in the US, people are choosing them as an alternative to central air conditioning or window units.

Mini-Splits Do Not Require Ductwork

It might seem obvious that a ductless mini-split does not require ductwork, and I suppose it is. However, this is a crucial benefit of a mini-split for several reasons.

Easier Installation

If your home doesn’t already have ductwork, installing it can be very disruptive and costly. In addition, sometimes it’s just not feasible to install ducting, for example, if you live in a tiny home that doesn’t have the space.

Mini-splits eliminate this expense and upheaval and allow cooling and heating to be installed in difficult-to-reach rooms such as add-ons or garage conversions.

Efficiency Gains

According to Energy.gov, ductwork accounts for over 30% of the losses in energy used to provide heating or cooling with a typical central air system.

This loss can be caused by leaky ductwork allowing air to escape or drawing in unconditioned air from roof spaces.

Even in the absence of leaks, ducting that is not sufficiently insulated and passes through attic areas scorching in the summer and very cold in the winter will allow heat transfer through its walls, making the system much less efficient.

A ductless mini-split eliminates this source of inefficiency.

Less Servicing and Maintenance

Ductwork needs to be cleaned regularly to avoid excessive dust and mold buildup. Failure to clean out your ductwork regularly can allow dust to build up, which decreases the efficiency of your system by obstructing the flow of air and can also give rise to allergies and other health problems.

Don’t believe me? Look at this video of a professional HVAC technician cleaning the ducts in a house where this simple maintenance task has been neglected for many years.

The technician uses specialist equipment to clean the vents with compressed air and then blows the dust along the ducts towards an industrial vacuum at the bottom of the house. 

At various points in the video, he mentions that there is just too much dust for the vacuum to handle and resorts to pulling it out by hand.

Dust is primarily dead human skin cells and can attract dust mites, which cause allergies. A couple of days after he finished this job, he received a phone call from the owners, who told him that all their allergies had gone.

In more humid climates, mold can be a problem. It releases spores into the atmosphere, which also causes allergies in sensitive people. Again, regular cleaning can prevent mold from occurring and will protect you and your family from respiratory illness and allergies.

Ductless mini-split systems don’t use ducts and will therefore save you from having to carry out all this maintenance.

If you have a ducted system you think might need a professional cleanout, you can read about the pros and cons of cleaning your ductwork in our article about that here.

Mini-Splits Are More Controllable

Mini-splits have head units in each room or zone to be cooled or heated. A critical benefit of this is the ability to set the temperature for each zone independently.

Even if you have multiple head units running off a single compressor, it’s possible to run them as different zones, which allows the temperature to be set individually for each specific one.

This feature is great if you prefer your bedroom to be a little cooler than your living room or if you have guests staying who have different preferences from you.

It is much more challenging to have rooms at different temperatures with a central AC system because it conditions the air and then blows it around the house at whatever temperature your central unit is set to.

Sure, you can play around with the registers in each room to let more or less air in and even try to direct it towards the occupants of a space for a better cooling effect. But this is nowhere near as powerful as setting the temperature lower in certain rooms like you can with a multi-zone mini-split.

Being able to completely turn off a head unit when it’s not required could also save you a lot of money compared with central air.

Mini-Splits are Scalable

When designing your system, you might not be sure whether every room requires a head unit. It is possible to add another head unit to a mini-split at a later date if you decide you need one.

This flexibility means you can be conservative and save money by only installing the air handlers you know you’ll need, and if you need more cooling or heating power in the future, all you need to do is add another unit.

Try doing that with central air, and you would find the upheaval of putting in the additional ductwork much worse than simply adding another head unit on the wall and hooking it up to the outdoor unit through a small hole in the wall.

Another situation where this could prove helpful is where you want to build an add-on room at the far end of the house. There might not be a feasible way to run ductwork into the new space.

No ductwork is required with a ductless mini-split, so that limitation is irrelevant.

Mini-Splits Also Provide Heat

For many of us in the US, heating the home in the winter and cooling it in the summer with a single mini-split system could be attractive. There is no need to install separate heating and cooling systems, which cuts down on the cost of installation.

A single system is also likely to reduce ongoing servicing and maintenance costs compared to running two separate systems.

Cons of Mini-Split Heat Pumps

Despite the many advantages of mini-splits, there are some drawbacks.

Not everyone will see some of these disadvantages as such a big deal, and it could depend on your location or personal preferences whether you feel they are severe or not.

Let’s look at the most often talked about disadvantages so you can decide for yourself.

Initial Setup Costs are Relatively High

A typical unit will set you back around $1,500 to $2,000 per ton.

The initial outlay for a mini-split heat pump is about 30% higher than for central air and perhaps twice the cost you would pay for a window unit of the same capacity.

Weighed against the savings you are likely to make in running costs, though the overhead can be viewed as an investment that pays off in the long run.

Mini-Splits Are Still Novel

The fact that mini-split heat pumps are not as standard as other types of HVAC systems could mean trouble finding a firm capable of, and happy to do, the installation work for your new mini-split system.

In a few more years, mini-splits will be as common in the US as they are in Asia, and you’ll have no shortage of firms in your local area willing and able to install and maintain mini-split systems.

Until then, though, you might find a shortage of qualified technicians in certain parts of the country.

Refrigerant Line Set Visibility on Exterior Walls

We’re all used to seeing functional items attached to the walls of our houses. We have pipes and cables in our homes that serve all functions, from plumbing to internet connections.

If you’re the type of person who doesn’t like having visible pipework on the side of your home, a mini-split might add to your frustration.

The lines running from the outdoor unit to each air handler are essential for operating ductless mini-split systems. If you have multiple head units serving different zones within your home, the lines will need to be routed along the house’s external walls.

They aren’t huge at just 5/8″ diameter or less. But if your design sensibilities are easily upset, perhaps they are something you’d prefer to live without.

It’s possible to get “line hide,” which is simple plastic covering that can be made to match the color of your home’s walls. This casing will do a great job of hiding the untidy wires and pipes, but it is still another thing on the side of your home that you might not want.

If you’re interested in learning more about the role of refrigerants in the operation of heat pumps, how much it costs if you need a top-up, and what the most environmentally friendly types are, please read our article on the subject.

Summary

Mini-split heat pump units are highly efficient, flexible, and cost-effective to run. They are comprised of two units, the exterior compressor, and one or more head units inside that blow conditioned air into your living areas.

Their popularity in the US is increasing, a testament to how well they do their job, keeping you cool in the hottest summers. They can also heat your home during periods of cold weather.

Pros of Mini-Splits

• No ductwork is required
• Easy installation with minimal disruption
• Highly efficient
• Low servicing and maintenance compared to central air systems that use ducts
• Highly controllable – homeowners can separately control the temperature of each zone
• Scalable – additional head units can be added later if needed
• Capable of providing heating as well as cooling

Cons of Mini-Splits

• The relatively high initial cost
• Mini-splits are still relatively new, and fewer companies have the skills and experience to work on them
• Refrigerant line sets are visible on external walls