Heating & Cooling

Disadvantages of Mini Split Systems: 9 Things You Should Know

ductless outside unit 2 lg

Ductless mini-split systems are dual-purpose heating and air conditioning systems growing quickly in popularity. They’re highly efficient, give off excellent heating and cooling, run quietly and smoothly, and take up limited space inside and outside your home. They also don’t always require the skills of an HVAC professional to install them. 

While mini-split systems have lots of upsides, they also have several disadvantages. Aside from being expensive, small, and difficult to install, there are also many other things to keep in mind when considering purchasing one. 

While there are plenty of articles out there talking about how great mini-split heat pumps are, this isn’t one of them. Our goal is to make sure that you get both sides of the story to make the most informed decision possible. Mini-split heat pumps are great systems, but they are not for everyone. 

What is a Mini Split Heat Pump System? 

Mini-split heat pump systems are systems that don’t require ductwork to operate. A traditional furnace and air conditioner have ductwork inside your home that carries air from the furnace throughout your home. However, with mini-split systems, ductwork isn’t necessary because the system functions more like a fan or a hotel heating system. 

The Components 

There is an indoor unit and an outdoor unit with mini-split systems. The outdoor unit sits on the ground gets mounted to the side of your house, similar to a traditional air conditioner is. The indoor unit gets mounted on a wall in the room that you’re attempting to heat or cool. 

The indoor mounted unit blows air directly out of itself and into the room. There are no ducts, vents, or other connections outside the indoor and outdoor units and the wires connected. A refrigerant line connects the indoor unit to the outdoor one, similar to how a traditional air conditioner and indoor coil work. 

Disadvantages of Mini Split Heat Pump Systems 

Now that you have a better idea of what a mini-split heat pump system is and how it works let’s get into some of the reasons people don’t like them. 

Aesthetically Unappealing 

One of the biggest gripes people have with mini-split systems is how they look. The outdoor unit isn’t a problem in most cases unless you live in an apartment or condo that prohibits having outdoor condensers. The outdoor unit is smaller and skinnier than its traditional counterparts. 

The inside unit, however, is a different story. Traditional furnaces usually get hidden from view in a basement, attic, or garage. With a mini-split system, the indoor unit must have an open and unobstructed view of the room it’s trying to cool or heat. If that room happens to be a family room or living room, you’ll have an extremely expensive and ugly wall hanging. 

Manufacturers are making efforts to make mini-split systems more appealing and less intrusive, but noone has found a good solution yet. 

High Installation Cost 

Mini-split heat pumps are also extremely expensive to install, depending on the brand you purchase. Like most heating and cooling appliances, you can opt for the cheaper brands and save money or go for the costlier ones. Unfortunately, cheaper mini-splits simply aren’t as good or reliable as expensive brands like Mitsubishi, and they’re more prone to problems and early termination. 

While Mitsubishi is often considered the top-of-the-line for mini-splits, it’s also extremely expensive. The units themselves cost several thousand dollars, plus the cost of installation. The average mini-split system costs between $5,000 and $7,000 per system when it’s all said and done. 

If you’re trying to condition your entire home and need multiple systems, you could easily pay upwards of $30,000. That’s much more than the cost of installing an air conditioner, a furnace, and the accompanying ductwork. In terms of pound-for-pound pricing, a mini-split costs 30% more per ton, which is a measurement of cooling capacity, than a traditional HVAC system. 

Difficult to Know What Size You Need 

It’s also important to know that you can’t install just any mini-split system in your home and expect it to do its job. You must have a qualified professional come to your home and calculate the heat pump size that you need. Mini-splits come in all shapes and sizes, just like a traditional heating and cooling systems. 

Installing a system that’s too big will mean that it cools the room too quickly and turns off prematurely. When this happens, your mini-split cannot get all the humidity out of the room, and it will be uncomfortable. 

On the other hand, installing a system that’s too small means that it will have to run longer and more often than it otherwise should. Because mini-split heat pumps operate purely on electricity, your utility bills will skyrocket, and your heat pump system won’t save you money like it was supposed to. 

A Different Level of Heating and Cooling 

Your mini-split salesman won’t tell you that these types of heat pumps don’t do well in extreme weather. On extremely hot or cold days, your mini-split will struggle to keep up and won’t provide the same level of comfort that a traditional HVAC system. 

Mini-splits and heat pumps, in general, are meant for moderate climates that don’t experience extreme temperatures. However, if you only deal with one extreme or the other, mini splits handle high heat better than freezing temperatures. 

They Won’t Save You as Much Money as You Think. 

One of the main reasons people install ductless mini-split systems is that they believe it will save them money. While this may be true in many cases, it’s debatable how much money a mini-split will save you. As we’ve just stated, mini-splits are expensive to install, often costing more than a traditional HVAC system if you’re installing them throughout your home. 

Additionally, mini-split heat pumps operate entirely on electricity. While mini-splits are proven to be up to 30% more efficient than a traditional furnace and air conditioner combo, their overall cost efficiency is subject to debate. Mini-splits often run longer and work harder to cool or heat different parts of your home than a furnace or air conditioner would. As a result, they use more electricity, albeit more efficiently. 

You’ll have to weigh the difference in cost between your mini-splits efficiency versus how long it runs. You should also consider the installation cost to determine how long it will take to pay for your system in terms of efficiency. 

Mini-Split Vs. Window Unit

In terms of installation cost, there’s no question that a window unit or a hotel unit is cheaper than a mini-split. However, mini-splits are up to 40% more efficient than window or hotel units in terms of efficiency. You’ll have to weigh both options’ overall cost and savings to decide which one is for you. 

Another thing to remember is that window air conditioning units can’t produce heat. That means you’ll have to invest in a hotel unit or install an alternative source of heat in addition to the window air conditioner

Not Meant for Whole Houses 

As a former HVAC installer, I ran into this problem more times than I care to relive. Many homeowners love mini-splits but overestimate their abilities in terms of heating and cooling. Mini-splits are ideal for large, open areas, such as basements, shops, garages, and individual rooms in a home. 

They run into trouble when you try to heat or cool multiple rooms at a time with a single mini-split system. Remember, there isn’t any ductwork involved, so the air coming out of the mini-split will only travel as far as the mini-split can push it. Homeowners then get forced to install additional mini-splits throughout the home, which pushes up the project’s overall cost.  

Mini-splits have multiple fan settings that allow for additional power to combat this problem. However, keep in mind that the higher settings use more electricity, which means higher operating costs and a drop in efficiency. 

Maintenance and Repair are Costly

Contrary to popular belief, the average mini-split will cost just as much in maintenance as a traditional heating and cooling system. Because your mini-split is a dual-purpose appliance that operates year-round, you should schedule maintenance every spring and fall. During a maintenance visit, an HVAC professional will clean and inspect each component of your mini-split system. 

They will check and clean the filters, coils, and units themselves and ensure no refrigerant leaks. You might be looking at between $150 and $300 per visit and an additional cost for any repairs made. If repairs are necessary, you’ll find that parts for your Mitsubishi are expensive, depending on which parts require replacement. 

Maintenance and repair for a mini-split system aren’t necessarily more than a traditional HVAC system but don’t fool yourself into thinking it’s cheaper. 

The Drainage System 

The drainage system for your mini-split heat pump is also a frequent subject of discouragement. Like all heating and cooling systems, mini-splits produce condensation as they cool the hot summer air in your home. This condensation accumulates in the indoor unit and travels through a pipe outside your home. 

Finding a good endpoint for the condensation is where things get tricky. Unless you want to construct an extensive piping system, the condensation typically ends up next to the outdoor unit. 

Additionally, mini-splits have a history of flooding in the indoor units. Because of how the drainage system gets set up and how the mini-split gets installed, there’s a chance for the indoor pipe to clog or kink. A clogged or kink drainage pipe means that condensation will gather inside the indoor unit and eventually overflow since it’s unable to travel to the outside. 

Installation Problem

Having spoken with numerous HVAC professionals over the years and installed over a dozen mini-splits myself, I understand firsthand the complications that routinely accompany the installation process. Mini-splits are advertised as easy-to-install, but they are anything but. We just touched on the drainage system, so let’s look at a few other possible complications. 

The Air Test 

One of the most crucial components of having an HVAC system that works is being able to vacuum down the refrigeration lines and perform an air test. While installers have no problem creating a vacuum in the refrigeration lines, gauging the vacuum level is difficult. Most mini-splits don’t have the same types of ports as traditional HVAC systems do, making it difficult to perform an accurate vacuum test. 

The Mounting

Additionally, there are several issues that inexperienced installers run into when mounting the indoor unit. There are many wires, pipes, tubes, and lines that all have to tuck neatly behind the hanging unit so that it can sit flush against the wall. It’s common for this tight fit to cause issues, especially with installers who are new to the mini-split game. 

Related Questions 

Do mini-splits use a lot of electricity? 

While mini-splits are 30% more efficient than traditional HVAC systems, they tend to use more electricity. This is especially true with an improperly-sized unit or on overly hot or cold days. 

Do mini-splits increase home value? 

Whether or not mini-splits increase a home’s value is dependent on the person buying the home. If they value efficiency and modern heating and cooling, then it very well could. Traditionalists, however, won’t always consider a mini-split as a benefit. 

Are mini-splits more efficient? 

Mini-splits are at least 30% more efficient than traditional air conditioners and 40% more efficient than window air conditioners. 

What is the life expectancy of a mini-split? 

Mini-splits, like most heat pumps and air conditioners, have a life expectancy of 10 to 30 years, depending on the brand and how well you maintain them. 

Final Thoughts 

Whether you’re a fan of mini-splits or not, there’s no doubt that they are the future of the heating and cooling industry. Their level of efficiency makes them one of the most desired HVAC systems on the market all across the world. However, it’s important to remember that they aren’t for everyone or for every situation. It’s also important to note that not everyone knows how to properly install a mini-split system, and you should search for an installer with adequate experience and knowledge.


Hubert Miles | Licensed Home Inspector, CMI, CPI

Hubert Miles is a licensed home inspector (RBI# 2556) with more than two decades of experience in inspection and construction. Since 2008, he has been serving South Carolina through his company, Patriot Home Inspections LLC. As a Certified Master Inspector, Hubert is dedicated to providing his expertise in home inspections, repairs, maintenance, and DIY projects.