Heat pump vs. mini-split: What’s the difference, and which is right for you?

So you’re ready for an HVAC upgrade, and you’re interested in a heat pump. Now, what’s all this about mini-splits?

Some of the terminology around heat pumps can get a bit confusing, and it isn’t helped by the fact that sometimes people use different terms for different things. What you want to ultimately know is how to affordably, comfortably, and most easily heat and cool your home. So let’s start with a basic refresher: what is a heat pump?

A heat pump is a highly efficient, fully electric, and versatile system capable of both heating and cooling your house. During warm months, a heat pump operates like an air conditioner – it uses indoor air handlers, refrigerant lines, and outdoor compressors to take heat out of the air inside your home and transfer it outside.

In the winter, even in very cold climates, it does the reverse; it takes heat from the outside air and brings it inside to warm you up. There’s a whole bunch of physics and laws of thermodynamics that makes this technology possible.

So what’s a mini-split? It is, in fact, a type of heat pump. Beyond that, however, the definition can depend on who you ask:

• Some HVAC professionals focus on specific technical features, such as whether the compressor has an inverter, a component that adjusts the unit’s speed based on heating or cooling demands.

• Others define it by the system’s ability to allow indoor and outdoor units to communicate for better temperature control.

But if you surf the web, you’ll see that the term “mini-split” is usually used much more colloquially, often referring to the types of wall-mounted, ceiling, or floor heat pump equipment installed in individual rooms. The most important thing to know about these units is that they directly heat or cool a specific space without requiring any ductwork. That’s a major distinction from heat pump systems that use ductwork to push warm air throughout the house like a central HVAC system.

This all makes for a bit of a rhetorical headache. But usually, if somebody is wondering if they should install a heat pump or a mini-split, what they’re actually asking is whether to install a ducted or ductless system.

“There’s a lexicon of terms,” said Rabi Vandergon, who leads the Minnesota Air Source Heat Pump Collaborative at the Center for Energy and Environment, a Minnesota clean energy nonprofit. “We're trying to center the discussion on ‘ductless’ and ‘ducted.’”

With that distinction out of the way, let’s dive into the factors you should consider when determining whether a ductless or ducted system is best for you and your home.

A ductless mini-split system uses an outdoor compressor that is connected by refrigerant lines that typically run along the outside of the home to one or multiple air handlers, which are often mounted on walls and referred to as a “head.” You’ve likely seen them around: they’re maybe three feet long and a foot tall, and are controlled by a remote. While wall-mounted models are the classic version, so to speak, manufacturers are increasingly offering ceiling- and floor-mounted air handlers that serve the same function but bring a different aesthetic touch.

Depending on the size, layout, and heating needs of your home, you may want or need several heads. For example, a home with an open plan on the first floor and three bedrooms upstairs may want two heads downstairs, and a head in each bedroom. Mini-splits come in different sizes that can appropriately heat everything from a small room to a large open space; a contractor will help you determine the right models.

A single outdoor compressor can serve several different indoor heads – up to eight for some manufacturers. However, whether it can fully support that capacity will depend on a number of factors, including the efficiency of your home and how much sunlight it receives. A contractor can help you determine what makes sense for your home.

Advantages of ductless mini-splits

Using ductless mini-splits offers several advantages, especially if you don’t already have adequate ductwork in your home. The work necessary to install the equipment – running refrigerant lines outside between the head units and the converter – is much simpler, quicker, and less disruptive than adding new ductwork throughout the house. 

Ductless mini-splits also allow you to separately control the temperature in different parts of your home, creating different zones and potentially saving you money by adjusting the heat or cooling as needed. And they’re also a great option if you only need to heat one room in your home, such as a newly finished basement or an added room that is not connected to your home’s existing ductwork.

Alternatively, if you have ductwork throughout your house, or are doing a major addition and can design ductwork into the plans, it may be easier to just install a heat pump with a larger air handler in your basement or utility closet and rely on those ducts to heat and cool the entire house. These types of systems are typically controlled with a wall thermostat.

According to the U.S. Energy Information Administration, the majority of homes across the country are equipped with ductwork, including nearly all homes built this century. You may very well be able to take advantage of that and save yourself a lot of money on the installation. (As relatively easy as ductless mini-splits are to install, doing so is still more complicated and labor-intensive than just setting up a heat pump system that blows air through ducts, which shows up in the price tag.)

Beware, however, that some ducts may not be suited to deliver the air you need to properly heat a home. That’s because heat pumps do not generate air as hot as a gas furnace, so the ducts need to be wider in order to deliver more air to make up for that difference. A contractor will help you determine whether your ducts are appropriate.

Advantages of a ducted system

A ducted system is likely the more affordable option if you have suitable ductwork already installed. Some people also prefer the aesthetic of not having mini-split heads on their walls, floors, or ceilings.

Several factors will play a role in determining how to best heat your home, and the best answers will likely differ considerably from home to home and from place to place. However, there are some key variables to consider:

Your home’s existing infrastructure

If you already have appropriate ductwork, you’re probably going to want to use it.

If you like the idea of a more centralized system without mini-split heads but don’t currently have ducts, you could of course have them installed. But be warned, that is a major home renovation project that will significantly expand the cost.

“If a customer has the ductwork, it is probably the most practical to just stick with that kind of heating or cooling distribution. And if they don't, that's where a ductless system is probably more logical,” said Vandergom at the Center for Energy and Environment.

Your comfort and preference

Let’s not forget the major advantage of the ductless system, though; this is the best way to zone your heating and cooling, allowing you to control the temperature in each individual room or space. If that’s important to you, or if heating and cooling can be uneven across your house, then you may want to rely more on mini-splits. 

Jared Grier, owner of Cape Cod Heat Pumps in Massachusetts, said it is possible to install dampers on your ducts to create different zones throughout the house, but they are typically not as effective as just installing new ductless mini-split heads.

"We zone with equipment, not with zone dampers,” he said.

Notably, this does not have to be an either-or proposition. Depending on the attributes of your home, it may make sense to operate both a ducted heat pump and ductless mini-splits.

Imagine, for example, a two-story house with ducts, in which heating and cooling tend to work pretty well downstairs but struggle to to get fully revved up on the second floor. In that case, you may want to install ductless mini-splits in the upstairs space while relying on ducts downstairs, Grier said. This, of course, will add to project costs.

There is another type of solution that could serve this scenario well – installing a separate air handler in the attic or an upstairs wall, and running a small amount of ductwork off of it into the rooms.

On the other hand, a single-story house with suitable ductwork probably would not benefit from any ductless mini-split heads.

Again, the right decision will depend on various factors – everything from the amount of energy required to heat different rooms, your budget, and other concerns that you can discuss with a contractor. But home infrastructure is going to play a major role.

Ducted heat pump systems are less efficient than ductless mini-splits. That’s because some air will inevitably be lost as it moves from the heat pump, through your home’s ducts, and into your separate rooms. Ductless systems, by contrast, handle air in the room they’re intended to heat or cool. 

However, the amount of energy that is lost to the ducts is relatively miniscule and unlikely to noticeably affect your energy bill, Grier said, so it should not be a major factor in determining the right setup for your house. And the better sealed the ducts are, the less they’ll lose.

The costs to install a heat pump system can vary dramatically, depending on factors ranging from the attributes, age, and location of a home to idiosyncratic swings from contractor to contractor. 

Recent research from EnergySage shows that in some places, installing a ducted system can be significantly cheaper than a ductless system:

• In Massachusetts, we found that the median ducted system cost about $12,000, whereas the typical ductless system included 4.5 zones and cost $17,500.

• In Colorado, however, it was actually more expensive to install a ducted system, but that is likely because the typical ductless system in that state used fewer indoor units.

Another way of thinking about it: Each individual ductless mini-split zone is likely to cost between $4,000 and $6,000. So the more places to heat or cool, the more you’ll wind up paying – a reflection of the costs of equipment, as well as the labor and infrastructure work that goes into installing it.

A typical ducted heat pump will likely cost something more like $15,000, according to EnergySage’s research.

Unless you have a very strong preference between ducted or ductless systems, you can’t really compare the financial considerations in a vacuum. Instead, it’s going to be guided by the pre-existing conditions of your home – namely, whether you already have appropriately sized ducts and how many units you’ll need to heat and cool your space to your comfort.

But in either case, you should be aware of some potential added costs, such as taking efficiency measures to ensure your home retains all the warm or cool air you’re bringing in and, if you don’t already have adequate electrical service, electrical upgrades that could run thousands of dollars. These, too, are things a contractor will be best suited to discuss as they check out your home.

You’ll also have the opportunity to recoup some of the costs through various incentives. As part of its effort to drive down carbon pollution, the federal government offers tax credits worth 30% of the cost of a heat pump installation, up to a maximum of $2,000, when you file for the year you installed the equipment. In addition, many states and utilities offer additional rebates that can shave thousands of dollars (in the case of Massachusetts, $10,000 or more) off the price.