The ductless mini-split system is a heat pump suitable for many homes and provides an energy-efficient climate system. It contains two parts: an outdoor unit and one or more indoor units, which can easily be suspended from a wall, mounted on a wall, or set on the floor (as shown in the next figure). This is a split system, meaning that the two main environmental units—the one designed primarily for the outdoor climate and the one designed primarily for the indoor climate—work primarily but not exclusively with each other. Indeed, the biggest selling point for these systems is that they are ductless, which means that they do not have the kind of long horizontal and vertical connected ducts that are often found in older homes. If a home does not have the kind of duct system that air conditioners traditionally work with, then it is a candidate for a ductless system.
When selecting a ductless mini-split system, you must consider both the size and the comfort demands of the area in question. If you wish to control the climate throughout your entire home, a multi-zone system might be for you, allowing different areas to be regulated independently. Each indoor unit is fully customizable as to the temperature settings and times of operation, so if you wish to have the unit in your master bedroom running at a low temp all the time, while the unit in your living area only runs when you’re down there, it could be done. If going that route, it’s worth saying that the kind of individual control you can get in a place with a multi-zone system is on par with any level of control you might have in a home that is fully ducted. If you aren’t looking to spend that much, a single-zone system is a good way to target one specific area, but it’s also a good way to not invest in an area that’s poorly connected to your existing HVAC systems.
When choosing a ductless mini-split system, it's also important to consider the technological features that match your lifestyle. Many modern systems have smart technology, which allows you to control the system from an app on your smartphone or with a simple voice command. These are useful for any kind of household, and especially for one that might keep erratic hours. And if you might get a Rebates for Efficiency program, because even the most sophisticated systems will net you inefficiency points that could lower your rebate or raise your taxes. That alone suggests you should aim for an Energy Star model. Another feature that speaks well of a system's worth is its variable speed compressor. And as we said, some models do indeed come with a compressor that speeds up and slows down naturally—like a human breath—when energy demand changes. Finally, consider the quietness of any system. Bedroom, living area, or "anywhere I might be" quietness is very seriously important for ducted mini-split systems.