The 10 Ways that Mini-Splits Pay for Themselves
Why exactly did it take so long for mini-split heat pumps (or mini-split air conditioners, for units without a reversing valve) to make it in in the U.S.? After World War II, whole-house heating became common. And, this same ductwork was easy to leverage for air conditioning by simply adding an a/c cooling coil. Meanwhile, in Europe, radiative heating was still more of a standard, and in Asia, localized heating (e.g., with kerosene) was commonplace. So, without any existing ductwork, but with the advent of air conditioning, the Japanese needed a small, quiet, ductless air conditioner for their sweltering summers and closeknit living quarters. The mini-split, first developed by Mitsubishi there, fit the bill, and was also a hit in Europe. Meanwhile, here in the U.S., if whole-house cooling wasn’t needed, or if the cooling load was small enough, window air conditioners were (and still often are) the path to comfort. If they didn’t exist, someone would eventually invent them for their simplicity and affordability. And yet, they tend to be loud, mostly because their condenser is really not behind the wall…it’s just behind the front of the unit. And they’re inefficient compared to mini splits, since both the indoor and outdoor coils are tiny, so the compressor needs to work harder. Next, they can present a break-in risk if the units are installed on the first floor of a house or apartment. It doesn’t take much for bad guy to yank them out of the window and crawl into the space. Finally, it seems like they never seal quite right around the window, and as such, on top of not being well insulated in this area, mosquitos and other vermin can sneak in, offsetting any comfort afforded. Oh, and they tend to block your view out the window.
So, the mini-split have reached the U.S. beach, solving these challenges in a price range that’s usually a bit more than a window unit (especially when considering the installation cost), but a lot less than whole-house cooling. With over $58 billion worth of units already installed, and another $34 billion forecasted to be installed by 2031, the mini-split market is growing nicely. Why are people latching on?
- They’re a problem solver to give cooling to a room without adding ductwork to the main unit for a house or taking away from the capacity of that unit to cool the rest of the house. And, the electrical installation is simple, since the outdoor unit usually also provides power to the indoor unit. And, for 12,000 BTU units, it’s possible to get a 110 -120v unit—just plug it in like any other device, no 220 – 240v wiring or electrician is needed. Oh, and no thermostat wiring is needed, since the included remote control and/or app takes over that function.
- This cooling is almost always less (in terms of $/BTU delivered) than the existing unit. The reason for this is that few whole-house air conditioners or heat pumps have SEER values in the +/- 20 neighborhood. Most installed units are at or below 14 SEER, and even less efficient when duct losses are taken into consideration. How much are duct losses? According to a Department of Energy Study, they vary from 20% to 40%! Why? Duct leaks (common), poor design, and poor insulation. So, really, delivered BTUs gets you down to only around 10 SEER.
- A bonus in the efficiency department is that if you install a mini split in a bedroom or a home office where you tend to spend a lot of time, you’ll save 2 to 3% for every degree you can increase the temperature of your main unit, according to APS (Arizona Public Service, AZ’s largest electric utility). So, set your office unit to a comfortable 75 degrees Fahrenheit, say, and set your main unit to 80 degrees, and you’ll save 12.5% (averaging the 2% and 3% to come up with 2.5%/degree increased, and multiplying this by 5 degrees). Nice savings for simply not cooling rooms that don’t need much (or any) cooling.
- They’re extremely quiet, with an average dB rating of 38 for the indoor units, vs. 58 for a window air conditioner, making window units around 4x louder than the indoor units for mini-splits.
- They’re more comfortable for the home’s occupants than traditional units. They have a tighter temperature dead band, Many now have variable-speed fan motors and variable-speed compressors, which in addition to adding to the aforementioned efficiency quietness, they also add to comfort. Why? They don’t constantly surge on and off. Instead, they run at a slower speed, but run all of the time, so you don’t go from being too hot waiting for a traditional unit to come on, and then too cold just before a traditional unit turns off. They have a tighter temperature range, or dead band, because of this. And, 3-ton and up mini spits come with 2 or more indoor units, so one can be in a bedroom, one in a family room, etc., allowing the occupants of a given room to adjust the temperature for their area as they see fit. And, this of course in turn saves energy, since you don’t need to run the indoor unit in any unoccupied rooms, so more energy savings, too.
- Do-it-yourself units are becoming available, so you may be able to install one of these units yourself; or, if you need to hire someone, the job should be quick and easy if you have the installer start with a DIY version. These units usually come with a pre-charged or pre-vacuumed refrigerant line, so you don’t need a vacuum pump or gauges. Some like Airspool’s Quick and Easy also have the electrical panels pre-wired.
- Washable filter. Filters can be upward of $10/month on whole-house units. Sure, you’re still going to need those, but if the run time of your main unit is, say, 20% lower, than means 20% less return air going through the filter, and 20% fewer filters.
- Updated control systems. Many, and soon most, mini spits have an app to control and schedule the unit remotely. If you want to add a smart thermostat to your main unit, you can of course do this, but it’ll cost you some time and $100 to $200.
- Most also do heating. These mini split units, known as heat pumps, mean that you can save on heating, too. To do this, the refrigerant directly is simply reversed, and the heat is move from the outside in the winter and moved into your home. Yes, there is heat outside in the winter! It’s all relative. Between around 30 degrees Fahrenheit and 65 degrees Fahrenheit, heat pump heating is more than 3x less costly than electric baseboard heating, and even less costly than burning natura gas. To make a mini split air conditioner into a mini split heat pump, a part known as a reversing valve is included. For a few dollars more for the controls and this reversing valve, you have yourself an efficient heater!
- And, units that are super efficient also may be Energy Star certified, giving purchases are 30% tax credit via the Inflation Reduction Act. Check the database here. Requirements are SEER2 of 16 (for cooling efficiency), HSPF of 9 (for heating efficiency), and EER2 of 12 (for cooling efficiency without taking into account seasonality). So, 30% off, in effect, for both the unit and any outside installation labor used for the project.
In short, mini splits provide a relatively-easy path to efficient and effective home heating and cooling that should only get more efficient and effective over time. Some of these units can now heat to 15 degrees below 0 Fahrenheit, quite a feat given that they are capturing the heat from outdoors and bringing it indoors. Soon, you’ll see more of these supplanting whole-house heating and cooling systems for many of the reasons outlined above.