The Best Over-the-Sill Air Conditioners of 2024

Over-the-sill air conditioners feature a unique design, but are they worth the cool cash? Use this guide to learn what we found out through hands-on testing.

Best Overall

The Best Over-the-Sill Air Conditioner: Soleus Air Over-the-Sill Air Conditioner

Soleus Air Over-the-Sill Air Conditioner

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Over-the-sill air conditioners have some huge benefits. These units have upside-down, U-shaped designs that saddle the window sill. The noisy stuff, such as the compressor and other mechanicals, lives outside while the fan and control panel (the quieter stuff) hang below the window, inside the house. This allows folks to open and close the window as they wish while enjoying less noisy operation—the best of both worlds.

But which is the best over-the-sill air conditioner? I think it’s the 6,000 BTU (British thermal units) model from Soleus Air. It’s quiet, provides plenty of power, and lets me open my office window anytime I want to. But is it perfect? Find out in this over-the-sill air conditioner review.

How We Tested the Best Over-the-Sill Air Conditioners

Air conditioners aren’t cheap, so we wanted to make sure that any model we suggested was truly up for the task. For that reason, we performed hands-on testing with the Soleus Air over-the-sill air conditioner to ensure it has what it takes. What’s more, we tested it along with multiple other air conditioners so we had some data to compare it to.

First, we installed the units and assessed that process. We noted how heavy or difficult the air conditioners were to lift and maneuver, as well as how easy or difficult it was to position and adjust each air conditioner according to the manufacturer’s instructions. Next, we cycled through the different modes and adjusted each AC to run at our desired settings. We allowed each model to run through hot weather, taking note of how quickly it cooled the room. We also assessed how quietly each model ran. Throughout these tests, we found the Soleus Air to be the best over-the-sill air conditioner.

Best Overall

Soleus Air Over-the-Sill Air Conditioner

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The Soleus Air over-the-sill air conditioner was my top choice for the best over-the-sill air conditioner. This model comes in three sizes; 6,000, 8,000, and 10,000 BTU (the largest of which also features heat). I tested the 6,000 BTU model, which features several modes, including air conditioner, auto, dehumidifier, energy saver, sleep mode, and MyTemp Sensor. A digital remote control is included. The unit boasts a low volume level of 38 decibels (dB), though in testing I clocked it at 42 dB.

Installing the Soleus Air over-the-sill air conditioner is a bit of a mixed bag. The installation itself is very easy, as the unit simply sits over the existing sill and the user adjusts two legs under the unit to level and secure the air conditioner. However, the air conditioner weighs about 68 pounds, and it’s longer front-to-back than standard window units, so it proved quite an armful to hold, maneuver, and get into place. However, once it was positioned properly, I was able to open and close my window whenever I liked, and the unit itself didn’t block my view or natural light.

Using the unit was simple as well. The digital display made the adjustments easy to toggle through, and the remote displayed all of the important readings, preventing the need to squint across the room at the air conditioner while making adjustments. The MyTemp sensor is also built into the remote. In this mode, the air conditioner uses the temperature sensor in the remote as a thermostat. As the air temperature in the space around the remote fluctuates, the air conditioner will turn on and off automatically.

My only complaint beyond the size and weight of the Soleus Air unit is something that appears to be unavoidable with all over-the-sill ACs: the necessity to drain condensation from the unit every few days. This involves pulling a silicone plug from the side of the unit and draining the collected water into a large jar or other container. While this doesn’t sound like a big deal, standard window units drain themselves, and users never have to worry about this step.

That chore aside, I really enjoyed this unit. It was one of the only air conditioners in the test that was suitable for use in my office, as the others were too loud to run during conference calls. It cooled my small-but-uninsulated office in short order—it only took about 10 minutes to go from 80 degrees Fahrenheit to 74 degrees Fahrenheit.

Note: My air conditioner is the 2021 model and does not have Wi-Fi. Newer models do have Wi-Fi and use the Soleus Air app, but I can’t speak to the app’s user-friendliness or compatibility.

Product Specs 

  • Size: 6,000 BTUs
  • Display and setting type: Digital
  • Additional features: Saddle style, remote control, Wi-Fi


  • Doesn’t block natural light or outside view; user can open the window once the unit is installed
  • MyTemp sensor will adjust the air conditioner’s output based on where the remote control is placed in the room
  • Runs very quietly compared to most other air conditioners (I clocked it at 42 decibels in my office)


  • It weighs 68 pounds, so it can be an armful to get it in place
  • Users must drain the condensation every few days, although this is a standard procedure with over-the-sill air conditioners

Get the Soleus Air over-the-sill air conditioner at Amazon.

More Over-the-Sill Air Conditioners Worth Your Money

The following are some other air conditioners worth checking out. The first option is a standard over-the-sill model, while the second is a U-shaped model, which has some significant differences but similar benefits (primarily window opening and noise level).


Those who want more information about choosing an over-the-sill air conditioner—or about our Best Overall pick—can read on for answers to two of the most frequently asked questions on the topic.

Q. What is the most efficient air conditioner design? 

U-shaped and over-the-sill air conditioners are some of the most efficient designs. These models separate the interior space from the exterior better, and many utilize inverter technology. This allows the air conditioner to regulate its electrical draw based on the machine’s needs and settings.

Q. What are the modes of Soleus Air?

The Soleus Air over-the-sill air conditioner offers auto mode, air conditioner, dehumidifier, energy saver, sleep mode, fan, and “MyTemp Sensor.” The largest Soleus Air model even features heat.

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Tom Scalisi


Tom Scalisi is a freelance writer, author, and blogger with a passion for building. Whether it’s a DIY project or an entire website, Tom loves creating something from the ground up, stepping back, and admiring a job well done.