10 Best Through-The-Wall Air Conditioners 2026 in the United States

The Keystone 12,000 BTU through-the-wall air conditioner is designed to cool medium-sized rooms up to 550 square feet effectively. Its cooling capacity is well suited for bedrooms, bathrooms, and nurseries, providing three cooling modes and three fan speeds, which allows you to customize comfort. The unit includes a built-in dehumidifier removing about 2.3 pints of moisture per hour, which is helpful in reducing humidity alongside cooling. At 56.5 decibels, the noise level is relatively quiet for an air conditioner of this size, making it suitable for spaces where low noise is appreciated.

Energy efficiency is decent with a Seasonal Energy Efficiency Ratio (SEER) of 10.5, and features like 'Energy Saver' and 'Sleep' mode help keep electricity costs down. It lacks a BEE star rating, which some may consider when comparing energy use. The dimensions (20.3"D x 24.2"W x 14.5"H) mean it requires a compatible wall sleeve for installation, but the included universal trim kit simplifies this process and keeps the look neat—plus, it saves window and floor space.

Additional features include a smart remote with an LCD screen that measures room temperature and adjusts settings regularly, a filter light reminder, and a programmable timer, enhancing usability. The unit runs on 230 volts and uses 1142 watts, which is typical for an AC of this size but might require electrical compatibility checks. The weight (78.1 pounds) may require professional installation. The one-year warranty on parts and labor, plus an additional four years on the sealed system, offers reasonable peace of mind. This air conditioner is a solid choice for someone looking for a reliable, moderately energy-efficient, and convenient through-the-wall cooling solution for medium rooms.

The Keystone 18,800 BTU Window-Wall Air Conditioner is a versatile unit that is well-suited for cooling and supplementally heating large spaces up to 1,000 square feet. With a substantial cooling capacity of 18,000 BTUs and a supplemental heating capacity of 16,000 BTUs, it can provide year-round comfort. However, it's important to note that the heating function is meant to supplement rather than replace primary heating sources, particularly when outside temperatures range between 23°F and 76°F.

This unit also offers dehumidification and fan-only modes, adding to its utility. The I Sense remote is a smart feature that ensures consistent comfort by regularly transmitting room temperature readings to the unit for accurate cooling adjustments. For energy-conscious users, the 'Energy Saver' and 'Sleep' modes can help reduce electricity bills, although it's worth mentioning that the unit is not Energy Star certified. Measuring 25.39 x 23.62 x 17.91 inches, it fits well in standard wall sleeves and comes with a window installation kit for flexibility. At 55 dB, the noise level is moderate, which might be a consideration for those sensitive to sound.

Additional features like a filter light reminder and a 4-way swing enhance convenience and airflow control. Despite its weight of 117.3 pounds, installation is manageable with the included kit. Its Seasonal Energy Efficiency Ratio (SEER) of 10.7 might be on the lower side compared to other models. The Keystone unit comes with a 1-year parts and labor warranty, plus an additional 4 years for the sealed system, offering peace of mind for potential buyers. This air conditioner is a strong contender for those needing reliable cooling and supplemental heating for larger rooms, though its noise level and lower energy efficiency might be points to consider.

The Keystone 23,200 BTU Window-Wall Air Conditioner is designed for large rooms up to 1,500 square feet, offering strong cooling power that can handle big spaces effectively. It also includes a 16,000 BTU supplemental heating feature, which is handy during milder cold days but shouldn’t replace your main heating system. With a Seasonal Energy Efficiency Ratio (SEER) of 9.4 and a 4-star BEE rating, it provides decent energy efficiency, helping to keep electricity bills reasonable, especially when using its 'Energy Saver' or 'Sleep' modes.

Its dimensions are fairly compact for the cooling power it delivers, measuring about 25.4 inches deep and 23.6 inches wide, fitting standard wall sleeves and even comes with a window installation kit for added flexibility. Noise-wise, it runs at around 56.3 decibels, which is moderate—noticeable but not overly loud for most home environments.

Additional features include a smart remote control that senses room temperature and adjusts settings accordingly, a dehumidifier to reduce moisture, and a 4-way swing for better air distribution. These extras improve comfort and convenience, making it more than just a basic cooling unit. The unit is quite heavy at 121 pounds, which may require professional help for installation. The supplemental heating is limited to certain outdoor temperature ranges, so it’s not a full heating solution. While energy efficiency is good, it is not the highest available for those prioritizing power savings. Some users have noted that the noise might be distracting in very quiet settings. This model is a solid choice for those needing powerful cooling and occasional heating in large spaces, wanting added comfort features, and preferring an in-wall installation to save floor space.