Larger Air Conditioners

Window AC units for larger rooms

If you need a window air conditioner for a room that's over about 450 square feet, you'll need something larger than about 10,000 Btu. Most air conditioners in this size range come with a slide-in chassis, which makes installation more secure.

In this size range, the 10,000-Btu Kenmore 75101 (*Est. $270) is Energy Star-rated and should cool a room of about 500 square feet. We found some nice owner-written reviews for this model, which is inexpensive for its size. Most reviews and owners say it's relatively quiet. One noted that although airflow is good, it blows primarily to the left. This may be a consideration, depending upon where you plan on placing the air conditioner. This Kenmore air conditioner has an auto-restart in case of a power outage. It also comes with digital controls and a remote control. An energy-saver mode turns off the compressor when the desired temperature is reached, further saving energy. Like many larger window air conditioners, the Kenmore has a slide-out chassis. That means you install the outer shell of the unit first, then slide in the heavier "guts" of the unit. Although they take longer to install, reviewers say this kind of installation is ultimately more secure.

Frigidaire's FAC106P1A (*Est. $270) is another good choice for larger rooms. This 10,000-Btu unit has received some good reviews and is Energy Star-rated. However, unlike the Kenmore model, the Frigidaire doesn't have a slide-out chassis. That makes it a little harder for one person to install without help. This model has all the usual features, including a digital display and remote control. An anti-microbial filter is supposed to reduce bacteria, room odor and other airborne particles (we didn't see this tested). It also has brownout protection. We did see a few complaints that the Frigidaire FAC106P1 isn't particularly quiet, however.

The Friedrich QuietMaster SS10L10 (*Est. $865) is the class leader in efficiency for its size. This room air conditioner is rated at 10,400 Btu, yet it attains an EER of 12.0, higher than any other model. It is also one of the quietest air conditioners in its size range. Although QuietMaster performance is impressive, experts say Kenmore units cool just as well for less money, though TheGreenGuide.com does recommend this model.

For a larger area of about 600 sq. ft., the 12,000-Btu Kenmore 75121 (*Est. $300) receives more recommendations than most air conditioners of any size. As with most larger units, it has a slide-out chassis and can be a bit time consuming to install. It does include a nice range of features such as electronic controls, auto restart, remote control, temperature display, timer and energy saver mode. Interestingly, we saw several comments from owners at Sears.com stating that this particular air conditioner works well enough to cool a small one-story house. In professional tests, the Kenmore 75121 air conditioner performs well and is quieter than most.

It's important to note that window air conditioners are intended to cool a single room, and few homes have rooms large enough to require an air conditioner of more than about 12,000 Btu. For whole-house cooling, experts say a central air conditioner or multiple window units are more effective and use less energy than a single high-powered window unit (even with strategically placed fans).

Still, there are some situations where a very high-Btu window unit can be a good idea. If you live in a very hot, humid climate -- such as the subtropical portions of Florida and South Texas -- standard Btu-per-square-foot charts won't accurately reflect the amount of cooling power you need. Similarly, if you have a lot of appliances or electronics (especially high-end computers) that generate heat in a single room, you may need a more powerful air conditioner. Unfortunately, professional reviews don't typically cover very high-Btu air conditioners, and there aren't a lot of owner comments for these models at retailer websites.

One high-capacity air conditioner that gets good reviews from owners is the 18,500-Btu Frigidaire FAM18ER2A (*Est. $655). This Energy Star-rated model includes a built-in 16,000-Btu heater, so it makes sense to leave it installed year-round -- a major benefit, since owners report it can be quite difficult to install (it weighs almost 120 pounds). As with most large air conditioners, it has a slide-out chassis for stability. It also includes a remote control, energy saver and sleep modes, 24-hour timer and electronic controls. Owners say it does a great job cooling and is fairly quiet. Be advised that this air conditioner does require a 220-volt outlet, which can further complicate the installation.

A less expensive option, the 18,000-Btu Kenmore 75180 (*Est. $430) has similar features but skips the built-in heater. Owners don't report as many difficulties installing this unit, which weighs 112 pounds, but we read quite a few complaints about noise. It's also not as efficient as the Frigidaire air conditioner. As with most high-capacity air conditioners, this model requires a 220-volt outlet.

If you need even more cooling power, the 24,500-Btu Kenmore 75251 (*Est. $570) is one of the most powerful residential window air conditioners available. This AC unit is Energy Star-certified, but it still uses a lot more energy than a smaller unit. It includes electronic controls, a remote control, timer and energy saver mode. It does require a 220-volt outlet and weighs about 150 pounds, so installation can be tricky. Owner reviews for this model are mixed -- while about half of the comments we read at Sears.com were very positive, the other half complain of breakdowns and noise.