Size matters when you’re buying a window air conditioner. Buy too small and it will struggle to keep the room at a comfortable temperature; buy too big and and the room will cool too quickly without removing enough humidity from the air. Buy just right and you’ll be comfy and save money too. At Consumer Reports, we test air conditioners in the size rooms that they're intended to cool. Here are the best small, medium, and large window air conditioners from our tests. Bedroom or office (100 to 300 square feet) For a small bedroom, home office, or guest room you’ll want an air conditioner with good scores for comfort and quiet. The GE AEM05LV, $170, a CR Best Buy, aced our comfort tests and was very quiet on both low and high fan speeds. The LG LW6016R, $175, was also excellent at cooling a small room and was very quiet on the low fan setting but a little nosier on high. The Frigidaire FFRA0511R1, $125, was a little nosier but the price is right. Master bedroom or playroom (250 to 400 square feet)

To cool a bigger or busier room, you’ll want to step up to a mid-sized air conditioner. The GE AEM08LT, $300, was tops in its class with excellent scores for cooling a medium-size room. It cruised through our brownout test, which tests if a unit can restart when voltage is low.  But it was a bit noisy when the fan was on high.central ac units used The LG LW8014ER, $240, a CR Best Buy, has very good scores for cooling and aced the brownout test.  car a c repair costsIt was also somewhat  noisy with the fan was on high.window type ac units Living room or family room (350 to 650 square feet) For a living room or family room, you’ll want a large air conditioner, especially if you have an open floor plan. The LG LW1214ER, $350, made our top picks list with its excellent scores for comfort.

And despite its size, it operates at a quiet hum. The Haier HWE12XCR, $310, was excellent at cooling but nosier than the LG. But it bounces right back in brownout conditions. Size up your needs Window air conditioners typically have cooling capacities ranging from 5,000 to 12,500 British Thermal Units (BTUs). But don’t buy by BTU alone. As a rule of thumb, an air conditioner needs 20 BTU for each square foot of living space but there are other considerations such as the height of your ceiling and the size of your windows and doorways. Energy Star recommends that you make adjustments for the following circumstances: If the room is heavily shaded, reduce capacity by 10 percent. If the room is very sunny, increase capacity by 10 percent. If more than two people regularly occupy the room, add 600 BTUs for each additional person. If the unit is used in a kitchen, increase capacity by 4,000 BTUs. To get the most from your window air conditioner, install it right.

If your window is not in the center of your room, check that the direction of the airflow is into the room, not into the corner. Here are some tips from EnergySavers.gov. Make sure it’s level so the drainage system works effectively.Some larger units need a dedicated circuit. Don’t put lamps or TVs near the air conditioner’s thermostat as the heat will cause it to run longer. Set the thermostat as high as is comfortable, typically 78° F. You’ll appreciate the savings. Don’t dial the temperature down when you turn the air conditioner on—it won’t cool the room any faster. On humid days, set the fan speed on low; the slower air movement removes more moisture from the air. Use an extra fan to spread the cooled air around. Energy standards for window air conditioners are getting tougher, making them cheaper to run. Look for an Energy Efficiency Ratio of 10 or above. The higher the EER, the more efficient the air conditioner. Look for models with filters that are easy to remove for regular cleaning.

All the air conditioners in our tests have remote controls, digital displays, and timers that you can set to cool down the room before you get home. —Mary H.J. Farrell (@mhjfarrell on Twitter) Designed to be built into the wall, these GE Air Conditioners do not have the side or top vents that are typical for window air conditioners. Built-in units offer a better weather barrier than standard window air conditioners and keep windows free of obstructions. Built-In Wall Air Conditioners Window AC units are portable, and are not installed into the structure of the home or building. GE window air conditioners are designed to fit traditional-style windows and come with our EZ-mount installation. Measure the square footage of the room or rooms to be cooled. If an exact match of cooling capacity is not possible, it is preferable to select a unit which is slightly undersize in BTUs, rather than oversize. If the area to be cooled includes a kitchen, add an additional 4000 BTU/hr.

When sizing larger living areas, it is usually better to use at least two air conditioners rather than one large unit. Doing so offers better air distribution which reduces the likelihood of hot and cold spots. The cooling capacity of window air conditioners is measured in British Thermal Units or BTUs. The air BTU rating refers to the cooling power of the product. It is critical that the capacity of a room air conditioner be the right size for the room being cooled. An improperly-sized air conditioner can result in a cold, clammy environment or an inadequately cooled room. What size GE room air conditioner is right for you? * Based on an 8-ft. ceiling height. Size requirements will vary based on other factors. This will be my first time purchasing a window unit, and I'm a little confused. Most charts indicate that a 7,000 BTU unit is appropriate for a ~250 square foot room, however from what I can tell, these do not exist (only 6,000 and 8,000 BTUs are available).

Also, none of the guides I see mention ceiling height, which I figured would be important (i.e. cubic footage seems more appropriate than square footage). Finally, many say that getting a unit that is too powerful actually won't cool as effectively, but don't really explain what this means exactly - if I put a 20,000 BTU unit in a 100 square foot room, would the room really be warmer than it would be with a 5,000 BTU unit? Or do they just mean that it would be overkill? Finally, some 6000 BTU units, like the GE AEL06LS say that they are only appropriate for 150 square foot rooms, and I don't understand why. Anyway, my room that is 233 square feet, with ~9.5 foot ceilings. Would it be best to get a 6000 BTU unit or a 8000 BTU unit? The EPA has room size to BTU chart with some caveats for certain situations: Room size A/C size 100 up to 150 -> 5,000 BTU/hr 150 up to 250 -> 6,000 BTU/hr 250 up to 300 -> 7,000 BTU/hr 300 up to 350 -> 8,000 BTU/hr 350 up to 400 -> 9,000 BTU/hr

400 up to 450 -> 10,000 BTU/hr 450 up to 550 -> 12,000 BTU/hr 550 up to 700 -> 14,000 BTU/hr 700 up to 1,000 -> 18,000 BTU/hr 1,000 up to 1,200 -> 21,000 BTU/hr 1,200 up to 1,400 -> 23,000 BTU/hr 1,400 up to 1,500 -> 24,000 BTU/hr 1,500 up to 2,000 -> 30,000 BTU/hr 2,000 up to 2,500 -> 34,000 BTU/hr Make any adjustments for the following circumstances: Consider where you install the unit. If you are mounting an air conditioner near the corner of a room, look for a unit that can send the airflow in the right direction. If you fall into any of those special situations, that may help you with sizing. Otherwise, since you're between sizes of available units, unless your climate is particularly mild, I'd go up a size to allow a bit extra cooling capacity for hot days. Height doesn't matter because cold air sinks. Regardless of the ceiling height, you only need to cool the bottom 6-7 feet. And none of these "room size basis" metrics pay any attention to the question of "what is the insulation level" "how much solar heat gain is there" "what is the window area and insulation"...since most consumers don't know - so they have handy rules of thumb...