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. The LG LW8014ER, $240, a CR Best Buy, has very good scores for cooling and aced the brownout test.  hissing noise coming from ac unitIt was also somewhat  noisy with the fan was on high.haier ac unit blowing water Living room or family room (350 to 650 square feet)car air conditioner repair rochester ny 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)Home / Other Calculators / BTU Calculator The BTU Calculator can estimate the amount of BTUs you will need to heat or cool your home, based on the size and the temperature you want for your home.Please note that this calculator can only gauge a rough estimate. You should also consider factors like efficiency decrease of the heater or air conditioner with time, the shape/type of your home or room, insulation conditions, and other factors. 1 watt is approximately 3.41214 BTU/h. good (very few leakages or windows) poor (many leakages or windows) Temperature to Increase or Decrease Depending on your local winter/summer temperature,e.g. 75F for Boston winter, 35F for Atlanta winter. Free Estimation of Your Heating or Cooling Project >>Reference

The British Thermal Unit, or BTU, is an energy unit. It is approximately the energy needed to heat one pound of water for 1 Fahrenheit. 1 BTU = 1,055 joules. 1BTU/hour = 0.293 watt. One very well-insulated 1,000-square-foot home in Boston needs around 24,000 BTUs to heat in winter. One 2,000-square-foot-home with normal insulation conditions in Washington, D.C., needs a 48,000 BTU air conditioner for adequate cooling in summer. Other CalculatorsLoveIP SubnetGas MileageConversionGPAGradeTime CardTime ZoneHeightGDPConcreteMarriageAgeMore Other CalculatorsFinancial | Air conditioner BTU requirements: this article provides an air conditioner BTU chart shows how to choose a room air conditioner for window or through-wall mounting. We provide room air conditioner or window air conditioner BTU sizing & choice charts. We also show how to actually calculate how much BTU cooling capacity you need based on building area or square feet, and we warn about dehumidification problems if you buy an air conditioner that is too big for the space you are cooling.

Portable, window, or through-wall air conditioners are typically described by their manufacturer as suited for: The table below gives recommended air conditioning BTU's necessary to cool a single room. The data in the table assumes that the ceiling over the room is insulated and that the room is not over or is not itself a special heat-producing area such as a kitchen or boiler room. Table 1: Base BTUs - Recommended Air Conditioner BTUs Calculating BTU Requirements: instead of using the table above, and particularly where factors may make the table inadequate (examples are given just below) you may want to CALCULATE the BTU COOLING REQUIREMENT using the procedure given below in this article. Ceiling height variations: BTU capacity tables for air conditioner selection typically assume typical 8 foot ceiling heights in residential spaces. If your ceilings are significantly higher, say 14 feet or more, you may want to use the next larger room area size when selecting the BTUh capacity needed for your air conditioner, particularly if your building is located in a hot climate with higher heating loads.

Building heat gain rate variations: in locations of high heat gain or high solar gain such as a significant exposure to direct sunlight or many sun-facing windows, or for buildings with little insulation, you may need to select a higher-capacity air conditioner than given by the table.of a typical home can be cooled per ton of cooling capacity: that is, one ton (or 12,000 btuh) of air conditioning can cool about 500 sq.ft. But the real answer is, it depends. Some of the factors that affect the ability of an air conditioner to cool a space need to be considered besides just the number of square feet. These include at least the following questions about air conditioning load and cooling requirements: Watch out: Do not buy an air conditioner which is oversized (too many BTUh) for the area you need to cool. You may think that bigger is better, but not in the case To make a room comfortable the air conditioner needs to both cool the room air AND dehumidify the room air.