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.how much is a new 3 ton ac unit The LG LW8014ER, $240, a CR Best Buy, has very good scores for cooling and aced the brownout test.  price for 3 ton ac unitIt was also somewhat  noisy with the fan was on high.wholesale home 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)How do you do air conditioning calculations on the capacity of air conditioner for your room? This calculation is important because if done wrongly, you will end up installing an oversize or undersize equipment. An oversized air conditioner is not good as the compressor will run and stop regularly and not able to cool the room uniformly. It will also cause discomfort to the occupants as the dehumidfication of the room is not properly done. On top of that, the electricity bill will be high as the compressor turns on and off too often.Every time the on/off type of compressor starts to run, its power consumption is 6 times higher than when it is running steadily.The cycling on and off of the compressor will lead to shorter life span of the compressor besides having to spend more on the unit price and installation cost.

An undersized unit will not be able to cool the room properly and more so if the weather is hot.Cooling capacity for a room is defined as the heat load in a room that have to be removed in order to achieve a certain room temperature and humidity. The typical design is set to 24°C temperature and 55% Relative Humidity. Study shows that this combination of temperature and RH is the most conducive for the human body. The unit used to measure heat load is BTU/hr. 1 BTU/hr is the heat energy needed to increase 1 pound of water by 1°F.When choosing an air conditioner, usually a 1 HP (horse power) equipment is able to remove 9,000 BTU/hr of heat. With better technology, some machines are able to remove 10,000 BTU/hr of heat with the same capacity. The higher the listed BTU/hr, the greater the cooling capacity.Air Conditioning Calculations - Rule Of ThumbCalculating the cooling capacity needed for your room is a complicated process as there are many factors to consider. However, there is a simple rule of thumb that you can use to estimate the required cooling capacity for your room.

Use this result to compare with the calculation done by the air conditioning contractors for your own checking purposes. Find the volume of your room in cubic feet. This is done by measuring the length, width and height of the room in feet and multiply all the three dimensions together.Volume = Width X Length X Height (cubic feet)Multiply this volume by 6.C1 = Volume X 6Estimate the number of people (N) that will usually occupy this room. Each person produces about 500 BTU/hr of heat for normal office-related activity. Multiply this two figures together.C2 = N x 500 BTU/hrAdd C1 and C2 together and you will get a very simplified cooling capacity needed for the room.Estimated Cooling Capacity needed = C1 + C2 (BTU/hr)Air Conditioning Calculations - Other FactorsOther factors that your contractor will consider to determine the sizing of the cooling capacity include the direction of your room. If the room is facing east or west, additional capacity is needed as it will be exposed to the morning and evening sun compared to a room that faces north or south.