Room air conditioners can be an affordable alternative to central-air conditioning systems. New models are considerably more energy-efficient than those made only a decade ago. One newer feature, electronic temperature control, is more precise than the older knob controls and can also save you money down the road.

Room air conditioners come in different sizes, with cooling capacities ranging from 5,000 BTUs (British thermal units per hour) to as high as 30,000 BTUs. The size you need depends on the room to be cooled. Most of the current models do a good job at cooling, with the better models keeping the temperature more even than the rest. Check the unit's EER (Energy Efficiency Rating), which is posted on every air conditioner. Also determine the right size air conditioner for the space you're cooling (see chart below).

Installation of room air conditioners will normally require two people. Some models have an outer cabinet that you anchor in the window and into which you slide the unit. To maintain your air conditioner's peak performance, clean the air filter every few weeks. Certain models have a washable filter that slides out easily. Some units may also have an indicator that tells you when it's time to change the filter.

Window Air Conditioners
For windows that slide up and down.

Casement Air Conditioners
For windows that swing out to the left or right (usually with a hand crank).

Wall Air Conditioners
These are installed through the wall of a building and require a sleeve. Sleeves are sold separately and can be found in the air conditioner accessories category.

Portable Air Conditioners
Can be used in a windowless office or room, although a room with a window is recommended for venting. These can be used in any room, but they must be ventilated so that the exhaust can go somewhere outside of the room.

What's The Big Deal About BTU Sizing?

BTU Size Too Large
An air conditioner that has a higher BTU rating than the room size requires will tend to cycle off too quickly. The unit will not properly remove the moisture from the air.

BTU Size Too Small
An air conditioner that has a lower BTU rating than the room size requires will run continuously. The unit will not adequately cool the room.

To select the correct BTU's you will need to cool a room, use the chart below:

Square Feet Approximate BTU'sNeeded 100-150 5,000 150-250 6,000 250-300 7,000 300-350 8,000 350-450 10,000 450-650 12,000 650-850 13,000 850-1100 18,000 1100-1400 24,000 1400-1800 25,000 1800-2500 29,000 Use this chart to determine the correct receptacle type for your unit: AC Unit Receptacle Types PARALLEL 125 Volts 15 Amps Up to 14,000 BTU on window units PERPENDICULAR  230/208 Volts 20 Amps Over 20,000 BTU on window units TANDEM 230/208 Volts 15 Amps 18,000 on window units 10,000 to 16,000 on wall units Please note- - Increase BTUs by 10% for sunny areas - Increase BTUs by 10% for second story (or higher) rooms - Increase BTUs by 4,000 if area to be cooled is in the kitchen - Increase BTUs by 600 for each additional person (using room) over 2 persons Click here to view all Window Air Conditioners Click here to view all Wall Air Conditioners Click here to view all Casement Air Conditioners Click here to view all Portable Air Conditioners Click here to view all Air Conditioner Accessories