It is extremely important to choose a room air conditioner of proper cooling capacity. A unit with too much cooling capacity will be inefficient and expensive to operate. A unit that’s too small won’t do a satisfactory job. To determine the best sized air conditioner for your room, click here  for our room calculator worksheet. There is also a close relationship between cooling capacity and dehumidifying the air. An oversized unit will quickly cool the air without remaining in operation long enough to dehumidify it, and a “cold, clammy” feeling will result. After determining the size unit needed, consider its operating efficiency. An efficient room air conditioner uses less electricity, so it costs less to operate. To measure efficiency, engineers have established a room air conditioner Energy Efficiency Ratio (EER). It is computed by dividing Btu/h (cooling output) by the watts of power (electrical input) in accordance with U.S. Department of Energy Test Procedures.

Federal Trade Commission regulations require that this value be placed on the label attached to the product. Thus, a 12,000 Btu/h model might use 1,900 watts and have an EER of 6.3, while another model of the same capacity might use 1,350 watts and have an EER of 8.8. The higher EER is the more efficient of the two. AHAM’s searchable directory lists EER’s for all units. Before installing room air conditioners, check your home wiring for the right circuit amperage and voltage. Avoid lines already loaded with appliances. Do not connect a 208-V unit to a 115-V line or a 115-V unit to higher lines. If a fuse blows, shut off the unit and check load and wiring. Be sure the outlet is properly grounded. Never remove the grounding prong from the plug. Install the unit in a shaded window, if possible. Keep warm air out by weather stripping doors and windows and keeping them tightly closed. Close fireplace dampers and seal openings to the attic or other uncooled areas. Seek professional advice on recommended ceiling and wall insulation.

For most homes in warm climates, air conditioning uses more electricity than any other use — up to 70 percent of a summer electric bill, according to some estimates. However, there are ways for most people to reduce this load by changing their air conditioning habits. ac unit no powerHere are the biggest air conditioning mistakes people make, and how to reduce usage and electric bills.how much for ac unitMistake No. 1: Buying Too Big an Air ConditionerBigger isn’t always better. window ac units for cheapMany people are inclined to get a bigger air conditioner, assuming it will make the home colder faster. However, an oversized air conditioner won’t generate uniform temperatures or reduce humidity. It will also run inefficiently by cycling on and off quickly.

Of course, a unit may also be too small to properly cool the space. To properly size a new air conditioning guide, start with this Consumer Reports worksheet.Mistake No. 2: Putting the Air Conditioner in a Hot SpotIt may seem convenient to put air conditioners in an unused spot on the southwest side of the house. However, such placement will make the unit work too hard. Instead, install the air conditioner in a shady spot on the east or north side of the house, where it will receive less direct sunlight.Mistake No. 3: Hiding the Air ConditionerThe air conditioner may not be pretty, but neither are excessive summer electric bills. Don’t try to hide air conditioners behind shrubs or other plants. It will hinder ventilation, clog condenser coils and make the air conditioner run less efficiently. Mistake No. 4: Ignoring MaintenanceAir conditioners are deceptively self-sufficient. Many homeowners ignore basic A/C maintenance that can improve efficiency and comfort, and extend the life of the air conditioner.

Clean or replace filters at least every two months. If it is used constantly or filters a lot of dust and pet hair, check the filters more often. Also check and clean the evaporator coil once a year. Run a stiff wire through the air conditioner’s drain channels regularly, and check the window seals around room air conditioners each year.Mistake No. 5: Leaving the Air Conditioner Running All DayUse a programmable thermostat or individual unit timer to start cooling off the house before you get home from work. This is cheaper and more efficient than leaving the air conditioner running all day, despite rumors to the contrary.Mistake No. 6: Blindly Closing Unused VentsOpinions vary on the efficiency of closing vents and doors to unused rooms. In many cases, this can decrease the efficiency of a central air conditioning system. Consult an expert before closing off any parts of the house for the summer. Also be careful about closing off any rooms that may have a thermostat.Mistake No. 7: Turning the Temperature Way DownIf you are comfortable at 78 degrees, don’t come home and turn the thermostat down to 70 degrees.

It will not get you to 78 any faster. It will just skip past 78 and waste ever more energy getting to excessively low temperatures.Mistake No. 8: Heating Up the ThermostatMake sure lamps, televisions, stereos or other heat-generators are not close enough to the thermostat to accidentally drive up the temperature reading and overwork the air conditioner.Mistake No. 9: Not Using Ceiling Fans or Running Them BackwardsMany people think their air conditioner is a substitute for ceiling fans. Instead, they should be used in tandem. According to Energy Star, make sure the fan is switched to push air downward (typically counter-clockwise). It may seem more logical to reverse the fan so it is pulling hot air upward. However, the downward airflow creates a “wind chill effect,” which makes you feel cooler.Mistake No. 10: Using the Wrong FansOn the other hand, exhaust fans in the kitchen and bathroom can push cool, conditioned air out of the house. They should not be used more than absolutely necessary in the summer.