Make the Most of Your AC
 
Make the Most of Your AC

Make the Most of Your AC
In addition to the annual checkup and routine cleaning, there are many things that you can do throughout the summer to ensure that your AC unit works efficiently.

Efficient thermostat settings are one of the easiest and most effective ways to save money on cooling costs. For each degree Fahrenheit you raise your thermostat, you can reduce your AC unit's energy use by 3% to 5%. For example, if you raise your thermostat from 74¡ã F to 78¡ã F (the setting recommended by the Department of Energy), you'll automatically save 12% to 20% on cooling costs. You should never set the thermostat any lower than 72¡ã F. If you must leave your AC unit on overnight, set the thermostat slightly higher than usual (ideally 78¡ã F to 80¡ã F).
Choose a good location for the outside portion of your central AC unit or window unit. Avoid unshaded areas on the south or west sides of your homes. It's best to put this unit on the north or east side of your home, where it will be shielded from intense sunlight. Doing this will automatically increase its efficiency by 10%.

If it isn't possible to place your AC unit in one of these locations, shrubs or trees can be planted by the unit to provide natural shade. Be careful, however, not to plant shrubs too close. Leave four to five feet of open air between any shrubs or trees and the unit to ensure proper ventilation.
Keep the grass around central AC trimmed so that air can circulate properly. When mowing around the unit, be careful not to blow debris or grass clippings into it.
Avoid locating the indoor thermostat near windows or heat-generating appliances like ovens and refrigerators. Also, keep lamps and televisions away from your thermostat. The heat from these can "trick" your AC unit into thinking that your house is warmer than it actually is, thus forcing the unit to run more often than necessary. The ideal location for the thermostat is in the room where you spend the most time.
Clean and/or replace the filters on your AC unit. This can dramatically increase your savings and reduce the load on your AC. Dirty filters cause your AC unit to work harder when circulating air and leads to both higher energy bills and a shortened life span. Some types of filters can be rinsed out and reused.
Check your air ducts for leaks and obstructions. A recent study of residential central AC systems found that almost 100% of homes had leaky ductwork, which means that there's a good chance that your AC system is losing some of its cooled air. Duct system leaks can account for up to 25% of the energy your central heating and cooling system uses, if your ducts run through an unheated basement, attic or under a trailer home.

Most air leaks in central AC units occur in the return air plenum. Plenums are the large ducts above or below the air handler. When these leaks occur, warm air is pulled into the system, and the cooled air is heated up. If your central AC system is unable to cool your home satisfactorily, leaky ducts may be the cause. Ducts can be sealed and insulated and thus improve your AC systems efficiency. (Figures 12, 13)
Use the correct refrigerant charge. This can greatly affect your air conditioner's efficiency. A system that is undercharged by 10% may have a drop in efficiency of 20%. By the same token, the refrigerant should never be overcharged because it can cause the refrigerant and oil to flood and damage the AC unit.

Only a professional service person should check and recharge your air conditioner's refrigerant. Refrigerants never "wear out" and refrigerant coils are completely sealed, closed systems. Therefore, if your refrigerant coils were properly charged during installation, but later need to be recharged, you have a leak in the system. Failure to repair the leak has two consequences. First, it allows refrigerants to leak into the atmosphere, and damage the ozone layer. Second, moisture can enter the AC system and combine with the chlorine and fluorine in the refrigerant to form acids which, over time, will damage the AC's compressor and coils.
Clean the indoor and outdoor coils of your central AC system. These coils are the heat exchangers between the refrigerant and the surrounding air. The indoor coil is cold, and as air moisture condenses on it, it filters out impurities which can build up very quickly and hamper the coil's performance. A recent study found that indoor coils lose about 8% of their efficiency each year due to dirt buildup. Indoor coils are sometimes difficult to find and access and extremely fragil. However they can be cleaned with a soft cloth and warm, soapy water. Outdoor (condenser) coils are easier to reach and can be cleaned the same way. Both types of coils need to be treated gently. If you have any questions on your AC unit's care, consult the manufacturer's recommendations.