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May 2008
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Cool runnings
Simple ways to keep your A/C in shape and slash your utility bill

It's likely that your utility bills will climb this summer. But instead of muttering about how the power company is ripping you off, you should be asking yourself if you're doing all you can to lower that bill—without having to switch to folding hand fans.

A great way to save is to replace an old air conditioner with a new, higher-efficiency unit. Replacing a 15-year-old room unit with a new high-efficiency model can reduce cooling costs 20 percent or more. The following tips will help extend the life of your equipment and cut the odds it will pump out its last Btu of cooling power on the hottest day of the year.

Central-air system
  • Install an electronic setback thermostat and automate settings. For instance, instead of running the air all day while you're at work, set the thermostat to turn on an hour before you get home.
  • Ensure that ducts throughout the system are sealed and insulated—as much as 30 to 40 percent of your cooling energy can be lost through leaks or heat when uninsulated ducts pass through uncooled spaces like the attic and garage. You'll find information on how to seal ducts on the Web site of the U.S. Environmental Protection Agency.
  • Keep the condenser coil clear of obstructions. Anything that impedes airflow makes the unit work harder to expel heat and raises energy consumption.
  • For more ways to keep cooling costs down and extend the life of your central air conditioner, read Save energy, save money.

Window air conditioners
  • Whenever possible, place the unit in a window that receives the least sunlight. Units in the shade require less energy to run.
  • Ensure that spaces around the air conditioner, whether in the window or a fitted sleeve, are completely sealed with foam weather seal, sold in various sizes in any hardware or home-improvement store.
  • Don't cool an unoccupied room.

Central and window units
  • Run your A/C at the lowest setting comfort allows; for every degree you raise a setback thermostat, you gain 3 percent savings on cooling costs. When temperature and humidity are low, use a whole-house fan to bring in cool air. And keep shades drawn to help negate solar heat gain. You can also cut costs as much as 20 percent by using a programmable thermostat to raise the temperature 5° F at night and 10° F during the day when nobody is at home.
  • Keep all filters clean, checking them monthly during the cooling season; clean them or replace disposable ones as necessary. Buildup on filters restricts airflow, which can reduce cooling and cause operating problems.

If you're considering buying a new air conditioner next year, here's how to make the most of your decision:
  • Don't wait for the warm weather to arrive to schedule installation; contractors might be too busy with other jobs to get to you in a timely manner.
  • Don't buy a higher-capacity air conditioner than a space requires, or it will cycle on more often and fail to control humidity. When shopping for window models, use our calculator to ensure you buy the right size units.
  • When buying, consider an Energy Star-rated model—you might be eligible for a tax break or rebate. (For central-air systems, the installer might need to be certified as well for you to get the rebate.) To learn more about tax credits and rebates, read Rebates and tax credits can lower appliance costs.