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Air-conditioner Efficiency: Each air-conditioner has an energy-efficiency rating that lists how many Btu per hour are removed for each watt of power it draws. For room air-conditioners, this efficiency rating is the Energy Efficiency Ratio or EER. For central air-conditioners, it is the Seasonal Energy Efficiency Ratio, or SEER. These ratings are posted on an Energy Guide Label, which must be conspicuously attached to all new air-conditioners. Many air-conditioner manufacturers are participants in the voluntary Energy Star labeling program. Energy Star-labeled appliances mean that they have high EER and SEER ratings.

In general, new air-conditioners with higher EERs or SEERs sport higher price tags. However, the higher initial cost of an energy efficient model will be repaid to you several times during its life span. Your utility company may encourage the purchase of a more efficient air-conditioner by rebating some or all of the price difference. Buy the most efficient air-conditioner you can afford, especially if you use (or think you will use) an air-conditioner frequently and/or if your electricity rates are high.

Room Air-conditioners-EER: Room air-conditioners generally range from 5,500 Btu per hour to 14,000 Btu per hour. National appliance standards require room air-conditioners built after January 1, 1990, to have an EER of 8.0 or greater. Select a room air-conditioner with an EER of at least 9.0 if you live in a mild climate. If you live in a hot climate, select one with an EER over 10. The Association of Home Appliance Manufacturers reports that the average EER of room air-conditioners rose 47% from 1972 to 1991. If you own a 1970s-vintage room air-conditioner with an EER of 5 and you replace it with a new one with an EER of 10, you will cut your air-conditioning energy costs in half.

Smaller room air-conditioners (i.e., those drawing less than 7.5 amps of electricity) can be plugged into any 15- or 20-amp, 115-volt household circuit that is not shared with any other major appliances. Larger room air-conditioners (i.e., those drawing more than 7.5 amps) need their own dedicated 115-volt circuit. The largest models require a dedicated 230-volt circuit.

Room air-conditioners generally range from 5,500 Btu per hour to 14,000 Btu per hour. National appliance standards require most new room air-conditioners to have an EER of 8.5 or greater. Select a room air-conditioner with an EER of at least 9.0 if you live in a mild climate. If you live in a hot climate, select one with an EER over 10.

The Association of Home Appliance Manufacturers reports that the average EER of room air-conditioners rose 47% from 1972 to 1991. If you own a 1970s-vintage room air-conditioner with an EER of 5 and you replace it with a new one with an EER of 10, you will cut your air-conditioning energy costs in half.

Central Air-conditioners-SEER: National minimum standards for central air-conditioners require a SEER of 9.7 and 10.0, for single-package and split-systems, respectively. But you do not need to settle for the minimum standard-there is a wide selection of units with SEERs reaching nearly 17. Before 1979, the SEERs of central air-conditioners ranged from 4.5 to 8.0. Replacing a 1970s-era central air-conditioner with a SEER of 6 with a new unit having a SEER of 12 will cut your air-conditioning costs in half.

National minimum standards for central air-conditioners require a SEER of 12. But you do not need to settle for the minimum standard; there is a wide selection of units with SEERs reaching nearly 17. Before 1979, the SEERs of central air-conditioners ranged from 4.5 to 8.0. Replacing a 1970s-era central air-conditioner with a SEER of 6 with a new unit having a SEER of 12 will cut your air-conditioning costs in half.

Hiring Professional Service: When your air-conditioner needs more than the regular maintenance described previously, hire a professional service technician. A well-trained technician will find and fix problems in your air-conditioning system. However, not all service technicians are competent. Incompetent service technicians forsake proper diagnosis and perform only minimal stop-gap measures. Insist that the technician:

  • Check for correct amount of refrigerant;

  • Test for refrigerant leaks using a leak detector;

  • Capture any refrigerant that must be evacuated from the system, instead of illegally releasing it to the atmosphere;

  • Check for and seal duct leakage in central systems;

  • Measure air flow through the evaporator coil;

  • Verify the correct electric control sequence and make sure that the heating system and cooling system cannot operate simultaneously;

  • Inspect electric terminals, clean and tighten connections, and apply a non-conductive coating if necessary;

  • Oil motors and check belts for tightness and wear

  • Check the accuracy of the thermostat.

 

Choosing a Contractor: Choosing a contractor may be the most important and difficult task in buying a new central air-conditioning system. Ask prospective contractors for recent references. If you are replacing your central air-conditioner, tell your contractor what you liked and did not like about the old system. If the system failed, ask the contractor to find out why. The best time to fix existing problems is when a new system is being installed. When designing your new air-conditioning system, the contractor you choose should:

  • Use a computer program or written calculation procedure to size the air-conditioner;

  • Provide a written contract listing the main points of your installation that includes the results of the cooling load calculation;

  • Give you a written warranty on equipment and workmanship; and

  • Allow you to hold the final payment until you are satisfied with the new system.

Avoid making your decision solely on the basis of price. The quality of the installation should be your highest priority, because quality will determine energy cost, comfort, and durability.

Installation and Location of Air-conditioners: If your air-conditioner is installed correctly, or if major installation problems are found and fixed, it will perform efficiently for years with only minor routine maintenance. However, many air-conditioners are not installed correctly. As an unfortunate result, modern energy efficient air-conditioners can perform almost as poorly as older inefficient models. Be sure that your contractor performs the following procedures when installing a new central air-conditioning system:

  • Allows adequate indoor space for the installation, maintenance, and repair of the new system, and installs an access door in the furnace or duct to provide a way to clean the evaporator coil.

  • Uses a duct-sizing methodology such as the Air-conditioning Contractors of America (ACCA) Manual D.

  • Ensures there are enough supply registers to deliver cool air and enough return air registers to carry warm house air back to the air-conditioner.

  • Installs duct work within the conditioned space, not in the attic, wherever possible.

  • Seals all ducts with duct mastic and heavily insulates attic ducts.

  • Locates the condensing unit where its noise will not keep you or your neighbors awake at night, if possible.

  • Places the condensing unit in a shady spot, if possible, which can reduce your air-conditioning costs by 1% to 2%.

  • Verifies that the newly installed air-conditioner has the exact refrigerant charge and air flow rate specified by the manufacturer.

  • Locates the thermostat away from heat sources, such as windows, or supply registers.

If you are replacing an older or failed split system, be sure that the evaporator coil is replaced with a new one that exactly matches the condenser coil in the new condensing unit. (The air-conditioner's efficiency will likely not improve if the existing evaporator coil is left in place; in fact, the old coil could cause the new compressor to fail prematurely.)

  • If you install a new room air-conditioner, try to:

  • Locate the air-conditioner in a window or wall area near the center of the room and on the shadiest side of the house.

  • Minimize air leakage by fitting the room air-conditioner snugly into its opening and sealing gaps with a foam weather-stripping material.

Paying attention to your air-conditioning system saves you money and reduces environmental pollution. Notice whether your existing system is running properly, and maintain it regularly. Or, if you need to purchase a new air-conditioner, be sure it is sized and installed correctly and has a good EER or SEER rating.

Using Your Air-conditioner: An air-conditioner will cool the air in your home fairly quickly. For economical operation, turn it on only when your home is occupied. You may consider installing a programmable thermostat. These allow you to set the time when the air-conditioner will turn on, such as 30 minutes before you arrive home from work on a hot day. See section Automatic And Programmable Thermostats. During the day, keep the drapes or blinds closed on windows that face east, south, and west. This will help reduce solar heat gain into your home.

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