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Buying Guide: Central Air Conditioners

By: Carl Laron on May 01, 2018

What the best air conditioner has

  • High efficiency. An Energy Star qualified air conditioner will have a SEER of at least 15 and an EER of at least 12.5, while the most efficient central air conditioner will perform even better. Note, however, that air conditioner installation and the specific components used can effect efficiency. This means some models that nominally meet the Energy Star threshold might not qualify as installed.
  • Good value. A high-efficiency central air conditioner can seem expensive to buy in the beginning, but can be less costly in the long run, especially compared to older, less-efficient models. Government and utility company rebates are often available for models that meet high Energy Star standards or even higher CEE ones. Check these out before you buy as the savings can be substantial.
  • A solid warranty. For quality systems, 10 years is now the norm, though better systems have stronger warranties still. Some models offer lifetime coverage on the compressor; a significant consideration since that's the most important -- and costliest -- part of a central air-conditioner system.
  • Quiet operation. All central air conditioners are relatively quiet inside the home, but that doesn't mean they aren't stirring up a racket outside. If you have neighbors nearby, or like to sit outside even when the system is running, a quieter system will be appreciated by all.
  • Quality installers. Experts say that when you get to the bottom line, there isn't a whole lot separating the highest quality central air conditioner systems from the lowest. However, there is a big gulf between the highest quality installers and those that are less-qualified -- and that's the reason behind wide swings in customer satisfaction between brands; the best brands are very picky about who they let represent them in the field. Because of that, it might be a good idea to find the top installers servicing your area, and look then to the brands they represent when narrowing down your selections.

Know before you go

Do you have the necessary ductwork? If you're replacing an existing central air conditioner, then your house will already have a system of ducts in place. However, your contractor should still check out the ducts to make sure they are in good condition. Be sure to tell the contractor about any problems you are having with airflow or uneven cooling with your existing system, since this may be a sign of poorly designed ductwork. If you are adding a new air conditioner to a home with forced-air heating, you may be able to connect it to the existing ductwork as well, although it may need some modifications.

Consider your climate. If you live in a hot, humid climate, it's especially important to choose an air conditioner with a high SEER, since the air conditioner will be running a lot. In a hot, dry climate, EER is more important than SEER; it measures how effective the air conditioner will be in the hottest weather. In mild climates, consider a heat pump, which could meet your needs for heating as well as cooling. We discuss heat pumps in our separate report on furnaces.

Get at least three quotes from contractors. Regardless of the central air conditioner system you select, the difference between a great choice and a poor one often comes down to the contractor you select. Referrals from friends, neighbors and co-workers can be a good starting point. You can also ask local trade organizations for names of members in your area. Organizations like the Air Conditioning Contractors of America (ACCA) have directories on their websites that can be searched by ZIP code. Consumer review sites that focus on local contractors and services, such as HomeAdvisior.com and Angie's List can also be a valuable resource.

Get all the details. Don't trust a contractor who gives you an estimate based solely on your home's square footage. Make sure the contractor calculates your home's cooling needs according to Manual J, a tool published by the ACCA, and get a written estimate that shows all calculations, including ductwork design.

Check out the contractor's credentials. Ask to see the contractor's license and proof of insurance, and find out how long the company has been in business. Consumer Reports recommends looking for a company whose technicians are certified by a trade organization, such as North American Technician Excellence (NATE) or HVAC Excellence. Get at least three references from each contractor, and be sure to check them. A check with your local Better Business Bureau is a good idea as well.

Don't forget to register your warranty. Good quality central air conditioner systems are typically covered by warranties of around 10 years, and sometimes longer. But there's also often a catch. Most manufacturers require owners to register their equipment within 60 to 90 days after installation or have the warranty period cut in half. Some makers have this requirement for their more basic systems, but not their top-end systems, and some states, namely California, bar that requirement altogether. The bottom line, however, is to read your warranty information, and talk to your contractor, to understand and comply with any manufacturer requirements to make sure you get the full warranty coverage you are entitled to.

Buying tactics and strategies

Compare bids. Don't rely solely on price; you should expect to pay more for quality work. An extremely low bid is a warning sign that a contractor is likely to cut corners.

Negotiate for the best deal. An estimate isn't set in stone. If you have another bid that's lower, ask the contractor to explain the discrepancy. If you ask for a relatively small discount, you will probably get it. You can also negotiate for a better warranty or a service contract.

Get it in writing. Make sure to get a written contract before the work begins. Project costs, scheduling, model numbers and warranty information should all be specified. This will protect you from unwanted last-minute changes.

Don't forget the rebates. Rebates come and go, and can vary by locality and power company, but when available, can help defray the cost of a new central air system. Check with your local authorities and energy companies to see what's currently available. A database of energy incentives and polices is also available here.

Keeping your air conditioner in shape

To keep your air conditioner running efficiently, you'll need to maintain it properly. Experts agree that keeping the air filter clean is the most important thing you can do to maintain an efficient unit. If the filter becomes clogged with dust and dirt, it can block the flow of air, increasing your energy use and possibly damaging the air conditioner.

During the cooling season, check all filters monthly and clean or change them as needed. It's also important to ensure the unit itself isn't blocked by debris; you should maintain a clear, 2-foot perimeter around the unit. You can also spray the condenser coils with a garden hose once a year to clear away twigs, leaves and dirt. Clean the vents as well, and wipe the unit down with a damp cloth.

Experts also recommend calling in a service professional regularly to give your central air conditioner a tune-up. Energy Star suggests doing this once a year -- preferably in the spring, before the cooling season starts. At Smarter House, a site run by the American Council for an Energy-Efficient Economy, the guidance is that every two to three years should be sufficient. During the service visit, the technician should change all the filters, vacuum the blower compartments, clean and flush the coils, and drain the pan and drainage system. After cleaning, the tech should check to make sure all parts are working properly: This will include checking electrical connections, lubricating all moving parts and checking airflow over the indoor coil. Keeping the airflow at the right level can boost the air conditioner's efficiency by anywhere from 5 to 15 percent.

What if you follow all these steps and the air conditioner still breaks down? Furnace Compare. says there are several possible causes that you may be able to fix on your own. First, make sure that the unit is getting power -- check fuses and circuit breakers, as well as the unit's electrical disconnect switch. Also, check the thermostat -- it may simply need new batteries or perhaps the switch wasn't pushed all the way to the "cool" position. Excess fan noise can mean a problem with the fan motor, but things like a rattling sound could be nothing more than a loose cabinet screw.

Also, if the unit won't turn on at all with the temperature set very low, feel the copper lines that lead from the condenser. If the larger line feels warm, you may be out of coolant. If it's frozen, the line may be clogged; shutting down the system and waiting for it to thaw may fix the problem. If that doesn't help, then it's time to call a professional.

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