The most common type of air conditioning system is the split system, which puts the air handler inside the home and the condenser and compressor outside the home. The technology used for these systems has not changed dramatically for decades, and different manufacturers make largely identical products. So when you're shopping for an air conditioner, consider efficiency as indicated by the SEER, manufacturer reputation and reliability, the size of the unit, any government rebates, and contractor expertise. The best place to buy a split system air conditioner is from a trusted HVAC (Heating, ventilating and air conditioning) contractor. Many work with a specific brand of equipment, but some install several different brands. Be sure the contractor is certified to install the brand you choose. For example, cheaper Goodman units (including Goodman, Janitrol, Amana) have high repair rates, but don't require certification from installers. Often problems are related to faulty installation rather than product.

Trane and Bryant are well known names, but GE and Westinghouse make comparable products, and may price aggressively or offer great warranties to compete. For a standard split system air conditioner (between 13 and 15 SEER rating), you can expect to pay about $3,000 for the equipment. how to build ac unitSpecial installation or ductwork may add another $3,000. how much would it cost to move an ac unitLarger capacity systems are costlier. how to fix your air conditioner unitInstalled split system heat pumps (both air conditioning and heating) cost about $5,500 for standard SEER. High efficiency air conditioners, between 16 and 18 SEER, usually run about $500 more, and ultra high efficiency (19 to 23 SEER) will add an additional $500 or so to the final cost.

Many experts agree that the extra cost for ultra high efficiency does not pay off. Be sure your contractor uses "Manual J" calculations in figuring the size of air conditioning unit needed for your home. If you like to have the "best of the best," then you may want an ultra high efficiency air conditioner. Otherwise standard or high efficiency is adequate. The accessory most often purchased for a split system is an extended warranty, either on the equipment or on the service. Depending on how long you plan to live in the home, a service contract can be a good idea, but don't buy into it without comparing costs. It may save you money on discounted repairs. Look for air conditioner warranties that cover the labor involved in repairs. There aren't many, but you can find them. This could represent a significant savings. The standard warranty is ten years on the compressor, five years on all other parts, and no labor costs covered. Some installers will give you a year's labor guarantee;

shop around before you buy. Don't fall for the "bigger is better" claim when it comes to air conditioners. The right size is most cost-effective and comfortable for your home. Unscrupulous contractors will sell oversized units, costing the homeowner both initially and throughout the life of the system. They are inefficient and cycle off and on frequently. A properly sized system will be on most of the time in very hot weather. Avoid calling the biggest contractor in town -- you'll pay for the name recognition. Ask friends for references, and you'll often find smaller contractors who are reliable and fair.Central air conditioning systems can last from 15 to 20 years. Sticking with an older unit may be less expensive in the short run, but not when it comes to helping you save money off monthly utility bills. Here’s some information to help you make a better decision when it comes time to get a new, energy-efficient central air conditioner. If you’re wondering whether it’s time to replace or upgrade your central air conditioning system, here are a few facts that might help:

- In the average air-conditioned U.S. home, air conditioners use more than 2000 kilowatt-hours of electricity per year. - Producing the electricity needed to air condition the average U.S. home causes the average power plant to emit about 3500 pounds of carbon dioxide and 31 pounds of sulfur dioxide per year. - The most energy-efficient air conditioners on the market today consume 30 percent to 50 percent less energy than models manufactured in the mid 1970s. - Even if your air conditioner is just 10 years old, upgrading to a new energy-efficient air conditioner could save you from 20 percent to 40 percent off your cooling costs. If you decide to replace or upgrade your central air conditioning system, the first thing you’ll need to know is whether you have a split-system central air conditioner or a packaged central air conditioner. Split-system central air conditioners are made up of an outdoor metal cabinet containing the condenser and compressor and an indoor cabinet containing the evaporator, which in many split-system air conditioners, also contains a furnace or the indoor part of a heat pump.

Packaged central air conditioners contain the evaporator, condenser and compressor in a single outdoor metal cabinet, usually placed on a concrete slab next to a home’s foundation. From the cabinet, air supply and return ducts enter a home through its exterior wall and connect to a series of internal supply and return ducts in order to circulate cool air throughout a home. Packaged air conditioners usually include a natural gas furnace or electric heating coils and eliminate the need for a separate indoor furnace. If your home already has a furnace but no air conditioner, then installing a split-system air conditioner is the most economical choice. When shopping for an energy-efficient central air conditioner, you’ll need to research a system’s seasonal energy efficiency ratio, or SEER, which indicates how much energy a model uses to produce a specific cooling output. If you have an older system, chances are it has a SEER rating of 6 or less. Since Jan. 23, 2006, models have been required by the Environmental Protection Agency to have a minimum SEER rating of 13, which require 30 percent less energy to run than models manufactured with the previous minimum SEER rating of 10.

The most energy-efficient central air conditioners on the market today are ENERGY STAR–certified with SEER ratings greater than 13. Buying a new central air conditioning system doesn’t have to be intimidating. Here are a few tips on what you should look for in a new system: - Size matters when it comes to a new central air conditioner. If your unit is too small, it will have to work too hard to cool your home, which can result in higher electric bills and damage to components. It may not even be able to reach comfortable temperatures on hot days. If your unit is too big, it will cycle on and off too quickly, which will prevent the unit from removing humidity from the air and can also damage components. Only a right-sized unit will provide the performance, operating life and energy efficiency you expect. Know your home’s square footage and consult with an HVAC contractor before you make a purchase. - Partial replacement may not be ideal. Although you can replace the outdoor compressor on an older model with a modern, high-efficiency unit, you should consult a local HVAC contractor to make sure that the compressor is properly matched to the rest of the older system.