Modern central air conditioning systems are engineered to provide exceptional levels of comfort while minimizing fuel expenses. Properly sized HVAC equipment can help maintain a healthy indoor environment by employing advanced filtration and humidity control technologies. Homeowners with heating and air conditioning equipment that is more than 10 years old can usually benefit by installing a new, energy efficient model. All air conditioners employ the same essential methodology to cool the air inside a home or building. The refrigeration cycle includes a compressor that pumps hot gas refrigerant into a condensing coil. The accumulated heat is then dissipated by the action of a forced air fan. The resulting cooled gas condenses into a liquid refrigerant that runs through an expansion valve, which dramatically reduces the pressure. An indoor blower pushes warm air over the evaporator coil, and the heat energy is absorbed by the liquid refrigerant. The resulting cooler air travels through the duct work into the living area, which signals the beginning of another cycle.

Air conditioning equipment is available in a variety of different designs, but every unit operates in essentially the same manner. Split systems are characterized by the separation of the condensing unit from the air handler. The purpose of the design is to isolate the fan and blower away from the living area in order to reduce noise levels. The condensing unit is placed outdoors, preferably outside an exterior garage wall, and the furnace is located inside, usually in a garage or specially designed closet. The individual elements that comprise a split system are highlighted in the following table: In the heating cycle, a relay in the furnace activates an inducer fan when the thermostat calls for heat. As the air flow becomes suitable for combustion, a valve opens and a specific amount of gas is ignited through a hot surface or spark ignition system. When the heat exchanger reaches its design temperature, the blower engages and warm air is pushed through the air distribution system.

In the cooling cycle, the thermostat senses the indoor temperature is rising and sends a simultaneous signal to the indoor blower, outdoor condenser fan, and the compressor. The refrigerant enters the compressor and is converted to a high pressure refrigerant, which begins the refrigeration cycle. When the thermostat senses that the predetermined temperature set point has been met, it sends a signal to the compressor to disengage. To measure efficiency, the government has mandated that manufacturers display standardized ratings data for both furnaces and air conditioners. These ratings provide consumers with a simple way to compare competing brands and models to determine annual fuel consumption relative to the cost of the equipment itself. Furnaces are rated according to the Annual Fuel Utilization Efficiency (AFUE) standard. This is a government mandated measurement used by the industry to compare furnaces produced by different manufacturers. A higher AFUE rating is associated with greater burn efficiency.

For example, an 80 percent AFUE rated furnace will use 80 percent of the fuel consumed to generate heat while 20 percent is vented outside. 5 ton package ac unitFurnaces purchased in the early 1990s may have an AFUE rating of 65 or less. how do outdoor ac units workReplacing an older unit with modern 90 AFUE rated furnace can save up to 30 percent on annual heating bills. carrier ac unit not turning onAir conditioning condensing units are rated according to the Seasonal Energy Efficiency Ratio (SEER). Like AFUE, this standard was designed to compare the energy consumption of different brands of air conditioning equipment. Higher SEER ratings indicate greater savings and lower energy consumption over the life of the equipment. In areas where summers are extreme, replacing air conditioning systems that are 10 years or older can provide substantial savings.

For example, replacing an eight SEER system with a standard 13 SEER machine can save as much as 40 percent on annual air conditioning costs. While efficiency ratings are dynamic, manufacturers currently offer air cooled condensing units up to 18 SEER. Split system technologies continue to emerge that provide greater comfort, lower levels of noise, and enhanced efficiencies. When comparison shopping, it is important to evaluate different models from both a construction and an energy efficiency standpoint. This includes identifying decibel noise levels, fan components, and furnace ignition systems. A visual inspection is always recommended to determine the quality of the cabinet, the thickness of the insulation, and accessibility for service and maintenance. To achieve greater efficiency, manufacturers have continued to improve designs and added additional features. The included following table highlights the most common split system configurations. Single stage equipment operates at full capacity until the load has been satisfied.

This configuration has a lower purchase price but is also the least energy efficient. Two stage compressors operate at a lower speed and reduced capacity in milder weather. When the weather is extreme and the load increases, the higher stage engages for greater capacity. Two stage compressors provide higher SEER ratings and better energy savings, but they are more expensive. Variable speed fans adjust their operation to match the accompanying load. In milder temperatures, the motor draws fewer amps to provide the same level of comfort as a single speed fan. Variable speed fans are often matched with two stage compressors to provide the ultimate in comfort and the lowest possible energy costs. Many air conditioning manufacturers market their equipment under several different brand names. In most cases, the equipment is identical across all brands with the exception of the label. Buyers can often save money by purchasing a lower profile brand produced by a major manufacturer.

The following table identifies the primary equipment manufacturers and their subsidiary brands. Selecting a split system requires careful research that encompasses more than just the equipment. To operate with maximum efficiency, the system must conform to the unique characteristics of the building. Every home or office presents structural challenges, and it is important that a new a/c system is properly sized for the application. Oversized air conditioners can short cycle, which may result in poor humidity control and insufficient air movement. Equipment that is undersized will not satisfy the cooling load and can prematurely fail. For maximum comfort and minimal expense, equipment should be selected and installed according to ACCA manual "j" standards. This thorough evaluation includes an assessment of the impact that windows, insulation, building orientation, and the air distribution mechanism will have on system performance. To prolong the life of an air conditioning split system and improve energy efficiency, there are several accessories that may be considered as useful add-ons.

These are identified in the following table: Provides set back points to raise or lower the temperature when the building isn't occupied Helps eliminate contaminants to maintain a healthier indoor environment and improve system efficiency Duct Cleaning and Sealing Improves system efficiency and removes mold and bacteria from the system Proper humidification helps maintain a healthier and more comfortable environment To locate a wide array of split system air conditioning choices, look on the left hand side of the home page and click on Home, Outdoors & Decor. Then follow the link to Home & Garden. Click on the Home Improvement link, and then finish by clicking Heating, Cooling & Air. The menus on the left side of the page will provide a complete assortment of options for different air conditioners and split systems. Split system air conditioners come in a variety of different sizes and energy efficiency ratings. It is important to understand the different available technologies and match the system to the specific requirements of the building.