Modern air conditioning systems are designed to provide exceptional comfort and efficiency when compared to units manufactured just over a decade ago. While there are many HVAC equipment options, a split system is the configuration most homeowners choose for central heating and cooling. Split system performance can be enhanced with a number of options designed to lower operational costs and reduce noise levels.

Split System Components

Split systems incorporate three separate components that work together in order to properly condition the indoor environment. In residential construction, isolating the condenser away from the blower helps reduce the noise associated with motor and compressor operation.

* Furnace: Furnaces are available in natural gas, propane and fuel oil models. Every furnace incorporates an ignition system, combustion chamber, burners and heat exchanger. When the thermostat calls for heat, the electronic ignition lights a pilot that ignites a mixture of gas and oxygen in the combustion chamber. The blower moves the cooler indoor air through the heat exchanger, and the resultant warmer air is pushed back into the building.

* Evaporator Coil: The evaporator coil is attached to the furnace to provide cooling in the summer. As an important element in the refrigeration cycle, the coil transforms a high-pressure refrigerant into a low pressure liquid. The blower pulls the warmer indoor air across the coil from the return side of the system. The heat is absorbed by the refrigerant, and the cooler air is forced back into the living area.

* Condenser: The condensing unit includes the condensing coil, fan and compressor. As the heat saturated low-pressure gas enters the condenser, the mechanical action of the compressor squeezes the refrigerant and transforms it into a high-pressure gas. As the refrigerant leaves the compressor and enters the condensing coil, a fan pulls heat out of the refrigerant and disperses it into the surrounding air.

Spit System Technologies

Split system technology continues to improve, and there are many different choices in styles and efficiencies. When comparing different brands and models, it is essential to assess build quality, ratings and features. The most common split system configurations include:

* Single-Stage Compressor: A single-stage compressor operates at full capacity regardless of the prevailing indoor load. While single-stage split systems are less expensive, they are also the least efficient.

* Two-Stage Compressor: A two-stage compressor runs on a lower speed in milder conditions. When the weather is severe, the second stage engages and provides greater capacity. Two-stage compressors help lower monthly operating costs, but they are more expensive to install.

* Variable Speed Blower: A variable-speed blower adjusts the fan speed to precisely match the indoor load. In mild temperatures, the blower motor draws fewer amps but still provides better comfort than single-speed fans. A variable-speed fan matched with a two-stage compressor provides the best possible comfort and the lowest associated utility costs.

AFUE and SEER Ratings

Since central HVAC systems are the most expensive appliances to operate, the Department of Energy provides a comparative rating system for both air conditioners and furnaces.

Furnace ratings are based on the Annual Fuel Utilization Efficiency (AFUE) standard. A higher AFUE rating signifies the unit has a greater burn efficiency. The rating number denotes the actual percentage of consumed fuel that is converted directly into heat energy.

Air conditioners are rated by the Seasonal Energy Efficiency Ratio (SEER) standard. Fundamentally, SEER is a measurement of the cooling output of the unit at a given temperature divided by the electricity that is consumed. A higher SEER rating indicates the unit is more efficient.

Major Equipment Manufacturers

Major split system manufacturers sell their equipment under different brand names in order to increase market share. In most instances, the furnaces and air conditioners are indistinguishable throughout the product line. Homeowners may find a bargain by purchasing a secondary brand from a major manufacturer.

* Carrier: Manufactures equipment under the Carrier, Bryant, ICP and Payne brand names.

* Ingersol Rand: Manufactures equipment under the Trane and American Standard brand names.

* Goodman: Manufactures equipment under the Goodman, Janitrol and Amana brand names.

* Lennox: Manufactures equipment under the Lennox and Ducane brand names.

* Armstrong: Manufactures equipment under the Armstrong and Airease brand names.

* Rheem: Manufactures equipment under the Rheem, Ruud and Weatherking brand names.

Other Buyers Guide Suggestions

Consumers are advised to check the manufacturer’s published extended ratings, which may be more applicable to local weather conditions. Also, it is important to ensure the blower, condenser and evaporator coil are matched for optimal efficiency. Using a lower SEER rated coil and an old furnace with a new condensing unit can negatively impact efficiency and may damage the equipment.