Properly designed air conditioning systems are extremely important, especially in the south where we are dealing with constant high temperatures and high humidity. The sizing (tonnage) of the a/c units is critical. If there is too much tonnage, the space gets cooled down too quickly and does not allow the humidity to be drawn from the air. Likewise, if the units are undersized, the units will constantly be running (not being energy efficient) in an attempt to cool the space. The old rule of thumb for estimating the size of the air conditioning systems for a home was one ton for every 500 square feet. This rule should not be used as it does not take into account many factors. There is specific information that should be gathered in order to determine the correct sizing for a particular space. Several of the factors are: room orientation to the sun, the type of insulation in the home, the volume of space in the room, size of the ducts and how the air is returning to the air conditioning units. The size of the unit always should be determined by a qualified a/c contractor or a mechanical engineer.

The efficiency rating (SEER) of the a/c units determines how well the units perform in regards to energy use. The higher the SEER, the more efficient the unit and thus, the less expensive the units are to operate on a monthly basis. As a rule, the higher efficiency a/c units also offer more features, better warranties, quieter operations and different designs. We have found that it is difficult to justify the increase in price for units having an SEER higher than 16.0. As electric pricing continues to escalate and the demand for higher efficiency unit increases, this will change.

For us, the short answer is that all our clients really want to know is that the a/c units will cool the space properly. We use Carrier, Rheem and Lennox products in all our homes. The a/c units that we choose are a function of the air conditioning sub contractor and their buying relationship with their preferred manufacturer. In saying this, we are generally very satisfied with all the equipment we purchase. Beware of ?builder models,? as these generally are of lesser quality with less comprehensive and shorter warranty packages.

All manufactures of a/c equipment have different models within a particular line that may have similar sizing (tonnage) but have significant other benefits. A builder can achieve a desired efficiency rating (SEER) on an a/c system by using different combinations of units within a manufactures line. However, the efficiency should not be the only criteria.