Air Conditioning

The air conditioning system is one of the most versatile and beneficial appliances. In addition to cooling the home, the air conditioning system dehumidifies, cleans and circulates conditioned air. In many cases, an air conditioner is taken for granted, receiving little or no maintenance unless the unit breaks down. If a system is neglected, there is a gradual loss of efficiency, which can add to operating costs without the homeowner's knowledge. Tuning up the air conditioner, just as tuning up a car, can reduce the operating costs and prolong the life of the equipment.

Selecting an Air Conditioner
When selecting an air conditioning system, a new home or replacing an existing system, consider the size of the system, energy efficiency, the cost relative to the size and achievable energy savings.

Sizing the System
Every unit, whether it be a central or window unit, has a cooling capacity expressed in BTU (British Thermal Units). This refers to the amount of heat it can remove in one hour's time. Houses in which careful attention has been devoted to energy conservation may require as little as 1 ton for each 1,000 square feet in regards to a central air conditioning system. Window units are designed for "spot" cooling. Thus, cooled air may not be distributed as evenly throughout the space as with a central system. All window unit manufacturers recommend the size area that can be adequately cooled by each of their unit models.

Energy Efficiency
The purpose of rating the efficiency of an air conditioner is to indicate the relative amount of energy needed to provide a specific cooling output. The more efficient the equipment, the less energy will be used to do the same job. It is similar to the miles-per-gallon rating for automobiles. Instead of mpg, central residential air conditioners now use the designated SEER, which stands for Seasonal Energy Efficiency Ratio. It is indicative of the unit's operation throughout the cooling season.

Air Conditioner Tune-up Tips

Inspect and, if necessary, oil fans and motors on the condensing unit and the inside evaporative unit.
Clean the outside condensing unit. Accumulated dirt, leaves and other debris increase electric consumption as they decrease the unit's efficiency.
Keep high grass, shrubbery, leaves or other obstructions from blocking air circulation around the outside of the air conditioner system. Shading the outside part of the system is a good idea as long as the air is still allowed to circulate freely around the unit.
Check filters. If filters can be cleaned, wash or vacuum them thoroughly. If disposable, they should be replaced with the proper size and type regularly (generally once a month).
Check the accuracy of the thermostat with a glass bulb thermometer.
Check the difference in temperature between your return air and your supply air. Place a thermometer at your return air grill and another in the air register nearest the inside evaporator unit. Allow the air conditioner to run for about 10 minutes. Check both thermometers. Less than a 12 degree temperature difference could indicate that additional refrigerant is needed.
From the example below, it can be seen that the higher-efficiency unit would save $108 (20%) each cooling season. Obviously this amount will vary in real-life situations depending on:

whether the unit operates more or less than the 1500 hours used in the example
family size & living habits
the electric rates
The higher the SEER, the more efficient the unit and the more money will be saved on cooling bills. Ratings generally range from 6 to 14, and the cost of the unit rises as the rating increases