Before refrigeration air conditioning was invented, cooling was done by saving big blocks of ice. When cooling machines were invented, their capacity was rated by the equivalent amount of ice melted in a day, which is where the term “ton” came from in sizing air conditioning systems.
A ton of cooling is now defined as delivering 12,000 BTU/hour of cooling. BTU is short for “British Thermal Unit”. The BTU is a unit of heating or cooling energy. A window air conditioner is usually less than one ton. A 2000 square-foot home needs a system that delivers about 4 tons (48,000 BTUs) of cooling though that will vary depending on how much sun/shade your home receives, the number of people who regularly use the room and whether there are heat-generating appliances in the room. The number of windows in your home and the amount of insulation also make a difference in the amount of cooling capacity needed. Homes with many windows will need more cooling capacity to make up for the heat radiated into the house while homes with poor insulation will allow cooling to escape from the home.
It is important to choose a system that is properly sized for the unique conditions of your home. An improperly sized AC system will not run efficiently – it will turn on and off too frequently, resulting in higher electric bills. It will not keep your rooms comfortably cool nor will it keep the humidity in your home under control. Keep in mind that the capacity of your air conditioning system is only one part of the equation. Many air conditioners that under-perform are a result of a duct system incapable of circulating the conditioned air adequately through the system. This is particularly true where air conditioning has been added to a house with ducts that were designed for a heating system only.
Undersized air conditioners may result from poor installation practices that do not include a heat gain calculation or do not adequately recognize the characteristics of the home. Undersized units may also be a result of home remodeling or additions. For example, the addition of skylights or the removal of mature trees can increase the heat gain dramatically. If you notice that your AC is constantly turning on and off, that your house is too hot in some areas and too cold in others or that you have mold/mildew issues (often accompanied by a musty smell), your AC system is probably not sized correctly for your home. Call us today to schedule an inspection of your air conditioning system so we can help you determine if your AC system is correctly-sized for your cooling needs.