Things you may need to know when discussing A/C terminology.

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• Seer Rating - Energy efficiency ratio (EER) is a measure of how efficiently a cooling system operates when the outdoor temperature is at a specified level (95°F). A higher EER means the system is more efficient and will use less energy for the same cooling output.

 

For example, a 2-ton air conditioner with a 10 EER rating uses 2,400 watts per hour, while a 12 EER unit uses only 2,000 watts—a savings of 20%. Seasonal energy efficiency ratio (SEER) is a measure of efficiency over an entire cooling season, as opposed to a single outdoor temperature. Residential units are rated in SEER. SEER is used as a more practical measure, since the temperature outside is not always 95ºF. In addition, the denominator is in watt-hours, not in watts. The same relationship holds—a higher SEER means the system is more efficient. SEER is the total amount of cooling the air conditioner provides over the entire cooling season divided by the total number of watt-hours it consumes, or: SEER = Seasonal Btu of cooling / Seasonal watt-hours used SEER ratings are specific to a climate zone, and vary slightly for different locations across the country.

 

• Tonnage- A ton is the cooling capacity of an air conditioning system. One ton is equal to the amount of heat required (288,000 Btu) to melt one ton of ice in a 24-hour period. A one-ton air conditioner is rated at 12,000 Btu per hour (288,000/24). A two-ton unit would be rated at 24,000 Btu per hour. Typical residential central heating systems provide up to 5-tons of cooling. Commercial systems can range anywhere from small, three-ton rooftop units, to 1,500-ton chiller systems. Why a ton of ice? The term is left over from the days before mechanical cooling when ice was an essential part of refrigeration.

 

• BTU/KW - A British Thermal Unit (Btu) is a commonly used unit of measure for energy use in heating and cooling equipment. It is the amount of heat required to raise the temperature of one pound of water by one-degree Fahrenheit. One kilowatt-hour (kWh) of electricity contains 3,412 Btu.