As is common the SEER rating is what is used to rate the cooling efficiency of an AC or heat pump system. But what does a high SEER rating get you? SEER is the seasonal energy efficiency ratio as defined by the Air Conditioning, Heating and Refrigeration Institute. The SEER rating of a unit is the cooling output divided by electric energy input. The higher the SEER rating the more efficient the unit is. The SEER rating is determined over what represents the overall efficiency of a typical year’s weather in each location. It uses a set indoor temperature but outside temps range from 65-104 degrees Fahrenheit. Eight bins or divisions of 5 degrees each with a percentage of time at each bin, giving a rating that spans the yearly seasons.
British Thermal Unit (BTU)
BTU or the British Thermal Unit is the heat required to raise the temperature of one pound of water 1-degree Fahrenheit. In refrigerant cooling systems, including AC and Heat Pumps, it is the measure of the heat removed from a room per hour. On BTU per hour equals 0.2931 watt-hours. In Europe the use the calorie which is the amount of heat required to raise the temperature of one gram of water by one degree Celsius. In thermodynamics heat is equivalent to energy and the energy unit is the joule. One BTU is approximately equal to 1055 joules (J). The calorie is a small unit equal to about 252-253 Btu, so most use the kilocalorie equal to 1,000 calories. Another unit is general use is the kBtu or 1,000 Btu’s. The SEER is Btu/w*h or British Thermal Unit divided by the watt-hours. Other ratings are the EER and COP.
Energy Efficiency Ratio & Coefficient of Performance
The EER or energy efficiency ratio is the Btu/hour divided by Watt at a given operating condition. The EER is rated using a 95-degree Fahrenheit outside temp and an inside temperature of 80-degrees Fahrenheit and 50% humidity. COP is the coefficient of performance and is commonly considered the most accurate estimation of the refrigerant based cooling systems. It is used in thermodynamics but is unit-less. The EER and SEER both use mixed units. EER = 3.41214 x COP. 13 SEER is the current minimum standard is equal to 11 EER and about 3.2 COP. Even though many are convinced that the SEER rating is more of a marketing item, a higher SEER should still save operating costs over a lower rating. Todays standard minimum is 14 SEER for new installs or replacement units in split systems. This rating is mandatory in both the Southeastern and Southwestern United States. Outside these regions the minimum rating stands at 13 SEER.
SEER ratings of split systems can climb to 42 SEERS. Ductless systems are more effective then central systems with a loss of about 10-20% lost through the ducts. High SEER ratings come at a high cost.
Heating Seasonal Performance Factor (HSPF)
HSPF or Heating Seasonal Performance Factor is the rating used for heat pumps operating in the heating mode, and the heat pump in heat mode is more efficient than resistance heating. A 13 SEER rated heat pump drops in efficiency and at about -10 degrees Fahrenheit equals resistance heating. Many have heat strips or heating resistance coils used for auxiliary heating as the outside temperature drops.
Central Air Conditioning Services & More in Summerlin, North LV, Henderson, Enterprise, Paradise, Sunrise Manor, Spring Valley, Aliante, Anthem, Desert Shores, Eldorado, Green Valley Ranch, Inspirada, Mountain’s Edge, Peccole Ranch, Providence, Rhodes Ranch, Seven Hills, Silverado Ranch, The Lakes, Tuscany Village & Las Vegas Nevada
Air conditioning and heating has a language of its own. And many of the familiar units of rating can be a bit misleading or difficult to grasp. Air Supply Heating & Air Conditioning can meet all of your HVAC needs. Contact us today!