What Is an HVAC AC Unit?
HVAC is an acronym that stands for “heating, ventilation and air-conditioning.” An HVAC system maintains air quality by regulating not only the temperature, but also the humidity of a room or building, creating a comfortable environment to live and work in. Central HVAC systems are used to heat and cool offices and homes, airports and shopping malls.
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History
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Although William Cullen first demonstrated the principal of refrigeration at Glasgow University in 1748, it wasn’t until 1851 that American John Gorrie filed the first patent for the first refrigeration and air conditioning units. Alexander Twining, also an American, started commercial refrigeration in the U.S. in 1856, although Willis Carrier, who invented a way to regulate both temperature and humidity in 1902, was a pioneer in air-conditioning.
Split Systems
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Although many air-conditioning systems use a separate gas or oil furnace to provide heat, a heat pump can provide both heating and cooling through a split system by way of a gas refrigerant. The refrigerant is changed to a high-temperature, high-pressure gas by the compressor, then flows through the outdoor condenser, where it changes again, this time into a high-temperature, high-pressure liquid. The liquid expands into a low temperature, low-pressure gas inside the indoor evaporator coil, where it removes heat. In the winter, the process is reversed, with the hot gas going into the home.
Package Systems
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Unlike a split system, where the components are in different locations, the package system has the compressor, cooling coil, air handling unit and the air filter housed in a single casing and assembled at the factory location, much like a window air-conditioning unit. They are available in fixed-rate capacities between three and 15 tons and are mainly used in restaurants, homes and small buildings. The package unit also requires a constant supply of water to cool the condenser coils, unless it is equipped with an air-cooled condenser.
Usage
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You must insure that your system is the correct size for your home or business, or it will not run efficiently. According to Tim Carter at Ask the Builder.com, the temperature difference between each room in your house should not be more than two degrees. The temperature spread between the outside temperature and the inside temperature will probably be around 20 degrees, so if it is 100 degrees outside, you shouldn’t expect your home to be 72 degrees. Installing a too-large system could also cause problems with your HVAC system, such as a short-cycling compressor.
Safety and Efficiency
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According to the EPA government website, although natural ventilation through the use of open windows can be cost-saving, sealed buildings such as schools with well-designed central HVAC systems can provide better indoor air quality than an open window. The Seasonal Energy Efficiency Ratio, or SEER ratings, is the federal government’s minimum efficiency standard. The minimum SEER rating is 13 for high-efficiency units and 11.5 for split systems.
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References
- Photo Credit Pompe à chaleur image by mattmatt73 from Fotolia.com
Comments
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very clear information of HVAC.
