Air Conditioning – Heating

There are different types of standard heating systems. Central heating is often used in cold climates to heat private houses and public buildings. Such a system contains a boiler, furnace, or heat pump to heat water, steam, or air, all in a central location such as a furnace room in a home or a mechanical room in a large building. The system also contains either ductwork, for forced air systems, or piping to distribute a heated fluid and radiators to transfer this heat to the air. The term radiator in this context is misleading since most heat transfer from the heat air conditioning exchanger is by convection, not radiation. The radiators may be mounted on walls or buried in the floor to give under-floor heat.In boiler fed or radiant heating systems, all but the simplest systems have a pump to circulate the water and ensure an equal supply of heat to all the radiators. The heated water can also be fed through another (secondary) heat exchanger inside a storage cylinder to provide hot running water.Forced air systems send heated air through ductwork. During warm weather the same ductwork can air conditioning be used for air conditioning. The forced air can also be filtered or put through air cleaners.Heating can also be provided from electric, or resistance heating using a filament that becomes hot when electricity is caused to pass through it. This type of heat can be found in electric baseboard heaters, portable electric heaters, and as backup or supplemental heating for heat pump (or reverse heating) system.The heating elements (radiators or vents) should be located in the coldest part of the room, typically next to the windows to minimize condensation and offset the convective air current formed in the room due air conditioning to the air next to the window becoming negatively buoyant due to the cold glass. Devices that direct vents away from windows to prevent “wasted” heat defeat this design intent. Cold air drafts can contribute significantly to subjectively feeling colder than the average room temperature. Therefore, it is important to control the air leaks from outside in addition to proper design of the heating system.The invention of central heating is often credited to the ancient Romans, who installed a system of air ducts called “hypocaust” in the walls and floors of public baths and private villas.

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