There are four meanings of the Radiator:
1.A heating device consisting of a series of connected pipes, typically inside an upright metal structure, through which steam or hot water is circulated so as to radiate heat into the surrounding space.
2. A cooling device, as in automotive engines, through which water or other fluids circulate as a coolant.
3. Physics. A body that emits radiation.
4. A transmitting antenna. Any of numerous devices, units, or surfaces that emit heat, mainly by radiation, to objects in the space in which they are installed. Because their heating is usually radiant, radiators are of necessity exposed to view. They often also heat by conduction to the adjacent thermally circulated air. Radiators are usually classified as cast-iron (or steel) or nonferrous. They may be directly fired by wood, coal, charcoal, oil, or gas (such as stoves, ranges, and unit space heaters). The heating medium may be steam, derived a steam boiler, or hot water, derived a water heater, circulated through the heat-emitting units.

Electric heating elements may be substituted for fluid heating elements in all types of radiators, convectors, and unit ventilators. See also Hot-water heating system; Radiant heating; Steam heating. Aluminum radiator.
Architecture: radiator A heating unit usually exposed to view within the room or space to be heated; transfers heat by radiation to objects within visible range, and by conduction to the surrounding air, which in turn is circulated by natural convection; usually fed by steam or hot water.

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