A radiator is a device used to transfer heat from one medium to another. Radiators are commonly used to heat buildings, and they work by circulating hot water or steam through a series of pipes. As the hot water or steam circulates through the pipes, it releases heat into the surrounding air, which helps to warm the building.
Radiators can be turned on and off manually or automatically. Manual radiators have a valve that can be turned to open or close the flow of hot water or steam. Automatic radiators have a thermostat that automatically turns the radiator on and off when the temperature in the room reaches a certain level.