Editing Radiator (section)

==Radiation and convection==
[[File:Vintage radiator in students laboratory (1904) at Gdansk University of Technology, Poland.jpg|thumb|upright|left|A cast iron convector radiator from 1904]]
[[Heat transfer]] from a radiator occurs by two mechanisms: [[thermal radiation]] and [[convection]] into flowing air or liquid. [[Thermal conduction|Conduction]] is not normally a major source of heat transfer in radiators. A radiator may even transfer heat by [[Phase transition|phase change]], for example, drying a pair of socks.  In practice, the term "radiator" refers to any of a number of devices in which a liquid circulates through exposed pipes (often with fins or other means of increasing surface area). The term "[[convector heater|convector]]" refers to a class of devices in which the source of heat is not directly exposed.

To increase the surface area available for heat exchange with the surroundings, a radiator will have multiple fins, in contact with the tube carrying liquid pumped through the radiator. Air (or other exterior fluid) in contact with the fins carries off heat.  If air flow is obstructed by dirt or damage to the fins, that portion of the radiator is ineffective at heat transfer.