Radiant panels have their own heat source (e.g. circulating hot water, electric heating elements) and use radiation as the predominant method of heat exchange. They are usually mounted on walls or suspended from ceilings.
Radiation involves the transfer of heat across the intervening space between a hot body and an object at lower temperature, without the space itself being heated. Radiant energy will heat all surfaces which are in the direct line of sight from the panel, such as walls, floor, furniture and of course, the room occupants.
Radiant panels transfer a small proportion of their heat to the air adjacent to the panel surfaces, thus creating convection currents.
The amount of heating delivered to any given room is in part determined by panel area. It follows that with large panel areas, it is possible to reduce panel surface temperature. Radiant panel systems normally use water hot enough only to provide a panel surface temperature of 29 – 30°C.
Radiant panels can be controlled by a simple room thermostat. Alternatively, they can be linked to more sophisticated control systems, to provide simultaneous zone and occupancy control as well as weather compensation.