Types of panel radiator.
A panel radiator is a mainly flat surface for conveying convective and radiant energy to an indoor space. Despite their name, radiators heat a room mainly by convection. Panel radiators may have one or two panels, and, if equipped with convector fins, one or, in the case of double-panel designs, two rows of fins. The panel or tank is filled with a fluid, such as oil or water. The longer the panel, the more surface area there is for the radiator to emit heat. Therefore, a radiator with a double panel of the same dimensions as a single panel radiator will give off more heat, as the total surface area is greater.
A panel radiator may also have convector fins – zig-zagging metal strips welded to the back of a single panel radiator or in the middle of a double panel radiator. These fins increase the surface area of the radiator still further.
Both single and double panel radiators, with or without convector fins, often come in round (or roll) top or compact forms. The main difference between these is aesthetic, with the compact radiators having a grill across the top and panels along the sides to obscure the view of the convector fins. Round top radiators don't have the grills or additional panelling and the final decision is purely down to personal preference.
Although single panel radiators don't give off as much heat as the double panel type, they may be a good choice where only limited space is available such as in a small hallway, or where aesthetics is important. For example, if a radiator is being installed beneath a wide window, a wider single panel design may suit the space better than a smaller, deeper double panel model.