This is a system of heating designed to raise the temperature of a room space by the admission of infrared energy, which is basically thermal radiation. Radiant heat passes directly through air and will only heat the more solid surfaces upon which it falls. Radiant heat panels are usually mounted in the floor, walls or ceiling of a room. The panels are heated electrically or by circulating hot water or hot air through them. Unlike other forms of central heating, the effectiveness of radiant heating does not rely on the efficient circulation of air due to direct contact with the heat source.
For an equal state of comfort in a room, systems relying mainly on convection currents (such as a radiator type system) must provide a higher air temperature within the room because the cold surfaces of walls and windows, etc., remove heat from the human body that can only be replaced by the surrounding/ambient air. Radiant heat on the other hand warms up the floors, walls, windows, etc., and thus reduces the heat lost from the human body. Therefore, lower air temperatures within the room are maintained; this also provides a greater feeling of freshness, and with the reduction of convection currents in the room, cold draughts and dust problems are reduced to a minimum.
Radiant heating can save fuel, unless the heating of the room is intermittent, as in, for example, a building which lowers its air temperature at night and requires it to be rapidly raised in the morning.
The design of radiant heating systems is quite straightforward, requiring only a coil
of embedded pipe funning through the surface of a floor, wall or ceiling; the only important requirement is that the surfaces of the radiant heaters should not be metallic. Fitted behind the heater should be a means of thermal insulation to give heat emission only into the room. With this system, one major disadvantage is the danger of a pipe leakage which can prove difficult to find and expensive to repair.
In the following table is given the recommended surface temperatures of walls, etc., fitted with embedded pipe panels. Notice how panels located in the ceiling can be used to give off a higher radiant heat emission, and therefore give a quicker room heating period and are generally chosen. The water temperature flowing through the pipes should be between 40 and 55°C. To achieve the higher surface temperatures used in the ceiling, the heating pipes are spaced closer together.
Panel location Surface temperature Heat given off
Ceiling 40 65
For a radiant system to operate efficiently and effectively the system needs to be on constantly, thus preventing the building fabric from cooling. Because the temperature flowing through the pipe work is greatly reduced, compared with the more traditional system using radiators with flow temperatures around 75°-82°C, these systems can be designed with a condensing boiler, which will increase the efficiency of the system even more. Plumber Fulham