Book - School of Science and Technology

Combined radiant and convective heating 191Panel radiatorExtended surfaceat rearPlain front panelSinuouswaterways(a)(b)Extended surfaceHeader(c)Boxheaders(d)StampedfrontgrilleFigure 7.14 Steel radiators (principally convective)(c) A multiple panel with so much additional corrugated surface added that the panels areno more than incidental waterways, a convector in all but name.(d) A tubular element attached to a front plate which acts as an enclosure and is providedwith top and bottom louvres, a convector in all but name.A summary of typical ratings is included in Table 7.5, again for a temperature difference,water to air, of 60 K which may be corrected as before, using Table 7.6, for otherconditions. Based on European research in an isothermal enclosure (a room having cooledexternal surfaces), Table 7.7 lists the relative proportions of radiant and convective outputfor a selection of radiator types.Aluminium radiatorsThere are two quite clearly discernible patterns of aluminium radiator, the die-castsectional type manufactured in Europe and the extruded high output type made in theBritish Isles. The former are very similar in most respects to the cast iron column radiatorsnoted previously but the latter are provided with extensive finned surface to the extentthat they should be categorised as convectors. Figure 7.15 illustrates the two types, (a) and(b) relating to the sectional arrangements and (c) to the convector. A digest of ratings isgiven in Table 7.5, for correction where necessary as before.