In applications where tubular heaters are exposed to forced convection, placing fins around tubular heaters increases their surface area and thus improves their heat transferring capacity. Finned tubular heaters, compared to regular tubular heaters, run at lower surface temperatures for the same watt densities when placed in identical air streams. Graph1 compares watt density, outlet air temperature, and the speed of air flow for regular and finned tubular heaters respectively. Despite their advantages, finned tubular heatersare not recommended for applications where outlet air temperatures exceed 600°F.
The physical characteristics of a finned tubular heater play a major role in the effectiveness of its heat transfer. The table below specifies the outside diameter of fins, their thickness, the spacing between consecutive fins, as well as the element sheath and fin material.
Threaded fittings, if required, are the standard mounting attachments supplied with finned tubular heaters. These fittings are brazed or crimped onto the heaters. For special applications, finned tubular heaters can be made with mounting brackets that have special designs.