With a tubular style heater, the infrared energy is radiated evenly around 360 degrees. The product directly above the tube is only seeing a small percentage (25% ??) of the direct energy.
By placing a refractory board behind the tubes, some of the energy that is absorbed by the board is re-radiated to the product. This energy is not nearly as effective as the direct energy but may add another 15%.
Reflectors are commonly placed behind the tubes to improve upon the board design. This does help re-direct more energy, as long as they are clean. As soon as they become hot, they begin to collect particulates in the air which compound the problem with contamination and results in decreased reflectivity. Not only is this an ongoing maintenance issue, efficiency is quickly lost.
Another style is a copy of our FS element that is formed into an inverted “V” and permanently glued to a board. Since the majority of energy is emitted perpendicular to the angle of an element surface, energy is directed outward, even onto its own heater case. Also the intensity of infrared energy decreases with distance so by nature heat transfer to the part directly above it is less. By standing off from the back board, this allows energy also to be radiated backward to the board for redirected energy and ambient heat loss.
Protherm, LLC Series FS elements are fastened flat directly to a proprietary board. This allows the majority of the direct energy to radiate straight out from the elements. Since the board can not absorb any more that 3%, this leaves 97% of the energy going forward to your product. Because there are no re-radiating surfaces or reflectors to keep clean, maintenance is eliminated. Speaking of maintenance, should an element become damaged after years of service, individual Series FS elements can be replaced