Heating devices.

摘要

Heating devices of improved efficiency are provided comprising a coil (1) supported and retained on a base (2) of castable refractory material by ribs (12) moulded with the base (2) and around part of the periphery of the coil (1), the material of the base (2) being moulded between adjacent turns of the coil (1), the core (3) of the coil (1) being free of refractory and open to the surface of the device.