A furnace heating coil is a device that transforms electric current into heat energy in a furnace. It's usually controlled by an independent temperature controller or a thermostat.
In the furnace, the heating coil is usually covered by an external metal cover that is secured in place with screws. During the repair of the furnace heating coil, this cover is unscrewed to access the coil. Beyond the cover, there is an insulation that shields the heating coil.
A furnace coil usually wears over time as a result of mineral water. This may lead to its eventual failure, which necessitates replacement.