How Do the Heating Elements in an Electric Furnace Work?
The heating element is located inside of your electric furnace.
Heating elements are tightly wound coils of resistive wire mounted inside of an electric furnace cabinet. The heating elements in a furnace look very similar to the elements in a toaster or a hot plate, and they operate under the same basic principle of electrical resistance. Their operation becomes clearer with an understanding of some electrical theory fundamentals.
Resistance is the basic electrical principle that explains how heating elements work. Electricity is the flow of electrically charged particles (known as current) through a conductive material, in this case electrons through metal wires. Different materials have different properties that inhibit electrical current. The cross-sectional size of the material also affects its resistance. A long thin wire has greater resistance than a short thick wire. Heat is a byproduct of electrical resistance, and the relationship between heat and resistance is directly proportional. More resistance means greater heat.
Heating Element Construction
Heating elements are basically long wires wound into tight coils mounted inside of the furnace cabinet. The resistivity of the wire creates heat as a byproduct. The wire used in electric heating elements is typically Nichrome 80, an alloy of 80 percent nickel and 20 percent chromium. It is characterized by its high resistivity and low susceptibility to oxidization. These heating elements can operate at extremely high temperatures in excess of 2,000 degrees Fahrenheit.
Electric Furnace Operation
The heating element is only one small part of an electric home heating system. Heating starts with the thermostat, which sends an electric signal to relays inside the furnace. Those relays apply voltage to the heating elements, causing them to build up heat. Next, forced-air blowers are automatically started to move hot air through the cabinet to eventually heat the living areas of the house.
Troubleshooting Heating Elements
Heating elements are relatively simple components. They either work or they don’t. Either the element creates heat or it does nothing. The passage of time, mechanical abuse and inferior construction are frequent causes for failed heating elements. Elements usually can’t be repaired, but they are replaceable. A continuity test performed with a digital multimeter is the easiest way to determine whether an element needs replacement.
About the Author
Charles W. St.Clair has been writing professionally since 2003. He lives in Oakland, Calif. working as an electrician and carpenter. St. Clair holds a bachelor s degree in public policy from Emory Henry College and a master s degree in city planning from University of North Carolina-Chapel Hill, where he specialized in food system planning.