Basic Description of a Household Electric Heat Furnace

Heating Element

The source for the heat in an electric furnace is the heating element. Usually, the furnace will have several elements arranged in a row to generate greater amounts of heat. Larger homes and businesses need more heating elements while a smaller home or apartment may need only one or two. 220-volt volt electric current is transmitted through the metal element (a solid metal bar) and the metal will warm instantly to a red hot temperature.

The heating elements raise the temperature in a metal box known as a heat exchanger. Here the heat of the elements is exchanged with cold air and raises the air's temperature. This method works better than just blowing the air over the heating elements because the air would work to cool the elements while the elements work to warm the air. The process is not energy efficient. Using a heat exchanger means any lost heat is actually contained in the exchanger and will heat the air faster.

An electric fan is needed to circulate the air through the heat exchanger and into the ductwork. The fan works on both sides by pulling warm air into the exchanger and then into the fan which pushes it into the living area of the building. It's important to remember that the elements, heat exchanger and fan all operate at constant temperature and speeds. The temperature in a given space is controlled by the duration warm air is circulated, not by the temperature of the air.

A centrally located thermostat controls the actions of the heating elements, heat exchanger and fan. Modern electric furnaces have thermometers in the heat exchangers and in the living space. The thermostat is set to activate the furnace with the temperature drops to determined degree. The heating elements are activated and the heat exchanger begins to warm immediately. In modern electric furnaces a second thermostat is in the heat exchanger. When it reaches a certain temperature the fan is activated. This prevents a blast of cold air from the vents from air forced by the fan before it is warmed.

An electric furnace may or may not have ductwork. Some smaller units only have one vent located on the furnace blowing directly into the living space. Other large units have insulated ducts carrying warm air from a distant furnace to different rooms within the living space.