An electric furnace uses resistance calrods to create heat directly in the air stream. Inside the jacket or cabinet will be controls, a blower, and the circuit breakers for the heating elements.
Some furnaces have the breakers accessible from the outside of the cabinet.
A system with central air might have a condensate pump to remove the water generated in the dehumidifying process of the air conditioning. A zone control panel and motor actuated dampers will be attached to the furnace or ductwork if the system is zoned. Routine maintenance includes monthly replacing the air filter or washing the electronic air cleaner grids during constant use, and cleaning the humidifier. Humidifiers can be of the steam generating type, which will be line voltage powered, and should be shut off before servicing. If the thermostat is programmable, be certain it has fresh batteries.