View A Video on Electric Heaters - A Quick Introduction
Electric Heaters
The variety of electric heaters on the market is astounding, sometimes with cross over styles and sometimes not. Cartridge heaters sometimes qualify as immersion heaters, but not always. Sometimes, a heater's name is descriptive of its use, as is the case with drum heaters. In other cases, a heater's name is descriptive of its configuration, as is the case with tubular heaters. Some heater terms can be used interchangeably; air heaters and duct heaters are both used in HVAC systems to heat air, though a free-standing space heater could also be considered an air heater but not a duct heater. Both could be described as circulation heaters, though some circulation heaters are used to heat liquids in a containment system. All of these heaters can be considered process heaters, depending on their use, and they are all likely to feature wire or coil heating elements with ceramic, mineral or other insulation material. Despite the seeming interchangeability of terms and the confusion it can cause, each variety contributes to an important industrial process or commercial utility as well as some purposes in the context of consumer products.
An electric heater is any electric-powered device used to create heat. They are used in a great variety of contexts. In manufacturing and industrial processing, electric heaters can provide localized heat to an area within a machine to help shape or melt materials, heat liquid tanks, radiate heat through the air or preserve the molten state of a substance. Strip and band heaters as well as cartridge and air heaters are all frequently used for these purposes. In metal, plastic and rubber extrusion, for example, the friction generated as a natural expression of the extrusion process does not always generate sufficient heat to plasticize the materials intended for extrusion. Heaters can be used as a supplement to generate and sustain material plasticization, which contributes to a more efficient process and helps yield a higher-quality extruded product. Heat is an essential part of many other manufacturing processes as well. In packaging, foam fabricating, metal fabricating and food processing industries, cartridge heaters are most often inserted through a custom-sized hole into equipment parts that require localized or high temperature heat. Radiating heaters like immersion heaters and tubular heaters are used to heat liquid or air in water treatment facilities, residential applications, commercial buildings and many other applications.
Every electric heater consists of a few parts that are essential for electrical heat generation. Electric heating is the process by which electricity is converted into thermal energy. An electric charge is usually conveyed by electrons flowing through a medium. When such a medium is connected to an electrically resistant material, the electrons collide with the atomic particles of the resistor, causing them to vibrate. The noticeable expression of that vibration is heat. In the case of electric heating, the resistor is called the heating element. Heating element composition and configuration is variable. Coil heaters can be a simple metal resistor coiled into a spiral shape. Others can feature elaborate configurations and advanced ceramic insulators to maximize heat generation, direct heat distribution and otherwise control the qualities of the heat more effectively. Electric heaters only need heating elements to generate heat, but most of them feature some kind of insulation, and almost all of them feature a sheath of stainless steel, aluminum, nickel or another material to improve performance and extend operating life. Insulation is necessary in many types of electric heaters to retain and absorb electrical energy so that it can be released as heat energy by surrounding coils or materials.
Ceramics are the most common types of insulation, although electric heaters can be fitted with mineral, mica or fiberglass insulation as well, depending on the heater's application requirements. Radiating types of electric heaters transfer heat from ceramic cores or complete heating elements by moving heat through the air with fans, as is the case with space heaters, or through hot air ductwork systems, as is the case with duct heaters. Each application for electric heaters will require a standard for material make-up, temperature capacity and power. Non-electric heating systems can involve coal, wood, gas or water, although most of these alternatives are far less energy-efficient than electric heat generation. Electric water heaters, for example, are more environmentally sustainable and economical than other heating methods. Safety is another crucial concern when purchasing a heater. Different heaters respond in different ways to different environments and applications. Successful industry professionals carefully choose electric heaters based on a foundation of clear knowledge about the operating conditions in which an electric heater will be employed and to what tasks a heater will be applied.
Electric Heaters Types
- Air heaters are electric heaters used to heat air in an enclosed volume or in tandem with a fan system for distribution throughout a building.
- Band heaters are small electric heaters that can be affixed to pipes, tubes and nozzles for the application of heat in a small area.
- Cartridge heaters are small electric heaters that can be inserted into machinery to provide heat in a small area; they are often used during extrusion and other thermoforming processes.
- Ceramic heaters are electric heaters whose heat coils or other heating element materials are insulated with ceramic materials.
- Circulation heaters are electric heaters used to heat a circulating volume of liquid or gas in an enclosed space.
- Coil heaters are electric heaters characterized by the shape and composition of their heating elements, which are coiled metal ribbons or other similar materials.
- Drum heaters are electric heaters used to heat drums; large quantities of industrial chemicals, water and even food products like chocolate (which are often stored or shipped in drums) can be heated with drum heaters.
- Duct heaters are electric heaters used in tandem with other HVAC components in order to provide heat to a building.
- Immersion heaters are electric heaters that can be immersed in liquids and some solids and retain their functionality; these can be used for efficiently and safely heating large volumes of liquid.
- Process heaters are electric heaters used to heat-treat or otherwise process raw materials with heat; process heaters can be used in surface treatment, raw materials shaping and in many other industrial applications.
- Strip heaters are small electric heaters used conduct controlled amounts of heat to a small area; they can be affixed to equipment, which they heat on contact, or they can be used to heat small volumes of air.
- Tubular heaters are electric heaters characterized by a tubular shape.
Electric Heaters Terms
AC Current - Short for "alternating current." An alternating current is characterized by the periodic reversal of the flow of electricity.
Ceramics - Non-metallic, inorganic, often crystalline materials used, in the context of electric heaters, as insulating materials.
Conduction - The transfer of heat. An object's atomic particles vibrate when heated; there is a linear relationship between temperature and vibration intensity. When these vibrating particles come into contact with other particles, they transfer their energy. Energy can be transferred amongst every state of matter via conduction.
Convective Heat Transfer - The transfer of heat between fluids because of the movement of those fluids. Instead of direct transmission (conductive heat transfer), the heat in liquids and gasses is dispersed as the molecules move.
DC Current - Short for "direct current." A direct current is characterized by the unidirectional flow of electricity.
Desalination - Process by which salt is removed from saltwater.
Ducts - Channels used to direct filtered or temperature-treated air throughout an area.
Electric Current - The movement of an electrical charge through a conductive medium.
Electro-polish finishing - Used to remove unwanted material from a surface during surface finishing.
Extrusion - The shaping of a raw material into a useful product through the use of a die. Plastic, metal, elastomers and other material can be formed into continuous profiles by extrusion.
Heat - The transfer of energy between objects; heat is the expression of atomic particles colliding with each other.
HVAC - Abbreviation for Heaving, Ventilating and Air Conditioning; HVAC equipment is any tool or component used in any HVAC process.
Incoloy - A proprietary superalloy characterized by its qualities of strength.
Insulation - Non-electrically-conductive material used to coat electrically conductive materials. In electric heaters, insulators are used to increase the efficiency of a heater and protect heating elements from becoming damaged.
Molding - The shaping of a raw material into a useful product through the use of a mod. Plastic, metal, elastomers and other material can be formed into complex, non-continuous shapes through molding.
NEMA Enclosures - Enclosures built to varying standards set by the National Electrical Manufacturers Association; these enclosures house electrical equipment of varying sensitivity and delicateness. Corresponding NEMA numbers indicate the intended use of a given enclosure.
Radiation - The travel of energy particles and waves. Examples of radiation include visible light, radio waves and heat generated by a heating coil.
Thermostat - A temperature-regulating device that employs the combination of a thermometer and mechanical parts to control heating and cooling equipment.
Watt - A unit by which the intensity of an electrical current is measured.
