Electric heating#Immersion heater
An immersion heater is a device for heating water using electrical energy. Purpose, it is immersed in a container filled with water.
Construction
An immersion heater essentially consists of a tubular heater, which is connected via a cable to a connector. The protective tube of the tubular heater is usually made of nickel-plated or gold-plated brass, copper or stainless steel and is connected with most newer devices through the protective conductor of the power cord into the earthing contact of the plug. The connection of the tubular heater to the cable is also designed as a heat insulating handle.
Continue a previous design is known, which has a sleeve-like heating element.
In particular, older immersion heaters have no protective conductor connection.
Immersion heaters that use means of electrodes, the water itself as heat conductors, also have no protective conductor connection, but only a protective cage to prevent direct contact of the electrodes.
Types and application
Immersion heaters are operated in a water bath. The water must on the one hand the entire heating area of the tubular heater cover and on the other hand may not come too close to the electrical connections under control. On the shaft of the heating element of the immersion heater are often for two markers ( knurling ) that characterize the maximum and minimum water level.
Small, so-called Reisetauchsieder are either also designed for input voltages of 230-250 V or 110-130 V, or other voltages such as 12 V, 24 V or 48 V.
Previously, in some countries to this day, there was an immersion heater with two electrodes, the heated water directly due to its resistivity. In the GDR, these immersion heaters were colloquially referred to as Atomino. Depending on the design, these devices have the electrodes a protective cage made of enamelled sheet to avoid direct contact or even shorts in containers made of conductive material. Homemade devices may consist only of wire, the two electrodes and an insulating spacer to avoid an electrical short circuit between the two electrodes. Although these immersion heaters offered security in verkochendem water but retrieved the risk of electric shock upon touching the water or metal pot. Moreover, the water has been contaminated due to electrolysis and thermal performance depended on the hardness of the water from ( ionic conduction ).
In contrast to the conventional metal immersion heaters, there are also quartz glass immersion heater which can be operated outside of the liquid to be heated long time without being damaged. The quartz tube is an electrical insulator and is resistant to acids, with the exception of hydrofluoric acid and phosphoric acid in excess of 300 ° C. With quartz glass submersible heaters can be as - in addition to water resource - other liquids are heated.
Older immersion heater without thermal fuse or thermal switch carry the risk of a fire at verkochendem water. Therefore, they should not be operated unattended and only on non-combustible surface.
Security
Most immersion heaters now have an overheat protection. There are two types here:
- Devices with a simple fuse in the heating element and
- Devices with a resettable thermal fuse, a controller with reset button in the handle.
Simple immersion heaters are often provided with a non-resettable thermal fuse ( fuse ) in the heating element. This is an inexpensive solution, but the fuse is blown again, the device can no longer be used.
Immersion heater with a resettable thermal fuse switch themselves off when overcooked water or umgefallenem pot / container, but are after cooling and, if necessary, after reset by pressing a button ready for use again. You have the outside next to the heating element has a separate sensor that monitors the temperature there and in case of overheating the rear derailleur trigger in the handle.
Particularly when importing devices without thermal fuse can cause a fire when boiling the water ( unattended operation, such as during a power interruption ) when the vessel or base are flammable. Immersion heater should generally be operated in metal or ceramic vessels on a noncombustible surface.
Since the cable leading from the upper end of the immersion heater, the vessel with the hot water can be knocked down by train on the cord when you about hanging up the cable, so the risk of scalding. Also, why are today kettle common, where the cable leads out of the socket.
Efficiency comparison
Immersion heaters are very energy efficient. The heating element is located in the operation directly in the water. The heat loss is very small, the efficiency is over 98 %. Which is, however, depending on the primary energy source, a considerably poorer efficiency of the generation of the current used against. In thermal power plants, this is depending on the design only between 30-60%. Immersion heater should therefore like all electric heating devices are used cost-conscious. Only the amount of water should be heated is needed.
Today common kettle work on the same principle, but are combined with a vessel and usually have a bimetal switch (temperature switch) which shuts off the power when it reaches the boiling temperature. Upon failure of this switch, an additional, often not resettable over-temperature protection ensures safe operation. Kettle should still not be operated unattended. They are similarly efficient as immersion heaters.
Many deep fryers, washers, samovars, dishwasher and electric water heater have heating elements in the manner of an immersion heater.
The heating of water on a hot plate is much less efficient, and therefore more expensive due to the heat capacity of the disk.
The heating of water on the gas stove, while providing higher heat losses, but it is cheaper than electric heating.