Immersion Heater

Water is most often heated electrically by putting a heating element in direct contact with it. Such an element is therefore called an immersion heater. The water to be heated is usually enclosed inside an insulated cylinder: a hot water tank. Such a heating element consists of a thin metal tube that contains an electrical resistance heater; this, in turn, is encased in an insulating material. To control the temperature of the water, a probe inserted alongside the element triggers a switch according to the temperature of the water, the system as a whole constituting a Thermostat.