An electric geyser is used domestically to heat water.
It is usually cylindrical shaped and mounted on walls. It may have a capacity
of 50 to 250 liters.
It consists of a water container vessel with an inlet for cold water and an
outlet for hot water. The heater contains a thick electric conductor coil
element. It gets heated due to the dissipation of energy when current passes
through it. The heat energy is transmitted to water through conduction and
convection mechanisms. Usually the heating element is made of Nickel or
There is a mechanism to measure the temperature of water using a thermostat. It
shuts off, automatically, the current supply to the heating element, when the
temperature is above a preset value. This is set in the factory. There
may be LEDs or small bulbs to indicate whether the heater is switched on or
The water container is usually made of a material which does not get corroded
or rusted easily. The water container is protected with insulating
material and air gap so that the heat energy is retained inside the
container. The materials for the outer casings are usually stainless
steel, plastic and china glass. Plastic is safer to prevent from leakages and
The heater is usually based on AC voltage. It is given a rating : power it
consumes, current it passes when the rated voltage is applied. Voltage rating
could be 220 V in countries like India and 110 V in USa. Power rating could be
1 KW to 5 kW depending on size.
There are also instant heaters available. They have very little water capacity
(2 litres). The water is heated at a constant rate as the water flows through
the geyser. There is no storage and not much insulation provided in this type
of heaters. A heating (electric resistor) coil is used in them. The wattage
could be around 2 kW. Care must be taken as if there is not enough water, it
may burn the coil.