how does a geyser work
Answers
Domestic
Electric Heater/Geyser
We use electric geysers at homes or in clinics or shops to heat
water. It is cylindrical shaped and is mounted on walls. It has a
capacity of 50 to 250 liters. See diagram.
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 chromium.
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 off.
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
shocks.
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Power and rating
related information:
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 V could be 220 V in countries
like India and 110 V in USA. Power rating P could be 1 KW to 5 kW
depending on size.
Heating Power P = V² / Resistance of heating coil.
If the water tank capacity is L liters, then rate of
heating is:
= P / (L * density *
specific heat ) = P / ( L * 1 * 4181) =
= P / (4181 L) °K /
sec
If we want to heat water from 20° to 50°, then it takes time T
=
T = 30 * 4181 L /
P = 2000 L / P minutes.
If people could wait for 15 minutes for L litres , then
Power
needed P = 2000 L / L = 2 kW
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Instant Heaters
We get instant heaters
also. They have a small 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. Flow
of water can be decreased or increased to have hotter or colder water.
