Electric water heaters use water heater elements as a way to heat the water using electricity. These elements work on exactly the same principle as the kettle in your kitchen. They are designed to allow current through, which will cause them to heat up and in turn heat the water.
There are a few different types of electric water heater elements. It's important to replace them with the right type of element. Over time, the elements can break, because they will burn out. Replacing them is pretty easy as long as you choose the right type.
1. Tankless Element
A tankless element is a special type of element which heats the water on demand. This has a number of advantages. A large body of hot water does not need to be stored anywhere, and you also don't need to worry about continually heating up the same water. A tankless element uses a heat exchanger to heat up the water. This is a highly efficient way of heating water. However, for it to be so efficient, the walls are very thin and this can mean that the heat exchanger and element can break down over time.
These only use electricity when the water is being used. This is an extremely efficient way of heating up hot water immediately. The only downside with this type of element is that you may have to run the faucet for a couple of seconds before hot water comes out.
2. Storage Heaters
A storage heater is basically like a big version of your kettle. There is a large container with an electrical water heater element at the bottom. This is controlled by a thermostat and it keeps the water at the right temperature, depending on what you have set it at. This can be inefficient, because if the tank runs empty you have to wait for a long time for all of the water to heat up again.
The elements, however, should last slightly longer because they're not required to heat to as high a temperature. Heating can be done much slower.
3. Heat Pumps
There is also the possibility to use a heat pump heating element. Rather than using electricity to directly generate the heat, they actually use the electricity to move around a compressed gas. This works in a similar way to your refrigerator, only backwards. This means that the water is getting hotter and the cold air is removed and pushed outside.
4. Indirect Water Elements
It's also possible to use an indirect electric water heater. This will feed water into the storage tank where it can be kept warm. As long as the hot water tank is of a high quality and lagged sufficiently, the entire system is actually pretty reliable and efficient. This also means that there is a minimal wait for hot water out of a faucet.