Invented back in 1833, an immersion heater is a type of heater that heats water from outside. Unlike a normal gas-heated water container, which typically has heaters underneath it, an immersion heater heats water directly from the outside. A strong electrical current is run through the device that heats the water within it. It operates on a large scale, just like the typical kitchen sink. Most immersion heaters are portable and can be moved from place to place. They are also used in small spaces for areas where direct sunlight may not reach.

The immersion heater is usually made out of metal or glass. They can have both a hot surface and a cold surface and can even be built with a lid and a cover. The bottom surface is made of metal or glass. Some immersion heaters may even contain a valve stem, which is attached to the water supply. This valve can open to allow water to enter the unit.
An immersion heater can also come in different sizes and shapes. This allows you to find one that is suitable for your needs. One of the best places to search for one is online. They often carry a wide range of designs, including those that are meant to be placed in a cabinet or even in your bathroom. There are even ones that can fit into small spaces and can operate on electricity or gas.