Are immersion heaters and over the side immersion heaters the same thing?
Yes, in principle they are very similar. Both are devices used to heat different types of liquids, where electricity passes through metal heating elements that in turn heat the water. Immersion heaters can, for example, be used to generate heat in boilers and buffer tanks when no other heat source is available. Over the side immersion heaters consist of well-insulated heating elements that are placed directly in the liquid and transfer heat to it.