There are several types of water heaters: instantaneous, capacitive, electric and gas. Flow-through water heaters include geysers and electric instantaneous water heaters. Capacitive ones have a storage tank in which water is not only heated, but also accumulated. Depending on the type of fuel, they are gas or electric, and can also use the residual energy of another heater - the boiler. Such water heaters are called indirect heating boilers.