We all need hot water for our shower and to wash our dishes. This is what water heaters are made for: they are dedicated appliances to provide water at the required temperature.

The production of hot water makes up an important share of the overall residential energy consumption for  heating  purposes  –  between  10  and  20%. There are many technologies available, the choice depends on the type of building and on the needs of those who will be using it.

A first differentiation is between on-demand and storage water heaters. On demand water heaters heat water instantly as it flows through them. Most of these water heaters run on gas or electricity. Storage water heaters offer instantaneous delivery of hot water and provide great comfort in case of simultaneous use, for example when two showers are running at the same time.

Storage water heaters directly produce hot water, therefore they combine in the same appliance a hot water storage tank and a heating element (a burner, an electric resistance heater or an air source heat pump). In other cases, hot water is provided by the same appliance that heats the building. This means that a heat pump, a boiler or solar collectors - or combinations of those, are connected to a hot water storage tank, which then releases hot water for domestic use. Other heating appliances, called combination heaters, provide heat for the building and on-demand water production.