Ariston Immersion Heater and Anode, 3kW output Product made in Italy An element is used to heat the water within a cylinder. This water can then be utilised by the end user to provide heating for the radiators and domestic hot water. The element also allows the cylinder to maintain its temperature, meaning the hot water will stay at the set temperature until it is given further instructions by the user. See suitability below: Ariston CLASSICO STI 125 Ariston CLASSICO STD 150 Ariston CLASSICO STI 150 Ariston CLASSICO STI 210 Ariston CLASSICO STI 300 Ariston PRIMO ITD - ITI 125 Ariston PRIMO ITD - ITI 150 Ariston PRIMO ITD - ITI 210 Ariston PRIMO ITD - ITI 300