Single phase electric instantaneous water heaters are small electrically powered units that heat water 'instantly' as it flows through the product. Instantaneous water heaters are compact, will not run out of hot water and have no stand-by energy losses but have to be wired to the electric consumer unit. The principal draw-back of instantaneous water heaters is that the available hot water flow rate is limited by the electrical power rating of the water heater. Single phase units have power ratings of up to 12kW and can provide maximum flow rates up to 6L/min (assuming a temperature increase from incoming cold supply of 30ºC). Units of 3 - 6kW are suitable for a wash hand basin. Units over 9kW can be used for a shower and wash hand basin (not at the same time) but they CANNOT be used with Thermostatic mixer valves. We do not advise instantaneous water heaters to be used with kitchen sinks.
Please note that units rated over 3kW are too powerful for connection to a 13A ring main and must be wired directly to the electrical distribution unit.