Ltpgtthe redring ws7 3kw water heater isampnbspone ofampnbspthe uks most popular 7 litre over sink water heater due to its excellent reliability and performanceampnbspampnbspdue to their point of use installation these units also benefit from minimal standing heat loss and when added to the fact that because this heater is only 3kw unlike instantaneous water heaters it can be spurred off a ring main rather than requiring its own dedicated circuit and then it becomes clear w